Combination of complex extraction with reverse osmosis for the treatment of fumaric acid industrial wastewater

This paper focuses on the design of a feasible and efficient method for the recovery and treatment of industrial fumaric acid (FA) industrial wastewater-combination technique of reverse osmosis (RO) with complex extraction and stripping (CES). As for relatively low acid concentration wastewater FA1, it was treated directly by RO technique. FA2 with high acid concentration and high TOC wastewater was firstly extracted by amine extractant N-7301 to recover FA and further treated by RO system. After RO, the concentrated wastewater was treated by CES. Through the combination technique, FA can be completely recovered. Many factors influencing the CES efficiency were considered and analyzed in detail. In RO system, fluxes for FA1 and FA2 were about 18.25 and 14.55 L h(-1) m(-2) respectively. Famous "trade-off" was observed between flux and TOC removal rate with increasing operating pressure. Results also revealed that the TOC concentration in permeate side depended largely on that in feed side. The TOC distribution profile was obtained. TOC of FA1 decreased from 6447 mg L-1 to below 350 mg L-1 and the total TOC removal rate come to 94.57% by RO treatment. After treated by the combination technique, TOC of FA2 decreased from 35,625 to 290 mg L-1, and the total TOC removal rate arrived at 99.2%. Furthermore, the extractant can be regenerated by 2% NaOH solution and reused 7 times without decreasing extraction rate. The stripping rate was almost 100%.