RESUMO
Coking wastewater contains high-strength refractory organic pollutants and is commonly treated by biological treatment processes. To improve the efficiency of biological treatment, two laboratory scale processes, anaerobic membrane bioreactor/anoxic/aerobic membrane bioreactor (AnMBR-A-MBR) and anaerobic/anoxic/aerobic membrane bioreactor (A2-MBR), were developed for coking wastewater treatment. The removal of main pollutants and the stability of different pollutant loadings were compared under the optimum operating conditions. Acute toxicity distribution, variations, and toxic matter characteristics of the two processes were investigated by solid-phase extraction, components separation, the luminous bacteria Q67 test, and three-dimensional fluorescence spectrometry. The results showed that the organic pollutant removal rate of AnMBR was 15.3%, which was significantly higher than the anaerobic stage of the A2-MBR system (3.4%), and the AnMBR-A-MBR system had greater resistance to pollutant loading. Acute toxicity of AnMBR-A-MBR system in each stage effluent was lower than the A2-MBR system and the total toxic unit removal rate of both were 85.2% and 79.2%, respectively. The acute toxicity of the polar component in each stage effluent was the highest, and the polar and mid-polar components contributed to the majority of the toxicity. The toxicity of each stage effluent mainly originated from Region â ¡ aromatic protein analogues, which could be the main acute toxicity substances of the polar component.