COMBINED HYDROCYCLONE AND FILTER SYSTEM FOR TREATMENT OF LIQUIDS

Abstract: A method for treating liquid from a liquid source and separating particulate matter from the liquid comprising the following steps: providing a liquid source; pumping said liquid source (3) into at least one hydrocyclone system (30) where said liquid source is gas sparged (448); collecting said liquid source (130) and removing flocculated particles (137) from the surface; and filtering said liquid source through at least one filter.

Description: Combined Hydrocyclone and Filter System for Treatment of Liquids Cross Reference to Related Applications This application is based on a U.S. Provisional Application Serial Number 60/104,175 filed on October 13, 1998 and is a continuation-in-part of U.S. Patent Application Serial Number 09/243,553, filed February 2, 1999 entitled "Fluid Conditioning System and Method", which is a continuation-in-part of U.S. Application Serial Number 09/096,254, filed June 11 , 1998 entitled "Fluid Conditioning System and Method", which in turn is based on U.S. Provisional Application Serial No. 60/052,626 filed on July 15, 1997 entitled "Apparatus and Method for Separating Hydrophobic Particles from a Solution" and U.S. Provisional Application Serial No. 60/073,971 filed February 6, 1998 entitled "Flotation Tank Apparatus and Method." Field ofthe Invention This invention relates generally to large scale industrial liquid conditioning and filtration systems and more specifically to liquid conditioning components, methods and systems including membrane filtration technologies to separate particulates, gases and fluid bound compounds from fluid streams. Background ofthe Invention Filtration technologies that are used to separate particulate matter and gases from fluid solutions such as wastewater are often compromised with the buildup of particulate matter on the membranes or filter media which renders the filter useless and severely disrupts the filtering process. For example, traditional static filtration mechanisms force fluids through membranes or other filtration media until the membrane is clogged or has to be cleaned or replaced. As filters become fouled, their operational performance becomes severely reduced. The complexity of particulates, compounds and microorganisms accumulate along the surface of the filters, retarding the flow of fluid through the filters and often irreversibly degrading the performance ofthe filter surface. This requires costly system shutdowns and replacement of expensive filters. One manner of avoiding the precipitation and compression on filter surfaces of bulk contaminants such as fine mineral clays, cellulosic fibers, fats/oils/greases (FOG), microorganisms and colloidal silica is to change the shape, format and packaging of filter membranes. For example, for situations with high contaminant or clogging agent loading, tubular filters and hollow fiber technologies have been devised. These filters coat either tubes or hollow fibers with large bore size passages, permitting the fluid streams to pass along the surface of the filters at elevated flow rates without being trapped by the support materials and the low tangential flow areas that are common on large, flat surface area membrane sheets. Some of these types of tubular and fiber based filters are mounted on inert support media such as sintered steel or ceramics and achieve reliable performance under aggressive and harsh chemical conditions while avoiding heavy buildup of clogging agents. While these filters have proved efficient, they often result in at least a tenfold increase in cost, requiring massive infrastructure and operational support in comparison to flat sheet or spiral wound filters that can package large filter areas into compact spaces at significantly reduced capital and operational expenses. The continued problem of tradeoff of filter surface area to resistance of fouling agents significantly hinders the implementation of filter technologies. Most applications where filtration technologies could provide a valuable service can not support the expense and complexity of appropriate filtration systems. Filter systems differ and are selective for defined size classes of particulates and dissolved compounds. Surfaces of filters can reject compounds based on charge and their ability to diffuse through filters. Membrane filters are generally defined in terms of microfiltration, ultrafiltration, nanofiltration and reverse osmosis filtration based on the size or molecular weight of the compounds that are being filtered, with microfiltration rejecting the largest compounds and reverse osmosis filtering the smallest compounds. Membrane filters are rated based on the flux of cleaned water across the membrane in given defined environmental conditions. The flux rate, defined as the rate of flow or transfer of fluid across a given membrane of a given surface area in a unit of time, is dependent on such factors as the pressure ofthe retentate (material that is rejected on the surface ofthe membrane) on the surface ofthe membrane, the temperature ofthe fluid, the loading of contaminants and the permeability of the membrane. Membranes are deliberately oversized to ensure that there is sufficient capacity for fluid cleaning and filtering when the membrane surfaces become fouled by retentate. To ensure and even maximize flow rates across the membrane surfaces, systems are operated at elevated pressures to overcome the resistance by the fouling agents and to increase flux rate. However, eventually a membrane will become too impacted by retentate and rendered useless. Regenerating the membrane for reuse often requires cleaning with chemical agents to remove retentate. However, these chemical agents are often corrosive to the membrane filter and degrade it after each cleaning. To address these fundamental limitations, fluid precleaning or prefiltering technologies are increasingly being employed to condition the fluid streams before filtration through filter systems, in an attempt to reduce the fouling agents and contaminants which interfere with optimal performance of filtering membranes. Fundamental to the concept of precleaning technologies is the removal of components from the fluid stream that obstruct fluid flow across filters. Examples of precleaning approaches include, clarification technologies and screening and removal of large particulates. Another precleaning device commonly used in treating fluid in non-membrane applications is the use of polymeric coagulants and flocculants. However, chemical agents used to trap coagulants such as polymeric coagulants, polymeric antifoam and dispersants are generally not compatible with membrane filters. For example, cationic polymers attract negatively charged compounds and collect on the filter surface disrupting the filtration process. This severely limits the potential utility of polymeric coagulants as effective precleaning agents and are therefore generally avoided. For this reason, many water treatment systems use filter systems in a series to compensate for the lack of efficient precleaning techniques. However, what is needed is a system whereby polymeric coagulants and other chemical treatments methods may be used prior to and in conjunction with the membrane filtration system. SUMMARY OF THE INVENTION The present invention is directed to the use of a conditioning chamber in combination with various forms of filtration systems designed to remove particulates, including solids, microbes colloids and microscopic gas bubbles in a fluid stream. The combination of pre-treating fluid with the hydrocyclone system prior to filtering the fluid stream in filtering systems results in a dramatically more efficient fluid treatment system and at a significantly reduced cost. Various embodiments ofthe invention are directed to one or more hydrocyclone systems in isolation or in combination with separation tanks in the fluid stream before, or interspersed between, various filtration systems. Preferred embodiments include hydrocyclone systems that reduce the load of filter fouling components from the fluid stream at various points before the filtration systems. Such points include the source of the fluid load components where these components are generated, collection points where various streams combine and fluid systems that directly feed the filtration system. After bubble-particle aggregates are formed, they need to be separated from the fluid. The separation tank ofthe present invention incorporates features which optimize flotation of bubbles and bubble-particle aggregates from the fluid stream and the accumulation of material at the top ofthe surface where it can be skimmed off the surface of the tank. Due to the specific design of the tank for this purpose, this task is accomplished in a fraction ofthe space required for other flotation systems. This combination of features of increased control of the operational parameters and, increased efficiency ofthe chemical usage in comparison to other treatment systems, permits the repeated treatment ofthe fluid stream in more compact equipment than prior filter pre-treatment technologies. Given the separation of components and small footprint ofthe claimed system ofthe present invention, several different pre-cleaning methods are economical for pre-cleaning ofthe fluid streams before the filter systems. Operational performance from hydrocyclone systems have demonstrated that these systems remove Total Suspended Solids (TSS), Biochemical Oxygen Demand (BOD), Volatile Organic Compounds (VOC), metals, microorganisms, Total Kjehldahl Nitrogen (TKN) and Total Dissolved Solids (TDS) at unprecedented levels from fluid streams. When used in combination with filter systems and prefilter chemical treatment by polymers, the versatility and exceptional performance of these systems are uniquely suited to pretreat the fluids before they are passed through the various filtration systems. Further, due to the optimal performance of the hydrocyclone systems of the present invention, prefilter chemical treatment is permissible and greatly improves the operation of the overall system. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a block diagram of the liquid conditioning system according to one embodiment ofthe invention; Figure 2 is a side perspective view of one embodiment of a conditioning chamber and separation tank; Figure 3 is a top plan view of a liquid conditioning chamber; Figure 4 is a cross-sectional view of a liquid conditioning chamber; Figure 5 is a cross-sectional view of another embodiment of a liquid conditioning chamber; Figure 6 is a cross-sectional view of a liquid conditioning chamber; Figure 7 is a partial cross-sectional view of a collector apparatus; Figure 8 is a cross-sectional view along lines 10 -10 of Figure 7; Figure 9 is a perspective view ofthe collector apparatus of Figure 7; Figure 10 is a partial vertical cross-sectional view along lines 12-12 of Figure 9; Figure 11 is a cross-sectional view of one embodiment of a skimmer apparatus; Figure 12 is a block diagram of the fluid conditioning system described in Example 1 ; Figure 13 is a block diagram of the fluid conditioning system described in Example 2; Figure 14 is a block diagram of the fluid conditioning system described in Example 3; Figure 15 is a block diagram of the fluid conditioning system described in Example 4; Figure 16 is a block diagram of the fluid conditioning system described in Example 5; Figure 17 is a cross-sectional view of one embodiment of a hydrocyclone system; and, Figure 18 is a cross-sectional view of another embodiment of a hydrocyclone system. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to liquid conditioning systems used to pre-treat fluid streams before filtration systems to reduce the load of fluid borne components that impede the flow of fluid through filters or membranes. As previously described, fouling agents and contaminants that reduce the flow of fluids through filters reduce the efficiency and raise the overall cost of fluid treatment systems. If these agents are removed from the fluid stream, the operational parameters of the fluid stream improve. For example, it has been observed in food processing streams that contain high levels of Total Suspended Solids (TSS) and Fats/Oils/Grease (FOG), that the filters clog and require frequent and intense cleaning. The FOG also proves to be damaging to the filtration material directly, irreversibly damaging the filters themselves. Removing these agents from the fluid stream can be accomplished to desired levels of contaminant parameters by systems as described below. For example, in a vegetable processing application, where high levels of TSS and FOG are encountered in the fluid stream, a major source of contaminants is encountered in the effluent from the cannery. To treat this fluid stream with peak flows up to 300 gallons per minute (GPM), a three pass chemistry enhanced system is appropriate. Each pass constitutes the pumping of the cannery effluent through a hydrocyclone system (defined as a cylinder or chamber into which a fluid stream is directed and swirled on the inside wall, thereby generating centrifugal forces in the fluid) which is independently sparged and from which the contaminants are floated to the surface of a flotation or separation tank. Flows of this volume are best accommodated by a 6" Internal Diameter (I.D.) hydrocyclone; however, it is possible to use smaller or larger hydrocyclone systems. In one such example, before the first pass, the fluid is pumped from a collection sump and the pH is adjusted to reduce the surface charges to relative electro-neutrality or near zero Zeta-potential (ZP). This commonly requires a pH control loop which automatically adjusts the delivery of a strong acid or compressed CO 2 or O 2 to the fluid stream before the hydrocyclone system to bring the solution zeta potential to zero. The fluid is pumped from the sump source directly over a coarse screen to remove large solids and debris from the stream. From a collection box of the screening device the fluid is pumped into the feed pump ofthe first hydrocyclone system. At the tangential injection point where the water is introduced into the hydrocyclone, a high molecular weight, high charge density cationic polyacrylamide polymer or other cationic reagent is injected at a concentration as required (e.g., 10- 15 ppm C-498, Cytec Industries). The effluent from the hydrocyclone is delivered into a separation tank that removes the bulk ofthe froth and associated floe particles with it from the water. Referring now to Figures 1 and 2, a liquid conditioning system according to a first embodiment of the present invention, generally designated 30, includes a plurality of modularized components to progressively process an influent carrier liquid stream 32 originating from a solution source (not shown). The respective modules include a conditioning chamber 36 which may be a hydrocyclone system disposed downstream of the influent carrier liquid to receive the liquid and create a bubble-rich environment for a high incidence of bubble-particle collisions and gas transfer from the liquid to the bubbles. However, the conditioning chamber 36 or hydrocyclone system may be open to the atmosphere at the top and without a gas sparge system. Further, the conditioning chamber 36 or hydrocyclone system may be closed at the top which results in a closed liquid vortex creating a partial vacuum or significantly lower than atmospheric gas pressure when liquid is passed through. The input to the conditioning chamber provides for the application of agents to modify the surface chemistry, such as chelating agents, detergents, surfactants, gases, salts, acids and flocculants, at 37, to promote the coagulation and/or modify the desired zeta potential of targeted contaminants for efficient collection and removal. Positioned proximate the conditioning chamber output is a separation or flotation tank 130. The unique modularized construction above allows efficient particle and gas flotation and separation for a wide spectrum of industries and applications while minimizing the footprint, and consequently the size, ofthe overall system. Particles or particulate matter are defined as including, but not limited to, solids, microbes, colloids and microscopic gas bubbles. With continued reference to Figure 1 , the input to the conditioning chamber or hydrocyclone 36 also allows for delivery, at 37, of surface chemistry such as liquid or solid coagulant agents and polymer compounds or other forms of applied energy (e.g., electromagnetic, sonic, ionic, and the like) injected into the liquid to break down and reverse the attraction of the particle to the water and increase particle-to-particle attractions or hydrophobic interfaces. One form of energy is disclosed in co-pending U.S. Patent Application Serial Number 08/979,405 filed November 26, 1997 and entitled "Multi-Modal Method and Apparatus For Treating a Solution", the disclosure of which is expressly incorporated herein by reference. Other potential inputs include in-line mixers or static oil interceptors, floe tubes, or chemical injection means. The general objective ofthe added surface chemistry is to change the natural particle attractivity with the liquid to a repulsion to the liquid and attractive to air bubbles. It is highly desirable to have the particles in the proper state for satisfactory performance of the present invention. The particles may then be extracted from the liquid by introducing large quantities of air, or gas bubbles, to which the particles have a greater likelihood of attachment. Referring now to Figures 1-6, gas bubbles such as air, ozone, or chlorine are injected into the liquid by the conditioning chamber 36 that preferably comprises an air-sparged hydrocyclone or referred to just as a hydrocyclone. The hydrocyclone creates a predetermined spectrum of bubble sizes from less than one micron to several hundred microns in very large quantities. The air-to-water ratio created in the chamber ranges from approximately 2:1 to 50:1, with relative velocities of particles and bubbles of approximately one meter per second. These high ratios and velocities ensure that bubbles and particles collide instantaneously to form an association. This is especially important for small colloidal particles. The relatively large ratio of gas/water and small bubble size creates orders of magnitude more surface area for gas transfer from the solution into the bubbles than in DAFs or other sparged systems. A fundamental principle of the hydrocyclone is derived from the centrifugal acceleration of particles, colloidal suspensions, oils and waters in the spinning fluid ribbon along the inside wall of the hydrocyclone tube. This causes classification by relative densities as well as kinetic coalescence of oil-in-water emulsion, forming larger aggregates which are separated by their relative density from water. The other advantage is the sparging of gases through the walls ofthe porous hydrocyclone wall. This permits large volumes of gases, such as air, to be sheared by the spinning fluid layer into bubbles of a large size range. The velocity ofthe fluid ribbon determines the bubble size inside the fluid layer and in combination with surfactants the bubble size can be controlled to optimally match the size ofthe contaminants that need to be removed from the fluid. The hydrocyclone of the present invention offers several advantages over other flotation systems. For example, air to water ratios of 2:1 - 100:1 can be utilized rather than the maximal 0.15:1 in DAF systems. The bubble size can be optimally tuned to match the particle or suspension components that need to be removed from the fluid stream. Because centrifugal acceleration can reach about one thousand gravity (Gs) and the ribbon is a fraction of an inch deep, coalescence of bubbles and bubble-particle aggregates and flotation to the inside surface of the spinning ribbon occurs in milliseconds rather than minutes in traditional flotation systems. The consequence of these advantages is that the bubble-particle interactions can happen in an extremely compact, highly controlled environment. Due to the kinetic nature of a tangential injection of the fluid at the top of the hydrocyclone, this portion of the fluid stream is very effective at mixing and instantaneously dispersing chemical additives that improve the formation and stability of particle aggregations and bubble formation. The intimacy ofthe mixing process and the rapid display ofthe particulates to the surface active agents, coagulants, flocculants, chelatins or pH adjusting agents ensure instantaneous reaction and adjustment of the surface chemical forces in the hydrocyclone system. Many applications of the hydrocyclone system require no chemical enhancements such as the use of polymers. However, when chemical enhancements are used, sufficient chemical quantities to achieve optimal flotation are often achieved at a concentration of 10 - 30% of those used in DAF or chemical precipitation. This results in operational cost savings as well as reducing the overall chemical burden on the fluid treatment system. Referring more particularly to Figures 2-4 and 6, the hydrocyclone 36 includes a cylindrical containment vessel having an open ended porous tube 40 (Figures 4 and 6) formed of a gas permeable material. The tube includes an interior wall 42 (Fig. 4) defining an inner liquid passage with respective inlet and outlet openings 44 and 46 (Fig. 6). An enlarged cylindrical hollow housing 48 is disposed concentrically around the first tube to form an annular chamber 50. The chamber includes a gas inlet 448 (Fig. 6) coupled to a source of regulated pressurized gas such as air or ozone. As an example, the porous tube 40 may be of a porosity having pore sizes within the range of about 20 to 40 microns. The shearing action of the high velocity water passing by the pores creates bubbles ranging from sub-micron to several hundred microns in size. Referring more particularly to Figures 2 through 5, the hydrocyclone 36 further includes a solution input apparatus or accelerator 52 mounted to the proximal end ofthe housing 48 of the hydrocyclone. The input apparatus may take many forms and acts to manipulate and tangentially direct the flow of input liquid into a helical ribbon- like stream through the liquid passage 42 to eventually exit into the separation tank 130. Figure 3 illustrates one form of input apparatus comprising a fixed restrictor 54 configured to generate a predetermined sized ribbon of helically flowing solution. The restrictor preferably generates an essentially continuous ribbon of solution that swirls around the inner wall of the hydrocyclone. To avoid turbulence that can disrupt the attachment of the particles to the gas-induced bubbles, it is desirable to avoid ribbon overlaps 56 (Figure 4, in phantom) or ribbon gaps 58 (Figure 5). As stated previously, other embodiments ofthe hydrocyclone system 36 may be appropriate. For example in Figure 17, the hydrocyclone 36 may be an open top, induced air hydrocyclone in which the hydrocyclone is not gas sparged. In this hydrocyclone system, the accelerator head 52 is opened to the atmosphere (see opening 49) where hydrocyclone system operates on the principle that high gravity loading centrifucated fluid induces very small bubbles dissolved in the fluid to move through the thin layer of fluid and contact the appropriately sized contaminants in the fluid to form bubble-particle aggregates. The accelerator head 52 also two has opening 51 and 53 for inserting chemicals wherein the openings normally remain sealed. While within the hydrocyclone 36, the bubble-particle aggregates spiral down the length of the hydrocyclone terminating in a vortex 55 and exit into the separation tank in a controlled manner such as not to disrupt the bubble-particle aggregates. Once in the separation tanks, the bubble-particle aggregates float to the surface ofthe separation tank to further aggregate into a large mass aggregation where the aggregation can be removed with a skimmer. Alternatively, the hydrocyclone system 36 may be a closed top, no air hydrocyclone system, whereby the accelerator head 52 is totally closed to the atmosphere as shown in Figure 18. In this embodiment, there is no gas sparging. With the accelerator head 52 closed to the atmosphere, no air is allowed in the vortex 55 region (opening 49 is shut by valve 47). This creates a vacuum within the vortex 55 that further pulls bubble-air aggregates out of the fluid. By removing air as a requirement in this embodiment, power and maintenance requirements are significantly reduced. The performance of this hydrocyclone system compares favorably with gas sparged hydrocyclone systems. With reference to Figures 7-10, the hydrocyclone 36 preferably includes at its outlet a collector apparatus, generally designated 80, to capture and controUably direct substantially particle-free solution. The collector apparatus 80 includes a conical- shaped splay section 82 coupled axially to the hydrocyclone outlet via a coupling ring 84 and a coupling cylinder 86 that concentrically bind the splay section to the hydrocyclone. The splay section is formed with a plurality of radially spaced-apart splay vectors (not shown) to urge the separated solution into a modified downwardly directed flow. The splay section may also be formed in a straight cylindrical configuration without any loss in performance. Further referring to Figure 7, the collector apparatus 80 further includes a torus-shaped trough 90 (see Figure 8) formed with an annular slot 102 and mounted to the distal end ofthe splay section 82. The slot includes an engagement edge or skimmer 101 positioned axially in-line with the expected laminar separation between particle-rich froth, and relatively particle-free solution to skim the separated particle-free solution splaying radially outwardly and downwardly from the conical section. The trough includes a unidirectional solution stop 103 (Figure 8) and an outlet formed into an outwardly projecting and downwardly directed spout 104 to discharge the captured solution as a collected stream. The central portion ofthe trough defines an exit passage 106 for discharging the particle-rich froth on the surface ofthe solution filled separation tank 130. With reference back to Figures 1 and 2, the separation tank 130 is positioned downstream ofthe hydrocyclone 36 and is substantially filled with the output ofthe hydrocyclone. The separation tank, as envisioned in one embodiment, may take the form of a modified dissolved air flotation (DAF) tank (Figure 2), with an open top to receive the separated solution and the froth from the hydrocyclone. A froth skimmer 135 having a plurality of paddles 137 (see Fig. 2) is positioned at the surface ofthe tank to push deposited froth or floe from the surface ofthe solution to a receptacle area 138. To exit treated solution from the tank, an effluent outlet 140 is formed near the bottom portion ofthe tank. In operation, the separation tank 130 is positioned downstream from a solution source that generates an untreated carrier liquid containing one or more varieties of particles or gases. For example, as shown in Figure 12, which illustrates Example 1, untreated carrier liquid originates from four separate sources: a cannery source; a vat room source; a flume source; and, a pitter source. In this Example, untreated carrier liquid (untreated wastewater) is first filtered through a coarse screen to remove large solids and then collected in a large reservoir tank. The untreated wastewater may optionally be pre-treated at this point by adding surface chemistry, at 37, to urge the particles to coalesce. The pH ofthe water may also be adjusted at this point. The water is then pumped to the hydrocyclone 36. The hydrocyclone input apparatus 52 (see Figure 2) receives the carrier liquid stream and restricts the stream to a narrow ribbon, consequently accelerating the resulting ribbon flow along the inner passage 42 in Fig. 4 ofthe housing 48. The ribbon flow is directed tangentially and downwardly to define a helical shape, and creates a substantial centrifugal force acting on the solution. As the solution swirls through the containment vessel, the sparged gas plenum 448 injects gas bubbles into the solution stream. The bubbles collide with particles in the solution and gases dissolved in the water transfer from the higher concentration in the water to the lower concentration in the bubbles. This process forms a froth that floats towards the center of the containment vessel as a result of the centrifugal force acting on the solution. The action of the hydrocyclone on the solution creates a non-turbulent flow between the relatively particle- free solution and the particle-rich froth. It has been discovered that by controlling the ribbon, a more uniform and turbulent-free ribbon through the hydrocyclone results. As the ribbon exits the distal end of the hydrocyclone 36, the swirling helical action causes the particle-free solution to splay outwardly for receipt in the separation tank 130. Simultaneously, the particle-rich froth is deposited on the surface of the separation tank solution for subsequent collection by the froth skimmer 135. In systems utilizing the optional collector apparatus 110 (Fig. 11), the outwardly splaying solution is selectively captured by the trough 115 and directed through the spout 117 for delivery into the body ofthe separation tank solution. This aids in reducing the level of turbulence at the surface of the tank which has been found to hinder flotation tank performance. The particle-rich froth passes through the center of the trough and deposits along surface of the tank. The performance of the collector apparatus is substantially improved by employing the optional skimming apparatus 116 to inject the annular gas stream at a predetermined point between the solution and froth. The effluent is then pumped into a volume control tank where the effluent surface is then skimmed. The effluent from the collection tank is then pumped into a second hydrocyclone for a second pass. In this pass which is treated at the same (or slightly higher) flow rate compared to the first pass, the pH may be adjusted and cationically treated effluent is divided into a parallel hydrocyclone systems where a very high molecular weight anionic, polyacrylamide polymer may be injected (e.g., 5 ppm A-130 HMW; Cytec Industries). The same process as stated previously is repeated. The effluent from these hydrocyclones is delivered to the attached separation tanks where the newly formed floe (a result ofthe formation of a tight network of residual cationic and newly introduced anionic polymer in the second series of hydrocyclones) is floated out of water and skimmed off the surface. This effluent is then pumped into a second storage tank for volume control. The effluent is then further treated in a series of filtration membrane steps which include in sequence bag filtration, ultrafiltration and reverse osmosis which will be described in greater detail in the Examples. Other filtration steps maybe included such as disc filtration, sand filtration, cross membrane filtration and fine screen filtration. These filtration steps remove particulates less than 2 mm in diameter. The treated effluent may then be further treated in activated carbon filters and chlorine dioxide and ozone treatments. Alternative chemical combinations than the ones stated previously may be appropriate. For example, fluid streams containing petrochemical products and metal contaminants may require alternative coagulants instead of pH adjustment before the first pass through the hydrocyclone system. Inorganic compounds such as aluminum salts or organic coagulants such as polyamines may be more appropriate conditioning agents than pH adjustments. These can be injected into the fluid stream, ahead ofthe hydrocyclones or directly into the hydrocyclones. Other agents that can be used to improve flotation include detergents or surfactants (e.g., non-ionic nonyl-phenols or anionic sodium dodecyl sulfate), that reduce the surface tension of the fluid and thereby reduce the bubble size as the gas is sheared off the wall of the sparge tubes. Hydrocyclones containing only surfactants have been very successful at emulsion breaking of both polar and non-polar oils, found in the food processing and petrochemical industries respectively. Other claimed combinations may include metal chelating agents that are injected into the first treatment pass and then followed by cationic and anionic polymers to remove the chelating agents with the associated metals from the stream, in subsequent treatment passes. These agents may be used where trace amounts of transition or heavy metals are found in large volumes of fluid. Combinations of such chemistries have been successful in the removal of cellulosic fibers and mineral clays found in such diverse streams as textile processing and paper and pulp manufacturing. These treatment combinations, because of their tailored chemistries and repeat treatments, exceed the performance of other pretreatments in both economic and operational factors. Due to high air:water ratios, the small bubble sizes and the dynamic path ofthe gas bubbles through the fluid, gas transfer rates are extremely high and the hydrocyclone system of the present invention can be used to remove Volatile Organic Compounds (VOC) or light organic compounds. While this may aid in the removal of components that interfere with membrane systems, it is also an opportunity to introduce reactive gases. Ozone, chlorine or other gases can be introduced in an early pass to disinfect, sanitize or deactivate microbial organisms. Since the filtration membranes are sensitive to oxidative compounds and must not be exposed to reactive gases such as chlorine or ozone, the initial disinfecting gas may be stripped or removed in subsequent passes through hydrocyclones sparged with inert or non-reactive gasses such as nitrogen or air. Examples or removal rates of reactive gasses in non-chemical applications with hydrocyclones are commonly 30 - 50% per pass. Sequential passes of fluid through hydrocyclones have removed VOC and reactive gasses to non-detectable levels. Other agents that are incompatible with membrane systems can be used in the hydrocyclones. For the same reason discussed above in the example of the reactive gasses, agents that interfere with membrane performance are commonly not used upstream of membrane filtration systems. The risk of leaks or residual treatment agents flowing through the system may not be warranted. However, with the option of repeat treatment and the ability to repeat and thereby remove the incompatible agents from the stream, the utility of these agents can be exploited. These polishing or self-cleaning treatments can be repeated several times before the stream is exposed to the membranes. The removal of such incompatible agents is a novel feature that has not yet been possible because ofthe size and operational limitations of prior pre-treatment systems. An alternative to the above treatment is a non-chemical flume or transport stream treatment (Example 1). In certain situations, chemical modifications of the water may be detrimental to the production process and non-chemical treatment may be more appropriate. In circumstances where recycled water passes through a partially or completely closed system or loop, the entire stream can be passed through the hydrocyclone systems repeatedly. However, generally, the average removal of components from the stream by non-chemical means usually is less effective than in chemically enhanced streams, frequent repeat treatment improves the overall stream quality and membrane fouling component load. The advantage of this repeat treatment is that variability of stream components is reduced while overall loads of TSS and associated parameters are commonly reduced as much as 85%. The drain off or spillage from this type of stream entering the general effluent stream is much less contaminated with the membrane fouling agents. Examples of such transport or flume treatments include but are not limited to processing of olives, raisins, grapes, lettuce, vegetables, fruits and sugar beats. In some situations, these streams would precede ultrafiltration to remove proteinaceous or microbial matter, nano filtration to remove sugars or low molecular weight organics or reverse osmosis to remove minerals. Often in these situations, due to lack of surface chemical agents that facilitate the attachment ofthe particles to bubbles, mechanical energy and large volumes of gas are required to improve the performance of non-chemical systems. For this purpose, the aiπwater ratios can be adjusted to 7: 1 - 10:1. This introduces more bubbles and opportunities for particles and microbes to attach and be floated out ofthe system, even if they are less tightly associated than in chemically enhanced systems. In streams that contain free oils or in oil-in-water emulsions, high G forces or acceleration can also be advantageous. When needed, several smaller ID sparge tubes may be run in parallel. For example, a 2" ID sparge tube for a given flow rate produces proportionately higher acceleration in the spinning fluid ribbon than a 6" tube does. To increase the treatment passes through the system, internally recirculating systems may be appropriate. In these situations, the discharge from the receiving tank is combined with the untreated effluent coming into the system. This combination ofthe influent with already treated effluent increases the flow and the volume ofthe fluid that needs to be passed through the hydrocyclones. Due to the acceleration ofthe fluid rate through the hydrocyclone, the resultant fluid volume has to be pumped through the hydrocyclone at an accelerated rate to accommodate the extra volume of recirculating fluid. Because of the acceleration of the fluid flow rate through the hydrocyclone, the bubble sizes sheared off the wall of the sparge tube is reduced, thereby improving the match of the bubble size with that of the particles that need to be removed. Another advantage ofthe adjustment is that the fluid is treated more frequently and the likelihood of successful particle flotation is increased even in situations where bubble particle aggregates are only temporary associations. Combined with the increased aiπwater ratios, these non-chemical systems can frequently attain removal rates of stream components similar to those of chemically enhanced hydrocyclone treatments. Bulk treatment of all plant or process effluents, in situations where all the sources are treated for reuse or discharge, can be warranted. In these situations, high volume treatments may be necessary. Hydrocyclone systems or modules are generally run in parallel to process large volumes of effluent as shown in the Examples. However, hydrocyclone systems may be placed in a serial arrangements. Systems with a footprint of 6' x 12' have been used to treat flows in excess of 900 GPM. Given these advantages in flexibility and modularity combined with the adjustments to operational parameters such as air-flow-rates and acceleration, permits the design of systems that are appropriate for different streams in many industries and processes. Because ofthe modularity, small size and the ability to selectively introduce and then remove agents from the fluid streams, unprecedented pretreatments for membrane filtration systems are attainable. Some of these systems are illustrated in the Examples shown below. Example I Non-chemical Treatment In Olive Processing Example I, which is illustrated in Figure 12, shows an example of non-chemical treatment of effluent from several sources in olive processing. Effluent or waste water is collected from several sources such as a cannery source 202, a vat room source 204, a flume source 206 and a pitter source 208. Waste water or effluent is then filtered through coarse screens 210 to remove large solids and debris from the effluent sources. The effluent is then collected in a large storage tank 212 of approximately 10 6 gallons and the effluent is at an ambient temperature of approximately 70° - 90 °F. The effluent is then pumped and divided into a parallel row of three hydrocyclone systems 214A - 214C in which each hydrocyclone system feeds effluent into an attached separation tank 30 as shown in Figure 2 which removed the bulk of the froth and associated bubble-particle aggregates by froth skimmer 138. Each hydrocyclone has an inner diameter of 6" and a length of 28". The average flow of effluent through each hydrocyclone is approximately 75 up to 310 GPM. The plenum pressure of the gas inside the hydrocyclone ranges from 2.5 psi to 6 psi. Thickness ofthe helical film ranges from 1/4 inch to 1 inch and the air to water ratio ranges from 2:1 to 10:1. The effluent was then pumped to a second central volume control tank 216 where resulting froth and bubble-particle aggregates are skimmed off of the surface of the effluent. The effluent was then pumped to a second trio of parallel hydrocyclones 218 A - 218C ofthe same type as the first set. In this pass, the flow rate was approximately the same compared to the first pass and the effluent was reintroduced into the parallel hydrocyclones 218A - 218C. Once again the effluent was sparged and collected into three separation tanks where the effluent was skimmed. The effluent was then pumped to another central volume control tank 220. Results ofthe pre-membrane or polisher portion ofthe system without the use of chemical additives are shown below. Parameter Lge of % Reduction Average % COD 0% - 20% 10% FOG 0% - 95% 10% TSS 0% - 76% 10% Microbes 5% - 67% 32% The effluent was then pumped though a bag filter system 222 comprised of static filtration bags (not cross flow) with 100 micron pore size (10 bags of approximately 3 feet square for a total of 30 ft 2 ) . The effluent was then pumped to a ultrafiltration system 224 comprised of 6 banks of 8" type JX constant pressure, variable flow filters manufactured by Osmonics. The membrane consists of spiral wound polyvinylidene diflouride. After the ultrafiltration step 224, the water was pumped through volume control tank 226 to a reverse osmosis filtration step at 228. The reverse osmosis filter comprised of a constant flow, variable pressure trilaminate type AG, Osmonic filter. The effluent was then passed through an activated carbon filter 230 and a chlorine dioxide and ozone disinfection step 232. The hydrocyclone system processing resulted in significant improvement to the effluent stream prior to the bag filter step 222. The results demonstrate that without the hydrocyclone system steps of 214A - C and 218A - C, the bag filters were required to be changed every 20 minutes to 2 hours. By utilizing hydrocyclone systems 214A - C and 218A - C, the bag filter replacement time increased to 4 - 8 hours. The chart below demonstrates the increase in runtime (defined as time from the start ofthe first bank of filter to startup of last bank. Banks are operated sequentially to a minimum flux before switching to the next bank), flux, number of banks used to treat the same volume of water and the runtime to shut down. UF BEFORE AFTER Runtime 2 hours 4 hours Flux 200,000 gal/day 350,00 gallons/day Number of banks 6 banks 4 - 6 banks used up treatment of required volume of water Run time to Shut down 8 - 12 hours 16 hours Reverse Osmosis no change The use of hydrocyclone systems ofthe present invention for treating the fluid stream demonstrate a significant increase in runtime of the ultrafilters with a compounding increase (200,000 to 350,000 gallons) of fluid processed. Thus, the run time increased by a factor of two and the flux nearly doubled. Further, the number of banks required to process this increased amount of water was nearly halved. Example II Non Chemical Treatment In Cheese Processing Example II, which is illustrated in Figure 13, illustrates an example of non- chemical treatment of wastewater from cheese processing sources. The object was microbe removal from a 350,000 gallon storage tank and to treat up to 400,000 gallons per day. The wastewater or effluent from the cheese processing source 240 was pumped to a collection sump 242 and then pumped to a 350,000 gallon volume control or equalization tank 244. The effluent was then pumped to three parallel hydrocyclone systems 246 with inner diameters of 6" and lengths of 27". Each hydrocyclone system was capable of processing 320 gallons per minute and had a stainless steel porous tube with 40 um pore size. The plenum pressure of the gas ranged from 6 to 7 psi, the aiπwater ration averaged at 6:1 and the water averaged a temperature of 128°F. The effluent was delivered through the hydrocyclone systems 246 and into separation tanks 30 as illustrated in Figure 2 which removed froth by froth skimmer 138. The water was then recirculated to the original 350,000 gallon storage tank to keep microbes from growing in the stored water. The effluent was then pumped and filtered through a nylon fiber screen 248 manufactured by Laikos. The pH of he effluent was then adjusted by the additional NaOH to pH 10 with 30% NaOH. The effluent was then heated to 140° F and pumped to oscillating ultra filter membranes for further filtration and then finally pumped to an oscillating reverse osmosis membrane systems 252 then to disposal by land application. The results demonstrated a dramatic reduction of TSS at the hydrocyclone step of 54.8%). There was a 16.1 % reduction of COD at the hydrocyclone step and a microbial reduction of 18 - 24 fold prior to entering into the filtration process. These results were achieved by recirculating the tank 244 water 3.8 times over a period of 22.5 hours. Without treatment, the microbes increased 4 fold (from 14 million to 54 million Standard Plate Count), significantly impending membrane flux. Microbial byproducts fouled the membranes within 8 - 12 hours. With the non-chemical pretreatment these runs were extended to 20 hours. Example III Chemical Treatment In Cheese Precessing Example III, which is illustrated in Fig. 14, shows an example of treatment of waste water in cheese processing with chemical additives. The objective was removal of Total Suspended Solids (TSS) and Chemical Oxygen Demand (COD) compounds in processing an amount of approximately 1,200,000 gallons of fluid per day. The waste water from the source 240 was pumped into a collection sump and then pumped into the 350,000 gal volume control or equalization tank 244. The effluent was then pumped to three parallel hydrocyclone systems 246 with inner diameters of 6" and lengths of 27". Each hydrocyclone system was capable of processing 320 gallons per minute. Each hydrocyclone system had a stainless steel porous tube with 40 um pore size. The plenum pressure of the gas ranged from 3 to 5 psi, air:water ratio was maintained at 4:1 and the water temp averaged at 128° F. Prior to treatment by the hydrocyclone systems, the pH of the effluent was adjusted by the addition of sulfuric acid to obtain a pH of 6.2. Also added prior to treatment by the hydrocyclone was the addition of high molecular weight polyacrylamide aqueous polymers at 10-20 ppm [Cytec 234GD]. The effluent was delivered through the hydrocyclone systems 246 and into separation tanks 30 as illustrated in Figure 2 which removed froth by froth skimmer 138. The water was then pumped to a second 350,000 gallon volume control tank 247 The effluent was then pumped and filtered through a nylon fiber screen 248 manufactured by Laikos. The pH ofthe effluent was adjusted by the addition of NaOH to pH 10. The effluent was then heated and pumped to oscillating ultra filter membranes for further filtration and finally pumped to oscillating reverse osmosis membrane systems 252. The results show a reduction of 96 to 98% of TSS and a 28% reduction of large molecular weight COD prior to entry into the filtration steps. This resulted in a major increase in efficiency of the overall system by increasing the runtime before system cleaning 8 - 16 hours (without treatment) to 16 - 36 hours with treatment. Example IV Non Chemical Treatment Poultry Effluent Example IV, shown in Figure 15, demonstrates an example of non-chemical treatment of effluent from an 80,000 gallon poultry chiller. The objective was fat/oil/grease [FOG] removal to increase flux rates and to increase run time before filter failure. The effluent was recirculated through a cooling tower 256 to cool the effluent to less than 40° F and then pumped to a first series of two hydrocyclones 258 in series each with a porous high density polyethylene tube of a length of 10" and an internal diameter of 2". The hydrocyclone systems 258 each have a positive displacement blower type. The flow rate of the water ranged from 5 to 12 GPM. The water was maintained roughly at a temperature of 48 ° F with an aiπwater ratio ranging from 4: 1 to 11 : 1. After the effluent was passed through the hydrocyclones, the effluent was delivered into the attached separation tanks for removal of surface froth. The effluent was then pumped to another hydrocyclone system 260 ofthe same type previously described and the same process was repeated. The effluent was then pumped to a surge tank 262 where the effluent was heated to roughly 120° F. The effluent was then pumped to an ultrafiltration system with polysulfone membranes manufactured by Koch with pore sizes of 0.02 um. The effluent was further pumped to a surge tank 266 and then pumped to a reverse osmosis system 268 and the effluent was disinfected 270 and then recirculated to the poultry chiller 254. The results demonstrated that treatment by the two sets of hydrocyclone systems 258 and 260 showed a decrease of TSS of 54% [433 ppm to 199 ppm], a decrease of CODs of 76% [5525 ppm to 1326 ppm] and a decrease of approximately 85% FOG. The downstream filter performance improved and the microfilters showed an ability to process 50 - 60 gallons of effluent in a range of 32 minutes to 50 minutes down from a range of 90 minutes to 120 minutes. The overall flux rate ofthe ultrafilter showed a 40% improvement. Example V Chemical Treatment Poultry Effluent Example V, shown in Figure 16, is similar to Example 4, but uses the addition of cationic and anionic polyacrylamide polymers in the pre-filtration steps. Effluent from an 80,000 gallon poultry chiller 254 was circulated through a cooling tower 256 to cool the effluent to 40° F. The effluent was pumped to the first hydrocyclone 258 ofthe type described in Example IV. However, prior to the effluent entering hydrocyclones system 258, a high molecular weight medium charge density, cationic polyacrylamide polymer was added to the effluent source at a concentration of 20 ppm. When air sparged operation was used, the aiπwater ratio ranged from 7: 1 to 4: 1 with 4: 1 being optimal. However, superior results were obtained running no air-sparge (hydrocyclone head open to atmosphere) induced air mode and in a partial vacuum mode (hydrocyclone head closed to atmospheric and no air sparging). After passing through the separation tanks 30 for removal of surface froth as previously described, the effluent was pumped to a second hydrocyclone 260 identical to the first one. However, prior to entry into the second hydrocyclone system, a high molecular weight anionic polyacrylamide polymer was added [A- 130 HMW Cytec Industries at 5 ppm]. After passage through the hydrocyclone system set 260 the effluent passed through attached separation tanks 30 for the removal ofthe froth. The effluent was then pumped to a surge tank 262 from where the effluent was then pumped to an ultrafiltration system with polysulfone membranes manufactured by Koch with a pore size of 0.02 um. The effluent was further pumped to a surge tank and then further pumped to a reverse osmosis system 268 and finally to a disinfection step 270 and then recirculated to the poultry chiller 254. The results demonstrated an 87% COD removal [4238 ppm reduced to 572 ppm] and a 97% TSS removal [1033 ppm reduced to 33 ppm] by the two sets of hydrocyclone systems 258 and 260 prior to the effluent entering the ultrafiltration step at 264. The flux rate increased significantly at the ultrafiltration step in comparison to the same step in Example IV. However, flux fell to where it would have been if there had been no hydrocyclone system treatment in 25 minutes due to residual polymers This Example illustrates the importance of choosing the correct polymer- membrane combination. If the surface chemical properties of the filtration medium is incompatible with the polymers (anionic surfaces such as regenerated cellulose, sulfonated polysulfone or polysulfone), then even very small amounts of polymers will eventually accumulate on the filtration media, degrading their properties. This also demonstrates the disproportional advantage of the non-chemical hydrocyclone, which significantly enhanced the performance of the filtration media.

Claims: WHAT IS CLAIMED 1. A method of conditioning fluid streams comprising the following steps: providing a fluid stream; providing at least one conditioning chamber in communication with the fluid stream; passing the fluid stream through the conditioning chamber to condition the fluid stream; and, passing the fluid stream through a filtration system wherein the filtration system filters particles less than 2 mm in diameter. 2. The method of claim 2 wherein at least one conditioning chamber includes a hydrocyclone system. 3. The method of claim 2 wherein the fluid stream passes through the hydrocyclone system is generally configured to pass the liquid therethrough in a generally helical manner. 4. The method of claim 1 wherein the fluid stream passes through the conditioning chamber and into a separation tank. 5. The method of claim 1 wherein the fluid stream is mixed with air by venting a fluid vortex formed within the hydrocyclone system to a gas source and using the vortex to induce the gas into the fluid stream. 6. The method of claim 2 wherein the fluid stream is gas sparged while the fluid stream is in the hydrocyclone system. 7. The method of claim 1 wherein agents that modify surface chemistry are added to the fluid stream before the fluid stream is passed through the conditioning chamber. 8. The method of claim 2 wherein the hydrocyclone system is closed to the atmosphere creating a partial vacuum inside the hydrocyclone. 9. The method of claim 7 wherein such agents include chelating agents, detergents, surfactant, coagulants, gases, polymers, salts, acids and flocculants. 10. A method for treating liquid from a liquid source and separating particulate matter from the liquid comprising the following steps: providing a liquid source; pumping said liquid source into at least one hydrocyclone system where said liquid source is gas sparged; collecting said liquid source and removing flocculated particles from the surface; and, filtering said liquid source through at least one filter. 11. The method of claim 10 wherein said liquid source is recycled by returning the treated liquid to its original source. 12. The method of claim 10 wherein the liquid source is passed into parallel hydrocyclone systems. 13. The method of claim 10 wherein the liquid is pumped or flows by gravity from the hydrocyclone system to a volume control tank. 14. The method of claim 10 wherein the liquid flows by gravity from the hydrocyclone system to a volume control. 15. The method of claim 12 wherein the liquid source is passed into a second set of hydrocyclone systems. 16. The method of claim 10 wherein the liquid source after passing through the hydrocyclone system is filtered through at least one filter capable of removing particles with a diameter less than 2 mm. 17. A method for receiving separating particulate matter from a liquid source comprising: providing a liquid source; moving said liquid from the liquid source to at least one conditioning chamber, the conditioning chamber comprising an inlet adapted to receive liquid and an outlet in communication with a separation tank; passing said liquid through said at least one conditioning chamber; passing said liquid to a volume control tank; and, passing said liquid through a series of filtration steps. 18. The method of claim 17 wherein O 2 gas or acid is added to the liquid prior to passing the liquid through said at least one conditioning chamber. 19. The method claim of 17 wherein acid is added to the liquid prior to passing the liquid through said at lest one conditioning chamber. 20. The method of claim 17 wherein said conditioning chamber comprises a hydrocyclone system. 21. The method of claim 17 wherein agents that modify surface chemistry are added to the liquid source. 22. The method of claim 17 wherein the filtration steps comprise bag filters, ultrafiltration and reverse osmosis. 23. The method of claim 17 wherein the filtration steps include at least one of the following filtration steps: microfiltrations; ultrafiltration; nanofiltration reverse osmosis; static filtration; cross-flow membrane filtration; disc filtration; bag filtration; sand filtration and fine screen filtration. 24. The method of claim 17 wherein the filtration steps are any filter capable of removing particles less than 2 mm in diameter.

Inventors: HENDRICKSON DEAN E, JOVINE RAFFAEL V M, MORSE DWAIN E, MORSE MICHAEL P, HENDRICKSON, DEAN, E., JOVINE, RAFFAEL, V., M., MORSE, DWAIN, E., MORSE, MICHAEL, P.
Applicants: HENDRICKSON DEAN E, JOVINE RAFFAEL V M, MORSE DWAIN E, MORSE MICHAEL P, ZPM INC, HENDRICKSON, DEAN, E., JOVINE, RAFFAEL, V., M., MORSE, DWAIN, E., MORSE, MICHAEL, P., ZPM, INC.
Application year: 1999
Main classification: B01D17
IPC codes: B03D1, B04C3, B04C5, B04C11, C02F1