Studying the efficiency of anaerobic stabilization pond on removing BOD and COD and changing the sulfur compounds in wastewater of Oil Refine

Oil refinery wastewater as the most polluting industrial wastewater contain various hydrocarbons and sulfur with its derivatives and can cause problems in biological systems by the production of sulfuric acid. Variations of amount of sulfur depending on bioreactor condition such as temperature, pH, microbial activity and other factors. This study focused on determining variations of sulfur in anaerobic ponds for treatment of oil refinery wastewater. Samples were taken every 6 days during eight consecutive months and the type of sampling was 24-hour composite. This means that each sample is composed of 12 samples in 24 hours. 40 samples were taken from inlet and outlet of anaerobic stabilization pond for measuring sulfate, sulfide and sulfur, so a total of 240 samples were analyzed in this study. The results of the study showed that removal efficiency of COD and BOD were obtained 43 % and 24 %, respectively. Variations of sulfide and sulfur were obtained 4 % and 44 %, which increase respectively, but for sulfate have shown 15.8 % reduction. It can be said that sulfate-reducing bacteria have had significant activity to produce sulfide and sulfur form and decrease of the amount of sulfate in bioreactor.