Recovery of triethylamine and phosphoric acid from wastewater using a novel hybrid process of bipolar membrane electrodialysis and resin adsorption

Triethylammonium phosphate wastewater, resulting from the absorption of triethylamine (TEA) exhaust gas by phosphoric acid, poses challenges in environmental protection. In this study, a novel combined process of bipolar membrane electrodialysis (BMED) and resin adsorption (RA) was proposed. Under the optimal conditions of 50 mA/cm2 and 5 cm/s, more than 96 % of the triethylammonium phosphate in real wastewater was converted into TEA and phosphoric acid during the BMED processes. Its current efficiency of 47 % and an energy consumption rate of 4.26 kWh/kg TEA. Furthermore, the low-concentration wastewater from BMED could be effectively treated through D001 resin at pH 2. Desorption of TEA loaded on D001 resin could be achieved using a 6 wt% phosphoric acid produced from the BMED process, and the concentrated desorption solution could be reprocessed through BMED process. The effluent of RA process could undergo chemical precipitation, thereby contained 18 mg/L COD, 0.43 mg/L TP and less than 3 mg/L TEA, meeting the first-class A standard of the Chinese "GB18918-2002 Discharge standard of pollutants for municipal wastewater treatment plant". This novel strategy offered an innovative and environmentally friendly method for recycling this type of wastewater within ecological industries.