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This study was conducted to treat dye manufacturing wastewater using H2O1/UV and H2O2/UV/Fe2+ processes, which serve to pretreat the loading in the subsequent treatment processes or polish the secondary effluent to comply with discharge regulation. Dye manufacturing wastewater, if not appropriately treated, might impose on the receiving waters a severe threat because of its high levels of refractory organic compounds, color, and chloride ion salt. Base on the literature report, it is understood that dyestuff can not be completely removed by biological treatment, due to its inhibiting effect microorganism. Both processes mentioned above are capable of generating strong oxidant, called hydroxyl radical, which can oxidize effectively the target organics to achieve the treatment goal. The emphasis of this study was placed on the effect of ferrous ions and peroxide dosages, UV intensity, chloride ions concentration, pH, and dilution ratio of original wastewater sample on the residual fractions of COD, H2O2, ABS254 and ADMI color value. As a result the enhanced effect by adding excess H2O2 is very limited due to its OH‧ scavenging. In general, the removals of ABS254, ADMI color value were found faster than that of COD. The pH condition for the best removal of ABS254, ADMI color value, and COD occurs at around pH=3 or pH=4. Chloride ions show some inhibiting in removing COD, ABS254 and ADMI color value, however, its inhibiting effect on peroxide decomposition dose not necessarily increase with its concentration. Although, both processes show the some removal efficiency at the end of 2 hour reaction period, the removal rate is much slower using H2O2/UV process than H2O2/UV/Fe2+ process. It is suggested that add appropriate ferrous dosage in the early reaction period and then followed by supplementing sufficient amount H2O2 in the late reaction, in order to achieve the best process performance.
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