Sludge, for example primary sludge or waste activated sludge or both from a wastewater treatment plant, is pre-treated prior to anaerobic digestion. The pre-treatment includes an optional mechanical treatment to reduce the viscosity of the sludge and a biological hydrolysis treatment. The biological hydrolysis treatment may be performed in a series of reactors some of which are maintained at a temperature in the range of 50 to 70° C. The reactors provide a combined residence time in the range of 0.5 to 6 days. Optionally, measurements of the pH of the sludge during or after biological hydrolysis, or the production of biogas from a downstream anaerobic digester, may be considered in adjusting the temperature of one or more of the biological hydrolysis reactors.

Provided is a biological treatment method and an apparatus that allow organic wastewater from a manufacturing process of electronic devices to be neutralized efficiently during its biological treatment with a less neutralizer in contrast to excessive use thereof in the conventional biological treatment and thereby make it possible to reduce an amount of an inorganic coagulant used in the downstream coagulation step and to reduce salt loads in RO membrane separation and ion exchange treatment. Wastewater from a process of manufacturing electronic devices is passed sequentially through two or more biological treatment tanks that include at least two aerobic biological treatment tanks including the final-stage aerobic biological treatment tank while adding a neutralizer to the biological treatment tank or tanks except the final-stage biological treatment tank so that an M-alkalinity of the liquid in the final-stage biological treatment tank is maintained at not more than 50 mg/L as CaCO.sub.3.

Systems and method for treating wastewater including a vessel having an inlet and an outlet, a pump in fluid communication with the outlet of the vessel, the pump configured to pump wastewater out of the vessel, a separator in fluid communication with the pump, the separator configured to separate grit from the wastewater, the separator having a first outlet for discharging a grit stream and a second outlet for discharging a wastewater stream, a grit washing system in fluid communication with a source of washing fluid and the first outlet of the separator, the grit washing system configured to wash and dewater grit from the grit stream, the grit washing system having an outlet for discharging a wash wastewater stream, and a return conduit configured to recycle the wastewater stream discharged from the separator to one of the inlet of the vessel and an inlet to the pump.

Provided is a water treatment device that suppresses the degradation of electrodes in a capacitive de-ionization treatment section and is capable of maintaining high water treatment capability. The water treatment device includes an activated carbon treatment section that receives an inflow of water having a total organic carbon concentration of 100 mg/l or less and adsorbs and removes organic matters contained in the water; and, on the downstream side of the activated carbon treatment section, a capacitive de-ionization treatment section including a pair of electrodes to which voltages having polarities opposite to each other are applied, a flow path, and ion exchange membranes. Ions contained in the water are adsorbed to the electrodes with voltages applied thereto, and voltages reverse to the voltages at the time of ions adsorption are applied to the electrodes to release the ions from the electrodes.

Provided is a water treatment device that suppresses the degradation of electrodes in a capacitive de-ionization treatment section and is capable of maintaining high water treatment capability. The water treatment device includes an activated carbon treatment section that receives an inflow of water having a total organic carbon concentration of 100 mg/l or less and adsorbs and removes organic matters contained in the water; and, on the downstream side of the activated carbon treatment section, a capacitive de-ionization treatment section including a pair of electrodes to which voltages having polarities opposite to each other are applied, a flow path, and ion exchange membranes. Ions contained in the water are adsorbed to the electrodes with voltages applied thereto, and voltages reverse to the voltages at the time of ions adsorption are applied to the electrodes to release the ions from the electrodes.

There are provided processes for treating wastewater. The processes can comprise treating a mixture comprising the wastewater and an activated sludge, in a single reactor, with an electric current having a density of less than about 55 A/m.sup.2, by means of at least one anode and at least one cathode that define therebetween an electrical zone for treating the mixture; exposing the mixture to an intermittent ON/OFF electrical exposure mode to the electric current in which an OFF period of time is about 1 to about 10 times longer than an ON period of time; and maintaining an adequate oxidation-reduction potential in the single reactor. Such processes allow for substantial removal of carbon, nitrogen and phosphorus from the wastewater in the single reactor of various forms and for obtaining another mixture comprising a treated wastewater and solids.

A batch reactor includes a first portion, a second portion, a first drainage tank, a second drainage tank, and a first flow control mechanism. The first portion includes a first chamber, a second chamber, and a third chamber in fluid communication with one another configured for a flow of at least one biomaterial therethrough. The second portion includes a first chamber and a second chamber in fluid communication with one another configured for a flow of the least one biomaterial therethrough. The first drainage chamber is in fluid communication with the first and second chambers. The second drainage chamber is in fluid communication with the third chamber of the first portion and the second chamber of the second portion. The first flow control mechanism is disposed between the third chamber of the first portion and the first chamber of the second portion.

Process for treating effluents containing nitrogen in ammonium form, using a sequential biological reactor (1), according to which: a volume of effluents to be treated in one complete cycle is introduced into the biological reactor in one or more successive fractions by volume, each fraction by volume being treated during a subcycle; each subcycle comprises a phase of feeding with a fraction by volume, and at least a first aerated step, during which total or partial oxidation of the ammonium to nitrites takes place by injection of air or of oxygen into the effluent, a settling out and emptying step taking place after the end of the complete cycle; the weight of N—NH.sub.4 to be treated is determined from the volume of effluents in the reactor at the end of the feeding phase, and from the difference between the initial N—NH.sub.4 concentration in the reactor and a concentration desired at the end of the aerated step, a maximum aeration time TM is dedicated to the aerated step, and an initial air flow rate Qairinit, for the beginning of the aerated step, is determined by taking into account the weight of N—NH.sub.4 to be treated and the maximum aeration time TM.

A process for reducing the production of sludge by municipal or industrial wastewater purification plants, comprising a step of mesophilic or thermophilic anaerobic digestion (20), or anaerobic digestion combining these two operating modes, of a stream of sludge to be treated (1), and at least one biological solubilization anaerobic treatment step (30); the process comprises, upstream of the anaerobic digestion step, a step of dehydration (10) of the sludge to be treated, followed by a step of mixing (15) the dehydrated sludge with a recirculated fraction of sludge that is more liquid, originating from recycling of the digestion (20), and/or from the anaerobic treatment step (30), and/or centrates originating from a final dehydration (50) of the treated sludge, wherein the recirculation rate is chosen such that the mixture has a dryness suitable for digestion, this mixture then being directed towards the digestion.

A hierarchical catalyst composition comprising a continuous or particulate macroporous scaffold in which is incorporated mesoporous aggregates of magnetic nanoparticles, wherein an enzyme is embedded in mesopores of the mesoporous aggregates of magnetic nanoparticles. Methods for synthesizing the hierarchical catalyst composition are also described. Also described are processes that use the recoverable hierarchical catalyst composition for depolymerizing lignin, remediation of water contaminated with aromatic substances, polymerizing monomers by a free-radical mechanism, epoxidation of alkenes, halogenation of phenols, inhibiting growth and function of microorganisms in a solution, and carbon dioxide conversion to methanol. Further described are methods for increasing the space time yield and/or total turnover number of a liquid-phase chemical reaction that includes magnetic particles to facilitate the chemical reaction, the method comprising subjecting the chemical reaction to a plurality of magnetic fields of selected magnetic strength, relative position in the chemical reaction, and relative motion.