Appling hydrolysis acidification-anoxic-oxic process in the treatment of petrochemical wastewater: From bench scale reactor to full scale wastewater treatment plant

•Hydrolysis acidification-anoxic–oxic process can be used to treat petrochemical wastewater.•The toxicity and treatability changed significantly after hydrolysis acidification.•The type and concentration of organics reduced greatly after treatment.•The effluent shows low acute toxicity by luminescent bacteria assay.•Advanced treatment is recommended for the effluent.