| The phthalates (PAEs) are a kind of synthetic organic compounds which widely used in plasticizers and additives. PAEs are progressively enriched in the living body which through the food chain, and had toxicity of carcinogenic, teratogenic, damaging the immune and the function of reproductive. In recent years, the residues of PAEs were detected in much water, due to the heavy use of plastics as well as the massive emissions of domestic sewage, industrial and agricultural wastewater. The main way of PAEs into the water is the discharge water by wastewater treatment plant which the major technology is activated sludge. Study on the adsorption and degradation of PAEs have great significance.Six kinds of phthalates was selected as the typical PAEs for the study, including diethyl phthalate (DMP), diethyl phthalate (DEP), deputy phthalate butyl (DBP), deputy phthalate (2-ethylhexyl) phthalate (DEHP) and dactyl phthalate (DOP), butyl benzyl phthalate (BBP). The experiments for adsorption and degradation of PAEs by activated sludge were conducted. The main contents and conclusions of the experimental are as follows:(1) The chromatography and mass spectrometry conditions of 6 kinds PAEs were established. The PAEs standard curve were obtained which according to the double qualitative of characteristic fragment ion and relative retention times, peak area-external standard. The linear ranger of PAEs was between 1.0mg/L-8.0mg/L, correlation coefficients were greater than 0.90, and had a good linear correlation, the lowest detection limit were 0.003-0.008μg/L.(2) Study on the adsorption of PAEs by activated sludge, which were influenced on environmental conditions as adsorption time, initial concentration, temperature, pH. The results showed that the concentration of PAEs rapidly decreased by the adsorption of activated sludge at the beginning of 15min. The higher the initial concentration of PAEs, the stronger the adsorption of activated sludge, but the adsorption equilibrium time basically unchanged. The adsorption of 6 kinds of PAEs by activated sludge was difference, DOP maximum, DMP minimum, and this results were more obvious when the initial concentration of PAEs were greater. The higher the octagon-water partition coefficient the more easily to been adsorbed. The adsorption of PAEs by activated sludge was exothermic processes, and the low temperature was conducive to adsorption, the high temperature was conducive to desorption. The optimum temperature of the adsorption was about 25 ℃, and the adsorption processes of DMP, DEP were affected by temperature. The PAEs which has small molecular weight and less branched alkyl was more soluble in water and not easily been adsorbed. The adsorption performance of activated sludge was DOP> DEHP> DBP> DEP> DMP. The adsorption of PAEs was poorer under acidic conditions and more effective under alkaline conditions. The adsorption of PAEs had not change significantly when pH was greater than 9.0.(3) Study the interaction for a variety of environmental conditions on activated sludge adsorbed PAEs. The results showed that the adsorption capacity of activated sludge was decreased by salinity under neutral conditions and improved under acidic conditions. Cell wall was broken had not significant effect on the adsorption of activated sludge under pH and salinity conditions.(4) The biodegradation processes of DMP, DEP, DEHP, DBP and BBP by activated sludge were in line with first-order kinetics, but the levels of degradation and degradation rate constant were difference for the 5 kinds PAEs. The adsorption isotherms processes of DMP, DEP, DOP, DEHP by activated sludge were addition to the Freundlich isotherm, the adsorption constant KF at 25℃was DOP> DEHP> DEP> DMP. |
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