Inthis paper has been presented a new treatment method for spent caustic wastewater. Spentcausticis a waste industrialcausticsolution that has become exhausted and is no longer useful. Spent caustics are made ofsodium hydroxideorpotassium hydroxide,water, and contaminants. The contaminants have consumed the majority of the sodiumor potassium hydroxide and thus the caustic liquor is spent, for example, in one common applicationH2S gasisscrubbedby theliquid NaOHto form NaHS (aq) and H2O (l), thus consuming the caustic. Spent caustics are malodorouswastewatersthat are difficult to treat in conventionalwastewaterprocesses. Some kind of treatment technologies are disposed of by highdilutionwithbiotreatment, deep well injection,incineration,wet air oxidation,Humid Peroxide Oxidationor other speciality processes. Most ethylene spent caustics are disposed of through wet air oxidation.
Sodium hydroxide (caustic) scrubbing solutions are commonly used in petrochemical and gas/petroleum refineries for the removal of acid components such as hydrogen sulfide, cresylic acids, mercaptan and naphthenic acids from the refined product streams[1]. Due to being hazardous, odorous, and/or corrosive components of spent caustic, handle and dispose of them, can be a challenge. Spent caustic streams may also have other characteristics that can create issues with conventional biological processes such as noxious odors, pH swings, foaming, or poor settling of biological solids [1]. Effluent requirements may be difficult to achieve because some spent caustic contaminants are not readily biodegradable. One of the key contributors to relatively high chemical oxygen demand (COD) and biological oxygen demand (BOD) is from the acid gas (both CO2 and H2S) and mercaptan removal system(s) typically using dilute caustic soda (NaOH) as the active reagent. The resultant waste stream is otherwise known as spent caustic. It’s difficult to clean up and dispose of due to its toxic properties. Typically, the material is disposed of by high dilution with biotreatment, acid neutralization, deep well injection, incineration, wet air/catalytic/Humid Peroxide Oxidation or other specialty processes [2]. The two basic methods for treating spent caustic solutions are wet air oxidation (WAO) and direct acid neutralization (DAN), respectively. But these methods are not efficient, Because of high acid consumption and large caustic waste to effluent. In this new process the spent caustic are refined and toxic materials are removed and two valuable products namely NaOH and Na2CO3are produced with high purity by an economical process [3].Effluent requirements may be difficult to achieve because some spent caustic contaminants are not readily biodegradable. Typically, the material is disposed of by high dilution with biotreatment, acid neutralization, deep well injection, incineration, wet air/catalytic/Humid Peroxide Oxidation or otherspecialty processes [4].
New Treatment Process, Wastewater, Spent Caustic, Sodium Hydroxide, Recovery, Wastewater treatment, Effluent treatment
The Efficient Process for Spent-caustic Wastewater Treatment
