Hundreds of active ingredients and tens of thousands of formulations are used to control agricultural pests and disease-carrying vectors. The pesticide manufacturing industry generates process wastewaters containing a variety of pollutants as a result of the wide variety of raw materials, processes used and products manufactured. Main pollutant parameters of pesticide manufacturing industry wastewaters are conventional pollutants (pH, biochemical oxygen demand (BOD5), total suspended solids (TSS)), a variety of toxic pollutants and a large number of non-conventional pollutants (i.e. chemical oxygen demand (COD) and pesticides). The pollutants or pollutant groups likely to be present in process wastewater of pesticide manufacturingindustry can be classified as volatile aromatics, halomethanes, cyanides, haloethers, phenols, polynuclear aromatics, heavy metals, chlorinated ethanes, and ethylenes, nitrosamines, phthalates, dichloropropane and dichloropropene, priority pollutant pesticides, dienes, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).
Chemical oxidation processes have a high potential to reduce or completely eliminate the pesticide contamination during water and/or wastewater treatment. Chemical oxidation processes are used as primary removal technology for the treatment of cyanide and priority pollutant pesticide pollutant groups in the pesticide industry.
An ideal treatment scheme for concentrated wastewater from pesticide manufacturing is the pretreatment of the wastewaters by proper physicochemical processes to remove or reduce the most of the toxic organics before biological treatment. Biological processes are well established and relatively cheap treatment techniques. However, these biological methods are susceptible to toxic compounds that inactivate the waste-degrading microorganisms. In such cases, a potentially useful approach is to partially pre-treat the toxic waste by chemical oxidation technologies in order to produce intermediates that are more readily biodegradable. Chemical oxidation processes such as ozonation, ozone-based AOPs, H2O2/UV, Fenton, and Fenton-based AOPs etc. are used as a pretreatment stage to enhance biodegradability and reduce toxicity, prior to biological treatment in pesticide industry and these technologies have been found to be effective.