Intensive removal of organic matter from a real hypersaline wastewater containing organic and inorganic salts

The existence of organic salts in hypersaline wastewater enlarges the difficulty of wastewater treatment. In this study, a real hypersaline wastewater containing both organic and inorganic salts from the bifenthrin alcohol production processes was firstly neutralized to convert and release the organic salt to organic compound and inorganic salt, and then adsorbed by macroporous resins. The optimal operating conditions and adsorption mechanisms were investigated and analyzed through the wastewater treatment. The experimental results show that after the wastewater is neutralized with the naturally accompanied evaporation of resulted organic compound, removals of chemical oxygen demand (COD) and ammonia nitrogen (AN) can reach up to 22.7% and 36%, respectively. Thereafter the wastewater was adsorbed by macroporous resins, the highest total COD removal can only reach up to 65.9% for the single resin adsorption case, which is not enough for the inorganic salt recovery with a high purity. Whereas the removal of organic matter can be remarkably promoted by the sequentially coupled macroporous resin adsorption case. The highest total COD and AN removals can reach up to 93% and 100%, respectively, when the neutralized wastewater is adsorbed firstly by resin NKA-II and then by resin XAD-4. The adsorption isotherms of sequentially coupled resins of NKA-II and XAD-4 are both better fitted by Freundlich's model and the adsorption processes can be well fitted by pseudo-second-order kinetic model.