Treatment of oilfield produced water by anaerobic process coupled withmicro-electrolysis

Treatment of oilfield produced water was investigated using an anaerobic process coupled with micro-electrolysis (ME), focusingon changes in chemical oxygen demand (COD) and biodegradability. Results showed that COD exhibited an abnormal change inthe single anaerobic system in which it increased within the first 168 hr, but then decreased to 222 mg/L after 360 hr. The biologicaloxygen demand (five-day) (BOD5)/COD ratio of the water increased from 0.05 to 0.15. Hydrocarbons in the wastewater, such as pectin,degraded to small molecules during the hydrolytic acidification process. Comparatively, the e ect of ME was also investigated. TheCOD underwent a slight decrease and the BOD5/COD ratio of the water improved from 0.05 to 0.17 after ME. Removal of COD was38.3% under the idealized ME conditions (pH 6.0), using iron and active carbon (80 and 40 g/L, respectively). Coupling the anaerobicprocess with ME accelerated the COD removal ratio (average removal was 53.3%). Gas chromatography/mass spectrometry was usedto analyze organic species conversion. This integrated system appeared to be a useful option for the treatment of water produced inoilfields.