The impact of ferrous iron/heat-activated persulfate treatment on waste sewage sludge constituents and sorbed antimicrobial micropollutants

Abstract The fate of the antimicrobial micropollutants oxytetracycline (OTC), ciprofloxacin (CIP), and triclosan (TCS) as well as that of the different constituents of sludge during treatment with ferrous iron and heat activated persulfate (Fe 2+ /heat/S 2 O 8 2 − ) was investigated with full factorial experimental design methodology. Owing to a sulfate radical mechanism, considerable degradation of the micropollutants was achieved in the sludge. Iron promoted the degradation of the zwitterionic OTC and CIP antibiotics, recovered the phosphorus in the solid phase of the sludge, and enhanced the solubilization of the metal. The average degradation rates of OTC, CIP, and TCS were 95%, 84%, and >99%, respectively, whereas the overall rate of solubilization of the metal and the rate of precipitation of phosphate were 53% and 74%, respectively with S 2 O 8 2 −  = 22.7 mM and Fe 2+ /S 2 O 8 2 −  = 0.5 at 75 °C in 120 min.