Treatment of persistent organic compounds by integrated advanced oxidation processes and sequential batch reactor

The objective of this study was to evaluate the extent of improvement in the biodegradability of persistent organic compounds by pre-oxidation by using Sequential Batch Reactors (SBRs). Dichlorodiethyl ether (DCDE), a non-biodegradable compound, was used as a test chemical. Ozonation, Fenton reagent and ultra-violet light coupled with hydrogen peroxide (UV/H₂O₂) were used for oxidation of DCDE at levels of 50-100%. Pre-oxidized DCDE solutions were then subjected to SBR studies using activated sludge to determine the rate and extent of biodegradation of oxidation by-products. The results indicated that the biodegradability of pre-oxidized DCDE increased drastically, reaching an average of 90% for all three oxidation methods versus zero for non-oxidized DCDE. It was concluded that the results of SBR experiments may be better indicators of biodegradability of chemically-oxidized wastewaters due to significant acclimation of microorganisms in SBRs, which cannot be observed in conventional respirometric laboratory studies.