Optimization of spent caustic neutralization of south Pars gas refinery using sulfuric acid method

Spent caustic is one of the most harmful wastes of refineries, gas and petrochemical industrial processes. Considering the CCD optimization methods, various experiments were conducted to neutralize the spent caustic  and then using the design expert software, the process parameters including initial temperature and reaction time were considered as effective parameters. The COD neutralization process was modeled as a linear equation. The main finding of the paper is that using the sulfuric acid neutralization method for spent caustic treatment, the COD of the spent caustic was reduced from a high value of ۳۴,۰۰۰ ppm to ۸,۰۰۰ ppm. All sources of harmful components of the spent caustic were converted to sulfate salts. The industrial limit for spent caustic wastewater is that the COD value should be in the range of ۶۰-۱۰۰ ppm. However, this value is difficult to achieve and is usually achieved by diluting the final spent caustic wastewater. pH changes during the neutralization process started from a maximum value of ۱۴ and was reduced to ۱۲ by neutralizing the free caustic values.. According to the explanations given, the COD amount in different stages ranges from ۳۴,۴۰۰ ppm to about ۲۰,۰۰۰ in the neutralization stage (pH ۷) and to ۸,۰۰۰ in the acidic stage (pH ۲).By neutralizing the above materials, the pH value decreases from a high value of ۱۲ to ۷ and finally to ۲.

کلیدواژه ها:

Spent caustic ، Neutralization ، South Pars gas refinery ، Sulfuric Acid ، COD reduction