Combination of Aerobic Starvation and Oxygen Restriction to Simultaneously Suppress Nitrite-Oxidizing Bacteria and Heterotrophs for Rapid Start-Up of Partial Nitrification

Abstract

Partial nitrification is of great significance to achieve carbon- and energy-efficient nitrogen removal. This study presents a sludge pretreatment strategy relying on starvation and dissolved oxygen (DO) for rapid start-up of partial nitrification. Through comparing four pretreatment conditions with different DO levels and starvation, the 10-day pretreatment under condition of low DO (1 – 2 mg/L) and starvation was the most efficient with nitrite-oxidizing bacteria (NOB) activity decreased by 46.5%. Further prolonging pretreatment time exacerbated inhibition on ammonium-oxidizing bacteria (AOB) activity. The biomass concentration deceased by 55.0% with autotrophic proportion increased by 51% within 5 days, ascribed to heterotroph death and lysis in initial 3 days. The pretreatment caused 53.1% decrease in abundance of the only NOB (Nitrospira). Partial nitrification was started up successfully within 13 days using the 10-day pretreated sludge. This study provided a valuable reference for promoting application of partial nitrification in wastewater nitrogen removal.

Keywords: starvation, dissolved oxygen, partial nitrification, nitrite-oxidizing bacteria, heterotroph