Effects of bioaugmentation on the performance of industrial-scale activated sludge sequencing batch reactor under load shock of heavy oil refinery wastewater

The stable and efficient operation of the cyclic activated sludge sequencing batch reactor (CASSBR) in heavy oil refineries has become an urgent necessity in wastewater biotreatment. Here, the present study focuses on the selection of inoculated strains, the optimization of process parameters, and the effects of bioaugmentation on the performance in CASSBR under the different rates of heavy oil refinery wastewater shock loading. Results showed that the shock resistance of the CASSBR gradually enhanced and the normal performance was restored in a short time by the addition of a 0.1% biofortifier, and the average removal efficiency of chemical oxygen demand and total nitrogen reached 86% and 55% within 15 days, respectively. The recovery time of the reactor was shortened to 6 days by bioaugmentation measures. This study not only presents a detailed case on the ecological tradeoff of the bioreactor and pollutant removal of inoculated strains during bioaugmentation, but also provides a theoretical basis and technical support for evaluating the effects of heavy oil refinery wastewater shock loading on biological wastewater treatment systems.