Removal of an Antibiotic in Algal Wastewater treatment Systems: Tetracycline

To determine if the conditions present in algal WWT systems enhance the removal of emerging pollutants, the fate of tetracycline is being evaluated in lab-scale high rate algal ponds (HRAP) continuously fed with clarified domestic wastewater. Results thus far show up to 90% removal of tetracycline when fed at an influent concentration of 2 mg/L. A current major difficulty is ensuring the lab-scale HRAPs maintain a steady representation of full-scale conditions. Prior research on lab-scale HRAP semi-continuously fed with synthetic wastewater (retention time 7 days) suggested that sorption and photodegradation were the main tetracycline removal pathways, with an overall tetracycline removal of 69 ± 1 % (influent concentration 2 mg L-1). However, this presentation will show results from batch tests conducted under dark conditions which reveal sorption was insignificant but that biodegradation caused 50 ± 8% removal over 14 days. Batch photodegradation tests in phosphate-buffered water showed an interaction of pH with photolysis, with pseudo-first order kinetic rates of 0.051 ± 0.005 h-1 at pH 8 and 0.0228 ± 0.0004 h-1 at pH 7. Further work is needed to narrow down kinetics of removal mechanisms to enable modelling and prediction of algal systems.