Abstract: The inventions describe a phased activated sludge treatment system that incorporates elements of batch treatment technology into a flow-through treatment process. Control of mixing and aeration systems are independent to facilitate the operation of the main reactor vessel in alternating aerated and anoxic conditions. Conditioning vessels in communication with the main reactor are employed to preferentially control the distribution and balance of nitrogen and phosphorus compounds in the reactor and to remove such biological nutrients concurrently with BOD and TSS in the wastewater. The inventions provide the beneficial results of providing greater operator control of flow-through treatment processes, power saving and reduced operation and maintenance costs in comparison to conventional flow-through treatment technologies.

Abstract: A computer controlled system for denitrification of a wastewater stream. The system provides real time analysis of primary parameters effecting both denitrification and nitrification. A computer controlled external source of carbon is added to the treatment process in order to remove nitrates.

Abstract: The invention discloses a wastewater ballast method that includes the steps of collecting wastewater, treating the collected wastewater, storing the treated wastewater, and discharging the treated wastewater during ballast operations.

Abstract: A packaged wastewater treatment unit has a compact configuration into which all subcomponents may be integrally molded. The compactness of the unit results from the arrangement of the subcomponents within the unit. In one embodiment, a clarifying unit and a basin into which a biological digester is mounted are formed within the top surface of a tank. The interior of the tank contains a collecting compartment separated from a secondary compartment by a baffle. In another embodiment, the housing of a disinfecting unit, such as an ultraviolet or chlorination unit, is also formed within the top surface of the packaged system. A method for treating wastewater includes using a single integrated unit to feed an effluent stream to a collection tank and then transport it to a biological digester, clarifying unit, and disinfecting unit. The effluent stream may be transported through the unit by a series of pumps and spillways. Optionally, the output stream may also be subjected to a sand filtration unit.

Abstract: The invention discloses a wastewater ballast method that includes the steps of collecting wastewater, treating the collected wastewater, storing the treated wastewater, and discharging the treated wastewater during ballast operations.

Abstract: Wastewater is delivered to a single tank of a bioreactor system to undergo biological treatment. After undergoing such biological treatment, the wastewater is centrifugally separated outside the tank into contaminated portions with lowered and increased concentration of solids therein to respectively undergo filtration within a small volume chamber of the tank and continuous return to a large volume chamber for biological retreatment during operation of the bioreactor system. Under different conditions of the wastewater delivered to the tank, one of the separated portions of the biologically treated wastewater is disposed of by direct discharge in by-pass relation to the small chamber when delivery thereof into the small chamber is interrupted under selective valve control.

Abstract: The present invention is a method for reducing the nitrate concentration in wastewater within a wastewater treatment apparatus configured to define an aeration zone and a quiescent zone or dilution zone. The method comprises the step of ceasing airflow into the aeration zone for a predetermined time period or until the dissolved oxygen level within the wastewater has reached a predetermined threshold. The method also comprise the step of mixing the wastewater in the aeration zone to prevent suspended particles within the wastewater in the aeration zone from settling and to avoid substantially disturbing the quiescence of the quiescent zone.

Abstract: Novel methods and apparatuses are disclosed for the treatment of wastewater to reduce often associated offensive odors by promoting aerobic conditions through decreasing the amount of oxygen required to maintain aerobic cultures and/or aerobic biological activity in the wastewater. Also, the wastewater is screened or otherwise separated the wastewater to remove or concentrate the solids which are anaerobically digested. By concentrating the solids, a smaller digester can be used. The anaerobic digestion produces biogas that may be collected and used, or burned by a flare or oxidized by a semipermeable membrane to deodorize the biogas. The heat produced from the biogas may have a variety of uses, including raising the temperature of the anaerobic digester and the bacterial metabolism. The wastewater is also clarified to remove nitrogenous and organic carbon wastes.

Abstract: The present invention relates to a bacterium strain of accession no. MTCC 5099, a process for the preparation of innoculum of the said strain, and a process for the reduction of color from pulp mill effluent using the above said innoculum, which comprises steps of inoculating appropriate aliquots of the pulp and paper mill effluent with the cell slurry obtained, incubating the mixture at about 37° C.

Abstract: A system and method are provided for aerobic treatment of waste, such as animal or human waste. The method includes the continual introduction of microalgae. The high amounts of oxygen produced by the microalgae satisfies the biochemical oxygen demand in the treatment process and also allows oxidation of undesirable contaminants. Delivery of the microalgae at a desired rate is achieved by incorporation of a series of electrical and mechanical devices housed within a greenhouse type structure which optimizes growth conditions for the microalgae, and also allows the system to be automated.

Abstract: A wastewater treatment system includes a first lagoon having an inlet for receiving wastewater to be treated and a first vertical flow marsh cell having a bottom outlet. Water can be transported from the first lagoon to the first marsh cell. A second lagoon has an inlet for receiving water from the first marsh cell outlet and a second vertical flow marsh cell having a bottom outlet. Water can be transported from the second lagoon to the second marsh cell. At least a portion of the water exiting the second marsh cell outlet can be recycled to the first lagoon. The first and the second lagoon are adapted to function essentially aerobically and to contain plants having roots positioned to contact water flowing thereinto. The first and the second marsh cell are adapted to contain plants having roots positioned to contact water flowing thereinto.

Abstract: A wastewater treatment apparatus has a manifold interconnecting two or more trickle towers to enable wastewater to be sequentially moved through the trickle towers in different selective sequences. One or more sensors may sense the growth of biogrowth in the trickle towers, and when the sensed growth reaches a predetermined value, valves or other parts change the interconnection of the manifold to the trickle towers to change the sequence in which the wastewater moves through the trickle towers. A method of treating wastewater includes changing the sequence of flow through the trickle towers to achieve manual or automatic grooming of the biogrowth on the biomedia, so both improving the overall efficiency of the system and also prolonging its running time between maintenance shutdowns. Another embodiment has one or more trickle towers with suspended strands of biomedia down which the wastewater passes; a sensor senses increase in growth of biomass on at least a portion of the biomedia.

Abstract: The invention relates to a liquid clarifier useful for removing solids suspended in a wastewater stream. Settled biological solids are taken from the clarifier and combined in a mixing chamber with a wastewater stream. The combined liquid is provided to a settling region of the clarifier, and suspended solids settle in a biological solids collection region, from which the solids are taken. Clarified liquid can be withdrawn or permitted to overflow from an outlet region in the settling region of the clarifier. The clarifier can enhance the degree of solids removal from wastewater streams having relatively low total suspended solids values, such as outlet streams from fixed film-type digesters. The clarifier is suitable for use in combination with other components of wastewater treatment systems, and can be included as a module in many kinds of wastewater treatment systems.

Abstract: A reactor has an aerobic tank, an anoxic tank and a sealed membrane tank with conduits for circulating mixed liquor between them. Permeation starts when the mixed liquor reaches a high level and stops when the mixed liquor reaches a low level. A sensor, for detecting the mixed liquor level, may stop and start permeation. Pressure builds in the membrane tank when membrane air is on. Transmembrane pressure is also provided by gravity flow or siphon. Membrane air generates an air lift which drives the mixed liquor circulation. The total amount of air provided by an air source is divided and varied in time between the membrane aerator and the process aerator. The process aerator acts as a screening inlet to the conduit to the membrane tank. Chemical maintenance cleaning is provided by gravity flow.

Abstract: A system and method for controlling treatment of the sewage/waste water. The method includes measuring attributes of inflow water flowing into a sewage/waste water treatment plant, attributes of an internal condition of a reaction tank having a first story and a second story, and fluid present values (PVs) of efficiency attributes of outflow water. The method also includes collecting data of the measured fluid PVs and operation-processing the data to convert the data into physical quantity data. The method also includes obtaining each optimum set point (SP) of each dissolved oxygen (DO) and solids retention time (SRT) of the first story and the second story of an exhalation tank by comparing PVs of the measured attributes using a neural network control program with a back-propagation algorithm.

Abstract: A process for purifying wastewater including the step: a) rating the tanks and the aeration means on the basis of the lowest pollution load, referred to as the low load, which corresponds to the plant load during dry weather; b) running the plant during dry weather, or at low load, according to the nitrogen treatment method in a tank with biological dephosphatation; c) running the plant during wet weather, or at high load, by performing the physicochemical phosphorus treatment technique and the nitrogen treatment technique in two tanks, and d) controlling the plant by detecting the load situation it is in (high load or low load) and to adapt the operating configuration of the tanks to the actual load situation.

Abstract: A method and apparatus for treating wastewater streams by adding, either separately or as a mixture, a nitrate containing compound and an alkaline material in an amount sufficient to achieve a lower concentration of atmospheric hydrogen sulfide and dissolved sulfides downstream of the addition as compared to the atmospheric hydrogen sulfide and dissolved sulfides present in the wastewater stream prior to the addition. By adding alkaline material in addition to a nitrate containing compounds, the amount of nitrate containing compound added can be reduced by at least 10% as compared to the amount of nitrate that would theoretically need to be added in the absence of alkaline material to achieve a comparable lower concentration of atmospheric hydrogen sulfide and dissolved sulfides in the wastewater stream.

Abstract: An integrated process for the treatment of organic waste comprising the steps of subjecting said organic waste to biological digestion with recycle of biosolids; contacting the resulting mixture of biosolids and unconverted organic material with one or more oxidizing agents in a chemical treatment unit; monitoring the oxidation-reduction potential (ORP) of the mixture of biosolids and unconverted organic material in the chemical treatment unit and adjusting the concentrations of the oxidizing agents to maintain the ORP within a selected range greater than 0 mV to condition the mixture so that it is more amenable to biodegradation; and returning the conditioned effluent to the biological reactor. The combined effects of improving biodegradability through chemical conditioning act and controlled recycle of biosolids act to reduce net biosolids production to nearly zero.

Abstract: In one embodiment, a filter media tower assembly is provided comprising a first portion and a second portion, wherein the first portion is suspended within the second portion. The first portion is a removable media tower or cage for holding filter media, whereas the second portion is a media tower guide support structure that is mounted to a surface of a tank.

Abstract: Septic systems for home and commercial use can be built or upgraded to be less prone to failure by adding aeration equipment in septic tanks and drain fields, in order to ensure proper oxygen levels in the waste effluent in the septic tank and in the drain field to ensure a healthy population of organisms. The septic system may also benefit from the addition of organisms, enzymes or chemicals to enhance the benefits of aeration. Proper organism populations, in combination with proper aeration in the septic tanks and drain fields, will greatly reduce system failures, or restore failed systems.

Abstract: A method and system for the treatment of wastewater is described herein. The system determines a quantity of fresh water entering a building and supplies a quantity of wastewater treatment solution on a basis of the quantity of entering fresh water. The system includes a conventional septic tank and two sanitization modules connected in series and automatically controlled by a controller. Compressed air and aseptic solution may also be supplied.

Abstract: Methods and apparatus for continuing, automated control of wastewater treatment processes. In certain preferred embodiments, method and apparatus for control of aeration in suspended growth biological treatment processes, especially in activated sludge processes.

Abstract: A sewage treatment plant, on the liquid side, is operated so as to effect nitrification and denitrification within a single tank and simultaneously to remove water, without the need for separate clarification. An aerobic/anoxic zone is maintained in a single tank, wherein the SymBio process of U.S. Pat. No. 5,906,746 is maintained. This is combined with the advantages of an MBR process, by placing a series of membrane separators within the tank and continuously withdrawing nearly pure water. Supplemental process air provided in the MBR tank is controlled by the SymBio process to maintain simultaneous nitrification and denitrification in a single tank and thus reducing the additional process air requirements.

Abstract: In the method of processing an organic chlorine compound in accordance with the present invention, slurry containing fly ash K including dioxins are supplied from a pretreatment bath to a biological treatment bath of a processing apparatus; nitrifying bacteria, denitrifying bacteria, aqueous ammonia, and methanol are supplied to the slurry from a nitrifying bacteria storage bath, a denitrifying bacteria storage bath, an ammonia storage bath, and a methanol storage bath, respectively; and a nitrifying reaction is carried out by the nitrifying bacteria in an aerobic atmosphere, so as to decompose the dioxins along with the nitrifying reaction.

Abstract: A method of conditioning an activated sludge in a membrane biological reactor comprising (i) adding to the activated sludge an effective amount of at least one water soluble cationic polymer to form a mixture of water and coagulated and flocculated suspended solids; and (ii) separating the coagulated and flocculated suspended solids from the water by filtering through an ultrafiltration or microfiltration membrane.

Abstract: In the liquid side of sewage treatment process, a combination aerobic/anoxic stage is closely monitored such that phosphorus can be removed as well as nitrogen. As in a known process, the aerobic/anoxic stage is monitored as to a coenzyme of the active bacteria. When the bacteria of flocs within this stage show a switch to anaerobic condition via such coenzyme, the low dissolved oxygen level in the stage is maintained for a preselected period of time or to a preselected extent of the anaerobic condition, before oxygen is added. This somewhat brief anaerobic condition within the flocs is sufficient to release significant amounts of phosphorus into the liquid. When aeration then is increased, enhanced biological phosphorus uptake is effected. A small aerobic stage is included after the aerobic/anoxic stage to ensure maximum phosphorus uptake, and in one embodiment this stage includes a membrane separator, allowing downstream secondary clarification to be eliminated.

Abstract: This invention relates to systems for treating wastewater and more particularly to removing nutrients from wastewater in a wastewater treatment system. Wastewater tanks, each having membrane filters, are arranged in series. Each tank is equipped with respective inlets and outlets and an air supply as well as detectors for monitoring various wastewater parameters. A controller is coupled to the detectors, inlets and outlets for effecting sequences of opening and closing the inlets and outlets and turning the air supplies on and off in response to various detecting conditions and effects different operations, including a cleaning mode, in different cycles.

Abstract: There is disclosed a method and apparatus for clearing waste water pipes and/or grease traps clogged with grease, with the method comprising the steps of: providing a dry agent comprising bacteria and enzymes; mixing dry agent comprising bacteria and enzymes with an amount of water sufficient to cause in-situ production of an aqueous mixture; maintaining the aqueous mixture in an activator vessel structure to activate the aqueous mixture for a time sufficient to form an aqueous solvent for cleaning or clearing fatty residues and/or grease; contacting the waste water pipes and/or grease traps containing fatty residues and/or grease with the aqueous solvent to dissolve the grease and/or fatty residues; and thus cleaning the waste water pipes and/or grease traps by biodigesting fatty residues and/or grease deposited in the waste water pipes and/or grease traps.

Abstract: An inter-zone aerobic to anoxic zone flow rate control system for single vessel multi-zone bioreactor plants for wastewater treatment is described herein. The system of the invention provides control of the relative treatment times of the mixed liquor in the horizontally disposed and adjacent aerobic and anoxic treatment zones of the bioreactor by providing one or more flow rate adjusting gates located between the aerobic and anoxic zones of the bioreactor. The opening of the gates is adjustable in accordance with sensed conditions in the treatment zones. An automated embodiment of the invention includes a programmable logic controller that provides control scripts for adjusting the opening of one or more flow control gates according to inputs from sensors and per programmed instructions. An automated and supervised embodiment of the invention includes a computer interfaced with a programmable automating controller.

Abstract: A wastewater treatment control system for controlling a wastewater treatment of using a microorganism that can degrade a specific compound, comprises measuring a specific value corresponding to a concentration of the specific compound in wastewater, and controlling the wastewater treatment on the basis of the specific value.

Abstract: Currently, wastewater treatment or processing decisions are based on pH, dissolved oxygen and biological oxygen demand of the water. These are narrow ranged indices and do not present information about complete biological status of water. There is no set protocol governing the addition of chemicals to wastewater. The management as well as operators use this information and decide the processing steps based on their ‘gut feeling’ or experience. As a result, many a times the addition a chemical to correct one problem creates another problem(s). As noted by the inventor at Detroit Wastewater Treatment Plant, often this practice leads to catastrophic results with serious legal violations and technical problems costing millions of dollars.

Abstract: A system and method for controlling treatment of the sewage/waste water. The method includes measuring attributes of inflow water flowing into a sewage/waste water treatment plant, attributes of an internal condition of a reaction tank having a first story and a second story, and fluid present values (PVs) of efficiency attributes of outflow water. The method also includes collecting data of the measured fluid PVs and operation-processing the data to convert the data into physical quantity data. The method also includes obtaining each optimum set point (SP) of each dissolved oxygen (DO) and solids retention time (SRT) of the first story and the second story of an exhalation tank by comparing PVs of the measured attributes using a neural network control program with a back-propagation algorithm.

Abstract: An improved digester apparatus converts wet carbonaceous biomass materials to biogas in a digestion unit operating at a controlled temperature and having a concentrator component and a pressure swing component each containing anaerobic bacteria. The apparatus conveys slurried aqueous biomass from a biomass source to the concentrator component and removes the biogas from the concentrator component and conveys concentrated aqueous biomass from the concentrator component to the pressure swing component and conveys digested aqueous biomass from the pressure swing component to the concentrator component. The apparatus removes waste solids from the pressure swing component and a pressure swing pump controls the pressure within the pressure swing component in a cycle comprising a sub-atmospheric first pressure phase and a second pressure phase at or above atmospheric pressure.

Abstract: The present invention provides a process and apparatus for autothermal aerobic thermophilic treatment of high strength and high temperature wastes. Waste material is injected into a reactor vessel (12) having thermophilic microorganisms to form a volume of bulk liquid in the reactor vessel (12). An oxygen-containing gas is also injected into the reactor vessel (12) for aerobic treatment of the waste material. The oxidation-reduction potential and temperature of the reactor bulk liquid are monitored and at least a selected one of the rate of injection of the oxygen-containing gas, the oxygen-transfer efficiency of the oxygen-containing gas and the volume of bulk liquid in the reactor (12) are adjusted in response to the oxidation-reduction potential and temperature of the reactor bulk liquid to maintain the temperature of the reactor bulk liquid within a predetermined range.

Abstract: Waste-treatment processes are enhanced through generation and introduction of specific biological populations customized to perform or favor specific tasks either during the main process, or for solids minimization purposes in a post-treatment process. These bacteria may be grown from specialized mixes of activated sludge and waste influent by exposing these materials to controlled environments (e.g., in an off-line treatment area). They may then be added back to the main process to perform certain tasks such as converting particulate cBOD into soluble cBOD for utilization, to reduce high solids yield organisms by supplementing the population with low yield organisms, to improve nitrification/denitrification efficiency, or to disfavor filamentous biology such as Norcardia sp.

Abstract: This invention relates to a wastewater treatment process for treating nitrogen-deficient wastewater. The process enables the production of a low soluble nitrogen processed wastewater, and avoids the need for nitrogen supplementation in the wastewater treatment process. The process includes providing a supply of nitrogen-deficient wastewater to a controlled environment. The conditions in the controlled environment encourage the proliferation of nitrogen-fixing microorganisms in particular by control of the stability of the dissolved oxygen level. This process may be used alone or in conjunction with a conventional wastewater treatment process, relying on non-nitrogen-fixing microorganisms, without the need for nitrogen supplementation.

Abstract: An improved digester apparatus for converting wet carbonaceous biomass materials to biogas comprises a digestion unit operating at a controlled temperature and having a concentrator component and a pressure swing component each containing anaerobic bacteria; means for conveying slurried aqueous biomass from a biomass source to the concentrator component and for removing the biogas from the concentrator component; means for conveying concentrated aqueous biomass from the concentrator component to the pressure swing component and for conveying digested aqueous biomass from the pressure swing component to the concentrator component; means for removing waste solids from the pressure swing component; and a pressure swing pump for controlling the pressure within the pressure swing component in a cycle comprising a sub-atmospheric first pressure phase and a second pressure phase at or above atmospheric pressure.

Abstract: A single tank submerged membrane bioreactor for treating feed water having unacceptable levels of ammonia or total nitrogen has both a membrane scouring bubble supply and an oxygenating bubble supply. The membrane scouring bubble supply continuously provides large scouring bubbles to clean the membranes. Permeate is continuously withdrawn from the membranes at a high rate but the large scouring bubbles do not transfer sufficient oxygen to the mixed liquor to create aerobic conditions in the reactor. The oxygenating bubble supply is operated to provide small bubbles of air or oxygen that intermittently produce aerobic conditions in a significant part of the mixed liquor. Alternating aerobic and anoxic conditions occur in a significant portion of the tank suitable for nitrification and denitrification.

Abstract: A fluid monitoring and control apparatus and method including providing a programmable and reprogrammable control unit comprising a display, user inputs, and input/output connections; placing a programmable logic controller in direct communication with the control unit, which programmable logic controller is programmable and reprogrammable through the control unit; and placing a plurality of fluid parameter sensors in direct communication with the control unit. The invention is also of a fluid control apparatus and method comprising providing a membrane and estimating salt rejection by the membrane.

Abstract: The present invention relates to novel ex situ processes for simple and economical destruction of air, water, and soil contaminants using naturally occurring microorganisms that are widely available in the environment. The processes utilize novel closed-loop recycle schemes which dramatically improve the efficiency, economics, and practicability of destruction of a wide variety of contaminants, especially VOCs and chloroethylenes, and particularly trichloroethylene (TCE). The processes may be applied on a batch or continuous basis to contaminated soil and groundwater, to contaminated effluents from a wide variety industrial operations, or to wherever such amenable contaminants are present. Certain contaminants, particularly chloroethylenes, are known to be difficult to biodegrade aerobically to non-toxic products without the employment of a primary substrate to induce cometabolic degradation.

Abstract: Disclosed is an improved, fully automated system for on-site growth and conditioning of microorganisms for use in water body restoration. The system includes a reservoir for the microorganisms and the nutrients, a bioreactor system, a water conditioning system, and an electrical control device.

Abstract: An enhanced activated sludge wastewater treatment method increases volumetric pollutant loading, hydraulic loading capacity and nutrient removal efficiency at a conventional activated sludge wastewater treatment plant. The method describes the control of return activated sludge rates, and the operation of partitioned aeration and reaeration zones according to measured properties of the mixed liquor to achieve the claimed benefits. Operating an existing treatment plant according to the enhanced treatment method provides a more consistent treatment process that is resistant to shock loading and increases plant capacity without the need for costly construction and operation of additional reactors and clarifiers.

Abstract: A wastewater absorption field reclamation and maintenance system, wherein effluent (wastewater) is oxygenated such that BOD is not reduced in the effluent, the oxygenated effluent being delivered to the absorption field. As the oxygenated effluent flows to the absorption field, the enhanced oxygen enables aerobic decomposition of organic matter which has reduced the infiltrative capacity of the absorption field.

Abstract: The present invention concerns the field of nitrification of fluids, and particularly relates to the treatment of aqueous fluids to oxidize ammonia and nitrites to produce nitrates. One aspect of the present invention seeks to provide an alternative nitrification process which is readily capable of commercial implementation, and in which the nitrification rate more nearly approaches the rate of ammonia generation. According to one aspect of the present invention there is provided a microbiological process for the nitrification of a fluid comprising passing the fluid to be nitrified through an immobilized biomass comprising nitrifying bacteria, characterised in that the bacteria are immobilized as a biofilm grown on porous particles, in particular coke.

Abstract: The control method and apparatus of the present invention is directed for an activated sludge wastewater treatment process. Instrumentation for measuring suspended solids concentration in the aeration tank and in the WAS flow stream communicates with a data processor having at least one data structure. The data structure stores algorithms, constant values including the volume of the aeration tank (VAerationTank), and unit conversion factors. In use, the user inputs to the data processor a desired solids retention time (SRTDesired) to optimize the treatment process.

Abstract: The method, in which the water to be treated is partly oxygenated by a specific aeration carried out before percolation through a biofilter having a bacteria-supporting bed of filtering material, has a measurement stage of at least one parameter constituted by the oxidation-reduction potential of the aerated water before passage into the biofilter, a transmission stage of measurement signals to a computer and comparison of the signal representative of the value of the measured parameter with at least one lower limit set in function of the measurement carried out in a second stage for measuring a parameter representative of the pH and a stage for correcting the air flow by a signal determined by the computer in function of the two preceding stages.

Abstract: A fluid treatment apparatus (100) and method having a variety of interchangeable input/output cards (10) capable of communicating with a variety of parameters including analytical parameters. A programmable central processing unit (124), input/output cards (10), data bus (30), display (102), and keypad (104) are integrated into a single integrated apparatus (100). Analytical parameters are received directly by the appropriate input/output cards for direct communication with the central processing unit (124). The central processing unit also outputs control parameters through the input/output cards.

Abstract: The present invention relates to a method for treatment of organic material, grown for energy production or being organic waste which is slurried, suspended or dissolved in liquid, in a two-step anaerobic biochemical reactor configuration comprising recirculation between the two reactors. The organic material is fed to the first reactor where most of the hydrolysis and dissolution of the organic material takes place, resulting in formation of volatile fatty acids (VFA). Liquid material from the first reactor is transferred to the second, methanogenesis reactor where the treatment is finalized. The amount of VFA in each reactor is forced to oscillate within pre-set upper and lower limits by pulsed recirculation between the two reactors. The amount of VFA in the reactors can be controlled by varying the recirculation rate of liquid between the reactors. The pH or the conductivity in the reactors can be monitored and used for calculating and controlling the amount of VFA in both reactors.

Abstract: A process is disclosed for regulating the aeration in a biological wastewater treatment plant using a carbon removal stage, a nitrification stage and a denitrification stage. The process includes the step of continuously measuring the value of oxidation-reduction potential of the treated medium as well as measuring oxygen concentration of the treated medium during aeration phases. This permits maintaining aeration if the oxygen concentration falls within a preselected reference range. Alternately there is reduction of the aeration if the oxygen concentration is above the preselected reference range, or increasing the aeration if the oxygen concentration falls below the preselected reference range.

Abstract: The invention relates to the purification of untreated water which is polluted with dissolved organic carbon compounds which can be biologically or adsorptively removed in a three-step process, whereby the upstream purification step is predominantly biological, i.e. operates as a biofilter (1), and both subsequent purification steps are predominantly adsorptive in nature, i.e. operate as adsorbers (2, 3). The biofilter (1) is purified by backwashing, whereby the backwashing periods occur according to the TOC determined between the biofilter (1) and the upstream adsorber (2) and/or running time and/or pressure loss. The upstream adsorber (2) is also cleaned by backwashing and is subsequently shifted into a downstream position alternating with the other adsorber (3). The method is suitable for obtaining TOC concentrations in treated water of less than 500 ppb.