A comparative study of conventional activated sludge and fixed bed hybrid biological reactor for oilfield produced water treatment: Influence of hydraulic retention time

This study focuses on the development of a hybrid biological reactor for treatment synthetic oilfield produced water. To face increasingly strict regulations concerning water discharge, fixed bed (FBHBR) containing combination free activated sludge and biofilm support was compared to conventional (CAS). After gradual microbial acclimation, 133-day experiment showed that both bioreactors were able efficiently remove phenol, toluene, xylenes, polycyclic aromatic hydrocarbons (PAHs) from wastewater with chemical oxygen demand (COD) removal rate above 95%, at hydraulic retention times (HRT) 24 h 18 h, only FBHBR maintain high efficiency an HRT 12 h. Ecotoxicity tests outlet waters non-toxic. Assessment bacterial population revealed notable differences between CAS FBHBR. In particular, wider diversity observed in The marked similarity composition suggests detachment played important part role sludge.