Study on removal effect of different organic fractions from bio-treated effluent of dye wastewater by UV/H2O2 process]

The pretreatment of bio-treated effluent of dye wastewater by UV/H2O2 process was studied. The influencing factors, such as H2O2 dosage, reaction time and pH values were evaluated for the removal efficiency of UV254, ADMI7.6, DOC and DOC of dye wastewater by UV/H2O2 process. The experimental results showed that,the optimal conditions determined were as follows: initial pH 7.4-8.1, H2O2 dosage 4.5 mmol x L(-1) and UV irradiation time of 50 min. Under the optimal conditions, UV254, ADMI7.6, DOC and COD removal rate could reach 77%, 94%, 40% and 69%. Removal effects of four different DOM fractions, hydrophobic acids, non-acid hydrophobics, tasnsphilics and hydrophilics separated by XAD-8 and XAD-4 resins. The experimental results show that: hydrophobic material was the main substance causing color, when it was characterized by ADMI7.6, the proportion could reach 92%, of which 53% was non-acid hydrophobics. It indicated that removal efficiencies of tasnsphilics, hydrophobic acids and non-acid hydrophobics were high through UV/H2O2, process, while hydrophilics' efficiencies were lower. The experimental results showed that organic molecules with molecular weight over 10,000 contributed greatly to UV254, ADMI7.6 and DOC removal rate.