Experimental study of ammonia removal from water by modified direct contact membrane distillation Original Research Article

In this work, a modified direct contact membrane distillation (MDCMD) with receiving solution in permeate was developed for accelerating ammonia removal from aqueous solution. The ammonia removal efficiency by means of DCMD, hollow fiber membrane contactor (HFMC) and MDCMD was comparatively investigated. And the effect of feed pH, temperature, flow rate and concentration on ammonia removal efficiency and the permeate flux in MDCMD process was studied. Experimental results showed that the ammonia removal efficiency of DCMD, HMC and MDCMD was 52%, 88% and 99.5% within 105 min, respectively. In MDCMD, feed pH value was proved to be the most dominant factor and the optimal feed pH was 12.20. Increasing feed temperature and flow rate led to higher ammonia mass transfer coefficient, ammonia removal efficiency and permeate flux within the range studied. The initial ammonia concentration had a negligible effect on ammonia removal efficiency.