Abstract: Method for treating a fluid aqueous waste stream comprising a biodegradable organic substance, comprising—feeding said stream into a bioreactor containing a fluid which contains biomass;—reacting the biodegradable organic substance with the biomass in the bioreactor under essentially anaerobic conditions;—taking a first flow from the bioreactor and using the first flow as a feed to a membrane filtration unit, in which said feed is subjected to filtration, thereby forming a permeate stream and a retentate stream;—returning the retentate stream to the bioreactor;—taking a second flow from the bioreactor as feed to a sludge treatment unit, in which sludge treatment unit the second flow is separated into a third flow, having an increased organic substance content compared to the second flow, and a fourth flow, having a decreased organic substance content compared to the second flow.

Abstract: Method for treating a fluid aqueous waste stream comprising a biodegradable organic substance, comprising—feeding said stream into a bioreactor containing a fluid which contains biomass;—reacting the biodegradable organic substance with the biomass in the bioreactor under essentially anaerobic conditions;—taking a first flow from the bioreactor and using the first flow as a feed to a membrane filtration unit, in which said feed is subjected to filtration, thereby forming a permeate stream and a retentate stream;—returning the retentate stream to the bioreactor;—taking a second flow from the bioreactor as feed to a sludge treatment unit, in which sludge treatment unit the second flow is separated into a third flow, having an increased organic substance content compared to the second flow, and a fourth flow, having a decreased organic substance content compared to the second flow.

Abstract: A wastewater treatment process that employs anaerobic granular sludge or biomass to remove chemical oxygen demand (COD) from the wastewater. Certain constituents, such as COD, nitrogen, calcium, other dissolved solids, suspended solids, can impair the effectiveness of the granular biomass. Thus, the process employs treatment units to remove these inhibiting constituents to produce a treated effluent or stream. At least a portion of the treated effluent is recycled and mixed with the influent wastewater to reduce the concentration of these inhibiting constituents.

Abstract: The invention is directed to a process for the anaerobic purification of waste water using a sludge bed system, which process comprises feeding waste water and recycle water to the lower part of an upflow reactor containing mainly granular biomass thus producing biogas in the treatment passing the resulting gas/liquid/solid mixture upward and separating the gas and solid from the liquid in a three phase separator and thereby generating an anaerobic effluent that is withdrawn from the top of the separator, the improvement comprising withdrawing the recycle water separately from the effluent, after the separation of the gas from the liquid, either from the three phase separator or from the top of the reactor outside the three phase separator, and to an upflow reactor suitable for this process.

Abstract: The invention is directed to a process for the anaerobic purification of waste water using a sludge bed system, which process comprises feeding waste water and recycle water to the lower part of an upflow reactor containing mainly granular biomass thus producing biogas in the treatment passing the resulting gas/liquid/solid mixture upward and separating the gas and solid from the liquid in a three phase separator and thereby generating an anaerobic effluent that is withdrawn from the top of the separator, the improvement comprising withdrawing the recycle water separately from the effluent, after the separation of the gas from the liquid, either from the three phase separator or from the top of the reactor outside the three phase separator, and to an upflow reactor suitable for this process.

Abstract: The invention is directed to a process for the aerobic purification of waste water in a reactor containing unsupported granular active sludge. The oxygen necessary for maintaining aerobic conditions within the reactor is provided in the form of an oxygen-containing gas. The oxygen-containing gas is preferably introduced into the reactor at such a place that the oxygen-containing gas provides at least some mixing action in the reactor. The invention also provides a reactor suitable for this process.