METHODS AND SYSTEMS FOR TREATING SPENT CAUSTIC AND REGENERATING MEDIA

Method and apparatus to treat a spent caustic from the petroleum industry , which may comprise sulfides, mercaptans , cresylic and naphtenic acids and phenols. The spent caustic is first acidified with an acid to produce an acidified stream. The acidified stream may be separated into an oily phase, a solid phase and an aqueous phase. The aqueous phase is sent to an adsorption stage. The adsorption stage may comprise a pre -filter such as a walnut shell filter. It comprises a main filtering stage in one or more adsorption vessels connected in parallel and/or in series. The vessels may comprise granular activated carbon and/or an adsorption polymer such as a styrene- divinylbenzen polymer. A polished stream is produced which is neutralized with a base and then sent to a biological treatment step. Regeneration of the adsorption media is carried out using the spent caustic stream itself and/or using steam. The waste regeneration effluent is sent back to the beginning of the treatment method.