| Removal effects of four different dissolved organic matters (DOMs), including hydrophobic acids, non-acid hydrophobics, tasnsphilics and hydrophilics separated by XAD-8 and XAD-4 resins, in biotreated effluent of dye wastewater by carbon adsorption process were studied. Analysis indexes included DOC, UV254, ADMI7.6, COD and toxicity. And the molecular distributions of DOMs in biotreated effluent of dye wastewater before and after the adsorption were determined by UF method. It could be helpful for the selection of advanced treatment technologies of bio-treated effluent of dye wastewater.The adsorption capacity experiments showed that three kinds of activated carbon had noticeable effects on DOMs removal, and coal activated carbon had the highest removal efficiency. The optimal conditions determined were as follows:initial pH, reacting temperature 20±0.5℃, adsorption equilibrium time 7 h, revolving speed 180 r·min-1. Under the optimal conditions, both Freundlich and Langmuir adsorption equations could be used to describe the performance very well, the Freundlich model was better than Langmuir model. When its dosage was 1.188g·L-1,the removals of DOC, COD, ADMI7.6 and UV254 could reach 76%,11%,85% and 82%, respectively. The research results on removal characterization of DOM fractions by different treatments showed that, when characterized by UV254, the removal efficiency of tasnsphilics was highest through activated carbon adsorption; when characterized by ADMI76, the removal efficiency of hydrophobic acids was higher; when characterized by DOC, the removal efficiency of hydrophobic was higher than hydrophilics. The molecular weight distribution experimental results showed that, organic molecules with molecular weight less than 4 K contributed greatest to UV254, ADMI7.6 and DOC removal efficiencies. After carbon adsorption, the biological toxicity of the raw water was obviously reduced.The breakthrough curve experiments showed that carbon adsorption process had noticeable effect on DOMs removal, and coal activated carbon had the higher removal efficiency. When characterized by UV254, the capacity utilization efficiency of coal and coconut activated carbon could reach 49% and 20%, respectively. When characterized by ADMI76, the capacity utilization efficiency of coal and coconut activated carbon could reach 52% and 22%, respectively. The research results on removal characterization of DOM fractions by different treatments showed that, the removal efficiencies of non-acid hydrophilics and tasnsphilics were very high through activated carbon adsorption, while the removal efficiencies of hydrophobic acids and hydrophilics were lower. The molecular weight distribution experimental results showed that, organic molecules with molecular weight between 1 K～4 K contribute greatest to UV254, ADMI76 and DOC removal efficiencies.The four indicators and the surface chemical property of the origin carbon were compared with the wasted carbon. It showed that the coal carbon was not only superior over coconut carbon at the completeness of cavities distribution, but also at the utilization efficiency of cavities. |
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