The regulation and control strategies of a sequencing batch reactor for simultaneous nitrification and denitrification at different temperatures

The performance of a sequencing batch reactor for simultaneous nitrification and denitrification (SBR–SND) was investigated under 5–30 °C and strategies against temperature influences were proposed. Aeration of 8, 7, 7 and 6 h were sufficient for 5 ± 2, 10 ± 2, 20 ± 2 and 30 ± 2 °C, respectively. Further extension was insubstantial, only increased the aeration cost. The adjustment of C/N ratio to offset the temperature impacts was not remarkable. Prolonged sludge retention time lessened the influences of low temperature but deteriorated the system at high temperature. The oxidation reduction potential, the dissolved oxygen concentration, the sludge volume index and the extracellular polymeric substances amount changed with temperature alterations and thus affected the system performance. In conclusion, measures should be taken for temperature oscillations and the regulation and control of the operational parameters could alleviate the influences of temperature on the performances of the SBR–SND system.