Desalination of produced water from oil production fields by membrane processes

Water co-produced with oil and gas is termed produced water. Produced water is very difficult wastewater to treat and characteristics changes by well to well. In this study, treatability of produced water generated from oil production fields in Trakya region which is operated by National Oil and Natural Gas Company of Turkey was investigated. The aim of this study is to investigate the pre-treatment alternatives of reverse osmosis and nanofiltration membranes and find the most appropriate treatment combination. Management of produced water was also evaluated. Dissolved air floatation (DAF), acid cracking (AC), coagulation (CA) with lime and precipitation, cartridge filters (CDF) (5 and 1 μm), microfiltration (MF) and ultrafiltration (UF) were used as pre-treatment techniques, and nanofiltration (NF) and reverse osmosis (RO) were carried out to reduce salt content of produced water as a final treatment. Different combinations were tried to determine the best pre-treatment combination regarding both the best effluent water quality and high permeate flux. According to the experimental results, treatment combinations provided required treatment to reach discharge standard for COD which is 250 mg/L for petroleum industry in Turkey. However, different treatment combinations should be applied to reach the discharge standard for sodium.