Rapid start-up of partial nitrification process using benzethonium chloride-a novel nitrite oxidation inhibitor

Benzethonium chloride (BZC) is an antibacterial compound with extensive applications in various anti-infective products. However, the feasibility of attaining partial nitrification of municipal wastewater using BZC has not been reported. In this work, BZC was used for the first time to attain partial nitrification. Batch experiments indicated nitrite oxidizing bacteria (NOB) was more vulnerable to BZC than ammonia oxidizing bacteria (AOB). When activated sludge was treated only once with 0.023 g BZC·(g MLSS)^-1 for 18 h, partial nitrification was attained at the 29th cycle with NAR of 97.46% and sustained 91 cycles in stability tests. Complimentary DNA sequencing analysis revealed the suppression of Nitrospira was the reason for partial nitrification. Oligotyping analysis indicated AOB could likely resist to BZC by both the species shifts and development of tolerance, while most NOB species could not adapt to BZC. This study revealed the feasibility of BZC as a novel NOB inhibitor.