Recovery of Ammonium Salt from Nitrate-Containing Water by Iron Nanoparticles and Membrane Contactor

Abstract

This study investigates the complete removal of nitrate and the recovery of valuable ammonium salt by the combination of nanoscale zero-valent iron (NZVI) and a membrane contactor system. The NZVI used for the experiments was prepared by chemical reduction without a stabilizing agent. The main end-product of nitrate reduction by NZVI was ammonia, and the solution pH was stably maintained around 10.5. Effective removal of ammonia was possible with the polytetrafluoroethylene membrane contactor system in all tested conditions. Among the various operation parameters including influent pH, concentration, temperature, and contact time, contact time and solution pH showed significant effects on the ammonia removal mechanism. Also, the osmotic distillation phenomena that deteriorate the mass transfer efficiency could be minimized by pre-heating the influent wastewater. The ammonia removal rate could be maximized by optimizing operation conditions and changing the membrane configuration. The combination of NZVI and the membrane contactor system could be a solution for nitrate removal and the recovery of valuable products.

Newly developed membrane contactor-based N and P recovery process: Pilot-scale field experiments and cost analysis

“…Viikinmäki WWTP reject was always the highest, whereas urine had the lowest mass transfer coefficient. Our results agree with the results reported in previous studies (Ahn et al, 2011;Hwang et al, 2012;Kartohardjono et al, 2015;Lauterböck et al, 2012;Semmens et al, 1990). The mass transfer coefficient was also found to be directly related to the feed and acid flow and inversely to the concentration of suspended solids in the feed (Hwang et al, 2012).…”

“…Increasing the feed flow can also increase the flow velocity close to the membrane interface, decreasing the concentration polarization effect. Both effects lead to an increase in the ammonia transfer across the membrane (Hwang et al, 2012). However, this is valid for streams that have low suspended solids, as in the case of synthetic samples (Lai et al, 2013) or the case of urine in this study.…”

Kinetics of Nutrient Removal by Nano Zero‐Valent Iron under Different Biochemical Environments

“…With appropriate configuration of biochemical settings (e.g., activated sludge operation under anaerobic, anoxic, and aerobic conditions), nutrient removal is achieved through nitrification/ denitrification and enhanced biological phosphorus removal (EBPR). Nano zero-valent iron can also be used in wastewater treatment for nitrogen removal through chemical reduction of nitrate (Hwang et al, 2012;Shin and Cha, 2008) and chemical phosphate precipitation (Chang et al, 2008). The release of ferrous ions (Fe 2þ ) associated with the dissolution of NZVI helps sludge flocculation, thereby resulting in better sludge settling (Wilén et al, 2004).…”

Environmental Engineering Research in June 2012

“…This paper is also noteworthy since, even though ocean sludge disposal is no longer possible, remaining sludge must still be disposed of. Hwang et al [3] investigated the removal of nitrate and recovery of ammonium salt by a combination of nanoscale zero valent iron (NZVI) and a membrane contactor system. They reported that the ammonia removal rate could be maximized by optimizing operation conditions and changing the membrane configuration.…”