Abstract:
A system and method for treating wastewater including: delivering untreated wastewater into a permeable container disposed in an impoundment. A wastewater input moves untreated wastewater to the interior of the permeable container. Treated wastewater is flowed through the permeable container and is removed via a wastewater output. A method of practicing wastewater treatment, comprising the steps of delivering untreated wastewater into a permeable container contained within an impoundment; treating the wastewater in the permeable container; moving treated wastewater from the interior of the permeable container to a position between the interior of the permeable container and the exterior of the impoundment; and removing the treated wastewater from the impoundment.

Description:
A portion of this patent document contains material that may be subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the U.S. Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to wastewater treatment. More particularly, this invention pertains to a system and method of treating wastewater in a single impoundment by employing an internal permeable treatment container (or a “permeable container”). The permeable container may be made of any permeable material including, but not limited to, geotextile fabric, fabric, porous concrete, sintered metal, or metallic screen. 
     Companies, farms, and governmental entities (such as municipalities) routinely have or receive, and subsequently treat, wastewater for re-use or discharge, the treating being performed under numerous federal and state regulations. Although configurations of wastewater treatment systems can vary widely from system to system, such systems normally operate in several stages. 
     In a first stage (i.e. a “permeable stage”), raw wastewater (influent) flows through a quiescent impoundment in which primary solids are allowed to settle to the bottom of the impoundment. In a second stage, the relatively solids-free wastewater then flows through a secondary treatment reactor where colloidal and soluble organic materials in the wastewater are used as a food source for a biological culture resident in the secondary treatment reactor, and the organic materials are thereby digested and converted to new cells and gaseous byproducts. This second stage may be performed aerobically or anaerobically. In aerobic treatment systems, the byproducts are new cells and carbon dioxide. In anaerobic treatment systems, the byproducts are new cells and other gaseous byproducts that may include methane, hydrogen sulfide, and nitrogen. 
     In a third stage, the wastewater and biological culture (biosolids) then flow through a final clarifier tank where the biosolids are allowed to separate, agglomerate, settle, and thicken. Solids-free wastewater may be discharged or undergo additional treatment. A portion of the biological cells may be returned to the secondary treatment reactor to maintain a desired mass for wastewater treatment. Excess biological solids and permeable solids may undergo additional treatment to reduce mass, reduce putrescible fraction, improve dewatering characteristics, or destroy pathogens. These solids are digested in either aerobic or anaerobic vessels. Digested solids may be then be dewatered, landfarmed, composted, incinerated or landfilled. Dewatering is typically accomplished using various means such as sand-drying beds, vacuum filters, or filter presses to filter in the water fraction from the biosolids. 
     The conventional wastewater treatment system as described above requires the use of three or more impoundments and a dewatering process. Each impoundment must be connected to at least one other impoundment by piping. Consequently, conventional wastewater treatment systems require substantial engineering design, construction expertise, high capital cost, and highly skilled operating personnel. 
     What is needed, then, is a system and method for completely treating wastewater and byproduct biosolids in a permeable container placed within a single impoundment. 
     SUMMARY OF THE INVENTION 
     This invention is a system and method that allows for the treating of wastewater within a single impoundment. Specifically, the invention is a two-part system that will contain wastewater during all of the stages of the wastewater treatment process (i.e., primary clarification, primary solids digestion, biological treatment of organics and nitrogenous compounds, final clarification, biological solids digestion, and solids dewatering). The two parts of the wastewater treatment system are a permeable container that holds the wastewater in contact with the biosolids while the wastewater is being treated, and an impoundment that holds the permeable container, its contents, and any wastewater that has already been treated. An important element of the invention is the permeable container, because it enables consolidation of multiple tanks and stages into one impoundment. This permeable container may be of any construction including, but not limited to, a woven geotextile fabric, a woven fabric, a woven synthetic fabric, a screen, or porous concrete. The permeable container is placed into the impoundment, which is a rigid container such as a tank or lagoon sufficient to completely house the permeable container and the wastewater. More than one permeable container may be housed in an impoundment. 
     In the method of the invention, untreated wastewater may be pumped or may flow via gravity directly into the permeable container. Air, oxygen, nutrients, or other additives may be added directly into the permeable container as well. The contents of the permeable container are completely mixed by either a recirculating pump, an aerator, or both. Biosolids grow and accumulate within the permeable container and on the container walls and provide for the following results: reduction of organic material, converting the material into new cells and gaseous byproducts; oxidation of nitrogenous compounds followed by the reduction of nitrates to nitrogen gas; and auto-oxidation of excess biological solids. The treated wastewater flows or is forced through the walls of the permeable container into the impoundment, from which it is removed by gravity or by pumping. 
     Eventually, the permeable container will reach the end of its useful life, as determined by deteriorating treated-wastewater quality over time. At the end of the permeable container&#39;s useful life, the permeable container will need to be removed and recycled or replaced. To remove the permeable container from the impoundment, biosolids are digested and gravity-dewatered at the end of the system&#39;s life cycle by stopping raw wastewater flow. Mixing or aeration continues for a predetermined period, then the impoundment is substantially drained of liquid, the permeable container will be allowed to drain more of its liquid contents, and the permeable container may be removed, where the remaining contents of the permeable container are allowed to dewater and desiccate. 
     Accordingly, it is an object of the invention to provide a system and method for treating wastewater and byproduct biosolids within a single impoundment. 
     It is a further object of the invention to provide a system and method for treating wastewater using a permeable material as a permeable container. 
     It is a further object of the invention to simplify the wastewater treatment process. 
     It is a further object of the invention to reduce wastewater treatment system construction cost. 
     It is a further object of the invention to have a wastewater treatment system that can be constructed in a short period of time. 
     It is a further object of the invention to reduce prerequisite skills, knowledge, and experience necessary to construct, operate, and maintain a wastewater treatment system. 
     It is a further object of the invention to be scalable -for any quantity of wastewater. 
     It is a further object of the invention to have a wastewater treatment system than can be operated in a limited land area. 
     In addition to the foregoing, further, objects, features, and advantages of the present invention should become more readily apparent to those skilled in the art upon a reading of the following detailed description in conjunction with the drawings, wherein there are shown and described illustrated embodiments of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a simplified schematic of a conventional wastewater treatment system. 
     FIG. 2 is a cross-sectional view of a first embodiment of the invention. 
     FIG. 3 is a plan view of the embodiment of the invention shown in FIG.  2 . 
     FIG. 4 is a cross-sectional view of a second embodiment of the invention. 
     FIG. 5 is a plan view of the embodiment of the invention shown in FIG.  4 . 
     FIG. 6 is a plan view of a third embodiment of the invention. 
     FIG. 7 is a view of the embodiments of the invention shown FIG. 2 or FIG. 4 during dewatering. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, a conventional wastewater treatment system is shown, with three typical water treatment stages, namely: a permeable clarification stage  10 ; an aeration biological treatment stage  11 ; and a final clarification stage.  12 . Arrows in the diagram indicate the flow direction of the wastewater, usually through pipes. In permeable clarification stage  10 , wastewater solids are allowed to settle out over a period of time. The settled solids are moved into a holding tank  13 , where they are digested with or without the presence of oxygen. 
     Further referring to FIG. 1, wastewater is continuously moved from permeable clarification stage  10  to biological treatment stage  11 , where the soluble and colloidal organic materials are utilized as a food source by a biological culture of bacteria. Additives such as nutrients may be added to the wastewater. The specific treatment requirements (such as oxygen requirement, nutrient requirement, or residence time) are prescribed for wastewater on a case-by-case basis as dictated by the composition of the wastewater. 
     Further referring to FIG. 1, wastewater and the biosolids flow continuously from aeration stage  11  to final clarifier stage  12 . The biosolids separate from the wastewater in final clarifier stage. Excess biological solids are wasted to holding tank  13  and are further treated. Remaining solids are returned to the aeration stage  11  to maintain the desired level of biosolids. The treated wastewater is either discharged or may receive additional disinfection or additional treatment. The treated biosolids may be removed to a solids dewatering stage  14 , where the biosolids are prepared for incineration, land application, or other disposal. 
     Referring to FIG. 2, the system of the invention comprises a permeable container  20 , and an impoundment  21 , being of a rigid construction and of sufficient dimensions to contain the permeable container  20  and a desired amount of wastewater. While permeable container  20  is preferably made of panels of geotextile fabric that are sewn together to make essentially a closed ball-shaped bag, permeable container  20  may be made of other types of aquapermeable materials such as fabric, porous concrete, sintered metal, or metallic screen. Impoundment  21  may be a tank made of concrete, steel or plastic, or impoundment  21  may be made of earthen materials (i.e. a lagoon). Any other impoundment sufficient to contain permeable container  20  and an amount of wastewater may be suitable for use as impoundment  21 . Impoundment  21  could even be a fluid-retaining membrane. Further, impoundment  21  may have an open top, or the top may be covered. If the top is covered, a vent would likely be desirable in the cover for venting gaseous byproducts from impoundment  21 . Conventionally, impoundment  21  would also include a discharge line or overflow weir  22  for the controlled discharge of treated wastewater. 
     Continuing in FIG. 2, wastewater is delivered into the permeable container  20  via an opening  23  and preferably a piping system, which may or may not include a pump for moving the wastewater into permeable container  20 . The wastewater may be aerated through a piping system including a known manifold/diffuser system  24  for distributing the air throughout permeable container  20 . Other additives may be added to the wastewater in permeable container  20 . For each additive, an additive delivery system would be required to apply the additives, in each case being delivered through a pipe-and-pump or other conventional additive delivery system peculiar to the additive being added. A mixing pump may also be incorporated with permeable container  20  for mixing the contents of permeable container  20  together during the treating process. 
     The wastewater is forced from the interior of permeable container  20  to the exterior of permeable container  20  into impoundment  21 . This may be accomplished by a pressure difference (called “differential head”) that forces the treated wastewater through the walls of permeable container  20  into the complement of impoundment  21 . The biosolids will remain inside permeable container  20 . 
     Referring to FIG. 3, an aerobic permeable container bioreactor configuration is shown in a plan view. A permeable container  30  may be housed in a natural or artificial impoundment  31 . An influent pipe  32  directs wastewater into the interior of permeable container  30 . An aeration blower  33  is attached via piping to the interior manifold of permeable container  30 , and is arranged to aerate the contents of permeable container  30  in a known manner. Treated wastewater is moved through the walls of permeable container  30  in the manner described above relating to FIG. 2, and an effluent pipe  34  directs treated wastewater from the upper portion of impoundment  31  that is external to permeable container  30 . 
     Referring to FIG. 4, an anaerobic permeable container bioreactor configuration is shown in cross-sectional view with a permeable container  40  housed in a natural or artificial impoundment  41 . An influent pipe  42  directs wastewater into the interior of permeable container  40 . A recycle pump  43  is attached via piping to the interior of permeable container  40 , and is arranged to mix the contents of permeable container  40  in a known manner. Treated wastewater is moved through the walls of permeable container  40  in the manner described above relating to FIG. 2, and an effluent pipe  44  directs treated wastewater from the upper portion of impoundment  41  that is external to permeable container  40 . In this anaerobic treating configuration, a cover  45  is placed over the top of impoundment  41 . The cover  45  may incorporate a vent  46  to allow for the release and collection of gases such as methane that are produced as a byproduct in the anaerobic wastewater treatment process. 
     Referring to FIG. 5, an anaerobic permeable container bioreactor configuration is shown in a plan view. A permeable container  50  may be housed in a natural or artificial impoundment  51 . An influent pipe  52  directs wastewater into the interior of permeable container  50 . A recycle mixer  53  is attached via piping to the interior manifold of permeable container  50 , and is arranged to mix the contents of permeable container  50  in a known manner. Treated wastewater is moved through the walls of permeable container  50  in the manner described above relating to FIG. 4, and an effluent pipe  54  directs treated wastewater from the upper portion of impoundment  51  that is external to permeable container  50 . 
     Referring to FIG. 6, shown is a two-stage wastewater treatment system in which wastewater is first treated anaerobically, then aerobically. In the anaerobic stage, an anaerobic permeable container  60  is housed in a rigid anaerobic impoundment  61 . Anaerobic impoundment  61  is covered in the same manner and for the same purposes as described above relating to FIG.  5 . An influent pipe  62  directs wastewater into the interior of anaerobic permeable container  60 . A recycle pump  63  is attached via piping to the interior of anaerobic permeable container  60 , and is arranged to mix the contents of anaerobic permeable container  60  in a known manner. Treated wastewater is moved through the walls of anaerobic permeable container  60  in the manner described above relating to FIG. 2, and an effluent pipe  64  gravitationally directs anaerobically treated wastewater from anaerobic impoundment  61  to the aerobic stage of the system. 
     Further referring to FIG. 6, in the aerobic stage, an aerobic permeable container  65  is contained within an aerobic impoundment  66 . An influent pipe  64  directs wastewater from anaerobic impoundment  61  into the interior of aerobic permeable container  65 . An aeration pump  67  is attached via piping to a manifold  68  which in turn is connected to a series of aeration pipes  69  interior to aerobic permeable container  65 . Manifold  68  and aeration pipes  69  are arranged to aerate the contents of aerobic permeable container  65  in a known manner. Treated wastewater is moved through the walls of aerobic permeable container  65  in the manner described above relating to FIG. 2, and an effluent pipe  70  directs treated wastewater from impoundment  66 . Although FIG. 6 shows anaerobic treatment followed by aerobic treatment, the treatment sequence could be reversed. Since the anaerobic treatment process produces significantly less weight of sludge per pound of organic material eliminated, the arrangement of the impoundments of FIG. 6 is preferable for treating high-strength wastewater (i.e., wastewater having a relatively high amount of organic material per volume). 
     Referring to FIG. 7, a section view of an aerobic or aerobic embodiment of the invention is shown in the dewatering stage, which would be preferably performed at the end of the useful life of the permeable container. The permeable container would reach the end of its useful life when the operator of the treatment system finds that the quality or quantity of the treated wastewater has deteriorated due to factors such as excessive buildup of biosolids on the permeable container. On a case-by-case basis, the operator of the system may determine that a new permeable container would return the system to its original level of effectiveness in wastewater treatment. At this point, a permeable container  74  would be collapsed as shown from pumping the contents of the impoundment  71  via a pump or gravity drain  73 . Removal of the liquid from permeable container would be performed, leaving essentially a mass of biosolids, organic materials, and inorganic materials in permeable container  74 . Permeable container  74  would then be removed and the contents of permeable container would be disposed of in any conventional manner. A new permeable container  74  would then replace the removed container and wastewater would resume flow as described above. 
     Thus, although there have been described particular embodiments of the present invention of a new and useful Wastewater Treatment System and Method, it is not intended that such references be construed as limitations upon the scope of this invention except as set forth in the following claims.