Low-carbon and high-ammonia nitrogen dispersed wastewater treatment: From "normal-sludge" to "low-sludge" to "no-sludge" modes

Abstract

Several biological enhancements were implemented in the aerobic tank to address the challenges of treating expressway service sewage (ESS) with low-carbon and high-ammonia nitrogen using A/O-MBR technology, aiming to improve TN removal efficiency and reduce excessive sludge production. A novel moving bed biofilm reactor (MBBR) inoculated with heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria was developed for ESS, and the results showed that HN-AD bacteria significantly improved TN removal efficiency, with an increase of 65% compared to the traditional activated sludge system. High-throughput sequencing revealed that Bacteroidotas contributed significantly to MBBR denitrification, and the genes nirK and nosZ played a significant role in denitrification. The HN-AD biofilm-forming MBBR achieved the transition of ESS treatment from "normal-sludge" mode to the more environmentally-friendly "low-sludge" and "no-sludge" modes by reducing the sludge concentration.

Keywords: Aerobic tank; Expressway service sewage; HN-AD bacteria; Low-carbon; Microbial community.