Abstract: Disclosed is a method of treating a process stream from a process producing a non-biodegradable alkylene carbonate stream. The alkylene carbonate is hydrolyzed in a strong, aqueous, alkaline solution to form an aqueous alkaline solution of the corresponding alkylene glycol. This solution is then acidified to a pH of about 8 to 8.5. The acidified solution is aerated in activated sludge to reduce the biological oxugen demand (BOD) of the solution.

Abstract: A waste liquid treatment system (10) includes an aeration chamber (10A) and a settling chamber (13). An aerator (11) is disposed within the aeration chamber (10A). A conduit (12) delivers liquid from the aeration chamber (10A) to the settling chamber (13). A gas pocket (P) is provided in the aerating chamber (10A), with at least a portion of the gas pocket (P) being situated beneath the liquid level line (L.sub.13) of the settling chamber (13). Conduits (18 and 19) are provided for delivering liquid from the settling chamber (13) to the aeration chamber (10A). The conduits (18 and 19) have respective outlets (24, 26) which empty into the gas pocket (P) at an elevation below the settling chamber liquid level line (L.sub.13). In one embodiment, a gas pocket (P) is provided in the interior of a tubular component (23) of the aerator (11). In another embodiment, a gas pocket (P') is provided beneath a concave hood (32) which traps gas bubbles (30) introduced into an aeration chamber (110A).

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 BOD-containing wastewater also containing unacceptable levels of phosphorous, nitrogen or mixtures thereof is introduced into and mixed with recycled activated sludge in a first aeration zone including at least one partially submerged rotatable biological contactor under conditions whereby the overall dissolved oxygen content of the mixed liquor in the first aeration zone is about 0.7 to about 1.5 mg/l so as to cause microorganisms capable of storing phosphates under oxidizing conditions to release soluble phosphates into the mixed liquor, the mixed liquor from the first aeration zone is transferred to a subsequent aeration zone and aerated under conditions whereby the overall dissolved oxygen content of the mixed liquor is greater than about 1.

Abstract: A system to treat wastewater from a metal-working facility, such as an automotive manufacturing plant in a bioreactor using live microorganisms. Such wastewater contains waste fluids which are a mixture of relatively easily biodegradable fats and oils, much less easily biodegradable synthetic fluids, oils and greases, and non-biodegradable material including inorganic finely divided solids such as metal and silicon carbide particles. Such waste fluids require a hydraulic retention time (HRT) and a solids retention time (SRT) which is 10 times greater than for sewage. High quality water is separated from suspended solids which are removed from the reactor at an essentially constant rate and fed to an ultrafiltration membrane. Concentrate is recycled to the reactor, except for a bleed stream to remove solids periodically.

Abstract: Bioremediation or other liquid waste biotreatment operations are enhanced by the use of turbulence promoters to create turbulent flow conditions in an oxygen/liquid waste dispersion prior to passage in an improved gas/liquid distribution system for passage through eductors into a lagoon or other holding source of the liquid waste being treated.

Abstract: A process for the biological treatment by nitrification and/or denitrification of an effluent containing nitrogen pollution includes the following steps:an incident flow of this water is brought into a mixing zone with at least one compartment in which, by turbulent mechanical agitation, an inconsumable and insoluble granular material, loaded with biomass, is put in homogeneous suspension in this water, and is maintained at a more or less constant mass concentration;this water and this granular material in suspension are circulated in a separation zone from which is extracted on the one hand clarified water, and on the other hand biomass loaded granular material; andalmost all of the active biomass fixed on said granular material is brought back by forced recycling to the mixing zone.

Abstract: A method for treatment of waste water by an activated sludge process wherein the aeration tank system is composed of three tanks: a first tank, a second tank and a third tank, in which sludge microorganisms adsorb the organic substances in the waste water to be treated and a part of them begin oxidation and decomposition of the substances in the first tank, the organic substances which are adsorbed by the sludge microorganisms are further decomposed by the microorganisms of the second tank, and the sludge microorganisms are activated in the third tank, is disclosed. The aeration amount to the respective tanks is controlled to fall within specified ratios. Further, the pH value in the aeration tank system is controlled to be slightly acidic, and the pH of the tanks increases in order from the first tank to the third tank. The process may also be carried out in a single tank using a three-step batchwise process, where the batches are subject to the aeration and pH requirements.

Abstract: A process and a plant for the purification of waste water wherein the waste water is alternatingly treated in the two treatment zones under anoxic and aerobic conditions and the waste water thus treated is subjected to an aerobic treatment in a separate zone before it is introduced into a clarification zone from which purified waste water and sludge is removed, at least a part of the sludge being recycled to the waste water which is introduced into one of the two treatment zones.

Abstract: A sewage treatment plant for the purification of waste water includes a chamber container (1) divided by partitions (4) into different sections (6, 7, 8) for pretreatment, biological treatment, chemical treatment, intermediate or retreatment of waste water, each section (6, 7, 8) having several chambers (6a through f, 7a through f, 8a through f) separated from one another by dividing walls (4, 5), chambers (6a through f, 7a through f, 8a through f) being linkable, with regard to inflow technique, in any pre-selectable association depending on the quantity and type of waste water to be treated, and at least one installation for removal of deposited treatment sludge in each of the areas for pretreatment, intermediate treatment and retreatment.

Abstract: In an orbal wastewater treatment process including a plurality of concentric, annular basins or channels having surface aeration means, wastewater and recycled activated sludge are mixed in a first channel by a combination of the surface aeration means and introducing an oxygen-containing gas such as air into the lower portion of the zone under conditions which produce a complete mix reaction and sufficient oxygen is supplied to meet the biological oxygen demands of the mixed liquor. The gas is introduced, preferably by a plurality of fine bubble membrane diffusers, in the form of fine bubbles having a diameter of less than about 4 mm. The mixed liquor is sequentially oxidized in second and third channels by a combination of surface aeration means and introducing an oxygen-containing gas into the lower portions of the channels, preferably by fine bubble membrane diffusers.

Abstract: Wastewater and recycled activated sludge are homogeneously mixed in a first aeration zone by injecting an oxygen-containing gas such as air into the lower portion of the zone under conditions which produce a complete mix reaction and sufficient oxygen is supplied to meet the biological oxygen demands of the mixed liquor. The gas is introduced, preferably by a plurality of fine bubble membrane diffusers, in the form of fine bubbles having a diameter less than about 4 mm. The bubbles provide both the mixing to keep solids in suspension and the oxygen required to maintain the overall dissolved oxygen content in the first aeration zone as close to 0 as possible. The mixed liquor is sequentially contacted with an oxygen-containing gas in second and third aeration zones under conditions which produce a complete mix reaction, preferably by fine bubble membrane diffusers, clarified and a portion of the settled sludge is recycled to the first aeration zone.

Abstract: A single-stage continuous aeration-batch clarification process for purifying wastewater containing pollutants includes the steps of continuously aerating the wastewater in the presence of biologically active solids and powdered absorbent in an aeration zone. A portion of the mixture of wastewater, biologically active solids and powdered absorbent is transferred to a settling zone where a settled solids phase and a clarified liquid phase are formed. During the settling step additional wastewater flows into the aeration zone. The clarified liquid phase is discharged from the settling zone while the settled solids phase may be returned to the aeration zone or sent to disposal.The process may be carried out with a single aeration basin and settling basin or with a plurality of aeration basins using a single settling basin.

Abstract: The present invention relates to a method for the treatment of sewage in which the sewage is supplied to an aeration basin and treated therein by a biomass of aerobic microorganisms with simultaneous supply of air and addition of calcium phosphate. Thereafter, the mixture of the biomass and the deteriorations being the substrate of said microorganisms (M. L. S. S.) is forwarded to a clarifier, wherein the biomass and the effluent are separated from each other and withdrawn separately. The calcium super phosphate is advantageously added in an amount of 0.35 mg/g-2 mg/g M. L. S. S. as a 10% aqueous slurry.

Abstract: A process is disclosed for treating food wastewaters by acidifying to a low pH, adding an alginate, and, preferably, adding lime to a pH of at least 7.0, without adding iron or aluminum to assist in coagulation and flocculation of the wastewater. A floc is formed at acid pH in some wastewaters and at neutral to alkaline pH in other wastewaters treated with lime. After recovery of the floc as a sludge, the process provides at least about 70% removals of Total Suspended Solids (TSS), Biochemical Oxygen Demand (BOD), and Chemical Oxygen Demand (COD) at reasonable costs and with negligible formation of free fatty acids in the resulting sludge.

Abstract: A two-stage, batch process for purifying wastewater containing organic and adsorbable pollutants includes the steps of introducing a predetermined quantity of the wastewater into an aeration and settling zone of a primary treatment zone and aerating therein in the presence of a powered absorbent, such as activated carbon, and biologically active solids, terminating aeration and retaining the thus-treated wastewater in the aeration and settling zone a sufficient time for a substantial portion of the suspended solids to settle by gravity. A predetermined amount of the partialy-treated wastewater is withdrawn from the aeration and settling zone and introduced into a contact zone wherein it is agitated, preferably by aeration, in the presence of a powered adsorbent, agitation is terminated and the solids are allowed to settle by gravity. After completion of settling, clarified, substantially solids-free water is withdrawn from the contact zone.

Abstract: A method and apparatus for purifying industrial waste fluids by an aerobic biological treatment is provided herein, which is capable of concurrently purifying waste gases emanating from such waste liquids. The improvement relates to the elimination or reduction of odors and volatile organic substances by enclosing all tanks and basins from the influent of the waste water treatment plant up to the aeration treatment zone for the liquid waste water and venting these gases to an aerobic digester and/or an aeration basin to biologically decompose or degrade the VOS in the waste gas by action of the microorganisms in the aeration basin or aerobic digester.

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 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 pretreated wastewater is conveyed through a series of treatment zones, which may include at least one anoxic treatment zone, where phosphorus and other pollutants are removed from the wastewater.

Abstract: A method for the treatment of wastewater wherein the turbidity level of the wastewater is monitored to control the operation of the aerating units, while simultaneously, the oxygen concentration in the aerating tank is monitored to control the staging of the aaerating units between the maximum and minimum turbidity levels.

Abstract: A bacterium has been isolated which is capable of degrading surfactants having an oxydibenzene nucleus, such as sodium dodecyl oxydibenzene disulfonate. Accordingly, it may be used in biological wastewater treatment plants to remove the surfactant. The preferred bacterium is Pseudomonas cepacia OLSA100.

Abstract: A method for treating waste water from a catalytic petroleum cracking unit is disclosed. The method includes receiving step, aeration step, settling step, and a discharging step. In the receiving step waste water from which hydrogen sulfide and ammonium have been stripped out is introduced into a biological treatment tank. In the aeration step, the waste water in the tank is subjected to aeration for a predetermined period of time. In the settling step, activated sludge within the biological treatment tank is settled for a predetermined period of time. And in the discharging step, the supernatant is discharged from the tank subsequent to the settling step.The total duration of the aeration step performed daily is set to no longer than 12 hours and the aeration step is performed intermittently. If these conditions are met, yeasts which form pseudohyphae will grow actively enough to facilitate settling and separation of activated sludge.

Abstract: A two-stage process for purifying wastewater containing organic and adsorbable pollutants includes the steps of first aerating the wastewater in the presence of a powdered adsorbent, such as activated carbon, and biologically active solids in the aeration zone of a primary treatment zone which also includes a quiescent zone. The thus-treated water passes from the aeration zone to the quiescent zone where it is retained a sufficient time for a substantial portion of the suspended solids to settle by gravity. The partially-treated wastewater overflowing from the quiescent zone is introduced into one or more contact zones wherein it is agitated, preferably by aeration, in the presence of a powdered adsorbent, agitation is terminated and the solids are allowed to settle by gravity and, after completion of settling, clarified, substantially solids-free water is withdrawn from each contact zone.

Abstract: Waste water purification employing the activated sludge process with batch-wise waste water feed to the aeration tank. There is continuous aeration and water discharge from the tank. The process has a fixed dosing cycle based on historical values for the curve of the bacterial activity with the batch-wise waste water feed or a function of indicator values for this activity, specifically as a function of the oxygen concentration in the tank through an appropriate control, which briefly opens the waste water feed when, for example, an oxygen electrode indicates that an adjustable limit value has been exceeded. By means of such an oxygen electrode, an alarm signal can simultaneously be tripped if the high oxygen consumption expected after the admission of the waste water does not occur. The process is specifically useful for the treatment of waste waters which tend to form too much bulking sludge.

Abstract: A method and apparatus for determining the oxygen uptake rate of bacteria in a body of liquid incorporates withdrawing a sample of the liquid into a chamber where a dissolved oxygen probe is located, the probe outputting a signal which is a function of the amount of dissolved oxygen in the sample. The sample is aerated, and a computer is used to sample the signal at regular intervals to produce a series of time-separated values corresponding to the sampled signals, the values representing the dissolved oxygen in the sample at the timed intervals. Repeated samples can be taken, so that the O.U.R. can be monitored on a continuing basis. The O.U.R. information can be used to control the rate of aeration in a tank, or to control the rate of recycling of activated sludge from the downstream to the upstream end of the tank.

Abstract: An activated sludge treatment process for waste water characterized in that, in the waste water treatment where waste water containing organic matter is introduced into an activated sludge reaction tank and the excess sludge formed in the reaction tank is introduced into a sludge digestion tank to effect the digestion of said excess sludge by intermittent aeration with air, a part of the digestion tank liquid is passed through a filtration apparatus having an ultrafiltration membrane, the filtrate passed therethrough is withdrawn outside the system, the remainder is circulated to the digestion tank to maintain the liquid volume of the digestion tank at a definite level, and when the amount of the reaction tank liquid introduced from the reaction tank into the digestion tank is taken as W.sub.1, the digestion tank liquid is returned in an amount of (0.2-0.8)W.sub.1 to the reaction tank, and thus the amount of excess sludge to be treated outside the system can be reduced or can be completely eliminated.

Abstract: The present invention relates to a process for the improved separation of clarified liquids from biomass in the aerobic and/or anaerobic biological treatment of sewage carried out using magnetically separable materials as carriers. The magnetically separable inorganic materials are used in quantities of from 1 to 150% by weight, based on activated sludge dry matter. The carriers consist of magnetically separable inorganic materials. The magnetically separable materials used are oxides or mixed oxides of heavy metals, preferably iron oxides, such as Fe.sub.3 O.sub.4 (magnetite) and .gamma.-Fe.sub.2 O.sub.3, which are used in average particle sizes of less than 50 .mu.m, preferably less than 10 .mu.m and more preferably less than 3 .mu.m (for example from 0.1 to 1 .mu.m). These magnetic carriers provide for improved sedimentation or for magnetic separation of the biomasses containing the magnetic materials in the biological treatment of sewage.

Abstract: A process for activated sludge treatment of industrial wastewaters which uses, in the aeration tank of an activated sludge treatment plant, at least one member of the group consisting of phytic acid, phytate salts and materials containing the same, as well as at least one other phosphorus-containing compound.

Abstract: Combinations of physicochemical and biological treatment processes are capable of removing dioxins, polychlorobiphenyls (PCB's) and other halogenated organic compounds from wastewaters. The dioxins and PCB's are removed by at least 90 percent in the pretreatment steps of neutralization, oxidation, and sedimentation; the residual amounts are removed in a powdered activated carbon enhanced sequencing batch reactor (PAC-SBR) operating at a high mixed liquor suspended solids concentration (>5000 mg/L). Powder activated carbon (PAC) is supplemented to the bioreactor to ensure complete removal of the dioxins (<0.8 ppt) and PCB's (<2 ppb).The PAC-SBR enhanced biological treatment process is capable of meeting stringent effluent limits on not only on dioxins and PCB's but also on other toxic halogenated organic compounds.

Abstract: Apparatus for jet aeration of wastewater which may be readily retrieved for cleaning or other servicing and replaced in service. Methods of placing the aeration apparatus in service are also provided.

Abstract: Methods and apparatus for decanting clarified waste water in a sequencing batch reactor or the like.

Abstract: Methods and apparatus for subcyclonic grit separation under aeration conditions utilizing elevated wastewater hydraulic jet recirculation systems.

Abstract: The problem of rising sludge in biological wastewater treatment secondary clarifiers is overcome by minimizing entrainment of nitrogen gas with mixed liquor entering the transfer pipe to the clarifier such that the level of dissolved nitrogen in the biomass settling in the clarifier remains less than that in equilibrium with nitrogen gas at the pressure prevailing in the biomass. This invention is most efficacious in cases where soluble oxides of nitrogen are present and are reduced by the biomass to elemental nitrogen. In accordance with one described embodiment the excess nitrogen is removed by degassing of the mixed liquor in the effluent pit of the system by deepening and widening the usual pit in such manner that the rate of descent of mixed liquor therein to a discharge outlet is less than 0.4 feet per second and the depth is greater than 4 feet, thus permitting the gas-containing macrobubbles to rise to the surface of the pit where these are degassed.

Abstract: This invention provides an activated sludge process for treating wastewater containing ammonia as a contaminant and further for treating wastewater containing ammonia as a contaminant and other contaminants which may possibly be present including cyanide, thiocyanate, sulfide and/or organics, wherein the process involves treating wastewater in the presence of an appropriate microorganism population acclimated to the wastewater contaminants and their levels in the wastewater, this microorganism population including (1) nitrifying microorganisms capable of converting ammonia to nitrite, (2) optionally, nitrifying microorganisms capable of converting nitrite to nitrate, and (3) facultative microorganisms capable of denitrifying nitrite and/or nitrate by oxidizing organic material and converting nitrite and/or nitrate to free nitrogen, with the process being operated under a series of controlled conditions to ultimately achieve in the activated sludge process a microbial conversion of ammonia to nitrite and/or ni

Abstract: A method and apparatus for achieving high quality treatment of organic waste water (both domestic and industrial types), which can also be used to treat organically contaminated water supplies or to reduce hazardous organic wastes (cyanides, PCBs, etc.)The apparatus operates at elevated pressures (up to about 35 psig), at high levels of dissolved oxygen (over 5 PPM), and at high concentrations of activated sludge (about 10,000 mg/l, MLSS). It consists of four separate process compartments (2 aeration compartments, a separator and a clarifier) which are contained within three vessels or alternatively in two vessels. The process compartments are linked in series by passageways and by piping and are maintained at a uniform pressure using a common manifold.The process is designed for simplicity of operation, compactness, and maintenance by a single part time attendant.

Abstract: An oxidative biological purification process for waste water in a fluidized-bed reactor at a pH between 5 and 8 in the oxidation space comprising passing waste water upwards through an air-sparged oxidation space containing aerobic biomass attached to insoluble carrier particles of a size of 0.1 to 2 mm with a specific gravity of 2 to 5 g/cm.sup.3 at such a rate that space loads of COD of 4-50 kg/m.sup.3 day are achieved while continuously and completely separating purified waste water leaving the oxidation space from said attached aerobic biomass, whereby the aerobic biomass prevails to at least a very substantial extent in a state of attachment to said carrier particles, undue surplus formation of said sludge being minimized by continuous control of the residence time of the waste water to be treated in the oxidation space between the limits of 0.3 to 20 hours, and at least all attached aerobic biomass is recycled to the oxidation space by way of settling.

Abstract: An effluent treatment system using a tank having a length between 3.5 and 6 times its width with an inlet at one end, a surface decanter at the other end, and submerged diffused aeration nozzles. Effluent input is continuous and cyclic operation involves air diffusion, rest period and then decanting. Transverse baffles may be used in the tank to cope with shock organic loads obviating the need for hydraulic or organic pre-balancing.

Abstract: A waste water stream is clarified by phase separation of a part of the stream in a clarifier positioned in an oxidation ditch, through the establishment of a head differential between the level of liquid in the clarifier and the level of liquid in the oxidation ditch.

Abstract: In a ring channel aeration system, circulation is provided by one or more hydraulic jumps while the major portion of the energy consumed in aeration is allocated to the release of oxidative process gas through horizontally non-propulsive bubble release means having an oxygen transfer efficiency of at least about 6. The hydraulic jump(s) may be powered by discharge of gas (e.g. the same gas used for aeration) through gas discharge means, in which case the system of gas discharge means and bubble release means may have an overall oxygen transfer efficiency of at least about 6. The invention has advantages of flexibility and resultant energy savings as compared to single device circulation/aeration systems, in that excessive energy need not be consumed in aeration to obtain the requisite circulation and vice versa.

Abstract: A method and an apparatus for dissolving gas in a body of sewage comprising providing a skirt member having a lower open end extending upwardly from said body of sewage to define a volume of said sewage separate from an adjacent body of clarified liquid in said tank, removing a flow of sewage from said body of sewage and pressuring said flow, introducing oxygen into said pressurized flow to form a mixture of oxygen and sewage, introducing said mixture as a jet downwardly into the inlet of a chamber disposed in said volume defined by said skirt member to induce sewage in said chamber and thereby oxygenate said sewage, discharging said oxygenated sewage downwardly through an outlet of said chamber at a reduced velocity, and reducing the momentum of said discharged oxygenated sewage by directing the same onto baffles spaced from the outlet of said chamber.

Abstract: It is necessary for maintaining a good assimilating characteristic of microorganisms upon organic matter in an aeration tank to control a gas flow rate and a return sludge flow rate to optimum values. To this effect, it is necessary to know a concentration of organic matter or a organic load. In the present invention, it is confirmed that carbon dioxide (CO.sub.2) or nitrous oxide (N.sub.2 O) in an exhaust gas from the aeration tank has a correlation with it, and the aeration tank is controlled as N.sub.2 O or CO.sub.2 as an index. Furthermore, it is confirmed that CO.sub.2 formation rate has a good correlation with COD or BOD in the upstream half section of the aeration tank, whereas N.sub.2 O formation rate has a good correlation with COD or BOD in the latter half section thereof along sewage flow direction, and more improved control can be attained by a combination of both CO.sub.2 and N.sub.2 O indices.

Abstract: Phosphorus, nitrogen and BOD are removed from organic waste liquid containing the same by mixing the organic waste liquid with activated sludge which is substantially free of oxygen, nitric acid and nitrous acid and subjecting the mixture to the action of the activated sludge under anaerobic conditions which forms a mixture of a liquid rich in soluble phosphorus and an activated sludge low in phosphorus. The sludge and liquid are separated. A portion of the liquid is subjected to solid-liquid separation to form a liquid high in phosphorus and a sludge low in phosphorus. This latter sludge is, along with the other portion of the liquid and the sludge from which the liquid has been initially separated are mixed with oxygen, in the presence of nitric acid or nitrous acid and subjected to aerobic biological oxidation. This results in the formation of a liquid low in phosphorus and an activated sludge.

Abstract: A pressurized aeration tank is provided which comprises an inner barrel arranged on the tank axis and an axial-flow impeller of optimum characteristics mounted therein, the inner barrel and the outer barrel or body portion of the tank being particularly proportioned and arranged relative to each other to define in the tank a circuitous flow passage of minimal total resistance loss. With this tank structure, a highly improved plant efficiency of BOD removal is readily obtainable with the use of concentrated activated sludge and aerobic microorganisms, mainly of the Opercularia group, in a specified range of tank pressure.

Abstract: A method for the secondary treatment of sewage (and apparatus therefor) having a step in which sewage is circulated in a system having a riser and a downcomer communicating with each other at their upper and lower ends and in which an oxygen-containing gas is supplied to the sewage as it passes through the downcomer. The method is intended for use in the aeration and/or digestion steps of the secondary treatment of sewage. The riser and downcomer are preferably located in a shaft extending into the ground for at least 40 meters below a basin containing the sewage.

Abstract: A method to upgrade existing sewage treatment plants which become overloaded in long-term continuous operation by passing waste water or a part stream thereof through a filter device which is installed additionally prior and/or subsequent to at least one overloaded stage of the treatment plant. Thus method replaces preclarification, clearing, thickening and sludge dehydration steps for a part of waste water to be treated and also a part of the biological degradation by a simple purification process using the separated solids as an alluvial filter layer. A sewage treatment plant for waste water treatment by said method is described.

Abstract: A method and apparatus for treating a continuous stream of organic wastewater using highly concentrated activated sludge (10,000 mg/l MLSS), elevated atmospheric pressure, and high levels of dissolved oxygen. The apparatus consists of three pressurized vessels linked in series by piping, and maintained at equal pressure by means of a common manifold.The first vessel receives the mixed liquor consisting of macerated sewage and return activated sludge and thoroughly aerates it with diffused air bubbles. The liquor then flows by gravity into the second pressurized vessel where flocculation and further aeration occur. From an overflow/transfer box in vessel 2, the liquor flows by gravity into the bottom tier of the third vessel which functions as a cyclone separator. The concentrate is drawn from the bottom of the vessel by a return sludge pump and recycled to the first vessel. The centrate rises into the upper tier of the third vessel where it is clarified and discharged as tertiary quality effluent.

Abstract: An improvement is provided in the operation of a long vertical shaft bioreactor in the treatment of waste which comprises circulating waste liquor and oxygenating gas through the bioreactor in which the uppermost portion of the shaft (the surface basin) is under supra-atmospheric pressure. The use of a pressurized surface basin subjects the waste to improved oxidizing conditions in a critical zone of the bioreactor and results in more effective biodegradation of the waste. By precise control of surface basin pressure, adequate levels of oxygen in the waste are maintained for biodegradation purposes while unwanted gas, such as carbon dioxide and nitrogen, are disengaged. The pressure on the surface of the waste in the basin is controlled so as to ensure that the concentration of oxygen in the waste is subsaturated and retained while the unwanted gas concentration is super saturated and becomes disengaged.

Abstract: An improved method and apparatus is provided for the treatment of sewage waste in a long vertical shaft bioreactor wherein waste sewage is caused to circulate under air injected oxidizing conditions around a loop comprising adjacent riser and downcomer chambers connected at their upper and lower ends. The improved method comprises the steps of introducing influent waste at depth into the riser chamber at a point higher in the riser than the point of air injection and withdrawing treated effluent from the riser at a point lower in the riser than the point of air injection. A separation chamber may also be operatively connected to the riser chamber to recover sludge for return to the bioreactor. The method provides an improvement in oxygen uptake rate and reduces the anoxic zone in the reactor thus providing additional capacity for BOD.sub.5 removal.

Abstract: The invention relates to an improvement of the floc-formation property of activated sludge contained in waste water.A waste water treatment process comprises steps culturing a novel strain--Alcaligenes faecalis HRL--1--and adding the cultured cells to to-be-treated waste water.

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: Treatment of waste streams, particularly acidic petrochemical wastes, in anaerobic filter at high loadings with high rates of recycle. The effluent from the top of the filter is passed into a gas-disengaging-solids-settling zone containing a quiescent body of the liquid of said effluent. Particles of solid biomass settle in that liquid body and are withdrawn, with the liquid, and recycled to the base of said filter together with fresh acidic waste and added inorganic alkaline material. The outfall from the settling zone is fed to an aerobic digester and the resulting activated sludge is recycled to the filter. The alkaline material is preferably magnesium oxide or carbonate. Sodium formate may also be used as the alkaline material.