Nitrogen Control of Complex Industrial Wastewaters

Abstract

A coupled biological fluidized bed system, operated in the pre‐denitrification mode, was used to evaluate its potential in implementing nitrogen removal from raw and diluted coking plant wastewaters and coal liquefaction condensates. The latter wastewater was also subjected to pretreatment by solvent extraction with light oil, methyl isobutyl ketone (MIBK) and 2‐octanone, and anaerobic degradation to evaluate the improvement in nitrification. Complete nitrification and denitrification was achieved for raw and diluted coking plant wastewater and for diluted and solvent extracted coal liquefaction condensates. Maximum specific nitrification rates increased with increasing dilution. Increased intensity of pretreatment led to stable nitrification at lower dilutions. Anaerobic pretreatment offered a possible alternative to solvent extraction. A complex tradeoff exists between the intensity of pretreatment, the degree of dilution and the size of the downstream biological treatment system.