An Extensive Review On Spent Caustic Treatment Methods In Oil And Gas Industry

Spent caustic is considered to be one of the liquid industrial wastes that are not easy to handle and to dispose of, due to its high content of pollutants, alkalinity (PH> 12), high salinity (sodium of 5-12 wt%) and high sulfide concentration (2-3 wt%). The composition of spent caustic streams is highly variable and can be categorised into three groups, depending on origin and composition in the groups of sulphdic, cresylic and napthenic. There are some methods for treatment of spent caustic including following list: 1. Neutralization with sulfuric acid
2. Injection in deep wells 3. Coagulation and floacculation 4. Wet air oxidation 5. Catalytic oxidation 6. Advanced oxidation 7. Biological method 8. physical method. Due to the presence loads of organic, inorganic and suspended compounds in a spent caustic, TDS and COD amounts of these compounds is high,COD value range is on limit of 2000-60000ppm and TDS value range is on limit of 100000-200000 and getting COD and TDS value to accepted level of environmental regulation different treatment methods shall be applied. Characterstics of spent caustic will be identified required process for treatment.