(497b) Brine Treatment for Recycle Via Crystallization

With the recent abundance supply of biodiesel byproduct glycerine in the market, a growing demand of epichlorohydrin, global pressure towards greener technology and waste minimization, The Dow Chemical Company (Dow) has rapidly developed Glycerine to Epichlorohydrin (GTE) technology that will meet those aspects. The waste minimization part of the GTE technology is the subject of this paper, which specifically involves cleaning up brine byproduct stream via crystallization process and recycling the clean brine to chlor-alkali plant.

The brine byproduct stream from GTE plant can contain up to approximately 25% NaCl and significant total organic carbon (TOC) in water with glycerine being the majority of organic component of TOC. In this process, the NaCl from the waste brine is crystallized and redissolved back to brine with low TOC process water to meet the very low TOC specification for brine feed to chlor-alkali membrane process.

Salt crystallization technology used as a brine purification process for brine feed to chlor-alkali membrane process is a well established unit operation. Turn-key crystallizer unit operation is readily attainable from several vendors. However, such process is generally for treating brine mined from salt dome with high level of mineral and non-glycerine TOC.

Different configurations will be explored that indicate that the final design proposed saves on capital, energy and minimizes wastewater discharge. This crystallization process is found to be favorable recycle brine treatment process for GTE brine when compared with other evaluated brine treatment processes such as Fenton Oxidation, Chlorinolysis, Resin Adsorption, etc.