The impact of single step ozonation of antibiotics-contaminated waste sludge to biogas production

Antibiotics contamination of the environment is a growing public health concern, due to their persistency, possible chronic effects and spread of antibiotics resistance genes. The aim of the study was to determine efficiency of ozonation of waste biological sludge, contaminated by various antibiotics (400 mg L−1 of Tiamulin, Amoxicillin and Levofloxacin) in terms of inreased biogas production potential. It was confirmed that contaminated waste sludge inhibits overall biogas production in further anaerobic stabilization for 10–30% resulting also in lower methane yield in the gas mixture (14–45%). Ozonation of waste biological sludge was accomplished in batch system for 10 (22–24 mgO3 gvss−1) or 20 (36–69 mgO3 gvss−1) minutes. The impact to biogas production potential was measured for untreated, contaminated, ozonated untreated and ozonated contaminated sludge after its addition to anaerobic sludge in closed system at 37 °C. Ozone at applied doses simultaneously removed antibiotics related inhibition of biogas production and in some cases enhances biogas production (13–18%) with improved methane yield (22–32%). The highest improvement in biogas production potential was determined for Tiamulin while ozonation of Levofloxacin contaminated sludge was less efficient. It was concluded, that proposed ozone doses resulted in removal of inhibition due to the antibiotics but did not lead to economically feasible increase of biogas production and methane yield.