MXPA97002325A

MXPA97002325A - Method and apparatus for the treatment of rich water in nutrien

Info

Publication number: MXPA97002325A
Application number: MXPA/A/1997/002325A
Authority: MX
Inventors: C Kimmel Ronald
Original assignee: Rjjb & G Inc
Priority date: 1994-09-28
Filing date: 1997-03-31
Publication date: 1997-06-01

Abstract

The present invention relates to a multi-stage treatment system (10) for treating water rich in nutrients containing nitrogen, phosphorus and other mineral compounds. Three or more containers or stages (20, 30, 40) typically constitute the multi-stage treatment system (10). Each stage of the system is a reaction vessel (20, 30, 40) having a first zone (22, 32, 42) containing a substantially insoluble salt to precipitate phosphorus and other mineral compounds, a second zone (24, 34, 44) containing a microorganism retained in an inert substrate to convert nitrogen compounds, and a separation device (26, 36, 46) to remove precipitates from water. The effluent from the multi-stage system can be further treated in ponds (60, 65, 70) grown with watergrass or in a packed algae filter (100) having a means (108) to support the growth of the algae and a artificial light source (104). The most representative figure of the invention is the number

Description

METHOD AND APPARATUS FOR THE TREATMENT OF RICH WATER IN NUTRIENTS Background of the Invention Technical Field This invention relates in general to the treatment of water rich in nutrients. More particularly, it is related to a physicochemical and microbiological process and to an apparatus for removing nitrogen and phosphorus compounds from bodies of water. Background of the Art Water typically contains a variety of contaminants. For example, the one that leaves agricultural land contains fertilizer, fertilizers and pesticides. The effluent from municipal secondary water treatment plants contains nitrogen and phosphorus compounds. Moreover, phosphorus and nitrogen compounds accumulate over time in aquaculture waters and aquariums. The above examples of contaminated water all have in common relatively high levels of nutrients containing phosphorus, nitrogen, and other mineral compounds. These types of waters receive greater scrutiny because of their detrimental effects on the environment. Various methods for handling organic and inorganic contaminants in waste water are known. For example, the Patent of the United States of North America Number: 3,957,622; U.S. Patent Number: 3,980,556; U.S. Patent Number: 4,500,429; U.S. Patent Number: 4,664,803; U.S. Patent Number: 4,780,207; U.S. Patent Number: 4,919,815; and U.S. Patent Number: 4,931,183 describe the use of biological treatment to remove carbonaceous and nitrogen compounds from wastewater. The description of the foregoing patents, and of other articles and patents cited herein, are incorporated by reference as if they were fully presented herein. Other processes use vegetation and soil to remove contaminants from wastewater, sometimes together with biological treatment. See, e.g., United States of America Patent Number: 681,884; U.S. Patent Number: 5,137,625; U.S. Patent Number: 5,156,741. Finally, U.S. Patent Number: 5,106,504 describes an artificial water reservoir system planted with aquatic vegetation to remove contaminants from standing water. However, there is still much to be done to treat water economically and compactly, which has a lot of nutrient content.

As a result, there is a need for a low cost treatment system to handle water that has a high nutrient content. This system would be useful to treat the contamination of stagnant water systems for agricultural use, aquaculture and aquariums, swamp water contamination and channels and effluents from municipal secondary sewage treatment plants. Description of the Invention A version of the invention provides a method of treating nutrient-rich water containing nitrogen, phosphorus, and other mineral compounds comprising the following steps in order: feeding the nutrient-rich water to at least one first container of reaction having a first zone containing a substantially insoluble basic salt and a second zone containing aerobic microorganisms retained in an inert substrate; controlling the flow rate of the water to carry out in the first reaction vessel the reactions of: maintaining the pH of the water in the first zone to precipitate at least a portion of the phosphorus compounds and other minerals, and oxidizing biologically in the second zone under aerobic conditions at least a portion of the nitrogen compounds in nitrites and nitrates, - separate the phosphorus and minerals precipitated from the water; feeding the water separated from the first container to at least one second reaction vessel having a first zone containing a substantially insoluble basic salt and a second zone containing anaerobic microorganisms retained in an inert substrate, - controlling the flow rate of the water to carry out in the second reaction vessel the reactions of: maintaining the pH of the water in the first zone to precipitate at least a portion of the phosphorus and other mineral compounds, and reducing biologically in the second zone under anaerobic conditions at least a portion of the nitrites and nitrates to nitrogenous gas; separating the phosphorus and minerals precipitated from the water, - feeding the water separated from the second container to at least one third reaction vessel having a first zone containing a substantially insoluble basic salt and a second zone containing aerobic microorganisms retained in a substrate inert; aerating the third reaction vessel; control the flow rate of the water to carry out in the third reaction vessel the reactions of: raising the pH of the water in the first zone and thereby precipitating at least a portion of the phosphorus and other mineral compounds, and oxidizing biologically in the second zone at least a portion of nitrogen compounds not oxidized in nitrates; Separate phosphorus and minerals precipitated from water; and removing the water separated from the third reaction vessel at a rate to reach a stable state.

Preferably, the substantially insoluble basic salt is dolomite and the inert substrate is volcanic rock. The method may also include the additional step of feeding the separated water removed from the third reaction vessel to at least one pond having an inlet, an outlet, and a plurality of flutes disposed at the bottom of the pond. Preferably, the at least one pond is progressively more shallow from the entrance to the outlet and is cultivated with watergrass. The water grass is preferably cabomba grass. The first reaction vessel, the second reaction vessel, and the third reaction vessel may be a plurality of vessels with zoneis in series. Another version of the invention provides an apparatus for treating nutrient-rich water containing nitrogen, phosphorus and other mineral compounds comprising: at least a first reaction vessel having a first zone containing a substantially insoluble basic salt and a second one zone containing aerobic microorganisms retained in an inert substrate, the first container having an inlet for feeding the nutrient-rich water to the first zone, and with the first zone and the second zone arranged adjacent to each other and separated by a perforated support adapted to the measure to retain the insoluble salt while allowing the nutrient-rich water to pass therethrough, - a first separation device arranged to receive water from the second zone of the first container and to separate the precipitates therefrom, -lement transfer to remove water from the first separation device; at least one second reaction vessel having an inlet for accepting water from the transfer element, the second vessel having a reaction. a first zone containing a substantially insoluble basic salt and a second zone containing anaerobic microorganisms retained in an inert substrate, the first zone in fluid communication with the inlet, and with the first zone and the second zone disposed adjacent to each other and separated by a perforated support of the appropriate size to retain the insoluble salt while allowing the water to pass therethrough, - a second separation device arranged to receive water from the second zone of the second container and to separate the precipitates from the same, - transfer elements to remove water from the second separation device, - at least ur. third reaction vessel having an inlet for accepting water from the transfer member, the third reaction vessel having a first zone containing a substantially insoluble basic salt and a second zone containing aerobic microorganisms retained in an inert substrate, the first zone being in fluid communication with the interdeck, with the first zone and the second zone arranged adjacent to each other and separated by a perforated support of adequate size to retain the insoluble salt while allowing the water to pass therethrough, - a third separation device arranged to receive water from the second zone of the third container and to separate the precipitates from it; a transfer element for removing the water from the third separation device; and an aeration device for injecting air into the second zone of the third container and a vent disposed in the first zone of the third container for removing gas. The substantially insoluble basic salt is preferably dolomite and the inert substrate is volcanic rock. The transfer element of the third reaction vessel is preferably a furrowed spill. The apparatus may include at least one pond in fluid communication with the furrowed spill having an inlet, an outlet, and a plurality of flutes disposed at the bottom of the pond. Preferably, the at least one pond is progressively more superficial from the entrance to the exit. At least one pond can be cultivated with water grass. The aquatic grass is preferably cabomba grass. The apparatus may include each of the first reaction vessel, the second reaction vessel, and the third reaction vessel being a plurality of vessels in series zones. Another aspect of the present invention provides an algae filter for treating water comprising a container having an inlet and an outlet, - a medium disposed in the container by which the medium is capable of supporting the growth of algae; and a source of artificial light mounted on the container so as to direct light on the medium that supports the growth of algae. "Mounted in the container" means either external or internal to the container. Preferably, the artificial light source contains ultraviolet light. Another aspect of the algae filter provides a full range in the container, the plenum having at least one transparent wall, wherein the means for supporting the growth of algae is external to the plenum and the artificial light source is mounted in the plenum. . Preferably, the at least one transparent wall of the plenum comprises a poly (methyl methacrylate) thermoplastic polymer ("Plexiglas"). The medium arranged in the algae filter preferably comprises one or a plurality of perforated trays. The perforated tray is preferably transparent, - more preferably it is "Plexiglas". The algae filter inlet advantageously has a spout for distributing water on the medium. The medium may also comprise a fixed or fluid bed of packing material or particles, respectively. The packaging material is preferably transparent. The objects of the invention, therefore, include providing a method and apparatus for treating water that has a high nutrient content which: (a) results in efficient removal of nitrogen and phosphorus compounds in the water; (b) provides cost effective installation and operation, - [c) provides a waste of ore and mud that has value to condition and fertilize the land; (d) provides a mineral waste and sludge that can be disposed of safely in the soil, - (e) provides the elimination of residual traces of contaminants by cultivating pastures that can be harvested and used as a fertilizer base; and (f) provides a nutrient-rich water treatment system that is capable of effectively removing nutrients in either fresh or salt water regimes. These and still other objects and advantages of the present invention will be apparent in the description that follows. However, this description is only of the preferred embodiments. Therefore, the claims should be consulted in order to assess the full scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic of the apparatus and method of one embodiment of the present invention. Figure 2 is a plan view of the apparatus of another embodiment of the present invention, and Figure 3 is a schematic of an algae filter. BEST MODALITIES FOR CARRYING OUT THE INVENTION Turning now to Figure 1, Figure 10 represents the multi-stage treatment system of the present invention. Three or more vessels or stages typically constitute the multistage treatment system 10. The nutrient-rich water source may include secondary or tertiary effluent from municipal waste treatment plants, stagnant water for agricultural use, aquarium systems or water treatment systems. aquaculture, canals, and other bodies of water (eg, marshy lands). The nutrient-rich water enters via line 21 into the first reaction vessel 20. The feed containment system 15 (eg, a pond or a container) stores nutrient-rich water for introduction into the stage treatment system. 10. The pumping station 17 feeds the water to the line 21. The first reaction vessel 20 can include enough dead work on top of the first zone 22 so that the nutrient-rich water can be fed by gravity through the remainder of the multi-stage treatment system 10. The reaction vessel 20 has a first zone 22 of substantially basic insoluble basic salt supported by a perforated sopoite 23 of adequate size to retain the salt but allowing water to pass through it. The first reaction vessel 20 also contains a second zone 24 having an inert substrate which retains an aerobic microorganism. The inert substrate is supported by the perforated support 25 which retains the inert substrate at the same interface that allows water to pass therethrough. The basic salt of the first zone 22 has a particle size that allows sufficient interparticle vacuum to allow water to pass therethrough while providing adequate surface area to make contact with water. The design is preferably that of a percolation packed bed filter. By "substantially insoluble" we mean that the basic salt is sufficiently insoluble in water so that it retains its packed-bed character while in operation. By "basic salt" we mean a salt in the sense of a Bronsted base that is capable of acquiring protons of another substance. Preferably, the basic salt is magnesium carbonate or calcium carbonate salt. More preferably, the basic salt is dolomite. By dolomite we mean a limestone (CaC03) typically comprising at least 5 percent MgC03. The basic salt should be able to maintain the pH of the water above 6.8, preferably above 7.2, and more preferably 8.5-9. The basic salt preferably is a mixture of particles ranging from 1.27 centimeters to 10.16 centimeters in diameter.

The inert substrate of the second zone 24 also preferably has the characteristics of a packed percolation bed filter. The inert substrate is preferably a solid such as activated carbon, various forms of clay, very fine ash and the like. The most preferred inert substrate is broken volcanic rock. The inert substrate preferably has a large ratio of surface area to volume to provide good contact with water and a support for bacterial growth. The inert substrate is preferably a mixture of particles ranging from 1.27 centimeters to 10.16 centimeters in diameter. The aerobic bacteria can be that of nitrosomonas or nitrobacteria. The second zone 24 can be planted biologically with a mixture of fertilizer and water. The volumetric ratio of the first zone 22 against the second zone 24 depends on the chemistry of the water and the application, but it can be typically 60:40 to 50:50. The reaction vessel 20 preferably has vent 29 to remove any ammonia formed by raising the pH. Each of the reaction vessels 20, 30, and 40 can be constructed of steel sheet material that is epoxy coated and preferably portable. For larger permanent installations reaction vessels are preferably constructed of concrete.

The lower zone 26 acts as a device to allow the precipitated minerals to separate from the water. This zone can be a sloping hopper that allows the precipitate to settle on a cone-shaped bottom where solids can be removed. The pump 27 removes the clarified water and injects it via line 31 to the second reaction vessel 30 (or the water can simply be fed by gravity.). The precipitation device of zone 26 can also be any conventional solid / liquid separation device such as a centrifuge or a rotary vacuum filter. The second reaction vessel 30 copies the design of the first with zones 32, 34, and 36 (corresponding to zones 22, 24, 26, respectively) except that the inert substrate of the second zone 34 retains an anaerobic microorganism. The elements 33 and 35 are also a perforated support member. The anaerobic microorganism of the second zone 34 is preferably an optional organism capable of using oxygen in nitrates. The second zone 34 can also be planted with a mixture of fertilizer and water. The second reaction cell 30 is constructed to eliminate any contact with air and light and is equipped with a vent 38 to remove the nitrogen formed by the microbiological activity. The volumetric ratio of the first zone 32 against the second zone 34 depends on the chemistry of the water and the application, but it can be typically 10:90. The pump 37 transports water separated from the reaction vessel 30 via the line 41 to the reaction vessel 40 (or the water can be fed by simple gravity). The reaction vessel 40 has the zones 42, 44, and 46 corresponding to the zones of the reaction vessels 20 (zones 22, 24, 26) and 30 (zones 32, 34, 36). However, the reaction vessel 40 is positively aerated through the line 48 to the second zone 44. A vent line 49 provides exhaust from the air and any nitrogen formed. The elements 43 and 45 are also a perforated support member. The second zone 44 contains an aerobic microorganism retained in the inert substrate to convert the residual nitrates to nitrogen. The volumetric ratio of the first zone 42 against the second zone 44 depends on the chemistry of the water and the application, but it can be typically 10:90. Turning now to Figure 2, the effluent 47 of the reaction vessel 40 travels over at least one weir 50 to at least one pond 60. The pond 60 is furrowed with progressively more shallow depths towards the outlet to the second pond 65. The second pond 65 preferably has a depressed settlement area 67 that is deeper than the rest of the pond: 65. This settlement area serves as an additional element to remove sludge and precipitate. The outlet of the pond 65 then enters the third pond 70. The pond 70 is also furrowed with progressively shallower depths towards the outlet 80. The outlet 80 can feed a final containment system 75 (eg, a pond :). The discharge 85 of the final containment system 75 can then be directed to feed the pond 15 as recycle, for agricultural irrigation, for the environment (eg a channel system), or to the reaction vessel 20 as recycle. The weir 50 is preferably stepped or ridged and is able to remove traces of elements through the movement of fluids in a manner similar to a tray of gold diggers. Ponds 60, 65, and 70 preferably have a dolomite bottom. Preferably, the ponds can be planted with aquatic grass that serves to eliminate any trace of contaminant. More preferably, the aquatic grass is cabomba grass. The system is best characterized as a combination of a physical / chemical process and a microbiological process. The main goal is the reduction of nutrients by effectively reducing the levels of phosphorus, ammonia, nitrite, and nitrate to acceptable limits for discharge.

The system is constructed to provide three or more processing recipients. For example, each container to react. it may be a plurality of containers in series each containing the aforementioned basic salt and inert substrate zones. Each container is designed to increase the reduction > n of the phosphorus and nitrogen levels in the water stream. The system mainly uses inorganic precipitation reactions for the elimination of phosphorus. Nitrogen is eliminated in the system by the microbiological nitrification / denitrification elements mentioned above. The first reaction vessel is constructed with a first zone of calcium carbonate or dolomite. This layer causes the typically acidic water flow to reach pH saturation levels that begin the process of precipitation of minerals and phosphorus. The high pH causes a reduction in phosphorus levels, since this element is precipitated along with other mineral salts. Also, pH levels above 6.8 begin to carry ammonium ions to the ammonia form. Accordingly, some ammonia gasification may occur at this point and the first reaction vessel should be vented. The second zone of the first reaction vessel. It is formed of an inert substrate, which is an ideal medium to support aerobic nitrification. Given the high pH and the long microbiological contact time, the nitrification of ammonia in nitrites and nitrates is accelerated in this step of the process. The final zone of the first reaction vessel is a collection sump for minerals, precipitated sludge, and treated primary wastewater. The precipitated minerals and mud are removed for disposal. The minerals: precipitates and mud are typically suitable for conditioning or fertilizing the soil. The treated primary wastewater can be pumped or fed by gravity into the second reaction vessel for further processing. The second reaction vessel also utilizes a first zone of calcium carbonate or dolomite. This material performs the same function as in the first reaction vessel by raising the pH and precipitating phosphorus compounds and minerals. The second zone of the second reaction vessel is formed of an inert substrate and is deprived of oxygen to promote anaerobic conditions. The second zone supports the anaerobic reduction of nitrite and nitrate levels in the water stream. The gasification of nitrogen is presented in such a way that the reaction vessel must be ventilated. The last zone of the second reaction vessel is a collection sump for precipitated minerals, sludge and treated secondary water. The precipitated minerals and mud are removed for disposal. Precipitated minerals and mud are typically suitable for soil conditioning or fertilization. Secondary treated wastewater can be pumped or fed by gravity! to the third reaction vessel for final processing. The third reaction vessel in the system also uses a first zone of calcium carbonate or dolomite, and performs the same function as in the two previous reaction vessels, namely, raising the pH and precipitation. The second zone of the third reaction vessel. again it is formed of inert substrate, but is enriched with oxygen through forced aeration for optimal aerobic conditions. The second zone reduces any remaining ammonia or nitrite contaminants to a more benign nitrate form. A vent is provided to eliminate the gas aeration and the nitrogen generated by the microbial action. The precipitated minerals and mud are removed for disposal. Precipitated minerals and mud are typically suitable for soil conditioning or fertilization. The tertiary effluent from the final aerobic reduction process is discharged into a series of ponds as explained above. The ponds are planted with grass that can absorb any remaining nitrogen and phosphorus compounds and / or traces of metal. The grass can be harvested for use as fertilizer. The grass is preferably cabomba grass. Example 1 A multi-stage treatment system having three reaction vessels, as described above, was installed to reduce nutrient levels in a saltwater aquarium of 0.51 cubic meters. The total cumulative volume of dolomite in the three vessels was 0.04 cubic meters. The cumulative total volume of volcanic rock in the three vessels was 0.13 cubic meters. The water feed speed (influent) in the multi-stage system was 0.35 liters per second. A fourth vessel contained algae that removed residual contaminants. The multi-stage system reached a steady state after day 28. The water analysis for the influent and effluent streams, from the start to the steady state and beyond is as follows: Day Analysis Influent Effluent 1 pH 7.0 8. .6 NH3 0.0 0 .0 7 pH 7.0 8. .2 NH3 6-8 ppm 6--8 ppm N02 1 ppm 1 ppm 12 pH 7.0 8 .4 NH3 > 10 ppm 8 ppm N02 2.0 ppm > 4 ppm NO, 0.0 0 .0 Day Analysis Influent Effluent 15 pH 6.8 8.4 NH3 > 10 ppm 0.5 ppm N02 > 4 ppm 2.0 ppm N03 0.5 ppm 0.05 ppm pH 7.0 8.4 NH3 > 10 ppm 0.5 ppm N02 2.0 ppm 0.2 ppm N03 0.5 ppm 0.5 ppm 28+ pH 7.0 8.0-8.5 (NH3 state> 10 ppm 0.0 ppm stable) N02 2.0 ppm 0.0 ppm N03 0.5 ppm 0.05 ppm P04 > 10 ppm 0.0 ppm To treat 3,800 cubic meters per day of nutrient-rich water, it is estimated that the volumes of dolomite and volcanic rock in each reaction vessel would be as follows: Recipierte 1 2 3 Total Total (mJ) 8.49 8.49 8.49 25.47 Dolomite (m3) 4.24 1.41 1.41 7.06 Volcanic rock (m3) 4.24 7.06 7.06 18.36 It should be understood that the multi-stage treatment system of the present invention can successfully eliminate nutrients in both freshwater and saltwater environments. One skilled in the art will understand that microorganisms that are compatible with the particular chemistry of water would be used. In the same way, suitable building materials would be chosen for a salt water environment.

It should also be understood that phosphorus and precipitated minerals do not necessarily need to be removed in each separate reaction vessel. For example, if the amount of precipitates in the water is low, then one can settle and remove the precipitates in a pond or container placed after the multi-stage treatment system. Alternatively, one can eliminate precipitates in any other or in all reaction vessels. depending on the load of precipitate. It should further be understood that the basic insoluble salt zone and the zone of microorganisms retained in an inert substrate can be in separate reaction vessels. Thus, the preferred multi-stage system having two-zone reaction vessels could, in fact, have six reaction vessels in series with each reciprocating alternating between having a load of salt or microorganisms. In accordance with the above, the claims should be consulted in order to assess the total scope of the petition. Algae Filter Referring now to Figure 3, an algae filter 100 is shown. The algae filter is useful for reducing nitrates and other contaminants from a variety of sources. An application is used in situations where the pond culture of algae is not practical for use with the multi-stage filter system described above. For example, the algae filter is particularly advantageous when used with the multi-stage filter system described above to treat aquariums! of fresh or salt water. The water of the multi-stage filter system described above enters an algae filter 100 through the inlet 102. The algae filter is adapted with separate, stacked perforated trays 108. The perforated trays 108 are capable of supporting the growth of algae. Preferably, the trays are made of a poly (methylmethacrylate) thermoplastic polymer ("Plexiglas") with perforations up to 0.63 centimeters in diameter. A plenum 106 is provided in the algae filter. The plenum has at least one transparent wall preferably made of "Plexiglas". The plenum 106 is sealed against the liquid environment and houses an artificial light source 104 which provides suitable light conditions for the growth of algae in the perforated trays 108. The artificial light source 104 may be, for example, fluorescent light or ultraviolet light. Preferably, the seaweed filter tank 101 is constructed of plastic such as polyethylene (if the artificial light source is mounted outside the container, the tank would preferably be constructed of transparent "Plexiglas"). Preferably, the tank lid 103 is fixedly attached to the plenum 106 for easy removal of the artificial light source. The plenum 106 is sealed to the bottom. Preferably, the inlet 102 is fitted with a spout that distributes incoming water onto the uppermost perforated tray. The water leaves the algae filter 100 via the outlet 110. Alternatively, the means for supporting the growth of algae can be a fixed or packed bed instead of the stacked perforated trays 108. For example, the packed bed can be composed of cylinders or transparent spheres. The cylinders would preferably be made of "Plexiglas" and have approximately 2.54 centimeters in length, and approximately 3.81 centimeters in diameter. The spheres would preferably be made of "Plexiglas" as well and have a size of approximately 1.27 centimeters in diameter. Another alternative is to use a fluidized bed for the medium instead of the perforated trays. In this case, an air or physical agitation source may be used to maintain the fluidized medium. The algae culture in the algae filter uses available nitrate in water as a nutrient for growth, food production and respiration. The biomass of the algae assimilates the nitrate, which is finally discarded during periodic cleaning of the algae filter. Example 2 Two saltwater aquariums were started with a pH of 8.4 and without adding bacteria. The aquariums were installed with a cycle of: continuous treatment, zero discharge, with the multi-stage filter system of Example 1 upstream of a packed algae filter (as described above and shown in Figure 3) used as a final nitrite / nitrate finish. Fish, crustaceans and anemones were added three days after preparing the aquariums. Approximately 10 days after the addition of marine life, there were no measurable levels of ammonia, nitrate or nitrite in either aquarium. At this time, 227 grams of ammonia for domestic use were added to the aquariums. Ammonia and nitrite measurements were taken 24 hours later and both species were elevated to toxic levels. Brown algae appeared in both aquariums for four weeks after the addition of ammonia. In this period of time, the biomass was developed in the multi-stage filter system and in the packaged algae filter. After this four-week period, the brown algae in the aquariums began to disappear. In 7 days (5 weeks after the addition of ammonia), all the brown algae of both aquariums disappeared. Small amounts of both green and green algae were discovered in the packed algae filter. The aquariums have now operated as a closed cycle system, free of algae for several months. This process of progression indicates that as soon as a biomass is established in the filter, the multi-stage filter system, together with the packed algae filter can maintain a recycled form free of nutrients for the aquariums. The packed algae filter can be easily cleaned on a scheduled basis. During this cleaning process, most of the algae culture is harvested, and the nutrients adsorbed by the algae are removed with the crop. This provides a safe and natural method of nutrient reduction of nitrates and nitrites.

Claims

NOVELTY OF THE INVENTION Having described the foregoing invention, it is considered as a novelty and, therefore, it is claimed as propiedcid contained in the following CLAIMS 1. A method for treating water rich in nutrients containing nitrogen compounds, phosphorus, and other minerals: s comprising the following steps: (a) feeding the nutrient-rich water into at least one first reaction vessel having a first zone containing a substantially insoluble basic salt and a second zone containing; aerobic microorganisms retained in an inert substrate; (b) controlling the flow rate of the water to carry out in the first reaction vessel the reactions of: (1) maintaining the pH of the water in the first zone to precipitate at least a portion of the phosphorus compounds and other minerals, and (2) biologically oxidizing in the second zone under aerobic conditions at least a portion of the nitrogen compounds in nitrites and nitrates, - (c) feeding the water of the first vessel to at least one second reaction vessel having a first zone containing a substantially insoluble basic salt and a second zone containing anaerobic microorganisms retained on an inert substrate; - (d) controlling the flow rate of the water to carry out in the second reaction vessel the reactions of: 1) maintain the pH of the water in the first zone to precipitate at least a portion of the phosphorus compounds and other minerals, and (2) biologically reduce in the second zone under anaerobic conditions at least a portion of the nitrites and nitrates to nitrogen gas; (e) feeding the water from the second container to when you are pulling a third reaction vessel having a first zone containing a substantially insoluble basic salt and a second zone containing aerobic microorganisms retained on an inert substrate, - (f) aerating the third reaction vessel; (g) controlling the flow rate of the water to carry out in the third reaction vessel the reactions of: (1) maintaining the pH of the water in the first zone to precipitate at least a portion of the phosphorus compounds and others minerals, and (2) biologically oxidizing under aerobic conditions in the second zone at least a portion of nitrogen compounds in nitrates; and (h) removing water from the third reaction vessel. The method of claim 1 comprising the additional step of separating the precipitated phosphorus and the other minerals from the water after at least one of steps (b), (d), or (g). The method of claim 1 comprising the additional step of separating the precipitated phosphorus and the minerals from the water after step (h). 4. The method of claim 1 wherein the substantially insoluble basic salt is dolomite. 5. The method of claim 4 wherein the inert substrate is volcanic rock. The method of claim 5 comprising the additional step of feeding the separated water removed from the third reaction vessel to at least one pond having an inlet, an outlet, and a plurality of flutes disposed at the bottom of the pond. The method of claim 6 wherein at least one pond is progressively shallower from the. entrance to the exit. The method of claim 7 wherein at least one pond is cultivated with watergrass. 9. The method of claim 8 wherein the aquatic grass is cabomba grass. The method of claim 1 wherein each of the first reaction vessel, the second reaction vessel, and the third reaction vessel are a plurality of vessels divided into series zones. The method of claim 1 wherein the insoluble salt zone and the microorganism zone of at least one of the reaction vessels are disposed in separate reaction vessels. 12. The method of claim 1 further comprising the step of feeding the water from the third reaction vessel to an algae filter comprising a vessel having a medium capable of supporting the growth of algae and an artificial light source. The method of claim 12 wherein the insoluble salt zone and the microorganism zone of at least one of the reaction vessels are disposed in separate reaction vessels. 14. An apparatus for treating nutrient-rich water containing nitrogen compounds, phosphorus compounds, and other minerals comprising: (a) at least one first reaction vessel having a first zone containing a substantially insoluble basic salt and one second zone containing aerobic microorganisms retained in an inert substrate, the first container having an inlet for feeding the nutrient-rich water to the first zone, and with the first zone and the second zone arranged adjacent to each other and separated by a perforated support suitable size for retaining the insoluble salt while allowing the nutrient-rich water to pass therethrough, - (b) a transfer element for removing water from the first container; (c) at least one second reaction vessel having an inlet for accepting water from the transfer element of (b), the second reaction vessel having a first zone containing a substantially insoluble basic salt and a second zone containing microorganisms anaerobes retained in an inert substrate, the first zone in fluid communication with the inlet, and with the first zone and the second zone arranged adjacent to each other and separated by a perforated support of the appropriate size to retain the insoluble salt at the same time as allows the water to pass through it, - (d) a transfer element to remove water from the second container, - (e) at least one third reaction vessel having an inlet to accept water from the transfer element (d) ), the third reaction vessel having a first zone containing a substantially insoluble basic salt and a second zone containing microor aerobic g-anisms retained in an inert substrate, the first zone being in fluid communication with the inlet, with the first zone and the second zone arranged adjacent to each other and separated by a perforated support of the appropriate size to retain the insoluble salt thereto time that allows water to pass through it, - (f) a transfer element to remove water from the third container; and (g) an aeration device for injecting air into the second zone of the third vessel and a vent disposed in the first zone of the third vessel for removing gas. 15. The apparatus of claim 14 further comprising at least one separation device arranged to receive water from at least one of the reaction vessels and to separate precipitates therefrom, wherein the transfer member is arranged to remove water from the device. from separation. 16. The apparatus of claim 14 wherein the substantially insoluble base salt is dolomite. 17. The apparatus of claim 16 wherein the inert substrate is volcanic rock. 18. The apparatus of claim 17 wherein the transfer element of (i) is at least one ridged weir. 19. The apparatus of claim 18 having a pond in fluid communication with the ridged weir having an inlet, an outlet, and a plurality of flutes disposed at the bottom of the pond. 20. The apparatus of claim 19 wherein the at least one pond is progressively less deep from the inlet to the outlet. 21. The apparatus of claim 20 wherein the at least one pond is cultured with watergrass. 22. The apparatus of claim 21 wherein the aquatic grass is cabomba grass. 23. The apparatus of claim 14 wherein each of the first reaction vessel, the second reaction vessel, and the third reaction vessel are a plurality of vessels divided into zones in series. 24. The apparatus of claim 14 wherein the insoluble salt zone and the microorganism zone of at least one of the reaction vessels are disposed in separate reaction vessels. 25. The apparatus of claim 14 further comprising an algae filter having an inlet for accepting water from the transfer element of (f), the algae filter comprising a vessel having a medium capable of supporting the growth of algae and a source of artificial light. 26. The apparatus of claim 25 wherein the insoluble salt zone and the microorganism zone of at least one of the reaction vessels are disposed in separate reaction vessels. 27. An algae filter for treating water comprising: a container having an inlet and an outlet, - a plurality of perforated trays disposed in the container in a separate vertically stacked relation, wherein the trays are capable of supporting the algal growth, - and a source of artificial light mounted on the container so as to direct light on the perforated trays. 28. The algae filter of claim 27 wherein the artificial light source contains ultraviolet light. 29. The algae filter of claim 27 further comprising a plenum disposed in the container, the plenum having at least one transparent wall, wherein the plurality of perforated trays arranged around the plenum and the artificial light source is mounted on the full. The algae filter of claim 29 wherein at least one transparent wall of the plenum comprises a thermoplastic polymer of the poly (methylmethacrylate) type. 31. The algae filter of claim 30 wherein the inlet is disposed in the upper part of the container. 32. The algae filter of claim 31 wherein the inlet has a spout for distributing water on the uppermost perforated tray. 33. A method for treating water comprising feeding the water to the apparatus of claim 27.