The availability of affordable and reliable clean water is one of the major global issues of present times. Water bodies are increasingly contaminated by various pollutants, rendering the water unsuitable for human consumption and posing ecological threats. Oxyanions such as perchlorate and chromate are detrimental to human health even at low concentrations while nitrate exhibits various levels of toxicity. Moreover, the excess discharge of nitrate and phosphate releasing mainly from agricultural run-offs, industrial wastes and untreated/partially treated wastewater incites ecological disruption by fostering harmful algal blooms. Traditional water treatment methods like adsorption, ion exchange, membrane filtration, and chemical or biological reduction can remove these oxyanions, but they have limitations, such as generating concentrated brine and causing secondary pollution. Further, it can be even more challenging to treat contaminated waters such as secondary effluents with low concentrations of pollutants.

Ion exchange membrane bioreactor (IEMB) is an integrated technology that combines the advantages of ion exchange processes and biological reduction to effectively eliminate the oxyanions from polluted water and degrade into harmless forms without compromising treated water quality. In current research, we have established a pilot scale IEMB plant with a capacity of 2 - 2.88 m3/day for treating secondary effluent for oxyanions like nitrate and phosphate. The transport of oxyanions through the anion exchange membrane was influenced by the composition of the feed water and the concentration of driving ions under the set operational conditions. Nitrate removal (transfer through membrane) of above 90% was achieved from the secondary effluent with driving ion concentration of 50 mM while it was degraded in an FBBR with an efficiency above 95% at optimal C/N of 1.8 – 2 and HRT of 2h. A life cycle assessment, conducted using a functional unit of 1 m3 of treated water, identified power consumption as the major contributor to most of the associated environmental impacts.

Further, the recovery of the accumulated phosphorous as vivianite along with the effect of parameters like pH, DO, Fe/P ratio, organic matter was studied. The recovered phosphorus as vivianite can serve as a potential slow releasing fertilizer thus helping in the circular economy and a step forward for achieving UN sustainable development goals such 6, 12, and 13.