Improvement of biotreatability of environmentally persistent antibiotic Tiamulin by O₃ and O₃/H₂O₂ oxidation processes

The aim of the work was to assess the efficiency of ozonation and ozonation in combination with H₂O₂ in jet loop reactor to increase biotreatability of persistent veterinary antibiotic Tiamulin. The efficiency of oxidative processes was monitored by combined approach based on determination of efficiency of wastewater treatment and impact to waste sludge stabilization. Degradation of Tiamulin in model wastewater (100 mg L^-1) during oxidation was followed by COD and DOC measurements while changes in biodegradability were determined by respirometric measurements. Biogas production potential was also determined to identify problems related to anaerobic digestion of waste sludge resulted in treatment of Tiamulin-contaminated wastewater. At ozone dose of 69 g_ozone g_COD^-1 and 220 g_ozone g_DOC^-1removal for COD and DOC was 26% and 17%, respectively. Better biotreatability was confirmed by respirometric testing. H₂O₂ addition did not improve removal efficiency (11-13%). The second stage of nitrification was suppressed by the addition of Tiamulin and ozonation again recovered $N\text{-}{\mathrm{NO}}_3^{-}$ formation. O₃/H₂O₂ treated sample reduced the nitrification, especially formation of $N\text{-}{\mathrm{NO}}_2^{-}$ in the first phase of the process. Simultaneously, quadratic model was developed to describe the relationship between oxygen uptake rate and changes in ammonium nitrogen concentration due to the oxidative treatment. The positive impact of ozone was also confirmed by ozonation of Tiamulin-contaminated (400 mg L^-1) waste sludge where biogas production potential was increased for 6-times. Combination of approaches confirmed, that O₃ effectively increase the treatability of Tiamulin in wastewater and sludge while addition of the hydrogen peroxide generally did not improve the performance of the processes.