Regeneration and treatment of sulfidic spent caustic using analytic hierarchy process

Abstract

Background: Sulfur compounds must be removed from petroleum because they contribute to environmental pollution. A strong alkaline solution such as caustic soda is used to remove these compounds. This spent caustic has high values for chemical oxygen demand (COD) concentration, pH and total sulfur. In this study, the regeneration and treatment methodology of sulfidic spent caustic was investigated by applying the analytic hierarchy process (AHP). Methods: The evaluation index system developed was based on group decision-improved AHP. Expert Choice software was used to simplify decision-making when choosing a practical method and prioritizing treatment of spent caustic. Cost, environmental considerations, availability and scale-up were chosen as criteria and wet air oxidation and biological and catalytic methods were selected as alternative methods. The treatment and regeneration of spent caustic was carried out in a batch bubble column reactor loaded with IVKAZ catalyst and the effluent was treated in a precipitation-stirred tank reactor. Results: Evaluation indicated that cost ranked first among criteria at 40.9%. The results showed that the proposed process produced about 13% (wt) of caustic, 50 g/L of COD and 36 g/L of S 2-. Conclusion: The results indicate that the catalytic method was more effective (0.45) than wet air oxidation and the biological method. This process regenerated more than 85% of initial caustic and the economy of the process improved by the recycling of the stream of caustic.

Characteristics and Treatment of Wastewater from the Mercaptan Oxidation Process: A Comprehensive Review

“…Tests and research are still carried out in order to improve this system, as well as combining this process with others. A way of reducing the severe operating conditions is the use of solid catalysts in the WAO to accelerate the reactions, and there are reports of cases where catalysts have been used in this process [8,41]. This innovative technique is referred to as catalytic wet air oxidation (CWAO).…”

Kinetic study of the regeneration of spent caustic via the genetic algorithm method

“…There are a couple of methods for treating spent caustic, such as incineration, disposal and oxidation methods, among which chemical oxidation is very practical and applicable (5). Some prominent methods are wet air oxidation (WAO), advanced oxidation process (AOP) and catalytic oxidation process (COP) that have been applied to treat spent caustic wastewater (6)(7)(8)(9)(10)(11)(12)(13)(14). WAO is carried out at high temperature and pressure depending on feed.…”

Qualitative zoning of groundwater for drinking purposes in Lenjan plain using GQI method through GIS

“…Another restriction of this method is the limited number of water quality parameters. For zoning and estimating groundwater quality, many water quality indexes have been developed in recent years (5)(6)(7)(8)(9)(10)(11). One of these methods is the groundwater quality index (GQI) method for drinking water that has been employed in the present study.…”