Abstract: A wastewater treatment process having improved solids separation characteristics and reduced biochemical oxygen demand (BOD) in the purified wastewater comprising the steps of: passing wastewater containing suspended solids and biodegradable organic substances through a main aerobic biological oxidation zone; passing the effluent from said aerobic biological oxidation zone to an aerobic/mixing zone and therein mixing said effluent with effluent from the anoxic/anaerobic zone; passing the effluent from said aerobic/mixing zone to a settling zone and therein separating purified wastewater and sludge containing suspended solids; passing a portion of the sludge formed in the settling zone and volatile acids to an anoxic/anaerobic zone; and recycling an effective amount of the effluent from said anoxic/anaerobic zone to said aerobic/mixing zone.

Abstract: A waste water treatment apparatus is provided which can treat a high-concentration waste water containing persistent chemical substances including nitrogen and surfactant simultaneously with small amount of exhaust gases and is yet simple in construction. The apparatus has a first bioreactor having a lower portion including an inflow pipe for admission of waste water to be treated and aeration means, and an upper portion packed with vinylidene chloride fillers; a second bioreactor including a filler-packed portion packed with charcoal and calcium carbonate fillers; and an exhaust gas introduction diffuser for directing exhaust gases generated in an uppermost portion of the first bioreactor into the filler-packed portion. The water under treatment is anaerobically treated in the lower portion and is subjected to aerobic treatment and also to anaerobic treatment in the upper portion.

Abstract: A method for waste water (1) treatment comprising the steps of: (a) combining waste water (1) with activated sludge (4) under anaerobic conditions; (b) transferring the products of step (a) to a container (B); (c) aerating the contents of the container (B); (d) allowing the contents of the container to settle and separate into an effluent layer (3) and an activated sludge layer; (e) decanting at least some of the treated effluent (3) and (f) recycling at least a proportion of the activated sludge (4) from step (d) to provide the sludge of step (a).

Abstract: A multistage biological treatment method receives material to be treated, and passes the material through multiple reactors. From each reactor some of the contents are removed and separated, and the biomass is moved into the previous stage while the material to be treated and metabolic products are moved into the succeeding stage. Thus, the predominant flow of the biomass is upstream and the predominant flow of the material to be treated in downstream. Preferably, alternate reactors are anaerobic, and alternate reactors are aerobic, so the material is alternately subjected to anaerobic, then aerobic, environments. The process can be improved by applying physical, physical-chemical, chemical, and biochemical actions to the treatment system.

Abstract: Processes for the treatment of organic waste are disclosed, including feeding the organic waste to an ATAD reactor and subjecting the organic waste to biological digestion in the ATAD reactor in order to produce a biomass and clear decant therein, oxidizing at least a portion of the biomass so as to produce an oxidized effluent therein, and returning the oxidized effluent to the ATAD reactor. Variations on these processes which are disclosed include the removal of nutrients from the clear decant, treating of the organic waste with a mixer prior to feeding it to the ATAD reactor, feeding the waste by a grinder upstream of the mixer, feeding the mixed material initially to an AAD vessel from which methane gas is removed, and then to the ATAD reactor, with or without nutrient removal, the use of solid separation for the effluent from the ATAD reactor, and other such variants.

Abstract: A sequencing batch waste treatment facility with pretreatment mixing and equalization by mixing with selectively bred bacteria to achieve a selected waste to bacteria ratio, wherein waste is treated and reduced to acceptable biological oxygen demand levels for municipal-type waste treatment or general discharge per regulatory permit. A treatment colony of mature bacteria is cultivated and maintained in a treatment tank while a colony of young bacteria, separate from the treatment colony, is selectively bred in a bacteria tank to be particularly adapted to digest the waste being treated. Newly received waste is mixed to break macroscopic solid waste apart, into microscopic solid waste and to blend solid waste and liquid waste components into a waste slurry. Some of the selectively bred bacteria are portioned and mixed into the waste slurry up to an equalization point. The equalized batch of waste slurry is subsequently transferred to treatment.

Abstract: Developer-containing waste water is subjected to a multi-stage biological treatment. A waste water treatment apparatus for carrying out a two-stage biological treatment has an adjustment tank for receiving raw waste water and for preliminarily adjusting water quality of the waste water. First and second contact aeration tanks are used to biologically treat the waste water. First and second settling tanks are connected to the first and second contact aeration tanks for separating by sedimentation sludge from the waste water. Specifically, the first settling tank is connected to the second contact aeration tank. Sludge separated from the waste water is returned from the first and second settling tanks to first and second mixing tanks, respectively, and mixed with Bacillus Subtilis Kubota (BSK) and excess household sludge. The mixture is aerated and then transferred to the first and second contact aeration tanks, respectively.

Abstract: A process and installation for the removal of organic matter, phosphate ions and nitrogenous compounds from sewage wastewater. The installation comprises a raw sewage feed line 12 shown feeding into a primary separation basin 14. The primary separation basin 14 has an overflow flow line 16, discharging separated effluent to an attached growth fermentation vessel or fermenter 18. The fermenter 18 is filled with solid supports 20 with sufficient voids therebetween to allow the effluent to pass through the supports 20 and to allow for the growth of fermenting bacteria (not shown) on the supports 20. The supports 20 are shown diagrammatically in the drawings, and can be in the form of rotating discs, hanging or suspended ropes which move as the liquid is passed through the system, a fluidized bed in which the solids are kept in suspension by upward movement of the liquid, rings, slats or plates. The liquid effluent then passes out of the fermenter 18, through flow line 26, for further processing.

Abstract: An activated sludge treatment process is disclosed wherein a sewage sludge component is fermented for a period of at least 15 days to form soluble carbonaceous substrates, the fermented sludge component is contacted with influent sewage to form a conditioned sewage, and the conditioned sewage is supplied to the activated sludge plant.

Abstract: A process and apparatus is disclosed for treating waste water. After treatment, essentially no sludge remains for disposal. The treatment includes mixing the waste water with activated sludge solids in an aeration tank (15). The mixed liquor from the tank is then moved to a clarifier settling tank (17). About 5-25% of the activated sludge separated in the settling tank is returned to an aerobic digester (23) and treated for about 16-24 hours. The aerobic digester can be a batch unit or a continuous process unit. After treatment in the aerobic digester, the activated sludge solids are returned to the aeration tank (15).

Abstract: The present invention is directed to a method for increasing the capacity of a sewage treatment plant. In the method, oxygen is injected into the recycle sludge stream from the settling tank prior to introducing the recycle sludge stream into the secondary waste water treatment tank.

Abstract: A process is disclosed for treating wastewater from a polymerization process. The wastewater contains volatile residual monomer, for example acrylonitrile monomer. The method includes the steps of pretreating the wastewater with an amount of oxygenated waste activated sludge to reduce the levels of residual monomer in the wastewater stream in order to reduce the volatilization of the volatile residual monomer into the atmosphere during further treatment of the wastewater stream. Preferably the process involves steps of neutralization, primary clarification, cooling, aeration and secondary clarification to provide a wastewater treatment process that has a minimum of air emissions of residual volatile hydrocarbon monomer and which provides a final treated water effluent that has the desired pH level, temperature, biological oxygen demand and a suspended solids level for emission of the treated water into the environment.

Abstract: A process is described for aerobically treating wastewater containing volatile compounds to degrade the volatile compounds without liberating them to the atmosphere. Influent wastewater and return sludge from an aerobic biophysical wastewater treatment system are contacted in a preaeration zone where a minimum dissolved oxygen concentration of about 1 mg/l is maintained. In this preaeration zone a significant portion of the volatile compounds are biologically degraded. The minimum oxygen concentration in the preaeration zone is attained by prior aeration of the return sludge or by adding a small amount of oxygen to the preaeration zone. The mixture of influent wastewater and biophysical solids depleted of volatile compounds then flows to an aeration zone for further removal of pollutants.

Abstract: A wastewater treatment system incorporates three interconnected, but separately controlled, processes to enhance biological phosphorus removal. The first process is a mainstream biological treatment process utilizing aerobic and solids separation zones and the provision of return activated sludge. The next is a first sidestream process for anoxic/anaerobic "selection" of desirable BPR organisms. Finally, a second sidestream process serves to ferment organic material in some of the return activated sludge to produce food utilized in the first sidestream selection process. The system permits the three processes to be separated from each other by creating two sidestreams, allowing all three processes to be controlled separately and optimized in satisfying their own specific goals.

Abstract: Raw sewage ("black water" from toilets), wastewater from showers, sinks, kitchen facilities ("grey water") and oily water from the bilge of a host vessel ("oily water"), in combination, unexpectedly provide the essential nutrients for a live mass of mixed microorganisms which are peculiarly well-adapted to ingest the nutrients. To facilitate availability of oxygen to the microorganisms so as to provide growth of the microorganisms, and also, to allow them destroy to themselves, excess oxygen is discharged, in a combination of microbubbles and macrobubbles, into a membrane bioreactor ("MBR"). The mixture of bubbles is preferably generated with coarse (>2 mm) and fine (<20 .mu.m) bubble diffusers. An auxiliary stream, whether alone, or a recirculating stream into which air is drawn, may provide the coarse bubbles. The air is entrained, in a jet aerator or eductor, in a recirculating loop of activated sludge taken from the MBR.

Abstract: A wastewater treatment process 100 comprises passing wastewater through an anaerobic reaction zone 12 so that organic matter in the wastewater is subjected to anaerobic biological degradation. Wastewater from the anaerobic reaction zone is passed through an aerobic reaction zone 18 in which organic matter in the wastewater is subjected to aerobic biochemical breakdown. A wastewater side stream 30 is withdrawn downstream of the anaerobic reaction zone and upstream of the aerobic reaction zone, and passed through a facultative oxidation zone 32, 33, 34 wherein organic matter therein is subjected to aerobic biochemical breakdown. At least a portion of the side stream is passed directly to the aerobic reaction zone. Optionally, a portion of the side stream can be returned to the anaerobic reaction zone.

Abstract: A method is disclosed for attaining concurrent biological nitrification and dentrification in an aerobic zone of an activated sludge treatment plant. The method comprises aerating a mixed liquor in an aerobic stage of a secondary treatment zone to attain nitrification of ammonia values to NO.sub.x, transferring the mixed liquor to a settling zone where activated sludge is allowed to settle from the mixed liquor, transferring at least a portion of the sludge to an anaerobic sludge holding zone where it is held for a prolonged period, and returning the aged sludge from the sludge holding zone to the secondary treatment zone for mixing with influent wastewater. By holding the sludge in the sludge holding zone for a prolonged period, a culture of organisms is developed which exhibits an oxygen respiration block in the presence of NO.sub.x. When returned to the aerobic zone where nitrification is achieved, these organisms utilize the NO.sub.

Abstract: In a system for biodegrading oxidizable organic waste in a bioreactor in combination with a membrane ultrafiltration unit used to separate a high quality permeate from activated sludge which is returned to the bioreactor from the membrane unit as a recycle stream, it has been found that an in-line fine bubble diffuser or "micronizer" takes advantage of the kinetic energy in the recycle stream to aerate the biomass with surprising efficiency. The micronizer is positioned external to the biomass in the bioreactor; the discharge from the micronizer provides a microaerated tail-jet of the recycle stream which has been infused with a mass of air bubbles from 1-1000 .mu.m in diameter. The velocity of the compressed air flowed into the micronizer keeps its pores from clogging with sludge. The energy of the recycle stream without the air is insufficient to provide the requisite motive force for adequate oxygen transfer and to establish a predetermined recirculation pattern.

Abstract: A wastewater treatment process having improved solids separation characteristics and reduced biochemical oxygen demand (BOD) in the purified wastewater comprising the steps of: passing wastewater containing suspended solids and biodegradable organic substances through an aerobic biological oxidation zone and therein oxidizing a portion of the BOD and converting a portion of the BOD into additional suspended solids; passing the effluent from said aerobic biological oxidation zone to an aerobic/mixing zone and therein mixing said effluent with effluent from the anoxic/anaerobic zone; passing the effluent from said aerobic/mixing zone to a settling zone and therein separating purified wastewater having reduced BOD and suspended solids, and sludge containing suspended solids; passing a portion of the sludge formed in the settling zone to an anoxic/anaerobic zone and therein increasing the extracellular polymer content of said sludge; and recycling an effective amount of the effluent from said anoxic/anaerobic zon

Abstract: A two-piece plastic container for handling and storing large quantities of bulk material such as food products comprises a unitary molded plastic liquid-tight single wall tank having a bottom wall and four upwardly extending side walls, and a replaceable pallet base mounted to the tank for supporting the tank and for providing spaces for entry of tines of a forklift truck or a pallet jack. The container is provided with gussets at the top of the walls of the container that support the lip, and is also provided with corner nesting stops located at each corner of the upper end of the container to facilitate nesting of containers. A lid fits over the container lip and has a skirt that is blended inwardly towards the lip so as not to catch on a lip or lid of an adjacent container. The lid also has recesses in its top surface that facilitate the stacking of containers.

Abstract: A method of treating water with activated sludge, comprising a process for depolluting said water including a stage in which carbon pollution is oxidized, a nitrification stage which may optionally be associated with a denitrification state and/or a dephosphating stage, and a sludge ageing process. The method further includes a sludge concentration stage, said stage being performed upstream from the sludge ageing stage, said concentration being performed by phase separation using compressed air, e.g. in a flotation tank (3), and the concentrated sludge being recycled via the sludge ageing stage.

Abstract: An improved powdered adsorbent enhanced sludge process for the treatment of wastewater is disclosed that allows for in situ recovery of unregenerated powdered adsorbent. In situ recovery is performed by contacting a mixture of activated sludge and spent powdered adsorbent at disassociation conditions whereby cell lysis occurs. The cell lysis allows for physical separation of the spent powdered adsorbent from the activated sludge, thus allowing for recycle of adsorbent without the need for a regeneration process.

Abstract: The present invention entails a process for treating wastewater utilizing a return activated sludge process. Primary sludge is separated from the wastewater stream and conveyed into a fermentation tank and held a sufficient time to permit hydrolysis of suspended solids so as to produce soluble substrates. Part of the soluble substrates are mixed with nutrified return activated sludge and held for a selected time period to form conditioned return activated sludge. Thereafter, the conditioned return activated sludge is mixed in an initial aerobic treatment zone with pretreated wastewater. Thereafter, the mixed conditioned return activated sludge and pretreatd wastewater is conveyed through a series of treatment zones, which includes at least one anoxic treatment zone, to which part of the soluble substrates are added, where nitrogen and other pollutants are removed from the wastewater.

Abstract: The present invention entails a process for treating wastewater utilizing a return activated sludge process. Primary sludge is separated from the wastewater stream and conveyed into a fermentation tank and held a sufficient time to permit hydrolysis of suspended solids so as to produce soluble substrates. The soluble substrates are mixed with the return activated sludge and held for a selected time period in an anoxic zone, to form conditioned, denitrified return activated sludge, followed by anaerobic treatment, to produce microorganisms that are capable of biologically removing phosphorus. Thereafter, the conditioned return activated sludge is mixed in an initial aerobic treatment zone with pretreated wastewater. Thereafter, the mixed conditioned return activated sludge and pretreated wastewater may be conveyed through a series of treatment zones, which may include at least one anoxic treatment zone.

Abstract: There is disclosed an activated sludge wastewater treatment process which comprises aerating a mixed liquor comprising phosphate-containing influent wastewater and activated sludge in an aeration or high-purity oxygen zone to reduce the BOD/COD content of the wastewater and to cause the microorganisms present to take up phosphate. A phosphate-enriched sludge in which the phosphorus is present primarily in the sludge solids is separated from the mixed liquor to provide a substantially phosphate-free effluent. At least a portion of said phosphate-enriched sludge is passed to a phosphate pre-stripping zone, either in a separate tank or within the phosphate stripper tank itself, where BOD/COD-containing water, or feedwater, containing at least 50 mg/L of BOD, is added to poise the sludge organisms to begin enhanced rapid release of dissolved phosphate by pre-stripping it from the sludge or poising the sludge for rapid, enhanced release of phosphate. Then, the sludge is passed to a phosphate stripping zone.

Abstract: This invention relates to an improved process for the treatment of municipal waste and particularly to the reduction of organic sludges generated in the biological digestion of organic material. In the conventional processes the waste containing organic matter is contacted with an oxygen-containing gas in the presence of biologically active organisms under conditions to produce biomass which, on separation, forms a sludge. A portion of the sludge often is returned to the aerobic digestion process. This invention relates to an improvement for sludge reduction in these processes wherein a portion of the sludge is hydrolyzed and then subjected to biological digestion in an autothermal aerobic digestion zone. The effluent from the autothermal aerobic digestion zone usually is returned to the initial aerobic digestion process or submitted for disposal.

Abstract: For improvement of the phosphate redissolution taking place under anaerobic conditions, the treatment is conducted under anaerobic conditions, preferably in a settling tank, into which unsettled raw sewage and a return sludge from the secondary settling tank are introduced. The sludge retention time of the return sludge is generally over 5 hours, preferably 10-24 hours. In any case, the sludge detection time exceeds the hydraulic detection time.The new process can be performed by using most existing plants with relative small investment expenditures and provides a phosphorus elimination on the order of magnitude of 90%.

Abstract: Water contaminated with at least one volatile compound is treated by air stripping the volatile compound into the gas phase, then removing the volatile compound from the gas phase by contacting it with an aqueous mixture of biological solids and powdered adsorbent. The partially-purified water is further treated by a biophysical aerobic process which in turn produces the aqueous mixture of biological solids and powdered adsorbent used to remove the volatile compound from the gas phase. The aqueous mixture of biological solids and powdered adsorbent containing the volatile compound is thickened and the solids slurry treated by regeneration, preferrably wet air oxidation, to destroy the biological solids and volatile compound as well as regenerate the powdered adsorbent. The regenrated adsorbent may be returned to the biophysical aerobic treatment process.

Abstract: A method for improving the SVI of the mixed liquor residing in an aeration tank in an activated sludge treatment system which also includes a sedimentation tank is provided. This method comprises the following steps:(A) feeding a concentration system other than said activated sludge treatment system with at least one of the mixed liquor in the aeration tank, the mixed liquor withdrawn from a line connecting the aeration tank and the sedimentation tank, and the settled sludge leaving said sedimentation tank;(B) introducing the concentrated sludge from said concentration system into a first mixing zone where said concentrated sludge is mixed with a resin having high water absorbing capability;(C) introducing a gel-like sludge-resin mixture from said first mixing zone into a second mixing zone where a metal salt is added to said mixture; and(D) returning to said aeration tank a contracted gel-sludge mixture leaving said second mixing zone.

Abstract: The ammonia concentration present in waste water is reduced by treating the waste water with a suspended growth microbial system such as an activated sludge containing organisms of the genus Nitrosomonas and organisms of the genus Nitrobacter, but in which the microbial activity of Nitrobacter is effectively inhibited. The process includes a step of treating the microbial system under conditions effecting inhibition of the Nitrobacter but substantially unaffecting the growth and metabolic characteristics of the Nitrosomonas, and subjecting the ammonia containing waste water to the so treated microbial system for a hydraulic retention time which is less than the recovery time of the inhibited Nitrobacter. As a result, the retrograde step of nitrite-nitrate conversion in the overall denitrification process also is reduced or eliminated, with consequent energy and cost savings.

Abstract: A nitrification process is disclosed wherein the population of the nitrifying bacteria in an activated sludge system may be increased by the addition of ammonium nitrogen to a return sludge reaeration zone. The increased nitrifying population results in increased reliability of nitrification and lower effluent ammonium nitrogen concentrations.

Abstract: A process is provided for the removal of heavy metals from wastewater prior to being fed to a wastewater treatment installation, with anaerobic sludge to cause the anaerobic sludge to absorb heavy metals in the wastewater. Thus, the heavy metals depleted wastewaters can then be treated in a conventional treatment plant and thereafter, the resultant sludge can be directly employed for agricultural purposes without requiring further treatment to remove heavy metals therein. To effect the process a preferred reactor is made up of two parts, a cylindrical mixing tank and a superposed funnel-shaped sedimentation zone.

Abstract: A method of biological purification of waste water by removing organic contaminants therefrom by activated sludge in two purification stages is proposed. The primary stage involves mixing waste water with activated sludge, aerating the mixture and separating recyclable sludge and sludge water. The recyclable sludge is regenerated and fed for mixing with waste water. At the secondary stage the sludge water of the primary purification stage is aerated and residual activated sludge is removed therefrom. The recyclable sludge delivered for regeneration is divided into two flows one of which is fed directly for regeneration, whereas the other is compacted prior to regeneration to be mixed with the first for joint regeneration. An invariable ratio between the amount of organic contaminants carried by incoming waste water and activated sludge is continuously maintained at the first purification stage. An aeration tank for carrying out the proposed method comprises mixing vessels of the primary and secondary stages.

Abstract: The present invention concerns a process and an installation for the treatment of waste waters issuing from the manufacture of sauerkraut, this process and installation comprising a biological treatment step for treating waste waters leading to the formation of a precipitate, and the subsequent treatment of the aqueous separated phase in a reverse osmosis apparatus.

Abstract: A method is disclosed for the biological aerobic purification of waste waters wherein a temperature from 30.degree. to 60.degree. C. is maintained in a first process stage and a temperature from 20.degree. to 40.degree. C. is maintained in a second process stage, with the temperature in the first process stage always being higher than the temperature in the second process stage and wherein a part of the activated sludge of the second process stage, after being seperated, is returned to the first process stage. The process provides a high decomposition output and produces an activated sludge which exhibits good sedimentation behavior.

Abstract: An activated-sludge process for wastewater treatment comprising the steps of:(1) feeding raw wastewater to an aeration tank containing activated sludge;(2) supplying air into the aeration tank to produce aerobic and anaerobic areas in said tank;(3) separating sludge from the mixed liquor coming out of the aeration tank and concentrating at least part of the separated sludge or said mixed liquor in a concentrator to thereby produce concentrated sludge and separated water; and(4) feeding the concentrated sludge into the aeration tank and maintaining the MLSS concentration in said tank at a value between 7,000 to 15,000 mg/liter, thereby removing the organic matter and nitrogen components from the wastewater within said aeration tank.

Abstract: A process and apparatus are provided for the biological purification of phosphate-containing wastewater, wherein the wastewater is treated, in the presence of activated sludge at least a portion of which is fixed on a carrier material. The process is conducted in at least one aerobic, an anaerobic, and optionally an anoxic zone, to thereby discharge a substantially phosphate-free wastewater stream. In order to attain a high purifying effect with low cost expenditure, the activated sludge is carried on a movable carrier. The carrier material is conveyed from the anaerobic zone, optionally through the anoxic zone, to the aerobic zone, and simultaneously a like amount of carrier material is returned from the aerobic zone, optionally through the anoxic zone, to the anaerobic zone. In this process, the activated sludge is enriched with phosphates, and a portion of the phosphate-enriched activated sludge is separated from the discharged effluent.

Abstract: The treatment of wastewater with activated biomass to remove BOD and phosphorus values in a system in which the wastewater influent is initially mixed with recycled active biomass in an anaerobic zone and then subjected to aeration in an oxic zone, wherein the residence time of the mixed liquor in the oxic zone is reduced. At least part of the biomass-containing sludge separated from the mixed liquor subjected to further oxidation in a separate zone before admixture with the wastewater influent.

Abstract: Wastewater containing phosphorus values and BOD is initially admixed with recycled sludge containing activated biomass under anaerobic conditions, then contacted with oxygen-containing gas, followed by separation of a dense sludge layer from the mixed liquor. A portion of the sludge layer, containing the activated biomass, is held under non-aeration conditions for sufficient time to reduce any nitrates and/or nitrites contained therein, before admixture of the recycled sludge with the wastewater influent.

Abstract: This invention relates to a process for the biological purification of phosphate-containing wastewater wherein the wastewater is gas-treated, i.e. aerated, in an oxygenation tank in the presence of activated sludge for degrading organic hydrocarbon compounds and absorption of phosphate by microorganisms present in the activated sludge. The wastewater-activated sludge mixture is then withdrawn from the oxygenated tank and divided, in a post clarification stage, into purified, essentially phosphate-free water and phosphate-containing sludge. The phosphate-containing sludge is recycled, at least in part, into the oxygenation tank. A partial stream of wastewater-activated sludge mixture is branched off from the oxygenation tank, and/or recycle sludge is branched off as a partial stream from the post clarification stage, and the mixture is subjected to flotation treatment for thickening. A thus-obtained, low-phosphate flotage, i.e. subnatant liquor, is discharged from the flotation unit.

Abstract: In the treatment of wastewater by the activated sludge process, mixed liquor in the aeration tank or settled sludge is drawn from the system and concentrated. The concentrated sludge is returned to the aeration tank either immediately or after being mixed with separated water and settled sludge to thereby reduce the SVI of the mixed liquor in the aeration tank.

Abstract: A method for biologically purifiying waste water which produces substantially no excess waste sludge is provided. In this method, a waste water containing biodegradable substances is treated in a biological fixed film type reactor and aqueous water sludge discharged from the reactor is aerobically digested after being separated from the biologically treated waste water. The digested aqueous sludge is returned to the reactor or the upstream thereof. This method can be advantageously combined with any installed activated sludge type water purification process, to thereby substantially eliminate the production of excess waste sludge from the water purification system.

Abstract: A substantially constant loading waste water treatment process and apparatus subjects the waste water to treatment with recycled sludge and oxygen in an activation basin. The suspension is separated into sludge and effluent and a portion of the recycled sludge, when the waste loading exceeds a threshold value, is aerated before being introduced into the activation basin in a separate aerating basin.

Abstract: In an activated sludge process for the biological purification of wastewater wherein undesirable bulking sludge is formed in addition to normal activated sludge, the improvement which comprises mechanically destroying the microorganisms causing the bulking sludge without substantially destroying the microorganisms required for the normal activated sludge.

Abstract: A method and apparatus for treating sewage and converting the sewage into organic fertilizer which utilizes equipment for converting the solid material of the sewage into patties and a mixing apparatus for mixing the patties with bulking agents. The mixture of patties and bulking agents is stored in a pile and subjected to a supply of air to enhance the self-combustion or oxidation of the organic material in the patties. The bulking agents provide the patty-bulking agent mixture with air passages and pockets and minimize compaction of the patties. The self-combustion of the patties continues until the organic material is burned out, leaving a residual ash. A shaker separator having an elongated longitudinal perforated member is reciprocated to separate the ash from the bulking agents. The ash is collected and utilized as organic fertilizer. The bulking agents are recycled back to the mixing apparatus.

Abstract: In a long vertical shaft activated sludge bioreactor for the treatment of waste water and the flotation/separation of solids therefrom, an improvement is provided whereby fluctuations in flow through the bioreactor are maintained level without the use of complex control mechanisms and whereby separation from the effluent of dispersed air bubbles occurs directly in the flotation/separation vessel rather than in the shaft or an auxiliary vessel. The improvement provides for the installation of a holding reservoir between the shaft and the flotation/separation vessel. Influent passes through the reservoir on its way to the bioreactor and some make-up effluent from the flotation/separation vessel is directed into the holding reservoir as the level of liquid in the reservoir falls. In addition, means are provided in the separation/flotation vessel to split off large dispersed gas bubbles which would otherwise disrupt sludge flotation.

Abstract: BOD-containing water is purified by oxygenation. The resulting sludge is subjected to flotation with a gas having a solubility in water higher than that of air.The preferred source of high solubility gas is the vent gas from the oxygenation zone or stack gas obtained by burning methane generated by anaerobically digesting the floated solids.Removal of insoluble contaminants from bacterial or bacterial-algal pond effluent using high solubility gas flotation is also disclosed.

Abstract: This invention relates to biological treatment of waste water using a carrier floatable on water, and more particularly to a novel process for treatment of waste water utilizing a fluidized bed which is formed by supplying waste water in a downflow operation. The process for treatment of waste water of this invention is applicable to both anaerobic and aerobic biological treatment. A good example of the former anaerobic biological treatment to which this invention is applicable is the process wherein the nitrate or nitrite nitrogen which is one of the nitrogen compounds that are at present believed to be one cause of the eutrophication in rivers, lakes, seas, etc. is treated with denitrifying bacteria in an anaerobic condition to be released in the form of nitrogen gas, and the typical of the latter aerobic treatment is the practice in the utilization of the action of the aerobic bacteria which can oxidize organic substances in sewage, industrial waste waters, etc.

Abstract: A deep tank reactor is utilized for fermentation of waste liquid or other liquid in a biological reaction resulting in a solid cellular material. The resulting solid material, which is in suspension, is initially separated from the bulk of the liquid by a gaseous flotation process, using the dissolved gas in the liquid as the source of gaseous bubbles for flotation purposes.