Simultaneous removal of phenol and ammonia by an activated sludge process with cross-flow filtration

.Attempts were made for removing ammonia from synthetic wastewater under th e presence of phenol, which is inhibitory to nitrification, by using a sing le-stage activated sludge process with cross-flow filtration. Activated slu dge biomass which had been acclimated with phenol for over 15 years was use d for the inoculum, and synthetic wastewater was continuously supplied to t he process retaining biomass at 8000mg VSSl(-1). Phenol was completely remo ved, and ammonia was simultaneously nitrified to nitrate; nitrification rat e reached 200mg Nl(-1) d(-1) when phenol was removed at a rate up to 300 mg l(-1) d(-1). It was observed that 0-13% of the ammonia was removed via deni trification. Intermittent aeration enhanced the denitrification rate to 160 mg Nl(-1) d(-1) by utilizing phenol, and approximately 24% of the denitrif ied nitrogen was recovered as nitrous oxide. Methanol, which is the most co mmonly used electron donor in conventional nitrogen removal processes, did not enhance the denitrification rate of the phenol-acclimated activated slu dge used in this study, however phenol did. The results suggest that this p rocess potentially works as a space- and energy-saving nitrogen removal pro cess by utilizing substances inhibitory to nitrifiers as electron donors fo r denitrification. (C) 2001 Elsevier Science Ltd. All rights reserved.