Method and apparatus for biologically treating coking-plant wastewater

Abstract

The invention relates to a process for the biological purification of coking plant wastewater that is loaded with nitrogen compounds, cyanides, phenols and sulphides. The coking plant wastewater, for removal of pollutants that inhibit a nitrification, is fed together with a biomass-containing stream of matter to a detoxification reactor that has a gas-treatment zone and a reaction zone. The feed mixture supplied to the detoxification reactor is exposed in the gas-treatment zone to a gaseous oxidizing agent. A stream of matter enriched with the oxidizing agent is fed to the reaction zone in which cyanides and other pollutants inhibiting the nitrification are biodegraded. A stream of matter is withdrawn from the reaction zone and returned to the detoxification reactor. In addition, a wastewater stream from the detoxification reactor is separated by a membrane filtration into a biomass-containing retentate stream and a purified permeate stream. From the retentate stream, a substream which entrains excess sludge is discharged. The retentate stream, after separating off the substream, is recirculated to the detoxification reactor. The permeate stream is further purified by nitrification and subsequent denitrification.

Dependencies are inferred from the claim text.