Achieving stable and long-term partial nitrification of domestic wastewater by side-stream sludge treatment using a novel nitrite oxidation inhibitor chloroxylenol

Abstract Using inhibitors to selectively suppress the activity of nitrite-oxidizing bacteria (NOB) was an emerging way to rapidly achieve partial nitrification (PN). This study explored the feasibility of inactivating NOB by a novel inhibitor chloroxylenol (PCMX) in real domestic wastewater. Different frequencies (periodic strategy: SBR-PCMX1 and concentrative time strategy: SBR-PCMX2) of PCMX side-stream sludge treatment were used to achieve and maintain PN during 250 days. PN was realized by PCMX treatment once a day about 20 days, due to the inhibition of Nitrospira. PN was completely destroyed after 212 days by periodic strategy, caused by the increase of Candidatus_Nitrotoga. PN maintained without PCMX in following 201 days by concentrative time strategy. The risks of PCMX were assessed and almost no PCMX was detected in the effluent of mainstream SBRs. These results meant PN realized by PCMX side-stream sludge treatment was feasible and concentrative time strategy was a better operating strategy.