Effective removal of ammonia from wastewater using hollow fiber renewal liquid membrane

A new method using hollow fiber renewal liquid membrane (HFRLM) for treatment of ammonia wastewater was proposed. Di-(2-ethylhexyl) phosphoric acid (D2EHPA)-kerosene and hydrogen chloride solution were selected as the extraction system and stripping phase for removal of ammonia from wastewater, respectively. The extraction equilibrium experiments were performed to confirm the feasibility of the extraction process. Effects of operating conditions and the composition of liquid membrane phase on mass transfer behavior of HFRLM were investigated. The treatment of ammonia wastewater with Mode 2 had a better mass transfer performance than that with Mode 1. In Mode 2, the feed phase and stripping phase flowed through the shell side and tube side, respectively. To a certain extent, the increases of D2EHPA concentration, hydrochloric acid concentration, and ammonia concentration were conducive to the increase of mass transfer flux of ammonia. After 10 stages of cascade experiments, the concentration of ammonia in wastewater at the outlet was less than 15mgL(-1). Besides, the final ammonia concentration decreased to 8.4mgL(-1) through the HFRLM recycling experiments. Based on series-resistance model and the surface renewal theory, an appropriate mass transfer model was established and verified, which could be used to predict experimental results.