Biological nitrogenous compound removal and subsequent rhodium recovery from simulated metal refinery wastewater

Developing bioprocesses to remove nitrogenous compounds from wastewater and metal recovery is important in the competitive metal refinery industry in terms of process economic factors such as efficient use of natural resources, low energy intensive processes and minimum discharge of contaminated process wastewater to the environment. Experiments were carried out to remove nitrogenous compounds from simulated metal refinery wastewater and to subsequently recover the rhodium it contained. A bench-scale serially connected continuously stirred tank and packed-bed reactor system removed >80% of NH4+-N and >95% of NO3--N over a period of 80 days. Subsequently rhodium recovery efficiencies of >50% and >66% were achieved using two biosorbents and an adsorbent without pH and sorbent optimisation. This study demonstrated the potential of biological removal of nitrogenous compounds and the effect of nitrogenous compounds on metal recovery from metal refinery wastewaters.