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The degradation processes of refractory substances in nanofiltration concentrated leachate using micro-ozonation

Wang, Hui, Wang, Yunhai, Lou, Ziyang, Zhu, Nanwen, Yuan, Haiping
Waste management 2017 v.69 pp. 274-280
byproducts, chemical oxygen demand, fulvic acids, humic acids, leachates, microbubbles, nanofiltration, ozonation, ozone, pH, waste management
Concentrated leachate (CL) is the byproduct of leachate treated by the membrane separation unit after bio-treatment processes, and contains many humic-like substances. Ozonation processes were applied and optimized for the further removal of those refractory matters in this work. Micro-bubble ozonation (MB-O3) possessed the best performance, and 76.0% and 69.9% of COD and TOC were found to be removed under the optimum conditions with ozone dosage of 2.4g/L, initial pH of 9 and reaction time of 120min. The reaction rate k in MB-O3 was 0.0104min⁻¹, three times higher than that in normal O3. The percentages of humic acid and fulvic acid in CL decreased from 24.1% to 14.3% and 49.6% to 25.0%, while that of HyI substances increased from 26.3% to 60.7%, which was also found in the fraction of <2000Da, with the occupied percentage increased from 0 to 63.0%. The humic acid-like substances might be transformed to matters with carbonyl and carboxyl group, since a continuous blue-shift was observed from Em/Ex 475/390 to 410/325nm. MB-O3 could be a promising method for the advanced treatment of CL.