Degradation of pesticide wastewater with simultaneous resource recovery via ozonation coupled with anaerobic biochemical technology

The effective treatment of pesticide wastewater with high organic content, complex composition and high-toxicity has attracted enormous attention of researchers. This work proposes a new idea for removing the pesticide wastewater with simultaneous resource recovery, which is different from the traditional view of mineralization of pesticide wastewater via composite technology. This novel strategy involved a sequential three-step treatment: (a) acidic Ozonation process, to remove the venomous aromatic heterocyclic compounds; (b) hydrolysis and ozonation in alkaline conditions, enhancing the biodegradability of pesticide wastewater, mainly due to the dehalogenation, elimination of C=C bonds and production of low molecular-weight carboxylate anions; (c) the final step is anaerobic biological reactions. Based on the characterizations, this two-stage acidic-alkaline ozonation can efficiently degraded the virulence of pesticide wastewater and enhance its biodegradability from 0.08 to 0.32. The final anaerobic biochemical treatment can stably remove the residuals and convert the low molecular-weight organics into CH4, achieving the resource recovery. This work explored the pH-dependent of ozonized degradation of pesticide wastewater and gives a new perspective of wastewater treatment.