Increasing biomass concentration facilitates simultaneous nitrogen removal and sludge reduction under low C/N conditions.

To overcome the issues of limited carbon source and high sludge production in partial denitrification/anammox (PD/A) process, the effects of mixed liquor suspended solids (MLSS) and carbon/nitrogen ratio (C/N) on PD/A were investigated through parallel experiments. Nitrogen removal efficiencies decreased significantly when C/N was reduced (1.5 → 0.

Migration of microorganisms between nitrification-denitrification flocs, anammox biofilms and blank carriers during mainstream anammox start-up.

To solve the shortage of inoculum, the feasibility of establishing simultaneous partial nitrification, anammox, and denitrification (SNAD) reactor through inoculating nitrification-denitrification sludge, anammox biofilm and blank carriers was investigated. Advanced nitrogen removal efficiency of 91.2 ± 3.

Enhancing nitrite production rate made anammox bacteria have a competitive advantage over nitrite oxidizing bacteria in mainstream anammox system.

Nitrite oxidizing bacteria (NOB) is easy to accumulate in the mainstream anammox process, leading to the decrease of anammox bacterial abundance and deterioration of nitrogen removal. In this study, anammox bacteria was gradually enriched by increasing nitrite production rate under intermittent aeration despite high NOB abundance. With the DO increased from 0.

A novel simultaneous partial nitrification, anammox, denitrification and fermentation process: Enhancing nitrogen removal and sludge reduction in a single reactor.

This study verified the feasibility of simultaneous partial nitrification, anammox, denitrification and fermentation process under intermittent aeration in a single reactor, and explored the impact of dissolved oxygen (DO) on the synergy between fermentation and nitrogen removal. An advanced nitrogen removal efficiency of 92.8 % and a low observed sludge yield of 0.