پديدآورندگان :
Bahramifar Nader Department of Environmental Science, Faculty of Natural Resources, Tarbiat Modares University, Tehran, Iran , Sedaghat Omid Department of Environmental Science, Faculty of Natural Resources, Tarbiat Modares University, Tehran, Iran , Haghgoo Seiran Department of Environmental Science, Faculty of Natural Resources, Tarbiat Modares University, Tehran, Iran
چكيده فارسي :
Access to clean and healthy water is one of the most basic human needs for life on Earth. The wastewater from oil and gas refineries is one of the main sources of water pollution due to the wide range of pollutants it contains, such as aromatic hydrocarbons and additives used in various processes. These substances have high corrosiveness and disrupt fuel stability. Actually, to removal of hydrogen sulfide, mercaptans, and organic acids from hydrocarbon compounds such as crude oil, caustic soda solution (sodium hydroxide) have use in oil and gas refineries and petrochemical Olefin units. Spent caustic is the effluent from this process, which has high concentrations of sulfide, COD, and a high pH (above 13). It s very toxic to humans and the environment due to the presence of hazardous and harmful compounds. There are various methods for caustic treatment each of which enjoys specific features. Nowadays, the electrochemical methods are a suitable alternative to the mentioned methods. The Electrochemical techniques to remove impurities from gases, liquids, or oils are using to prevent or minimize environmental pollution. In this method, using an electric current, active agents for purification are produced in the environment (metal hydroxide in electrolysis or oxidizing compounds in electrochemical oxidation). the electrochemical have been interested in two decades past due to environmental compatibility, high purification efficiency, high speed, simplicity, and relative cost-effectiveness. One of the strengths of electrochemical methods is the significant reduction in COD in wastewater or even the removal of color, to achieve wastewater standards. The purpose of this study is reduction of COD in spent caustic wastewater by utilizing electrochemical techniques. In general, spent-caustic has resistant organic compounds that are considered dangerous for the environment. The effective parameters such as pH, current intensity, time, temperature, type of electrode and electrode were evaluated for optimization. According to the results, the optimal operating conditions of electrochemical process for oil and gas factory effluent treatment can be determined as pH equal to 8, current intensity 7(A), time 30 (min) and temperature 25°C, respectively. Finally, COD removal efficiency reached 55 % by electrochemical method. Changing the distance between the electrodes has little effect on the purification efficiency. However, the use of long electrode spacing in the electrochemical reactor causes a significant increase in energy consumption. The results of this study can lead to effective wastewater treatment and reduce the environmental effects of the treatment process.
