Simultaneous ammonium–nitrogen and copper removal, and copper recovery using nitrifying biofilm from the Ultra-Compact Biofilm Reactor

Simultaneous ammonium–nitrogen (NH4+–N) and copper removal, and copper recovery in synthetic wastewater using nitrifying biofilm from an ultra-compact biofilm reactor (UCBR) was demonstrated in batch studies, which consisted of three phases: Phase 1 for NH4+–N and copper removals, Phase 2 for copper recovery, and Phase 3 for NH4+–N removal. The results showed that more than 96.3% of copper was removed within 60 min, while 60.1% of the adsorbed copper was recovered through rinsing the biofilms with 0.1 mM of ethylenediaminetetraacetic acid (EDTA). The nitrifying biofilm was able to adsorb 0.245 mg of copper/g of biofilms. After recovery treatment, 29.4% of copper remained bound within the nitrifying biofilms. No significant inhibitory effects towards NH4+–N removal in the presence of 0.92 mg copper/L was noted in Phase 1 compared with the control test. However, lower initial pH condition in the recovery process and the accumulation of copper on the biofilm led to 50% inhibition on NH4+–N removal efficiency in the subsequent phase.