Effects of adding different ratios of residual sludge and food waste co-anaerobic fermentation liquid to AAO wastewater treatment process

Carbon sources are the main bottleneck which limit the biological treatment of wastewater. In this study, the effects of temperature on the preparation of RFCF and focused on exploring the removal of pollutants in wastewater treatments by the addition of different ratios of CFRF were investigated using residual sludge and food waste co-anaerobic fermentation liquid (RFCF) as external carbon sources. The results showed that anaerobic fermentation at 40 °C had elevated the concentrations of NH4+-N, TN, and volatile fatty acids (VFAs) in the RFCF. It was found that under anaerobic fermentation at 20 °C, increases in RFCF additions significantly increased the average removal rates of NH4+-N, TN and TP by 30.44 %, 66.51 % and 60.90 %. The increase in nitrogen and phosphorus removal efficiency was mainly attributed to the increase of RFCF addition promoting the relative abundance of denitrifiers, denitrification functional genes and phosphate accumulating organisms (PAOs), and phosphorus metabolism functional genes. The control guidelines for the RFCF addition amounts were dependent on the pollutant removal indexes. Therefore, this study is an important guide to the practical engineering application of RFCF.