Upgrading the Chinese biggest petrochemical wastewater treatment plant: Technologies research and full scale application.

The components of petrochemical wastewater (PCWW) are very complex and it is one of the most important sources of organic micropollutants (OMPs) in water bodies. To improve the effluent qualities of PCWW, the Chinese government has promulgated a new Emission Standard of Pollutants for Petroleum Chemistry Industry. More than 60 types of OMPs, most of which are toxic organics, are added and strictly limited in the standard. Based on the bench- and pilot-scale experiments, a pretreatment (microaerobic hydrolysis and acidification, MOHA), biological (anoxic/oxic process, A/O) and advanced treatment (micro-flocculation dynasand filtration and catalytic ozonation, MFDF-CO) integrated process is proposed. The full-scale application in the Chinese biggest petrochemical wastewater treatment plant has demonstrated that the performance of the integrated process is stable and it can significantly improve the effluent qualities. The effluent COD decreased from 84.7 to 47.0mg/L and most of the OMPs were removed. The EC50 of the effluent for luminescent bacteria assay, algal growth inhibition, Daphnia magna inhibition test and zebrafish eggs test are all higher than 100% and the induction rate (IR) for genotoxicity is only 0.76. The energy demand, however, with the electricity consumption increase by 44.1%, is very high for OMPs removal, leading to high indirect carbon emission.