Impact of combined biological hydrolysis and anaerobic digestion temperatures on the characteristics of bacterial community and digestate quality in the treatment of wastewater sludge

Abstract

This work investigated the impact of temperature on the digestate water quality and bacterial community in the treatment of wastewater sludge using biological hydrolysis (BH)-anaerobic digestion (AD). The results showed that the BH 55 °C followed by AD 35 °C or 42 °C was the optimal temperature combination in terms of methane yield and digestate water quality. High-throughput sequencing revealed the key differences in bacterial communities for different BH-AD temperature combinations. Microbial source tracking showed only minor microbial migration from raw sludge and BH pre-treated sludge to the AD stage. Strong correlations between the residual sCOD, BH-AD temperature conditions, and dominant bacteria were identified. Clostridiales, Bacteroidales, Cloacimonadales, Thermotogales, and Anaerolineales were closely related to the digestate water quality and methane yield. Overall, the results showed that AD temperature exerted a dominant impact on methane yield, digestate water quality, and bacterial compositions in the BH-AD of wastewater sludge.

Keywords: Bacterial community; Digestate water quality; Dissolved organic content; Temperature; Temperature phased biological hydrolysis-anaerobic digestion.