Patent Publication Number: US-8992776-B2

Title: Methods for treating waste water

Description:
RELATED APPLICATIONS 
     This application is a divisional or continuation or U.S. patent application Ser. No. 12/854,855 filed Aug. 11, 2010, now U.S. Pat. No. 8,557,117, which claims the benefit of and priority to U.S. Provisional Application Nos. 61/232,850, filed 11 Aug. 2009, 61/232,861, filed 11 Aug. 2009 and 61/352,724, filed 8 Jun. 2010. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Embodiments of the present invention relate to systems, apparatuses and methods for treating waste water including high concentrations of nitrogen contaminants. The waste water can include other contaminants in addition to nitrogen contaminants. 
     Embodiments of the present invention relate to systems, apparatuses and methods for treating waste water including high concentrations of nitrogen contaminants, where the system includes three subsystem arranged in series: 1) a precipitation and conditioning subsystem, 2) an ammonia stripper subsystem, and 3) a denitrification subsystem. The system is adapted to reduce nitrogen contamination to a level below about 10 ppm and in certain embodiments below 3 ppm and in other embodiments, to a level below about 1 ppm. 
     2. Description of the Related Art 
     There are various types of readily available, conventional and advanced treatment processes that can be used to treat contaminated waste water containing high levels of nitrogen contaminants for subsequent discharge. Most of these treatments processes are of three basic types: agricultural reuse (trucking water), deep well injection, and treatment. The agricultural reuse and deep well injection processes are generally considered short term options, because there is an uncertainty of the long term agricultural needs for the high nitrogen contaminated waste water and deep well injection is dependent on the availability of injection wells. 
     There are treatment processes, which appear to be long term solutions. These treatment processes can be organized into three categories: reverse osmosis treatments, ion exchange treatments, and biological treatments. Commercial biological ammonia removal systems cannot directly process urea and commercial biological nitrate removal systems are currently limited to 100 mg/L due to nitrate inhibition (toxicity). Physical processes do not reduce the waste, they either concentrate it exchange it for a different chemical waste. Ion exchange produces a chemical waste and reverse osmosis simply concentrates the waste producing large volumes of hazardous waste. 
     Although numerous treatment options exist, there is a need in the art for a system that will treat high nitrogen-content waste water in an efficient and controlled manner, especially in a manner that is quickly adjustable with respect to the volume or amount of waste water required to be treated such as waste water created during rain falling on a site having a source of nitrogen containing compounds. 
     SUMMARY OF THE INVENTION 
     Embodiments of the present invention provide systems of treating waste waters having a high nitrogen content, where the system includes three subsystem or major components arranged in a series configuration: 1) a precipitation and conditioning subsystem, 2) an ammonia stripper and neutralization subsystem and 3) a denitrification subsystem. The system is capable of reducing a nitrogen level of a waste water from hundreds of parts per million (ppm) to levels below 10 ppm or to nitrogen levels below applicable discharge requirements established by federal, state or local governmental entities. The system is also adapted to reduce other contaminations by means of precipitation using caustic and ammonia removal through the formation of an ammonium salt. 
     Embodiments of the present invention provide apparatuses for treating high nitrogen content waste waters including a precipitation and conditioning unit, an ammonia stripper and neutralization unit, and a denitrification unit. The precipitation and conditioning unit includes an optional water aeration apparatus and one or a plurality of precipitation and conditioning stages. The ammonia stripper and absorber or neutralization unit include a plurality of ammonia air stripper assemblies and absorber assemblies. The stripper assemblies strip ammonia from the water, while the absorber assemblies convert the absorbed ammonia gas to an ammonium salts by reaction with a mineral acid such as sulfuric acid. The ammonium salt is accumulated and stored as an ammonium salt liquor such as an ammonium sulfate liquor. The denitrification unit includes a plurality of absorber columns, where the absorbent is circulated in a bacteria supporting medium. The absorbent is adapted to absorb all or substantially all nitrogen-containing compounds remaining in the water from the ammonia stripper and neutralization unit, while the bacteria convert the absorbed nitrogen-containing compounds into nitrogen gas or into amino acids used by the bacteria to make proteins. The apparatuses can also include a polishing unit. The apparatuses are adapted to convert waste water having a high nitrogen content and other unacceptable contaminants into an effluent water that meets or surpasses all applicable regulations concerning contaminants in water to be discharged into the environment from retention ponds or other sources of waste water. 
     Embodiments of the present invention provide methods for treating waste water including a high level of nitrogen contaminants, where the method includes supplying a waste water stream to an apparatus of this invention. The method may optionally include the step of aerating the waste water prior to it being pumped into a precipitation and conditioning unit of the apparatus of this invention. The method also includes the step of adding a sufficient amount of caustic from a caustic source to raise a pH of the waste water (aerated or not aerated) to a pH of at least 8. The method includes the step of removing precipitate from the resulting pH-adjusted waste water. The method includes the step of adding sufficient caustic from the caustic source to increase the pH to at least 10. The method includes the step of removing precipitate. In certain embodiments, the caustic can be added in a single addition to raise the pH to at least pH 10. In other embodiments, the caustic can be added in two or more stages to effect selective precipitation of various precipitatable contaminants. The method includes the step of heating the resulting water to a temperature of about 70° C. However, the system can operate between about 40° C. and 70° C. The temperature adjusted waste water is then passed through a plurality of ammonia strippers to remove ammonia from the water. The method also includes the step of adding sufficient sulfuric acid to stripped and absorbed ammonia to form an ammonium salt liquor such as an ammonium sulfate liquor. The method also includes passing a portion of the resulting waste water into a plurality biological denitrification units. The method also includes adding active denitrifying microorganisms and a microbial nutrient formulation to the waste water. The denitrification units include an absorbent and a bacterial population sufficient to consume residual ammonia and other nitrogen-containing compounds and to convert nitrates and nitrites into nitrogen gas to produce a water effluent having a nitrogen content of no more than 10 ppm. In certain embodiments, the water effluent has a nitrogen content of no more than 5 ppm. In certain embodiments, the water effluent has a nitrogen content of no more than 3 ppm. In certain embodiments, the water effluent has a nitrogen content of no more than 1 ppm. In certain embodiments, the water effluent has a nitrogen content of no more than 0.5 ppm. In certain embodiments, the water effluent has a nitrogen content of no more than 0.4 ppm. In certain embodiments, the water effluent has a nitrogen content of no more than 0.1 ppm. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be better understood with reference to the following detailed description together with the appended illustrative drawings in which like elements are numbered the same: 
         FIG. 1  depicts a block diagram of an embodiment of a waste water treating apparatus or facility of this invention including a waste water source, a precipitation and conditioning unit, an ammonia stripping and neutralization unit, and a denitrification unit. 
         FIG. 2A  depicts another embodiment of a water waster treating apparatus or facility of this invention, with a single stage precipitation subsystem. 
         FIG. 2B  depicts another embodiment of a water waster treating apparatus or facility of this invention, with a two stage precipitation subsystem. 
         FIGS. 3A&amp;B  depict another embodiment of a water waster treating apparatus or facility of this invention. 
         FIGS. 4A-C  depict an embodiment of a two stage precipitation subsystem of this invention. 
         FIGS. 5A-E  depict an embodiment of an AR subsystem of this invention. 
         FIG. 5F  depict another embodiment of an AR subsystem of this invention. 
         FIG. 6A-C  depict an embodiment of a denitrification subsystem of this invention. 
         FIGS. 7A-I  depict another embodiment of a denitrification subsystem of this invention. 
         FIG. 8A  depicts an embodiment of a heating, heat exchange or recovery subsystem of this invention. 
         FIG. 8B  depicts another embodiment of a heating, heat exchange or recovery subsystem of this invention. 
         FIG. 9A-C  depicts 3D renderings of the system of  FIG. 3A  illustrating the safe path feature of the invention. 
         FIGS. 9D-G  depict 3D renderings of a safe path section featuring a momentum block and pump configuration for feeding the denitrification units. 
         FIG. 10  depicts another embodiment of a denitrification subsystem of this invention. 
         FIGS. 11A&amp;B  depicts embodiment of a denitrification subsystem of this invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The inventors have found that a system, an apparatus, and a method can be constructed and implemented for reducing nitrogen contaminants in waste water to levels below Federal, State and/or Local regulatory requirements. The system and apparatus includes at least three components: 1) a precipitation subsystem, 2) an ammonia stripping subsystem, and 3) a denitrification subsystem. The system can also include a polishing subsystem. The inventors have found that by using these three subsystems in series, waste water having a nitrogen level in the hundreds to thousands of parts per million can be reduced to a water effluent having a nitrogen level below about 10 ppm. In certain embodiments, the nitrogen level can be reduced below about 7.5 ppm. In other embodiments, the nitrogen level can be reduced below about 5 ppm. In other embodiments, the nitrogen level can be reduced below about 4 ppm. In other embodiments, the nitrogen level can be reduced below about 3 ppm. In other embodiments, the nitrogen level can be reduced below about 2 ppm. In other embodiments, the nitrogen level can be reduced below about 1 ppm. 
     The inventors designed the present systems and apparatuses to handle waste water such as storm water runoff associated with various rain events, which results in a potentially large range of hydraulic loading conditions that would prevail during and after various storm events (ranging from a light sprinkle to a continuous heavy driving rain). The systems and apparatuses were engineered to (a) treat contaminated waste water such as storm water runoff in consistent manner, as needed to prevent uncontrolled overflows at retention ponds, while (b) ensuring compliance with the federal, state and/or local rules and regulations pertaining to a discharge of contaminated water and to a quality of water releasable into a given environment. 
     The systems and apparatuses of this invention were designed to achieve the following characteristics: 
     First, the systems and apparatuses of this invention will be capable of reducing trace metal concentrations that may be present in the waste water at a concentration level exceeding applicable surface water quality standards imposed by law and/or pose potential toxicity issues to the aquatic life in the desired discharge area such as a river, bay, or the like. The trace metals include, without limitation, copper and/or zinc. Embodiments of the systems and apparatuses will reduce the concentrations of these trace metals to acceptable or desired low concentrations. In certain embodiments, the low concentrations will be in the parts per million range and in other embodiments the low concentration will be in the parts per billion range. 
     Second, the systems and apparatuses of this invention will be capable of reducing relatively large nitrogen concentrations on the order of 400 to 4,000 milligrams per Liter (mg/L), which are present in various forms including ammonia, nitrate, nitrite, and urea. 
     Third, the systems and apparatuses of this invention are capable of achieving levels of treatment necessary to remove sufficient contaminant mass at all times under all conditions. The systems are designed to be able to operate even at near saturated conditions of various ionic species such as sulfate, silica, calcium, and other contaminants. 
     Fourth, the systems and apparatuses of this invention are capable of reducing contaminants from potentially large volumes of waste water generated by sudden rainfall events, especially, in situations, where the facility undergoing the runoff has limited storage volume. The treatment system are designed to be capable of being quickly activated and to quickly achieve a desired level of treatment within hours or days so that an overflow condition of the retention ponds or other temporary storage vessels does not occur. 
     Fifth, the systems and apparatuses of this invention will be capable of reducing to adjust the hydraulic flow-through capacity of the system downward in order to optimize and operate the system through the rainy season of the year while avoiding multiple start-ups and shut-downs of the system; 
     Sixth, the systems and apparatuses of this invention are capable of properly treating storm water runoff in contact with a high strength nitrogen source such as a fertilizer material as runoff amounts and concentrations of dissolved nitrogen compounds vary with time due to rainfall intensity. The systems are capable of consistently producing an effluent meeting the requisite water quality criteria as well as passing toxicity testing requirements associated with a given facility. 
     Seventh, the systems and apparatuses of this invention are capable of properly addressing potential emissions of ammonia into the atmosphere by means of selecting suitable control strategies and technologies. 
     Eighth, the systems and apparatuses of this invention are capable of minimizing the overall complexity of the system so that it can be operated by a typical waste water operator, who will be capable of controlling the treatment process, absent of extreme conditions, thus, reducing the annual cost to operate and maintain the system. 
     Ninth, the systems and apparatuses of this invention will be capable of configuring and situating the system in such a manner so that the overall footprint of the system minimizes impact on use and configuration of the existing site, even though there may be limited open area surrounding a given facility. 
     Suitable Reagents and Components 
     Suitable mineral acids for use in the present invention include, without limitation, nitric acid, phosphoric acid, sulfuric acid, hydrochloric acid, acetic acid, or mixture or combinations thereof. In certain embodiments, the mineral acid comprises nitric acid or sulfuric acid. 
     Suitable bases for uses in the present invention include, without limitation, alkali metal hydroxides, alkaline metal hydroxides, alkaline metal oxides, certain transition metal hydroxides, and mixture or combinations thereof. In certain embodiments, the base comprises sodium hydroxide, potassium hydroxide, calcium oxide, calcium hydroxide, cesium hydroxide, barium hydroxide, and mixtures or combinations thereof. 
     Suitable microorganisms for use in the present invention include, without limitation, any denitrifying bacteria or other microbes or mixtures or combinations thereof. Exemplary examples include, without limitation, heterotrophic bacteria (such as  paracoccus denitrificans  and various  pseudomonads ), although autotrophic denitrifiers have also been identified (e.g.,  thiobacillus denitrificans Micrococcus denitrificans/Paraoccus denitrificans, Pseudomonas , etc.). Denitrifiers are represented in all main phylogenetic groups. Generally several species of bacteria are involved in the complete reduction of nitrate to molecular nitrogen, and more than one enzymatic pathway have been identified in the reduction process. Any suitable bacteria may be used in the denitrification cells or units of this invention, such as bacteria of the genera  Aeromonas, Psuedomonas, Bacillis , or mixtures or combinations thereof. In certain embodiments, the culture used in the bio-denitrification units include about 5% aerobic microorganisms, which are used to control the dissolved oxygen (DO) level in the units. However, the exact ratio of anoxic microbes to aerobic microbes may be varied based on the waste water contaminant composition. Measurements of the DO level in two zones of the units are in a cascade control loop to control food and micro-nutrients to the column to support robust microbial growth. The terms microorganism and microbes are used interchangeably throughout the specification. In certain embodiments, the microbes are mesophilic microbes, while in other embodiments, the microbes are heterotropes, while in other embodiments, the microbes are thermophilics microbes, while in yet other embodiments, the microbes are mixture of two or more of these classes of microbes. 
     Suitable absorbent media for use in the present invention include, without limitation, natural zeolitic materials, surfactant modified zeolitic materials, synthetic zeolitic materials, surface modified synthetic zeolitic materials, clays, activated carbon and other adsorbing and or absorbing granular materials. Exemplary examples of suitable zeolitic materials include, without limitation, naturally occurring zeolitic materials and synthetic zeolite materials. Zeolites are minerals that have a micro-porous structure. They are basically hydrated alumino-silicate minerals with an “open” structure that can accommodate a wide variety of cations, such as Na + , K + , Ca 2+ , Mg 2+  and others. Natural zeolites form where volcanic rocks and ash layers react with alkaline groundwater. Zeolites are the aluminosilicate members of the family of microporous solids known as “molecular sieves”. The term molecular sieve refers to a particular property of these materials, the ability to selectively sort molecules based primarily on a size exclusion process. This is due to a very regular pore structure of molecular dimensions. The maximum size of the molecular or ionic species that can enter the pores of a zeolite is controlled by the diameters of the tunnels. These are conventionally defined by the ring size of the aperture, where, for example, the term “8 ring” refers to a closed loop that is built from 8 tetrahedrally coordinated silicon (or aluminum) atoms and 8 oxygen atoms. These rings are not always perfectly flat and symmetrical due to a variety of effects, including strain induced by the bonding between units that are needed to produce the overall structure, or coordination of some of the oxygen atoms of the rings to cations within the structure. Therefore, the pore openings for all rings of one size are not identical. The adsorption properties applicable to the present application are primarily electrostatic in nature and are primarily surface charges. The crystal structure is of interest only in the context of the structures ability to trap micelles or micellular structure in such a way as to make nearly permanent the surfactant such as a hexadecyltrimethylammonium (HDTMA) surfactant in surfactant modified zeolitic material, where the surfactant flips the surface charge to a specific charge density per unit area producing nitrate selective binding sites. 
     Suitable microorganism nutrient mixtures for use in the present invention include, without limitation, methanol, ethanol, or any other carbon source for use with the above listed microorganisms or any other microorganisms that degrade nitrates and/or nitrites and/or other nitrogen containing compound amendable to biodegradation; 
     System and Apparatus Configurations 
     The system and apparatus configurations are divided into three primary physical/chemical operations: trace contaminant precipitation and solids handling, ammonia removal and recovery, and nitrate/nitrite removal. 
     Trace Contaminant Precipitation and Solids Handling (TCP) System 
     In certain embodiments, the TCP subsystem includes a two stage precipitation process, TCP1 and TPC2, intended to reduce trace metals, phosphates, scale-producing compounds and/or other components that can be precipitated by caustic concentrations in waste water or other suitable reagent or combinations of suitable reagents or combination of other suitable reagents and caustic. Waste solids from all process subsystems are also returned to the TCP subsystem for removal and primary dewatering. The conditioning and precipitation process can include four unit operations. First, the raw waste water is degassed/oxidized using a static venturi aerator to equilibrate the raw waste water to atmospheric conditions prior to introducing the waste water into the first stage TCP1. In certain embodiment, the raw waste water is heated either before or after degassing to a temperature of about 72° C. or 160° F. Second, caustic or another equivalent base is added to TCP1 to convert trace metals and scale-producing compounds into insoluble hydroxides or oxide to facilitate removal of these components from the waste water via precipitation. Caustic or another equivalent base is added to TCP2 to further raise the pH to further raise the pH for ammonium recovery. Third, precipitation/desaturation is mechanically enhanced in each stage, TCP1 and TCP2, by flow control. A type of upflow fluidized bed is created to desaturate the pH adjusted or neutralized stream. Fourth, primary dewatering via a contact clarification process removes the bulk of the solids precipitated as well as those returned from other processes. pH adjustment, precipitation/desaturation and primary dewatering unit operations are accomplished in two steps to prevent metals such as zinc precipitated in TCP1 from re-dissolving at higher pH needed in TCP2. 
     In TCP1 sufficient caustic or other equivalent base is added to adjust the pH of the waster water to about pH 8.0, in a first step neutralization. Raising the pH to about pH 8 causes trace metals, limestone and silica to precipitate. In TCP2, sufficient caustic or other equivalent base is added to further increases a pH of the waste water to about pH 10. Raising the pH to about pH 10 causes phosphates, magnesium hydroxide, limestone and the remaining silica to precipitate and causes ammonium to be converted to gaseous ammonia for stripping. Accumulated solids are stored within the TCP basins for seasonal removal and disposal. Each stage is of a length sufficient to permit time for precipitate to sink into a precipitate reservoir formed in the TCP between its inlet and its exit. Clean water is allowed to flow out of the exit, which is above the precipitate height. In certain embodiment, especially, when treating waste waters including urea as one of the nitrogen-containing contaminants, the raw water is pre-heating to a temperature of at least 50° C. and providing additional water hold up time until the urea thermally hydrolyzes to ammonia and carbon dioxide. In other embodiments, the temperature is at least 60° C. In other embodiments, the temperature is at least 70° C. In other embodiments, the temperature is at least 80° C. At the completion of the urea hydrolysis the nitrogen-containing water with or without concurrent metal precipitation is processed through the ammonia stripping (AS) system. In other embodiments of this invention, hydrolyzing water containing urea by pre-heating the water to a temperature of at least 50° C. and thermally hydrolyzing the urea to ammonia and carbon dioxide, with or without concurrent metal precipitation, and processing the hydrolyzed water through the ammonia stripping (AS) system. In other embodiments, the temperature is at least 60° C. In other embodiments, the temperature is at least 70° C. In other embodiments, the temperature is at least 80° C. 
     Ammonia Removal and Recovery 
     Overall nitrogen removal from waste water streams including relatively high nitrogen contents is accomplished in this application through the combination of mechanical stripping and absorbing of ammonia. Mechanical driven processes such as ammonia stripping and absorption are relatively insensitive to ammonia concentration so the processes work as a first pass system to remove ammonia freed during the final raising of the pH of the water to a pH of about 10. 
     The ammonia stripping (AR) subsystem comprises a closed loop ammonia recovery process including five unit operations designed to recover ammonia, control ammonia emission, and control heat recovery and conservation. The first unit operation comprises a heat transfer component to heat the effluent from the TCP to a temperature optimal for economical and efficient stripping of ammonia. In certain embodiments, the temperature is about 70° C. Recouperative and booster exchangers are used in a heat exchanger subsystem. The second unit operation comprises neutralization to liberate gaseous ammonia, which occurs in the TCP just prior to entry into the ammonia recovery subsystem. The third unit operation comprises stripping employing mass transfer to move ammonia to the gas phase. The fourth unit operation comprises chemical absorption or reaction of the ammonia rich gas from the stripping operation to form an ammonium rich liquid product. In certain embodiments, the ammonium rich liquid product can be a liquid ammonium sulfate product or ammonium nitrate product depending on whether sulfuric acid or nitric acid is used to absorb the gaseous ammonia. The fifth unit operation comprises post neutralization and is employed to return the pH of the ammonia stripped water to a value suitable for the denitrification subsystem. The ammonia recovery (AR) subsystem includes a plurality of coupled stripper and absorber units. The stripper units remove ammonia gas to form a gas streams including the stripped ammonia gas. The stripped ammonia rich gas streams are transferred to the coupled absorber units, which absorb the ammonia in an acid solution to form an ammonium salt solution. The acid can be any mineral acid. In certain embodiments, the mineral acid is either sulfuric acid and/or nitric acid. In the AR subsystem, the stripper units are disposed on one side of the subsystem and their associated absorber units are disposed on the other side. The stripper units feed the absorber units and each stripper absorber pair form an essentially closed loop gas processing assembly. The AR subsystem also includes a safe path through which water is extracted for ammonia stripping and into which ammonia stripped water is returned. The AR subsystem also includes an integrated series ammonia stripping/scrubbing or absorbing stages and an ammonium sulfate product control process using a specific recirculation scheme. In certain embodiments, the absorber units are interconnected so that ammonium salt liquor flows forward from the last absorber to the first absorber, which includes a weir connected to the ammonium salt reservoirs. The embodiments also include a single point acid introduction at a vortex mixer of the second absorber. The embodiments also include an uncontrolled liquid conduit connecting the second absorber to the last absorber and a controlled liquid conduit from the first absorber to the last absorber. The embodiments also include a clean water introduction conduit connecting a clean water source of the first absorber. The single point acid introduction, the uncontrolled interconnecting conduits and the pH monitoring are used to control the efficiency of the AR subsystem with minimal control devices. The absorber  1  clean water introduction, the controlled interconnecting conduits and pH monitoring are used to produce a commercial byproduct ammonium salt. The AR subsystem, therefore, requires only monitoring of a pH in the second absorber which is adjusted to a pH of about 2, a pH of the first absorber to a pH of the ammonium salt liquor, such as pH of about 5.5 for ammonium sulfate and a density of the liquor so that the liquor does not get to concentrated. 
     Denitrification Subsystem 
     The denitrification subsystem for nitrate/nitrite removal and ammonia polishing comprises as plurality of series configured biological regenerated adsorptive cells. The cells use two different treatment techniques. Initially, the cells employ a single unit operation, physical absorption of nitrogen-containing compounds. The second operation employs a biological denitrification process that requires a period of time to reach steady state. The denitrification subsystem also includes a safe path from which untreated water is removed and treated water is returned. 
     The physical adsorption process is used to absorb nitrogen contaminants for subsequent biological denitrification. The absorbent is especially useful during start up, nitrogen surges, or other disruptions. For example, when the system is initially activated, the nitrogen mass of a waste water or the remaining nitrogen mass in the partially treated waste water is absorbed to permit the biological denitrification process to start and achieve steady state. The volume of media needed until the biological denitrification process takes over, is determined by time, hydraulic capacity of the system and the average nitrate/nitrite and other nitrogen contaminant concentrations. Subsequently, once a satisfactory biomass is established, the denitrification process removes nitrogen-containing compounds present in the water as well as nitrogen-containing compounds absorbed on or in the media. Nitrates/nitrites and nitrogen-containing compounds are converted into nitrogen gas which is removed from the system as an inert gas. 
     The cells are arranged in a series configuration to achieve the nitrogen treatment goals. Each cell is essentially an upflow absorber for nitrates, nitrites, ammonia and some additional anions. 
     The cell media are regenerated by the bacteria in the cells. Bio-regeneration produces a symbiotic effect. The biological activity reduces the waste produced by regeneration of the media and the media reduces the toxic effects of the contaminants on the bacteria, while acting as a surge device to permit treatment during startup and smooth out rapid changes in nitrogen contaminant concentrations in the waster water caused by accidental spills or other accidental contaminations. 
     Bench and full scale testing of the cells was used to verify that bio-regeneration cells were cost effective for the specific type of water that would be treated and to evaluate the efficiency of media regeneration. Testing was also performed to determine the effects of the super-salinity on the media and to determine some estimate of the attrition rate of the media. 
     Embodiments of the BioRA apparatuses, methods and enabling technologies of this invention comprises adsorption/desorption, continuous plug flow device and method for denitrification of high nitrogen content waste waters. Each BioRA cell supports a dual isolated recirculation loop system comprising a media recirculated loop and a water treatment loop providing for be expansion. The media loop provides sufficient particle shearing to dislodge dead or weakly bond microorganism films growing on the exterior surface of the media, but insufficient to cause degradation of the friable media that is the shear causes only minimal degradation (reduction of particle size) of the media. The term minimal in this context means less than about 1 wt. % of the media undergoes a size reduction per day (24 hours) or less than about 0.1 wt. % per cycle. In other embodiments, the term minimal in this context means less than about 0.5 wt. % of the media undergoes a size reduction per day or less than about 0.05 wt. % per cycle. In other embodiments, the term minimal in this context means less than about 0.1 wt. % of the media undergoes a size reduction per day or less than about 0.25 wt % per cycle. In other embodiments, the term minimal in this context means less than about 0.09 wt. % of the media undergoes a size reduction per day or less than about 0.015 wt % per cycle. Thus, the loops achieve media washing, while causing minimal particle size reduction. The media recycle loop comprises inducers where downward flowing media enters one of a plurality of inducers which is swept along the inducers by the recirculating backwash. The flow the recirculating backwash is sufficient to shear the media dislodging dead or weakly bond biofilm from the media and lifts the media to the ultra low pressure drop hydrocyclone. 
     Raw water is introduced into the cells via a distributing header that produces a substantially even or even distribution (i.e., a uniform or substantially uniform distribution) of incoming water that carries microorganisms, microorganism nutrients and other materials to achieve a desired environmental profile throughout the cell. The term substantially here means that the profile of incoming nutrient rich water is even or uniform across the cells cross-section at the header, with no more the a 10% different in nutrient concentration across the cross-section at the header. In certain embodiments, the nutrient concentration difference by no more than 5%. In other embodiments, the nutrient concentration difference by no more than 1%. Such even or uniform distribution improves microorganism utilization and reduces hot spots and channeling. The even or uniform distribution is achieved through a designed pattern of holes in the header so that each hole attains a near equal flow of nutrient rich incoming water. The even or uniform distribution cause the zone above the header to operate in an expanded bed mode, where particles are separated, but do not move independently. Thus, the cells becomes a plug flow reactor with improved microbe activity throughout the zone above the header. 
     A portion of the recirculating water used in the inducers is feed into the raw water before it enters the distributing header to complete the backwash recirculation loop. By controlling the microorganism composition and the nutrient balance in the cells, the cells achieve an integrated production of anoxic conditions above the distributing header and a respiratory inhibited zone below the distributing header. The respiratory inhibited zone is the zone where electron donors, carbon and or other inhibiting nutrients are supplied to the biomass by desorption and endogenous decay. The zone becomes suboxic just prior to the slurry entering the collection and up lift assembly. 
     Each cell will generally include three zone: an aerobic zone, an anoxic zone and a respiratory inhibited zone. However, in certain cells, the aerobic zone may be minimal or absence depending on the initial conditions of the incoming water. The microorganisms that degrade nitrate and nitrite are relatively sensitive to dissolved oxygen (DO). At DO values above about 0.8 mg/L, these microorganism use molecular oxygen as the electron acceptor instead of oxides of nitrogen until the DO value falls below about 0.4 mg/L. Such an aerobic zone will exist whenever the DO value is high enough to inhibit the nitrate/nitrite destroying microorganisms proliferation and aerobic microorganism are added to the water to reduce the DO value so that an active anoxic zone can be established in the cells. Thus, the aerobic zone can range between about 0% of the height of the cell to about 30% of the height of the cells. The respiratory inhibited zone can range from about 7% to about 30% of the height to the cell. The remainder of the cells will be the anoxic zone. The height is measured from the exit of the ultra low pressure drop three phase separating hydro cyclone. The cell condition are thus adjusted so that a desired ratio is produced between the three zones: the aerobic zone, the anoxic zone and respiratory inhibited zone. The ratio can be about 30:40:30 to about 0:70:30 to about 0:93:7 to about 30:63:7 or any other value depending on the waste water to be treated and on the desired outcome. 
     The cells operate on an indirect biological desorption process. The media is primarily responsible for fast absorption or adsorption of the nitrates/nitrites in the waste water and to support the formation of microbial film on the surfaces thereof. The microorganisms degrade the nitrate/nitrite in the water. As the water levels of the nitrate/nitrite are reduced, absorbed or adsorbed nitrate/nitrite in or on the media desorb into the water so that the bulk of the nitrate/nitrite degradation occurs at the film-water interface. 
     The distributing header is designed to achieve bulk flow distribution control so that nutrients and nitrate/nitrite rich water is evenly or uniformly distributed across a cross-section of the cells as described above. 
     The cells also include a gas back pressure control utilizing the media recirculation loop. As nitrogen gas and carbon dioxide gas are produced due to microbial degradation of nitrates/nitrites in the water, a substantial amount of the gas collects as bubbles on the media, which is flowing down through the cells to be collected and recirculated through the inducers in the respiratory inhibited zone of the cells. Thus, the gas pressures in the BioRA cells can be effectively controlled by the speed of the recirculating media upon which a substantial fraction of the produced nitrogen and carbon dioxide gas accumulate as bubbles. Oxygen gas content can optionally be controlled by an aerator connected to the media recirculation loop. Thus, each BioRA cell can be operated with different gas back pressure control using microbial produced nitrogen and carbon dioxide in the absence or presence of added oxygen gas in the form of pure oxygen, air or any other oxygen containing gas. 
     The media recirculation system is not only used to recirculate the media, the recirculation also server as a selective biomass reject and media cleaning system. As stated above, the media is collected into a plurality of inducers, where a recirculating backwash water flow subjects the media particles to shear sufficient to dislodge dead microorganisms and/or weakly bound microbial films as the media is being recirculated. Thus as the recirculating media stream enters the ultra low pressure drop hydrocyclone, the media is cleaned from shearing and clean water entering the exit of the hydrocyclone acts to achieve a separation between the cleaned media and the dislodged dead microbes and weakly bound microbial films. The recirculation loops also act as a biomass growth limitation process, where biomass growth can be regulated to reduce biomass plugging and other adverse tendencies of bio-remediation processes. The loops and removal systems also permit continuous decay and respiration product removal from the biomass. 
     As stated above, the ultra low pressure drop three phase separating hydrocyclone provides upper flow of cleaned water to wash the sheared media as the sheared media particle flow downward through and out of the hydrocyclone. The inducer system of media pickup and recirculation is specifically designed to control shear (energy) for handling friable solids so that dead and weakly bound microbial films can be removed from the media with minimal particle size reduction of the friable solid particulate media. 
     The denitrification system includes a safe path as described below as a dilution control system. Each BioRA cell pulls water from the safe path and discharges clean water to the safe path. Thus, for series arranged BioRA cells, the first cell draws water from the safe path that is a mixture of all the untreated water entering the safe path and a portion of the treated water from the first cell, while the second BioRA cell draw water from the safe path that is a mixture of all the treated water from the first cell not mixed in its feed and a portion of the discharge of the second cell and subsequent cells operate in the same method. As a result, the safe path water has a continuously decreasing nitrogen content as the water flow downstream through the denitrification system. While many of the embodiments of this invention utilize series configured BioRA cells, the denitrification system can use parallel BioRA cells or a combination of series and parallel BioRA cells depending on outcome and design requirements. 
     In series operations, a denitrification system of BioRA cells configured in series can be operated so that water passes downstream and rejected water can be passed upstream or downstream. Moreover, the cells or units can be configured in a manner to take advantage of endogenous decay, thereby reducing the methanol consumption as well as the amount and characteristic of the waste production. 
     In series operations, the denitrification system includes a two stage methanol control. Intentional methanol slip with DO measurement of aerobic zone is used for automatic feedback control of methanol introduction, while methanol control trim using DO measurement of enzymatic nitrite reduction is used as cascaded trim of automatic feedback control of methanol introduction. While methanol is used as the carbon nutrient source, any other nutrient source can be used depending on the microorganisms being used and the environment to be achieved, e.g., the ratio of aerobic, anoxic and respiratory inhibited zones. 
     Because the biomass synthesis or proliferation consumes ammonia, ammonia reduction in the denitrification system is reduced by biomass reject and a caustic lysing scheme. For system where the denitrification system is part of a treatment system that include a precipitation system and an ammonia stripping/absorbing system, this rejection and lysing is achieved in the precipitation system where caustic is used to precipitate certain minerals in the water prior to subsequent process. 
     There are two distinctly different BioRA cell apparatus designs, possibly three that can produce a desired BioRA effect. A number of different media are envisioned for handled other constituents. The present design can be use with only minor variations to remove sulfates and there are several versions for BTEX biomass. 
     New Embodiment—Multipoint Pickup with Inducers 
     Another embodiment the present invention provides a denitrification system including at least one denitrification column, where the column or unit includes an inlet, an outlet, an optional aerobic zone, an anoxic zone, a clean water zone, a respiratory inhibition or inhibited zone, and a gas overhead zone. The unit also includes an ultra low pressure drop hydro cyclone, a water recirculation and media recirculation subsystem. The unit also includes a nitrogen-rich, nutrient rich, and microbial rich raw water supply distributor adapted to produce an even or substantially even distribution (i.e., a uniform or substantially uniform distribution) of nitrogen-rich, nutrient rich, and microbial rich raw water across a cross-section of the column to improve nutrient utilization and reduce hot spots and channeling. The column is a counterflow column with water flowing up as it is being denitrified and absorptive media flowing down. The absorptive media is collected in the water recirculation and media recirculation subsystem, where collected media is mixed with recirculating water and lifted into the hydrocyclone. The water entering the water recirculation and media recirculation subsystem is sufficient to dislodge dead microbes and weakly bound microbial films from the media, but insufficient to reduce media particles size. Thus, the shear is carefully controlled to achieve media cleaning, while minimizing particle size reduction of the media. The inlet is adapted to receive an aqueous stream to be treated containing an unacceptable concentration of total nitrogen. The water and media recirculation subsystem includes a solid nitrogen absorbent and a bioactive slurry, where the assembly is adapted to circulate the slurry from a bottom of the respiratory inhibited zone to a top of the anoxic zone. The absorbent absorbs the nitrates and nitrites in the aqueous upflowing stream, while microorganisms in the bioactive solution convert the nitrates and/or nitrites into nitrogen gas in all of the zones of the column, except of gas overhead zone, while ammonia and other nitrogen-containing compounds are consumed by the microbes. The water in the slurry as it is being treated progresses from the stream inlet to the stream outlet. 
     Another embodiment of the water and media recirculation subsystem of this invention includes a plurality of media lift headers and at least one inducer feed header. Each media lift header includes a straight stem having a plurality of branches and an output manifold. The media lift headers also include a flush line having an input manifold. Each flush line includes a first bend and a straight segment, where the first bend positions the straight segment to run above the stem of the media lift header. The flush line includes a second bend, where the flush line enters the stem just upstream of the output manifold. The second bend is a complex bend have an upward segment and a downward segment angled into the stem. The angled segment makes an angle g with the stem of between about 15° to about 45°. In other embodiments, the angle γ is between about 20° and 40°. In other embodiments, the angle γ is between about 25° and 35°. In other embodiments, the angle γ is about 30°. 
     Each branch includes an inducer and an aperture. The branches make an angle δ with the stem between about 30° and about 60°. In certain embodiments, the angle δ is between about 40° and 50°. In other embodiments, the angle δ is about 45°. The inducer feed header includes a plurality of distribution nozzles. 
     The subsystem also includes a plurality of conduits connecting the nozzles to the inducers. 
     As the media rich slurry flows down the column, the media rich slurry is funneled into the apertures in the media lift headers. The number of apertures is designed to be sufficient to provide a more uniform collection of the slurry, while minimizing inhomogeneities in collection of the slurry into the media lift headers. The conduits supply recirculation water to the inducers associated with the apertures at a non-aspirating flow rate. In certain embodiments, the flow rate is the same or substantially the same as a flow rate of the slurry entering the branches of the media lift header through the pickup apertures. The terms substantially the same as used here means that the flow rate of the recirculation water and the flow rate of the slurry into the branches through the apertures is within about 10% of each other. In other embodiments, the flow rates are with about 5% of each other. In other embodiments, the flow rates are with about 2.5% of each other. In other embodiments, the flow rates are with about 1% of each other. The diluted medium slurry then proceeds down the media lift header. 
     The media lift headers taper down from their output manifolds to their last branches. The tapering is designed to maintain the slurry flow through the header at a rate that reduces media particle size reduction and reduces slurry separation. 
     The header output manifolds are connected to lift lines situated exterior to the column. The lift lines are combined into a main line prior to the main line entering the column to feed the hydrocyclone. The lift lines and main line are configured in such a way as to reduce or eliminate flow into an unused or plugged lift line as is well known in the art. The lift lines and main line is constructed with branch connections to form a distributed slurry systems. 
     The input and output manifolds of the lift header and feed headers are all situating so that they all have the same or substantially relative hydraulic loss distribution. The term substantially means that the relative hydraulic loss distribution of the headers are within about 20% of each other. In other embodiments, the relative hydraulic loss distribution of the headers are within about 10% of each other. In other embodiments, the relative hydraulic loss distribution of the headers are within about 5% of each other 
     The recirculation water is supplied by the recirculation water pump assembly to the input manifolds of the feed headers at a rate to maintain a non-aspirating flow into the inducers. The recirculation water pump assembly is also connected to the input manifolds of the flush lines of the media lift header. The flush lines are used to unplug the manifold and lifts lines if they plug. Flushing of the manifold and lift lines may be performed on a regular schedule for maintenance purposes or only when needed. 
     Aspects of Methods Associated with Operation of the Denitrification System 
     Embodiments of this invention relate to an adsorption method including supplying a waste water stream having a high level of a contaminant such as oxides of nitrogen to a bio-denitrification column through a distributor. The distributor is located in a lower middle region of the column. The method also includes supplying a medium slurry into an upper middle region of the column through a venturi feed apparatus. The two supplies produce a counter-flow zone in the column, which extends from a position immediately below the distributor to an output of the venturi apparatus. The counter-flow comprises medium flowing down from the venturi feed apparatus and water flowing up from the distributor. The water distributor supplies water distributed across the entire cross-section of the column at a rate that produces an expanded bed under plug flow conditions throughout the column. The expanded bed is defined as an upward liquid flow through medium bed at such a velocity as to cause the individual particles to partially separate, increasing the placed volume of the bed, but not at a velocity to change their relative position to each other. In certain embodiments, the velocity is sufficient to partially separate at least 70% of the particles in the medium. In other embodiments, the velocity is sufficient to partially separate at least 80% of the particles in the medium. In other embodiments, the velocity is sufficient to partially separate at least 90% of the particles in the medium. The expanded bed reduces or eliminates channeled flow in the column. Below the counter-flow zone is a co-flow zone, where the medium and residual water flows into a respiratory inhibited zone (RIZ) and ultimately into a medium slurry collection and uplift subsystem. 
     Embodiments of this invention relate to an adsorption method including establishing a stationary, mass transfer zone within the counter-flow zone of the column, where the medium is continuously replaced maintaining a static adsorptive capacity in the counter-flow zone of the column. In this zone, active microbial growth is occurring at a rate of at least doubling a microbe population in the counter-flow zone. The stationary zone is limited by x/m ratio at maximum concentration verses breakthrough at minimum x/m. The stationary zone reduces the total volume of medium required to operate the bio-denitrification unit regenerated medium is always being introduced, while fully populated medium is withdrawn and regenerated. 
     Embodiments of this invention relate to an adsorption method including biologically assisted regenerating the medium, which is an integral feature of the method of this invention as this assisted regeneration is integral to maintaining the stationary, mass transfer zone. The microbes in the medium slurry forms a film on the medium. The medium is an active nitrate/nitrite adsorbent/absorbent. Thus, a portion of the nitrate/nitrites in the waste water is adsorbed and/or absorbed in and on the surface and pores of the medium. The microbes actively convert nitrates/nitrites in water surrounding them, the water between the particles of the medium. This generally causes the microbes near the surface of the medium to be starved of nitrates and/or nitrites. However, because the medium is an active nitrate/nitrite adsorber and/or absorber, as the nitrates and/or nitrites are depleted in the interstitial water, the nitrates and/or nitrites adsorbed and/or absorbed in and on the surface and pores of the medium is desorbed becoming a source of nitrates and/or nitrites for the microbes near the surface and via diffusion for the microbes on the outer part of the film. In this way, the adsorptive/absorptive capacity of the medium is regenerated so that upon collection, uplift and reintroduction through the venturi feed apparatus, the medium is now capable adsorbing/absorbing nitrates and/or nitrites in the upflowing water as the medium proceeds down through the expanded bed portion of the columns. 
     Embodiments of this invention relate to an adsorption method including continuously cleaning the medium of foreign material in the co-flow zone of the column and the up-lift subsystem of the column. The column is divided by activity into four primary zone. The upper most zone comprises cleaned up-flowing water. The upper middle zone comprises an expanded bed medium zone in which anoxic denitrification occurs. The middle zone is marked by rapid microbial growth at a rate that results in a 1.5 to 5 times growth rate or increases viable or volatile microbes from about 1000 mg/L at the exit of the slurry feed to about 3000 mg/L at the distributor. The next zone is adjacent the water distributor and is an aerobic zone, where aerobic microorganisms reduce the dissolved oxygen (DO) levels to promote anoxic microorganism growth in the anoxic zone of the column. The in-coming waste water has a defined and controllable DO level and the amount of aerobic microorganisms are controlled by the DO level and are sufficient to reduce the DO level into an anoxic DO level. The lower zone is the respiratory inhibited zone (RIZ), where the medium is no longer in an expanded format and microbial growth is inhibited. The zone becomes suboxic just prior to the medium collectors and results in a reduction of a viable or volatile microbial population, which is rapidly re-established as the slurry is up-lifted and reintroduced into the column through the slurry feed unit. 
     Embodiments of this invention relate to an adsorption method including establishing a safe path to which the bio-denitrification unit acts as an attached reactor in an adsorption scheme. Mathematically, the safe path and the bio-denitrification units may be modeled as a continuous stirred tank reactor (CSTR), where the units or attached reactors are operating under plug flow conditions. Thus, the safe path is a fixed volume path into which a waste water stream is added and a cleaned water stream exits. Along the length of the safe path, waste water in different degrees of cleaning is being continuously withdrawn into the attached reactors and cleaner waste water is being sent back to the safe path, where that water is mixed with the water in the safe path to form the water for the next bio-denitrification unit (which are arranged in series). The water exiting the last bio-denitrification unit has a desired low nitrate/nitrite level and is now safe to be discharged into the environment. In certain embodiments, the water exiting each bio-denitrification unit is aerated as it flows through a spiral configured outlet pipe into a holding area, where the aerated water is allowed to attain a given dissolved oxygen value before it overflows into the safe path for use as a part of the water going into the next bio-denitrification unit or ultimately exits the bio-denitrification system. 
     Embodiments of this invention relate to a bio-filtration method including establishing a fixed microbial film surrounding the particles of the medium producing a two sided electron acceptor supply—part of the supply from the interstitial water between the particles and part of the supply from the adsorbed and/or absorbed electron acceptors on and/or within the medium, with the fixed or attached side supply maintained for the longest time and is the most consistent throughout the biomass life, when RIZ is considered. 
     Embodiments of this invention relate to a bio-filtration method including establishing rapid biomass generation due to the expanded bed, which provides underlying continuous logistics, i.e., supply of carbon, electron acceptor, and micro-nutrients to all of the biomass and removal of products from all of the biomass and due to a fixed film biomass that moves, within column, toward greater levels of carbon and electron acceptors—toward the waste water distributors. In the present configuration, traditional inhibition limiting carbon and/or electron acceptor only takes place as the downwardly flowing medium exits the anoxic zone. 
     Embodiments of this invention relate to a bio-filtration method including establishing a continuous growth of biomass in the counter-flow, which provides a microbial environment allowing removal of ammonia through bio-synthesis. 
     Embodiments of this invention relate to a bio-filtration method including sustaining a sufficient amount of aerobic microbes in the microbes culture in the column to control a dissolved oxygen (DO) environment by controlled introduction of a DO level into the safe path connected to the denitrification units and via the counter flow of fixed film biomass and water to be treated from the anoxic zone to the aerobic zone. 
     Embodiments of this invention relate to a bio-filtration method including establishing of a safe path attached to the reactors (denitrification units) in biological treatment scheme. Mathematically, the reactors may be described as a Continuous Stirred Tank Reactors (CSTRs) operated under plug flow conditions. The safe path coupled with the reactors disposed in a series configuration, produces the mathematically smallest volume of biomass required to remove substrate while allowing unlimited range of flow treatment. 
     Embodiments of this invention relate to a biologically assisted adsorbent regeneration method including continuous integral regeneration of adsorbent by desorption of adsorbed and/or absorbed nitrates and/or nitrites driven by the biocleansing of interstitial water and pore water in the co-current flow zone of the column. 
     Embodiments of this invention relate to a biologically assisted adsorbent regeneration method including establishing a regeneration area or a respiratory inhibited zone (RIZ), where the medium and interstitial water enters with a largest biomass, a highest concentration of carbon, electron acceptor and nutrients producing the highest specific denitrification rate in column. In certain embodiments of the column, the RIZ may be adjusted to intentionally reduce volatile biomass to support ammonia removal by synthesis. 
     Embodiments of this invention relate to a biologically assisted adsorbent regeneration method including establishing a suboxic zone in the column to determine nitrate to reductase interaction by DO measurement. 
     Embodiments of this invention relate to an electron donor and carbon supply control method including measuring dissolved oxygen in the aerobic zone to control substrate addition by feedback control. In other embodiments, the electron donor and carbon supply control method including measuring dissolved oxygen in the suboxic zone of the RIZ to trim the control of substrate addition by cascaded feedback control. In certain embodiments, the carbon supply, generally methanol, but other carbon sources or combinations are equally useable, is controlled to maintain a DO level between about 0.19 and 0.12. If the DO level goes above 0.19, then more carbon source is added. If the DO level drops below about 0.12, less carbon source is added. 
     In certain embodiments of the methods of this invention, microbe seeding is only performed at startup, planed shut downs or operational disruptions. However, in all cases, microbe seeding may occur during the course of routine operation, if the microbe population drops below a viable or volatile population insufficient to repopulate a sufficient population in the counter-flow and co-flow zone of the denitrification units. 
     Additional Effluent Polishing &amp; Conditioning 
     Absolute full scale plant performance and effluent water characteristics through toxicity testing cannot be determined from a bench scale treatability study. An additional post-treatment conditioning step may be required to adjust the chemistry of the treated effluent to achieve desired or required water release specifications. Thus, polishing units are optional to polish and condition the final effluent to meet a given discharge water profile, to meet levels of various contaminants required by applicable regulations. 
     Ancillary Components 
     In addition to the primary components that comprise the treatment system of this invention, there are a plurality of ancillary components that may or may not be required depending on operational parameters. 
     Air Emissions Control 
     The majority of the entire treatment process will be operated under anoxic to anaerobic conditions and, consequently, various reduced vapor-phase ion species such as hydrogen sulfide can be liberated during treatment. The system will include a return gas scrubber with barometric leg to capture sulfur based emissions from the biological processes. A closed loop scrubber system is utilized to recover ammonia removed from the pond water minimizing the potential for ammonia emission issues. 
     Solids Production and Disposal 
     At this time, it is anticipated that the majority of solids (sludge) that will be produced through the treatment process can be properly managed within the tanks where the TCP occurs and as stated above will result in the primary dewatering of solids. If the TCP produces significant quantities of solids, the TCP can include a solids withdrawal system and/or additional conditioning means such as a secondary dewatering step to concentrate the solid for removal. 
     Chemical Support Systems 
     A series of chemical systems are needed to support the operation of the treatment system. Caustic such as lime or sodium hydroxide is used to increase a pH of the waste water in the TCP treatment step at the front of the system. A mineral acid such as sulfuric acid is used to absorb ammonia gas converting into to a ammonium salt liquor and to reduce a pH of the ammonia stripped waste water to a pH level optimal for denitrification prior to routing the waste water into and through the BioRA cells or units. A nutrient such as methanol is used as a substrate source as well as nutrients for the biological denitrification process. All chemical supplies will include a dedicated area for proper storage and protection. The chemicals storage tanks or vessels will include secondary containment provisions. The system will also include dilution facilities, metering pumps, piping, valves, and transfer lines. 
     Instrumentation &amp; Controls 
     Instrumentation and controls for the treatment system will be integrated and configured to minimize the amount of time that an operator will need to monitor and remain with the system to ensure that it is operating properly. 
     System Flow, Reliability and Control Discussion 
     The three subsystems are connected by a gravity flow scheme using as so called and well known safe path format. A safe path format was developed to extend integrity management into process design. 
     Simply stated, in safe path configured system, process performance and bulk flow through the treatment system are separate independent controls. Material flow is controlled by passive friction devices (e.g., openings in baffles, etc.). Several systems have been produced to-date using concrete basins with factory supplied critical components bolted in. A safe path configured system is usually cheaper to build, simpler to operate and easier to maintain than traditional, tank batteries, piping racks, valves and pumps. In the system of this invention, an intake structure is placed next to a pond side treatment system. Raw water is delivered to the TCP operation through a venturi aerator from a lift pump located in the intake structure in the pond. Simple reagent addition equipment also discharges into the venturi in the first stage TCP. pH is monitored in the reaction sump of the first stage TCP. The partially neutralized water underflows from the reaction sump to a type of upwell fluidized bed called a Floc Tunnel. The reaction chamber and floc tunnel are part of the stage one contact clarifier, separated by concrete baffles. The partially treated water overflows a submerged baffle into the contact clarifier. 
     TCP1 and TCP2 are separated by a concrete wall. Partially treated water from stage one (TCP1) overflows into a stage two reaction chamber, where the process is repeated. Other than the lift pump and metering equipment, there are no moving parts in the TCP. 
     Stage two TCP overflows to an empty chamber separated by a baffle into two sump zones. Water can be drawn from the first sump for heat exchange and then returned to the second sump or allowed to pass around the baffle, where the now un-ionized water underflows into the stripping system. Water flows through the multi-stage stripping system by gravity, underflowing from stage to stage in series. The operation of a recirculation pump connected to the stripper venturi determines whether the stage is operating or a spare. Water passes through the system regardless of stage operation. Stripped water overflows from the last stripping stage to the denitrification subsystem. Treated water underflows from the denitrification subsystem to an empty chamber, where it overflows to discharge. For these portions of the operation, there are no active level or flow controls used. All processes are side streams to the central flow of water. 
     Gas control devices will also use a safe path construction. Each ammonia stripping stage is connected to a complementary absorber via gas ducts. The aspirating characteristic of Maxi-Strip Venturi mixer moves the gas regardless of the operation of the complementary absorber or stripper. The H 2 S scrubber has similar characteristics. 
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Embodiments of Systems and Apparatuses for Treating High Nitrogen Waste Water 
     First Embodiment 
     Referring now to  FIG. 1 , an embodiment of the system, generally  100 , includes a source  102  of waste water such as a retention pond. The source  102  includes a sump pump  104  having an outlet  106  connected to a first end  108  of a source input conduit  110 . The conduit  108  is connected at its second end  112  to an inlet  114  of a precipitation and conditioning subsystem  116 , sometimes referred to herein as the TCP subsystem. The precipitation and conditioning subsystem  116  includes a source of a base  118 , which is connected to the inlet  114  by a base supply conduit  120 . The base is used to adjust the pH of the waste water effluent to a pH sufficient to precipitate precipitatable contaminants. In some embodiments, the subsystem  116  is divided into two or more compartments as described more fully below. The subsystem  116  also includes an outlet  122  connected to a first end  124  of a base treated effluent conduit  126 . Sufficient base is added to the TCP subsystem  102  in one or more additions so that the final pH of the base treated effluent is at least pH 10. 
     The conduit  126  is connected at its second end  128  to an inlet  130  of an ammonia recovery subsystem  132 , sometimes referred to herein as the AR subsystem. The AR subsystem  132  includes a safe path  134 , a stripper section  136  and an absorber section  138 . The absorber section  138  includes a mineral acid reservoir  140  and a mineral acid conduit  142  for supplying the mineral acid to the absorber section  138  to convert stripped ammonia gas into an ammonium mineral acid salt liquor for disposal or use as a fertilizer. The AR subsystem  132  includes an outlet  144  connected to a first end  146  of an ammonia stripped effluent conduit  148 . Effluent water from the safe path  134  is withdrawn into the stripper section  136 , where an ammonia rich gas is extracted and forwarded to the absorber section  138 , where it is reacted with mineral acid such as sulfuric acid or nitric acid to form an ammonium mineral acid salt liquor. The details of the stripper section  136  and the absorber section  138  are shown herein. 
     The conduit  148  is connected at its second end  150  to an inlet  152  of a denitrification subsystem  154 , which uses an absorbent and microorganisms to convert nitrates, nitrites, residual ammonia/ammonium, or other nitrogen-containing compound to form nitrogen gas. The denitrification subsystem  154  includes a safe path  156 , an absorber/biological denitrification section  158  and a nutrient supply section  160 . The denitrification subsystem  154  includes an outlet  162  connected to a finished effluent conduit  164 . Effluent water from the safe path  152  is withdrawn into the absorber/biological denitrification section  158 , where the nitrogen-containing compounds are absorbed by the absorbent and converted to nitrogen gas. The nutrient supply section  160  supplies nutrients for the microorganisms. The details of the absorber/biological denitrification section  158  are shown herein. 
     Second Embodiment 
     Referring now to  FIG. 2A , an embodiment of the system, generally  200 , includes a source  202  of waste water such as a retention pond. The source  202  includes a sump pump  204  having an outlet  206  connected to a source input conduit  208 , which in turn is connected to an inlet  210  of a precipitation and conditioning subsystem  212 , sometimes referred to herein as the TCP subsystem. The precipitation and conditioning subsystem  212  includes a source of a base  214 , which is connected to the inlet  210  by a base supply conduit  216 . The base is used to adjust a pH of the waste water effluent to a pH sufficient to precipitate precipitatable contaminants. In some embodiments, the subsystem  212  is divided into two or more compartments as described more fully below. The subsystem  212  also includes an outlet  218  connected to a base treated effluent conduit  220 . Sufficient base is added to the TCP subsystem  216  in one or more additions so that a final pH of the base treated effluent is at least pH 10. 
     The conduit  220  is connected to an inlet  222  of an ammonia recovery subsystem  224 , sometimes referred to herein as the AR subsystem. The AR subsystem  224  includes a safe path  226 , a mineral acid supply path  228 , a stripper section  230  and an absorber section  232 . The stripper section  230  includes a plurality of stripper units  234  and an equal plurality of absorber units  236 . Each stripper unit  234  includes a waste water supply line  238 , a vortex water gas separator  240  and a stripped water reservoir  242 . Each stripper unit  234  is connected to an absorber unit  236  via a gas conduit  244   a  and gas return conduit  244   b  for equalizing air flow between the stripper unit and its associated absorber unit. Each absorber unit  236  includes a vortex gas water mixer  246 , a mineral acid supply line  248  and an ammonium mineral acid liquor reservoir  250 . The AR subsystem  224  also includes four ammonium mineral acid liquor storage tanks  252  connect to the liquor reservoirs  250  via conduits not shown. The strippers and absorbers are paired so that the ammonia-laden air is continuously feed back and forth between the stripper and absorber until the ammonia content has been reduced to desired low level. The series of coupled stripper/absorber pairs withdraw water from and discharge water to the safe path. Although acid can be introduced at all or any number of the absorber units, in certain embodiments, the acid is introduced into only a single absorber. Although the ammonium mineral acid liquor can be withdrawn from all of the absorber units, in certain embodiments, the absorber units include weirs that allow the ammonium mineral acid liquor to flow toward the first absorber in the series, which includes a weir that empties into the liquor storage reservoirs. 
     The AR subsystem  224  also includes an outlet  254  connected to an ammonia stripped effluent conduit  256 . Effluent water from the safe path  226  is withdrawn into the stripper units  234 , where an ammonia rich gas is separated via the vortex separator  240  and forwarded to its corresponding absorber unit  236  via the conduit  244 , where it is reacted with a mineral acid such as sulfuric acid or nitric acid in the vortex mixer  246  to form an ammonium mineral acid salt liquor such as an ammonium sulfate or ammonium nitrate liquor. The mineral acid supply path  228  is supplied from a mineral acid tank  258  via a mineral acid supply conduit  260  into a mineral acid inlet  262 . Further details of the stripper section  230  and the absorber section  236  are shown herein. 
     The AR subsystem  224  also includes a heating, heat exchange and heat recovery subsystem  264  includes a heating and exchange/recovery unit  266 . A stream of based treated effluent is taken from the safe path  226  via a base effluent heat exchange conduit  268 . The stream paths through the unit  266 , where it is heated by heaters (shown in detail below) and brought into heat exchange relationship with a stream taken from the ammonia stripped effluent via an ammonia stripped heat exchange conduit  270 . The unit  266  heats the base treated effluent water to a temperature optimal for ammonia stripping. In certain embodiments, the temperature is between about 40° C. and about 70° C. In other embodiments, the temperature is between about 45° C. and about 70° C. In other embodiments, the temperature is about 70° C. The unit  266  is designed to use the “hot” ammonia stripped stream to heat the in coming “cool” base treated stream to reduce the energy supplied to the heaters to increase the temperature of the in coming stream to the desired higher temperature. 
     The conduit  256  is connected to an inlet  272  of a denitrification subsystem  274 , which uses an absorbent and microorganisms to absorb and convert nitrates, nitrites, residual ammonia/ammonium, or other nitrogen-containing compounds into nitrogen gas. The denitrification subsystem  274  includes a safe path  276 , an absorber/biological denitrification section  278  and a nutrient supply section  280 . The denitrification subsystem  274  also includes a waste water inlet conduit  282 , a nutrient supply conduit  284  and a treated water outlet  286 . The denitrification subsystem  274  also includes an outlet  288  connected to a finished effluent conduit  290 . 
     In the denitrification subsystem  274 , the effluent water from the safe path  276  is withdrawn into the absorber/biological denitrification section  278 , where the nitrogen-containing compounds are absorbed by the absorbent and converted to nitrogen gas by the microorganisms. The nutrient supply section  280  supplies nutrients for the microorganisms. Further details of the absorber/biological denitrification section  278  are shown herein. 
     Third Embodiment 
     Referring now to  FIG. 2B , another embodiment of the system, generally  200 , includes a source  202  of waste water such as a retention pond. The source  202  includes a sump pump  204  having an outlet  206  connected to a source input conduit  208 , which in turn is connected to an inlet  210   a  of a first stage  213   a  of a precipitation and conditioning subsystem  212 , sometimes referred to herein as the TCP subsystem. The precipitation and conditioning subsystem  212  includes two precipitation stages  213   a  and  213   b . The subsystem  212  also includes a source of a base  214 , which is connected to the inlet  210   a  by a base supply conduit  216   a . The base supplied through conduit  216   a  mixes with the waste water in conduit  208  at the inlet  210   a  and is sufficient to adjust a pH of the waste water to a pH sufficient to precipitate precipitatable contaminants such as trace metal contaminants or other precipitatable contaminants. In certain embodiments, the pH in the first stage  213   a  of the subsystem  212  is adjusted to a pH between about 4.8 and about 8.8. In certain embodiments, the pH is adjusted to a pH of about 8. At this pH, trace metals are precipitated, but the pH is not too high to cause the precipitate to re-dissolve. The base source  214  is also connected to an inlet  210   b  associated with the second stag  213   b  of the subsystem  212  via a base supply conduit  216   b . The base supplied through conduit  216   b  is sufficient to adjust a pH of the first stage waste water effluent to a pH sufficient to precipitate other precipitatable contaminants. In certain embodiments, the pH in the second stage  213   b  is adjusted to pH a value between about 9.8 and 11.0. In certain embodiments, the pH is adjusted to a value of about 10. At this pH, substantially all precipitatable contaminants are precipitated and the pH is optimal for converting ammonium in the base treated effluent into gaseous ammonia for extraction in the AR subsystem set forth herein. The subsystem  212  also includes an outlet  218  connected to a base treated effluent conduit  220 . 
     The conduit  220  is connected to an inlet  222  of an ammonia recovery subsystem  224 , sometimes referred to herein as the AR subsystem. The AR subsystem  224  includes a safe path  226 , a mineral acid supply path  228 , a stripper section  230  and an absorber section  232 . The stripper section  230  includes a plurality of stripper units  234  (here three) and the absorber section  232  includes an equal plurality of absorber units  236  (here three). Each stripper unit  234  includes a waste water supply line  238 , a vortex water gas separator  240  and a stripped water reservoir  242 . Each stripper unit  234  is connected to an absorber unit  236  via a gas conduit  244   a  and gas return conduit  244   b  for equalizing air flow between the stripper unit and its associated absorber unit. Each absorber unit  236  includes a vortex gas water mixer  246 , a mineral acid supply line  248  and an ammonium mineral acid liquor reservoir  250 . The AR subsystem  224  also includes four ammonium mineral acid liquor storage tanks  252  connect to the liquor reservoirs  250  via conduits not shown. The AR subsystem  224  also includes an outlet  254  connected to an ammonia stripped effluent conduit  256 . Effluent water from the safe path  226  is withdrawn into the stripper units  234 , where an ammonia rich gas is separated via the vortex separator  240  and forwarded to its corresponding absorber unit  236  via the conduit  244 , where it is reacted with a mineral acid such as sulfuric acid or nitric acid in the vortex mixer  246  to form an ammonium mineral acid salt liquor such as an ammonium sulfate or ammonium nitrate liquor. The mineral acid supply path  228  is supplied from a mineral acid tank  258  via a mineral acid supply conduit  260  into a mineral acid inlet  262 . Further details of the stripper section  230  and the absorber section  232  are shown herein. 
     The AR subsystem  224  also includes a heating, heat exchange and heat recovery subsystem  264  includes a heating and exchange/recovery unit  266 . A stream of based treated effluent is taken from the safe path  226  via a base effluent heat exchange conduit  268 . The stream paths through the unit  266 , where it is heated by heaters (shown in detail below) and brought into heat exchange relationship with a stream taken from the ammonia stripped effluent via an ammonia stripped heat exchange conduit  270 . The unit  266  heats the base treated effluent water to a temperature optimal for ammonia stripping. In certain embodiments, the temperature is between about 40° C. and about 70° C. In other embodiments, the temperature is between about 45° C. and about 75° C. In other embodiments, the temperature is about 70° C. The unit  266  is designed to use the “hot” ammonia stripped stream to heat the in coming “cool” base treated stream to reduce the energy supplied to the heaters to increase the temperature of the in coming stream to the desired higher temperature. 
     The conduit  256  is connected to an inlet  272  of a denitrification subsystem  274 , which uses an absorbent and microorganisms to absorb and convert nitrates and nitrites into nitrogen gas and consumes residual ammonia/ammonium, or other nitrogen-containing compound. The denitrification subsystem  274  includes a safe path  276 , an absorber/biological denitrification section  278  and a nutrient supply section  280 . The dentrification section  278  include a plurality of absorbent/microorganism denitrification units  282 , here three denitrification units. Each unit  282  includes a water inlet conduit  284 , a water outlet conduit  286  and a nutrient inlet conduit  288 . The water inlet conduit  284  withdraws water from the safe path  276  into the unit  282 , while the water outlet conduit  286  returns denitrified water to the safe path  276 . The nutrient inlet conduit  288  supplies microorganism nutrients from the nutrient supply section  280  to the units  282 . The denitrification subsystem  274  includes an outlet  290  connected to a finished effluent conduit  292 . 
     In the denitrification subsystem  274 , effluent water from the safe path  276  is withdrawn into the absorber/biological denitrification units  282 , where the nitrogen-containing compounds are absorbed by the absorbent and converted to nitrogen gas by the microorganisms. The nutrient supply section  280  supplies nutrients for the microorganisms. Further details of the absorber/biological denitrification section  278  are shown herein. 
     Fourth Embodiment 
     Referring now to  FIG. 3A , another embodiment of the system, generally  300 , include of a two stage precipitation and conditioning subsystem  302 , sometimes referred to herein as the TCP subsystem, having a first stage  304   a , sometimes referred to as TCP1 and a second stage  304   b , sometimes referred to as TCP2. The subsystem  302  also includes a waste water input conduit  306  connected to an inlet  308  to the first stage  304   a . The subsystem  302  also includes a base reservoir  310  having a base supply conduit  312  and an access hatch  313 . The base supply conduit  312  supplies base through a base outlet  314   a  to the inlet  308 . Sufficient base is added to the inlet  308  to adjust a pH of the waste water to a pH sufficient to precipitate precipitatable trace metal contaminants. In certain embodiments, the pH in the first stage  304   a  is adjusted to a pH between about 7.5 to about 8.5. In other embodiments, the pH is adjusted to about 8. At this pH, trace metals are precipitated, but the pH is not too high to cause the precipitate to re-dissolve. The base conduit  312  also supplies base to the second stag  304   b  at a second base outlet  314   b . The base supplied through the second outlet  314   b  is sufficient to adjust a pH of the waste water leaving TCP1  304   a  to a pH sufficient to precipitate other precipitatable contaminants. In certain embodiments, the pH in the second stage  304   b  is adjusted to pH 10. At this pH, substantially all precipitatable contaminants are precipitated and the pH is optimal for converting ammonium salts into gaseous ammonia for extraction and recovery in the AR subsystem set for herein. The subsystem  302  also includes an outlet  316  connected to a base treated effluent conduit  318 . TCP1  304   a  also includes a hatch  320   a  for removing precipitate periodically thereform. TCP2  304   b  also includes a hatch  320   b  for removing precipitate periodically thereform. 
     The conduit  320  is connected to an ammonia recovery subsystem  330  at an inlet  332 . The subsystem  330  is sometimes referred to herein as the AR subsystem. The AR subsystem  330  includes a stripper section  334  and an absorber section  336 . The stripper section  334  includes a plurality of stripper units  338  (here eight), and the absorber section  336  includes an equal plurality of absorber units  340  (here eight). The stripper units  338  and the absorber units  340  are described in greater detail herein. The AR subsystem  330  also includes four ammonium mineral acid liquor storage zones  342  for storage of the ammonium mineral acid liquor and corresponding hatches  343  to remove the liquor. The AR subsystem  330  includes an outlet  344  connected to an ammonia stripped effluent conduit  346 . 
     The conduit  346  is connected to a denitrification subsystem  360  at an inlet  362 , which uses an absorbent and microorganisms to absorb and convert nitrates, nitrites, residual ammonia/ammonium, or other nitrogen-containing compound into nitrogen gas. The denitrification subsystem  360  includes an absorber/biological denitrification section  364  and a nutrient supply section  366 . The absorber/biological denitrification section  364  includes a plurality of absorber/biological denitrification units  368 . The nutrient supply section  366  includes microorganism nutrients tanks  370  and associated hatches  371  for filling the tanks. The nutrient supply section  366  also includes mineral acid tanks  372  and associated hatches  373  for filling the tank. The mineral acid is used in the AR subsystem and in the denitrification subsystem. In the AR subsystem, the mineral acid is used to convert ammonia gas into the ammonium mineral acid salt liquor. In the denitrification subsystem, the mineral acid is used to adjust the pH to the optimal pH for supporting the microorganisms used to convert nitrogen-containing oxide, residue ammonia and other species into nitrogen gas. The denitrification section  364  includes media lift pump assemblies  374  for supplying waste water to the units  368  and recirculation pump assemblies  375  for supplying nutrients to the units  368 . The denitrification section  364  also includes access hatches  376 . The denitrification subsystem  360  includes an outlet  378  connected to a finished effluent conduit  379 . 
     The system  300  also includes a heating, heat exchange and heat recovery subsystem  390  having a base treated water inlet  392   a , a heated base treated water outlet  392   b , a hot ammonia stripped water inlet  394   a  and a cooled ammonia stripped water outlet  394   b . The subsystem  390  also includes a base treated water supply and return unit  396  and an ammonia stripped water supply and return unit  398 . The subsystem  390  heats the base treated water before entering the stripper units  334  and the absorber units  340 . The water is heated to a temperature optimal for ammonia gas removal in the stripper units  334 . In certain embodiments, the temperature is about 50° C. Before the water is discharged in the denitrification subsystem  360 , the water is cooled by transferring a portion of its heat to heat the base treated water as it enters the AR subsystem. Thus, the combination of heating and heat recovery is used to heat the base treated water at it enters the AR subsystem. The subsystem  390  is described in more detail herein. 
     Referring now to  FIG. 3B , the embodiment of the system of  FIG. 3A , generally  300 , is shown absent in covering and equipment. The system  300  includes the subsystem precipitation and conditioning subsystem  302 , the AR subsystem  330 , and the denitrification subsystem  360 . The subsystem  302  is shown to include outer and inner walls  322   a &amp; b . The subsystem  302  also include a base tank enclosure  323  housing the base tank  310 . The subsystem  302  also include a first flocculent tunnel  324   a  associated with the first stage  304   a  and located at the inlet  308 . The flocculent tunnel  324   a  provides efficient mixing of the waste water and the base to facilitate precipitation of the trace metals and other contaminants that precipitate at a pH of about 8. The subsystem  302  also includes a first stage precipitate enclosure/reservoir  325   a , where the pH 8 precipitates settle. The subsystem  302  also includes transfer conduit  326 , which allows water to flow from the enclosure  325   a  to a second flocculent tunnel  324   b  associated with the second stage  304   b  and located at the second base outlet  314   b  and the transfer conduit  326 . Like the first flocculent tunnel  324   a , the second flocculent tunnel  324   b  provides efficient mixing of the waste water and the base to facilitate precipitation of the trace metals and other contaminants that precipitate at a pH of about 10. The subsystem  302  also includes a second stage precipitate enclosure/reservoir  325   b , where the pH 10 precipitates settle. The reservoirs  325   a &amp; b  are of sufficient length and the transfer conduit  326  and the outlet  316  are of sufficient height from a bottom of the reservoirs  325   a &amp; b  to insure that all or substantially all of the precipitate formed settles in the reservoirs. The term “substantially” as used here means that the effluent water includes less than about 10 wt. % precipitate. In certain embodiments, substantially shall mean that the effluent water includes less than 5 wt. % precipitate. In certain embodiments, substantially shall mean that the effluent water includes less than 2.5 wt. % precipitate. In certain embodiments, substantially shall mean that the effluent water includes less than 1 wt. % precipitate. 
     The ammonia recovery (AR) subsystem  330  includes outer and inner walls  348   a &amp; b . The subsystem  330  also includes a base treated water input reservoir  349  into which the inlet  332  empties the base treated water and associated with the supply and return unit  396  of the subsystem  390 . The subsystem  330  also includes a plurality of stripper unit enclosures/reservoirs  350  (eight here) and an equal plurality of absorber unit enclosures/reservoirs  351 . The subsystem  330  also includes a first groove  352   a  in the inner wall  348   b  for receiving the air conduit  244   a  and a second groove  352   b  for receiving the air conduit  244   b . The subsystem  330  also includes the ammonium mineral acid enclosure/reservoirs  342 . The subsystem  330  also includes an ammonia stripped outlet reservoir  353  out of which the ammonia stripper water flow out of the outlet  334  and associated with the supply and return unit  398 . 
     The denitrification subsystem  360  includes outer and inner walls  380   a &amp; b . The subsystem  360  also includes a nutrient enclosure  381  of the nutrient section  366  housing the nutrient tanks  370  and a mineral acid enclosure  382  of the nutrient section  366  housing the mineral acid tanks  372 . The subsystem  360 . The subsystem  360  also includes safe paths  383   a - c , one for each absorber/biological denitrification section  368 . The paths  383   a - c  are associated with the recirculation pump assemblies  375 . The subsystem  360  also includes auxiliary safe paths  384   a - c  for use with an optional final treatment subsystem (not shown) if needed to bring the denitrified water into final compliance with appropriate federal, state and local governmental regulations. The subsystem  360  also includes a discharge enclosure/reservoir  386  connected to the outlet  378 . 
     Detailed Description of TCP Subsystem 
     Referring now to  FIG. 4A , an embodiment of the precipitation and conditioning subsystem, generally  400 , is show to include a source  402  of waste water  403  such as a retention pond. The source  402  includes a sump pump  404  connected to a waste water input conduit  406 . The subsystem  400  can also include an optional aeration unit  408 , which aerates the incoming waste water  403  to a desired input condition. The subsystem  400  also includes an inlet  410  of associated with a first precipitation stage  412 . The subsystem  400  also includes a second precipitation stage  414 . The subsystem  400  includes a source of a base  416 , which is connected to the inlet  410  by a first base supply conduit  418 . The base supplied through the conduit  418  mixes with the waste water  403  entering through the conduit  406  at the inlet  410  and is sufficient to adjust a pH of the incoming waste water to a pH sufficient to precipitate precipitatable contaminants such as trace metal contaminants or other precipitatable contaminants. In certain embodiments, the pH in the first stage  412  of the subsystem  400  is adjusted to a pH between about 7.5 and about 8.5. In certain embodiments, the pH is adjusted to a pH of about 8. At this pH, trace metals are precipitated, but the pH is not too high to cause any or substantially any of the precipitate to re-dissolve. The base source  416  is also connected to a second base supply conduit  420 , which is connected to an base outlet  422  associated with the second stage  414 . The base supplied through conduit  420  is sufficient to adjust a pH of the first stage waste water effluent to a pH sufficient to precipitate other precipitatable contaminants. In certain embodiments, the pH in the second stage  414  is adjusted to pH a value between about 9.5 and 10.5. In certain embodiments, the pH is adjusted to a value of about 10. At this pH, substantially all precipitatable contaminants are precipitated and the pH is optimal for converting ammonium in the base treated effluent into gaseous ammonia for extraction in the AR subsystem set forth herein. 
     The subsystem  400  also includes a first flocculent tunnel  424  associated with the first stage  412  and located so that the inlet  410  empties into the tunnel  424 . The tunnel  424  is adapted to provide sufficient mixing of the base and the entering waste water so facilitate precipitation formation. The subsystem  400  also includes a second flocculent tunnel  426  associated with the second stage  414  and located so that the outlet  422  empties into the tunnel  426 . The tunnel  426  is adapted to provide sufficient mixing of the base and the entering waste water so facilitate precipitation formation. The first flocculent tunnel  424  is formed by a first downward extending wall  428  and a first upward extending wall  430 . After passing through the first flocculent tunnel  424 , the first base treated water flows into a precipitation settling zone or reservoir  432 . The second flocculent tunnel  426  is formed by a second downward extending wall  434  and a second upward extending wall  436 . After passing through the second flocculent tunnel  426 , the second base treated water flows into a precipitation settling zone or reservoir  438 . The subsystem  400  also includes a transfer conduit  440  from the first stage  412  to the second state  414 . The subsystem  400  also includes an base treated waste water outlet  442  connected to a base treated waste water conduit  444 , which forwards base treated water to the AR subsystem described below. 
     The optional aerator unit is adapted to adjust oxygen content of the waste water prior to pumping the waster water into the precipitation unit. As the waste water is pumped into the precipitation unit, sufficient caustic is added to raise a pH of the water to a pH sufficient to precipitate some to substantially all precipitatable components in the waste water. The precipitation unit includes a precipitate retention zone and an outlet. Precipitate free or substantially precipitate free water is forwarded to the ammonia stripping unit. In certain embodiments, the precipitation zone is defined between baffles that permit precipitate free or substantially precipitate free water to flow in into the outlet. In other embodiments, the precipitation unit include at least two precipitation zone. Caustic is added to each zone. Sufficient caustic is added to waste water as it enters each zone to adjust the pH to a desired pH to affect a given precipitation. In certain embodiments, sufficient caustic is added to the first zone to raise the pH of the waste water to about pH 8. At this pH, certain metals precipitate as oxide or hydroxides. As the waster water enters the second zone, sufficient caustic is added to raise the pH of the waste water to about pH 10. At pH 10 other contaminants precipitate. Each zone is baffled so that as the water flows through the zone, precipitate settles in the area between the baffles and water free or substantially free of the precipitated solid in the stages spills over the baffle and either into the next zone or into the output of the unit. The water exiting the precipitation unit will have a desired pH optimized for ammonia stripping. 
     The subsystem  400  also includes pH monitors used to measure pH at various points to control a rate of caustic input relative to a rate of waste water being pump into the subsystem  400 . The monitors permit the pH of water in each stage of the subsystem to be monitored so that base treatment can be adjusted continuously, semi-continuously or periodically to insure optimal base treatment of the waste water. 
     Referring now to  FIG. 4B , the embodiment of  FIG. 4A  is shown in a linear cross-sectional to show the water and base flow in the subsystem  400 . The water  403  enters the subsystem  400  through the inlet  410  along with a first amount of base  445 . The base  445  and the water  403  mix in a mixing zone  446  of the first stage  412  and then enter into the first flocculent tunnel  424  formed from the walls  428  and  430 . The water  403  then flows through the remainder of the first stage  412  and precipitate collects in the precipitate zone  432 . The waster  403  then flows into a second mixing zone  448  of the second stage  414 , where a second amount of base  447  is added. The water  403  and the base  448  then enter into the second flocculent tunnel  426  formed from the walls  434  and  436 . The water  403  then flows then through the remainder of the second stage  412  and precipitate collects in the precipitate zone  438  to form a base treated water  449 , which exits through the outlet  442  through the conduit  444 . 
     Referring now to  FIG. 4C , the embodiment of  FIG. 4A  is shown in a side view. On the top of the subsystem  400  is positioned the heating, heat exchange and recovery subsystem  700  disclosed below. 
     Detailed Description of AR Subsystem 
     Referring now to  FIG. 5A , an embodiment of the AR subsystem, generally  500 , is show to include an inlet  502 , an incoming supply and return unit  504 , an outgoing supply and return unit  506 , an outlet  508 , a stripper section  510 , and an absorber section  512 . The stripper section  510  includes a plurality of stripper units  514  (here eight) and the absorber section  512  includes an equal plurality of absorber units  516  (here eight). Each stripper unit  514  includes a waste water supply line  518  and a stripper gas supply line  520 . Each absorber unit  516  includes a mineral acid supply line  522  and an absorber gas supply line  524 . The AR subsystem  500  also includes four ammonium mineral acid liquor storage tanks  526  for storage of the ammonium mineral acid liquor. 
     Referring now to  FIGS. 5B&amp;C , a view of a stripper unit  514  and its corresponding absorber unit  516  is shown. Each stripper unit  514  is paired with an absorber unit  516  so that ammonia gas separated from the waste water in the stripper unit  514  can be transferred to the absorber unit  516  for reacting with the mineral acid to form an ammonium mineral acid liquor. The subsystem  500  includes outer walls  528 , a bottom  530 , inner walls  532  and top walls  534 . The subsystem  500  also includes a waste water safe path or conduit  536  and a mineral acid supply conduit  538 . The stripper unit  514  includes a stripper enclosure  540 , a stripper pump  542 , the waste water supply line  518  connected to a liquid inlet  544 , the stripper gas supply line  520  connected to a gas inlet  546 , and a stripper vortex mixing zone  548 . After passing through the vortex mixing zone  548 , the resulting effluent exits through a stripper orifice  550  opening into the enclosure  540 . The absorber unit  516  includes an absorber enclosure  552 , an absorber pump  554 , the mineral acid supply line  522  connected to a gas inlet  556 , the absorber gas supply line  524  connected to a gas outlet  558 , and an absorber vortex mixing zone  560 . After passing through the vortex mixing zone  560 , the resulting effluent exits through an absorber orifice  562  opening into the enclosure  552 . 
     Referring now to  FIGS. 5D&amp;E , waster water  564  is pumped from the conduit  536  into the line  518  as a waste water flow  566  and directed into the stripper vortex mixing zone  548 , where the waste water  566  flowing into the vortex mixing zone  548  draws an ammonia deplete gas  568  from the absorber enclosure  552  as an ammonia depleted gas flow  570 . In the stripper vortex mixing zone  548 , ammonia gas entrained in the waste water  566  is separated producing an ammonia stripped waste water  572  and an ammonia rich gas  574 , both exiting the orifice  550 . The water  572  flows into the enclosure  540  and collects in an ammonia stripped waste water reservoir  576 . 
     Mineral acid  578  is pumped from the conduit  538  into the line  522  as a mineral acid flow  580  and directed into the absorber vortex mixing zone  560 , where the mineral acid  580  flowing into the absorber vortex mixing zone  560  draws the ammonia rich gas  574  from the stripper enclosure  540  as an ammonia rich gas flow  582 . In the absorber vortex mixing zone  560 , ammonia gas in the ammonia rich gas  582  reacts with the mineral acid in the mineral acid flow  580  producing an ammonium mineral acid salt liquor  584  and the ammonia depleted gas  570 , both exiting the orifice  562 . The ammonium mineral acid salt liquor  584  flows into the enclosure  552  and collects in an ammonia stripped waste water reservoir  586 . 
     Referring now to  FIG. 5F , another embodiment of the AR subsystem, generally  500 , is show to include an inlet  502 , an incoming supply and return unit  504 , an outgoing supply and return unit  506 , an outlet  508 , a stripper section  510 , and an absorber section  512 . The stripper section  510  includes a plurality of stripper units  514   a - h  (here eight) and the absorber section  512  includes an equal plurality of absorber units  516   a - h  (here eight). Each stripper unit  514  includes a waste water supply line  518  and a stripper gas supply line  520 . Each absorber unit  516  includes a waste water supply line  522  and an absorber gas supply line  524 . The AR subsystem  500  also includes four ammonium mineral acid liquor storage tanks  526  for storage of the ammonium mineral acid liquor. The AR subsystem  500  also includes a first interconnecting conduit  588  connecting the second absorber  516   b  to the eighth absorber  516   h . The AR subsystem  500  also includes a second interconnecting conduit  590  connecting the first absorber  516   a  and the eighth absorber  516   h , where the flow from the first absorber  516   a  and the eighth absorber  516   h  is controlled by a control valve  591 . The AR subsystem  500  also includes a mineral acid supply conduit  592 , which connects an acid source (not shown) to the vortex mixing  548  of the second absorber  516   b . All mineral acid is added via the mineral acid conduit  592  at a rate to maintain the pH in the second absorber  516   b  at a pH of about 2. All ammonium mineral acid flows out of the first absorber  516   a  into the storage areas via a weir  594 . The interconnecting conduits  588  and  590  are designed to permit control of the overall ammonia stripping and absorption from the coupled stripper and absorber units  514   a - h  and  516   a - h , where the stripper  514   a  is paired with the absorber  516   a . The AR subsystem  500  is designed so that the eight paired stripper/absorber units exchange ammonium mineral acid liquor so that all the liquor exits the AR subsystem  500  via a weir  594  into the storage containers  526 . The AR subsystem  500  also include a clean water makeup conduit  596  connected from the outlet  604  of the denitrification unit  600  and controlled by a control valve  597 . The make up water is used to reduce the density of the liquor in the first absorber  516   a . In certain embodiments, the mineral acid is sulfuric acid and the liquor is ammonium sulfate. In these embodiments, the pH of ammonium sulfate is 5.5 so that the overall ammonia stripping can be controlled by monitoring the pH is the first absorber  516   a  and the pH in the second absorber  516   b  where acid is added to maintain a pH is the second absorber  516   b  at about 2. Of course, the pH in the other absorbers will vary between pH 2 and pH 5.5 depending on the ammonia content in the water. 
     Detailed Description of Denitrification Subsystem 
     Referring now to  FIGS. 6A&amp;B , an embodiment of the denitrification subsystem, generally  600 , is shown to include an inlet  602  and an outlet  604 . The subsystem  600  includes a water and nutrient supply section  610  and an absorber/biological denitrification section  660 . 
     The water and nutrient supply section  610  includes a safe path  612 , optional final stage treating compartments  614  and an exit enclosure  616 . The section  610  also includes a microorganism nutrient tank enclosure  618  including four microorganism nutrient tanks  620  and three access covers  622 . The section  610  also includes an mineral acid enclosure  624  including two mineral acid tanks  626  and an access cover  628 . The mineral acid from the tanks  626  are used in the AR subsystem to neutralize the ammonia and in the gentrification subsystem to adjust the pH of the waste water to a pH optimal for microorganism growth and stability. The section  610  also include access covers  630 . 
     The water and nutrient supply section  610  further includes three medium uplift pumps  632   a - c  connected to a medium collection conduit  634   a - c  (see  FIG. 6C ) and a medium supply conduit  636   a - c . The section  610  also includes a waster water and nutrient supply and recirculation pump  638   a - c  connected to a nitrogen rich waster water and nutrient supply conduit  640   a - c  and a nitrogen lean water return conduit  642   a - c.    
     The absorber/biological denitrification section  660  include three denitrification units  662   a - c  and a top member  664 . The conduits  634   a  and  636   a  recirculate an absorbent through the unit  662   a , while conduits  640   a  and  642   a  feed nitrogen-rich waste water to and withdraw nitrogen-lean water from the unit  662   a . Similarly, the conduits  634   b  and  636   b  recirculate an absorbent through the unit  662   b , while conduits  640   b  and  642   b  feed nitrogen-rich waste water to and withdraw nitrogen-lean water from the unit  662   b . Similarly, the conduits  634   c  and  636   c  recirculate an absorbent through the unit  662   c , while conduits  640   c  and  642   c  feed nitrogen-rich waste water to and withdraw nitrogen-lean water from the unit  662   c.    
     The section  610  and  660  also include inner walls  666 , outer walls  668  and top walls  670 . The denitrification units also include outer walls  672  and a top wall  673 . The subsystem  600  also includes a bottom wall  674 . 
     Referring now to  FIG. 6C , the operation of the units  662   a - c  are described in conjunction with the details of the structure of the units  662   a - d . Nitrogen rich waste water from the AR subsystem enters into the safe path  612  of the denitrification subsystem  600 , the nitrogen-rich waste water is removed from the safe path  612  and pumped into the units  662   a - c  by the pump  638   a - c , respectively. For the unit  662   a  (true for the other two), the nitrogen-rich, nutrient rich waste water is pumped through a nitrogen-rich waste water conduit  676  into a distributing header unit  677 , where the nitrogen-rich waste water is introduced into a first absorption/denitrification zone or region  679   a  comprising a first absorbent/water/microbe mixture. In this zone, nitrogen species are absorbed into or onto the absorbent or absorbing media indicated by the dots. Depending on the oxygen content of the water entering the header  677 , the zone  679   a  may be an aerobic zone, where aerobic microorganisms reduce the DO value to a value below about 0.04; otherwise, the zone  679   a  is an anoxic zone, but with evenly or uniformly distributed nutrients from the header  684 . If the zone  679   a  is an anoxic zone, then nitrates/nitrites are actively converted to nitrogen gas by the action of microorganisms in the fluid inside the unit  662   a . The distributing header unit  677  is designed to introduce the nitrogen-rich, nutrient-rich waste water into the zone  679   a  in an even or substantially even distribution or a uniform or substantially uniform distribution. This even or substantially even distribution or uniform or substantially uniform distribution is achieved through a pattern of holes and shape of the distributor  677  so that a flow through each hole is substantially identical. This even or uniform distribution insures that nutrients for the microbes are even or uniform distributed to reduce hot spots, dead spots or channeling of the water upward through the down flowing media. The nitrogen-rich, nutrient-rich waste water flows up as nitrates/nitrites are being absorbed and degraded to denitrify the water, while the media flows down so that the water and media form a counter-flow system. 
     As the media flow down past the header  677 , the media enters a third zone  679   c . The zone  679   c  is the respiratory inhibited zone, where microbial activity is substantially arrested. In this zone  679   c , the media is collected and recirculated through a plurality of media collectors or inducers  680   a - e , here five inducers are shown. In certain embodiments, the collectors or inducers  680   a - e  have different opening sizes, while in other embodiments, the collectors or inducers  680   a - e  have the same opening sizes. In the collectors or inducers  680   a - e , the collected media is mixed with a recirculating flow of waste water, which enters the pump  632   a  via a recirculating conduit  682  having its end  682   a  centered in an ultra low pressure drop three phase separating hydrocyclone  684 . The pump  632   a  pumps the recirculating flow into a recirculation exit conduit  686 . The exit conduit  686  is divided into five inducer inlet conduits  686   a - e , a shunt conduit  686   f  and a rejection conduit  686   g . Fluid flows through the inducer inlet conduits  686   a - e , the shut conduit  686   f  and the rejection conduit  686   g  are controlled by valves  687   a - g . The recirculating fluid flowing through the inducers  680   a - e , sweeps the collected media out of the inducers  680   a - e  and into outlet conduits  688   a - e , which are combined into a medium return conduit  688 . Fluid flow through the outlet conduits  688   a - e  is controlled by valves  689   a - e . The flow rate of fluid through the inducers  680   a - c  is sufficient to dislodge dead microbes and weakly bound microbial films disposed on the surface of the media, but insufficient to reduce the particle size of the friable media to minimal extent. The conduit  688  can optionally include an aeration conduit  698  connected to an aeration unit  699 . The rejection stream flowing through the conduit  686   g  is forwarded to a caustic lysing process, in this case to the precipitation subsystem  302 . 
     The conduit  688  terminates in an upper part  684   a  of the hydrocyclone  684 . In the hydrocyclone  684 , the media stream mixes with clean water from a clean water zone  679   d  as the action of the hydrocyclone  684  separates the media from the water and the dead and weakly bound microbes and microbial films. The recirculating media then flows out of the hydrocyclone  684  through an hydrocyclone exit  684   b , where the media is distributed in a second and an anoxic zone or region  679   b , comprising a second absorbent/water/microbe mixture, where nitrogen species are absorbed into or onto the absorbent or absorbing media indicated by the dots and the nitrogen species are converted to nitrogen gas by the action of microorganisms in the water in this zone  679   b . Nitrogen-lean water accumulates in the fourth zone  679   d . Cleaned water is withdrawn from the unit  662   a  in the nitrogen-lean region  679   d  through an exit trough  690  connected to a nitrogen-lean water exit conduit  691 . The two absorbing and denitrification regions  679   a - b  are designed to absorb and to convert nitrogen species into nitrogen gas. The resulting nitrogen-lean water exiting through the conduit  691  contains nitrogen concentration less than or equal to (≦) about 20 ppm. In certain embodiments, the nitrogen concentration is less than or equal to (≦) about 15 ppm. In certain embodiments, the nitrogen concentration is less than or equal to (≦) about 10 ppm. In other embodiments, the nitrogen concentration is less than or equal to (≦) about 5 ppm. In certain embodiments, the nitrogen concentration is less than or equal to (≦) about 4 ppm. In certain embodiments, the nitrogen concentration is less than or equal to (≦) about 3 ppm. In certain embodiments, the nitrogen concentration is less than or equal to (≦) about 2 ppm. In certain embodiments, the nitrogen concentration is less than or equal to (≦) about 1 ppm. In certain embodiments, the nitrogen concentration is less than or equal to (≦) about 0.5 ppm. In certain embodiments, the nitrogen concentration is less than or equal to (≦) about 0.4 ppm. In certain embodiments, the nitrogen concentration is less than or equal to (≦) about 0.1 ppm. 
     Fourth Embodiment 
     Referring now to  FIGS. 7A-I , an embodiment of the media collection and lift subsystem, generally  700 , is shown to include three media lift headers  710 , two inducer feed headers  740  and eighteen conduits  760  mounted in a third zone  702  of a denitrification unit  704 . Each media lift header  710  includes a straight stem  712  including six branches  714  distributed in a spaced apart and side to side configuration down a length of the stem  712 . Each branch  714  includes a funneled shaped aperture  716  and an inducer  718 . Each media lift header  710  includes an output manifold  720 . Each media lift header  710  also includes a flush line  722  having an input manifold  724 . The flush line  722  includes an S-bend  726  at a first location  728  near the input manifold  716  so that a straight segment  730  of the flush line  722  is disposed above the stem  712 . The flush line  722  include a second bend  732  at a second location  734  near the output manifold  720 , which angles upward and then downward until it ties into the stem  712  at the second location  734  near the output manifold  720 . The second bend  732  is angled downward by an angle γ as set forth above. The branches  714  are angled with respect to the stem  712  by the angle δ as set forth above. The straight segment  730  of the flush line  722  held in place by standoffs  736 . The media lift headers  710  are held in place by brackets  738 . 
     Each inducer feed header  740  includes an input manifold  742 , an output manifold  744 , two S-bends  746  and a straight segment  748  including nine nozzles  750  distributed in a spaced apart and side to side configuration down a length of the straight segment  748 , with six nozzles on one side and three nozzles on the side. Each nozzle  750  extending out from the header  740  at the angle δ. The S-bends  746  occur at a first location  752  after the input manifold  742  and a second location  754  before the output manifold  744 , where the S-bends  746  position the straight segment  748  between the lift headers  710  and below the lift headers  710  so that the conduits  760  extend up to the inducers  718  of the lift headers  710 . 
     The conduits  760  connect the nozzles  750  of the feed header  740  to the inducers  710 . 
     The manifolds  720 ,  724 ,  742  and  744  extend through an outer wall  706  of the unit  704  at a distance d about a bottom  708  of the unit  704 . The feed header output manifolds  744  are equipped with valves  756  as are the input manifolds  720 ,  724  and  742  (not shown). The output manifolds  720  of the media lift headers  710  are connected to lift lines  770 . The lift line  770  connect to a main line  772 . The main line  772  feeds the hydrocyclone as previously described in the other embodiments. As is true in the embodiment of  FIG. 6C , the embodiment of  FIGS. 7A-I  is capable of the same levels of reduction of nitrogen contaminants as if the case of the embodiment of  FIG. 6C . The main difference between the embodiment of  FIG. 6C  is the medium collection subsystem in the lower zone of the denitrification units. The collection subsystem of  FIG. 7A-I  differs from the collection system of  FIG. 6C  in all of the collections openings are disposed in the same or substantially the same plane, while the collection system of  FIG. 6C  is a staged collections subsystem with collection openings disposed in stages down the length of the RI zone. 
     Detailed Description of Heating and Heat Transfer and Recovery Subsystem 
     Referring now to  FIG. 8A , an embodiment of the heating, heat exchange and recovery subsystem, generally  800 , is shown to include a cool ammonia rich waste water stream  802 , which represents a portion of the effluent from the subsystem  400 . The cool stream  802  is brought into heat exchange relationship with a warm ammonia stripped stream  804 , which represents a portion of the ammonia stripped effluent stream. The streams  802  and  804  are brought into a counter flow relationship with each other in a heat exchanger or heat exchange zone  806 . After passing through the heat exchanger  806 , the cool stream  802  is heated to a heated ammonia rich stream  808  and the warm stream  804  is cooled to a cool ammonia stripped stream  810 , which is returned to the AR subsystem  500 . The heated ammonia rich stream  808  is then passed through a heater  812 , where it is heated to its final temperature to form a hot ammonia rich stream  814 , which is sent back to the AP subsystem  500  to raise a temperature of the subsystem  400  effluent to an optimal temperature for ammonia stripping. A flow rate of the water into and out of the heating, heat exchange and recovery subsystem  800  is controlled such that a temperature of the stream entering the stripper and absorber units is optimal for ammonia gas removal and ammonia gas recovery. 
     Referring now to  FIG. 8B , an embodiment of the heating, heat exchange and recovery subsystem, generally  850 , is show to include a cool ammonia rich waste water stream  852 , which represents a portion of the effluent from the subsystem  400 . The cool stream  852  is brought into heat exchange relationship with a warm ammonia stripped stream  854 , which represents a portion of the ammonia stripped effluent stream. The streams  852  and  854  are brought into a counter flow relationship with each other in a first heat exchanger or heat exchange zone  856 . After passing through the first heat exchanger  856 , the cool stream  852  is heated to form a heated ammonia rich stream  858  and the warm stream  854  is cooled to form a cool ammonia stripped stream  860 , which is returned to the AR subsystem  500 . The heated ammonia rich stream  858  is then passed through a second heat exchanger or heat exchange zone  862 , where it is brought into heat exchange relationship with a hot heat exchange fluid stream  864 . The streams  858  and  864  are brought into a counter flow relationship with each other in the second heat exchanger or heat exchange zone  862 . After passing through the second heat exchanger  862 , the heated stream  858  is heated to its final temperature to form a hot ammonia rich stream  866 , which is sent back to the AP subsystem  500  to raise a temperature of the subsystem  400  effluent to an optimal temperature for ammonia stripping. A flow rate of the water into and out of the heating, heat exchange and recovery subsystem  800  is controlled such that a temperature of the stream entering the stripper and absorber units is optimal for ammonia gas removal and ammonia gas recovery. 
     After passing through the second heat exchange  862 , the hot heat exchange fluid stream  864  forms a cooled heat exchange fluid stream  868 . The cooled heat exchange fluid stream  868  is forwarded to an upper portion  870  of a heat exchange fluid reservoir  872 . A recirculating stream  874  of the heat exchange fluid is pumped by a pump  876  and forwarded to heater  878 , where its temperature is raised to a temperature sufficient to heat the stream  858  to its final temperature to form the stream  864 . 
     Electrical Supply and Control 
     It should be recognized that all sensors, all pumps and all other equipment requiring electric energy to function is supplied through control panels (not shown) connected to a power distribution system. The control panel can include on site or remote control capabilities. If on site, then the control panel will be wired or wireless connected to a control room (not shown). Otherwise, the system can be controlled remotely either via an intranet or the internet. 
     Safe Path Description and Operation 
     The safe path of the present invention is primarily incorporated to overcome the reduced efficiencies of the traditional continuous stirred tank reactor (CNTR) designs and the lack of turndown capability in the plug flow reactor (PER) designs. Using reactor terminology, the safe path is a mixed feed attached reactor. The reduced efficiency arises from a lack of turndown capability in a plug flow reactor (PER) model. Using reactor terminology, the safe path is a mixed feed with attached reactors. 
     Referring now to  FIGS. 9A-C , an embodiment of the system of this invention, generally  900 , is shown to include a precipitation and conditioning stage  902 , an ammonia stripping and neutralization stage  904 , and a denitrification stage  906 . The safe path  908  begins near the effluent  910  from the stage  902  and passes through the other two stages  904  and  906 , sequentially. When all unit operations are off, the inflect flows through the safe path  908  continuously from the inflect to the effluent of the stages  902 ,  904  and  906  as shown in  FIGS. 9A-C . 
     As shown in  FIGS. 9A-C , inflect flows into the stages  904  and  906  through an opening  912  in the stage wall  914  as shown in  FIGS. 9A-C . The momentum of the inflect flow carries it into an apparatus  916  called a momentum block shown in  FIGS. 9D-G  disposed in the safe path  918 . If a stage  904  or  906  is off, pressure will increase in the momentum block  916  forcing the inflect to swirl out of the momentum block  916 , flow around it and pass through the stage into the next downstream stage. 
     If a stage  904  or  906  is on, a recirculation pump  920  draws from the momentum block  916 . If the recirculation pump  920  flow is greater than the incoming inflect flow, the pressure inside the momentum block  916  will lower causing water already in the stage to flow back into a space  922  between the inflect or safe path wall  924  and the momentum block  916 , supplementing flow to the recirculation pump  920 . This mixed flow is described schematically below in  FIG. 10  to illustrate the calculations. 
     The momentum block  916  is shaped for efficient flow, but when placed against the safe path wall  924  is essentially a 3 sided box  926  with a hole  928  in its top  930 . The hole  928  is designed to accept a pump suction tailpipe  932  in such a fashion as to allow top pull out maintenance and reassembly without being able to see the momentum block  916  as shown in  FIG. 9D .  FIG. 9E  shows the safe path opening  934  before placement of the momentum block  916 .  FIG. 9F  shows the momentum block  916  with a separation  936 , in certain embodiments, the separation  936  is about 4½ inch, from the safe path wall  924  containing the safe path opening  934 .  FIG. 9F  shows a fully assembled reactor feed pump assembly  938 . 
     In the safe path configuration of this invention, all liquid entering the tank after the momentum block  916  is from an attached reactor, in this case a denitrification unit discharge. In the denitrification stage  906 , because all safe path discharges are from the denitrification units in this area of the safe path, the safe path may be described as a plug flow tank; therefore, discharge may be mathematically modeled as a PER. The reactor treats a diluted feed like a CNTR model, except that the dilution is controlled because the reactor, the denitrification units, act as attached reactors to the safe path. In the safe path model, the size or volume of the tank (safe path sump) has no relationship to system performance in any steady-state calculation. 
     An Alternate Denitrification Embodiment 
     Referring now to  FIG. 10 , an embodiment of a denitrification system, generally  1100 , is shown to include a waste water inlet conduit  1102  connected to a waste water inlet  1104 . The system  1100  uses an absorbent and microorganisms to absorb and convert nitrates and nitrites into nitrogen gas and consume ammonia/ammonium and/or other nitrogen-containing compound. The denitrification system  1100  includes at least one absorber/biological denitrification unit  1106 . The unit  1106  includes microorganism and microorganism nutrients supply unit  1108  connected to the conduit  1102  via a microorganism/nutrient conduit  1110 . The system  1100  can also include a supply of mineral acid (not show) to adjust the pH of the water to an optimal level and a heating unit (not shown) to adjust the temperature of the water to an optimal temperature. The unit  1106  includes media lift pump assemblies  1112  for recirculating water and media in a two loop configuration. Recirculation water enters the pump  112  through conduit  1114 , which originals in a central region of an ultra low pressure drop hydrocyclone  1116 . The pump  112  pumps the recirculation water into an outlet conduit  1118 . The outlet conduit  1118  is split into three conduits: a reject conduit  1120 , a shut conduit  1122  and a recirculation conduit  1124 . The reject conduit  1120  forwards biomass debris for process. The shut conduit  1122  sends part of the recirculation water into the raw water to improve nutrient utilization. The recirculation conduit  1124  is forwarded to an inducer or media lift subsystem  1126 , where the water flow is used to sweep media collected in the inducer or media lift subsystem  1126  out through a media recirculation conduit  1128 . The water flow into and out of the inducer or media lift subsystem  1126  is sufficient to lift the media for discharge into the ultra low pressure drop hydro cyclone  1116 . The water flow in the inducer or media lift subsystem  1126  is sufficient to shear the media dislodging dead microbes and weakly bound microbial films from the media, but insufficient to reduce the particle size of the media to any appreciable extent, generally less than 0.05% of the particles undergo a reduction in size per cycle with the ultimate goal being less than 0.015% or no particles undergoing a reduction in size per cycle. Minimal reduction in size can be achieve through careful inducer design and water flow rate. The inducer has holes in the top through which the media are collected. The incoming water inlet  1104  is connected to a distributor  1130 . The distributor  1130  include holes in its bottom which are patterned so that the incoming nitrogen-rich, microbial rich and nutrient rich water is evenly or uniformly distributed through the unit  1106  across a cross-section in a first zone  1132   a . In the first zone  1132   a , nutrient and water is evenly or uniformly distributed and, if present, oxygen is depleted through the action of aerobic microbes. As the water flow up and the oxygen contents is dropped below about 0.4 mg/L, an anoxic zone  1132   b  is produced, where the microbes degrade nitrate and nitrites to nitrogen gas. As the water continues to rise, denitrified water accumulates in a clear water zone  1132   c  and is exits the unit  1106  through a trough  1134 , which is connected to an outlet conduit  1136 . As the media enter the hydrocyclone  1116 , clean water from the zone  1132   c  is pulled into a bottom of the hydrocyclone  1116  cleaning the media of the dislodged debris. As the media falls through the denitrification zone  1132   b , microbes degrade nitrate and/or nitrites from the water and from any adsorbed or absorbed nitrates/nitrites in the media. As the media fall past the distributor  1130  and out of the zone  1132   a , the media enters a respiratory inhibited zone  1132   d , where microbial activity is arrested. The media is then collected in the inducer  1126  and recirculated. The final zone  1132   e  in the unit  1106  is a head space filled with gas. 
     Another Alternate Denitrification Embodiment 
     Referring now to  FIG. 11A , a denitrification system  1200  includes at an inlet  1202  connected to an inlet conduit  1201 , where the system is designed to use an absorbent and microorganisms or microbes to absorb and convert nitrates, nitrites, residual ammonia/ammonium, or other nitrogen-containing compound into nitrogen gas or amino acids through bio-synthesis. The denitrification subsystem  1200  includes an absorber/biological denitrification section  1204  and a nutrient supply section  1206 . The absorber/biological denitrification section  1204  includes a plurality of absorber/biological denitrification units  1208 . The nutrient supply section  1206  includes microorganism nutrients tanks  1210  and associated hatches  1211  for filling the tanks  1210 . The nutrient supply section  1206  also includes mineral acid tanks  1212  and associated hatches  1213  for filling the tank. The mineral acid is used in the AR subsystem and in the denitrification subsystem. In the AR subsystem, the mineral acid is used to convert ammonia gas into the ammonium mineral acid salt liquor. In the denitrification subsystem, the mineral acid is used to adjust the pH to the optimal pH for supporting the microorganisms used to convert nitrogen-containing oxide, residue ammonia and other species into nitrogen gas. The denitrification section  1204  includes media lift pump assemblies  1214  for supplying waste water to the units  1208  and recirculation pump assemblies  1215  for supplying nutrients to the units  1208 . The denitrification section  1204  also includes access hatches  1216 . The denitrification subsystem  1200  includes an outlet  1218  connected to a finished effluent conduit  1219 . 
     Referring now to  FIG. 11B , the denitrification subsystem  1200  includes outer and inner walls  1220   a &amp; b . The subsystem  1200  also includes a nutrient enclosure  1221  of the nutrient section  1206  housing the nutrient tanks  1210  and a mineral acid enclosure  1222  of the nutrient section  1206  housing the mineral acid tanks  1212 . The subsystem  1200 . The subsystem  1200  also includes safe paths  1222   a - c , one for each absorber/biological denitrification section  1208 . The paths  1222   a - c  are associated with the recirculation pump assemblies  1215 . The subsystem  1200  also includes auxiliary paths  1224   a - c  with overflow walls  1226  for use with an optional final treatment subsystem (not shown) if needed to bring the denitrified water into final compliance with appropriate federal, state and local governmental regulations or to allow water to de-aerate as the water is discharged from the units  1208 . In certain embodiments, the unit discharge is a partially spiral discharge line that mixes the discharge water with air. The system  1200  also includes a discharge enclosure/reservoir  1228  connected to the outlet  1218 . 
     All references cited herein are incorporated by reference. Although the invention has been disclosed with reference to its preferred embodiments, from reading this description those of skill in the art may appreciate changes and modification that may be made which do not depart from the scope and spirit of the invention as described above and claimed hereafter.