Impact of low and high temperatures on aerobic granular sludge treatment of industrial wastewater

Abstract

The goal of this study was to unravel the impact of high and low temperatures (T) on glycogen-accumulating microorganisms (GAOs) which were stimulated in an aerobic granular sludge plant fed with industrial wastewater, which is derived from the cleaning of trucks transporting chocolate and beer. Among GAOs, Candidatus Competibacter (Ca. Competibacter) was the most abundant. The long-term impact on (1) anaerobic dissolved organic carbon (DOC) uptake, (2) sludge morphology, and (3) microbial community composition was investigated. In addition, the short-term impact of T changes on the anaerobic uptake rate was evaluated. High T (above 38 °C) and low T (below 11 °C) had a negative impact on the relative read abundance of Ca. Competibacter and the anaerobic DOC uptake. Nevertheless, the carbon removal efficiency and the settleability of the biomass were not affected. Denitrifiers such as Thauera and Zoogloea were promoted over Ca. Competibacter under high T and low T, respectively, indicating their positive contribution to granulation maintenance. HIGHLIGHTS The long-term exposure to high T completely inhibited Ca. Competibacter.; The long-term exposure to low T decreased the Ca. Competibacter population but not at an alarming level.; The short-term exposure of sludge enriched with Ca. Competibacter to high T did not affect the carbon uptake rate.; The short-term exposure of sludge enriched with Ca. Competibacter to low T negatively affected the carbon uptake rate.;

Keywords

• aerobic granulation
• anaerobic selector
• feast famine regime
• microbial community
• sequencing batch reactor (sbr)
• substrate storage