Fate of Eleven Phthalic Acid Esters in Aerobic Sewage Treatment System

Phthalic acid esters have potential environmental risk due to their endocrine disrupting effect. The biodegradable and removal characteristics of 11 phthalicacidesters were studied. The results showed that dimethyl phthalate(DMP), dimethoxyethyl phthalate (BMEP), diethyl phthalate(DEP), dibutyl phthalate (DBP), diisobutyl phthalate(DIBP), dinamyl phthalate (DNPP), di-n-hexyl phthalate(DNHP)and bis (2-ethylhexyl) phthalate (DEHP) had ready biodegradability, dinonyl phthalate (DNP)and dicyclohexyl phthalate (DHP)could be biodegraded but did not pass the 10 d window-period, and only 43.5% of diphenyl phthalate (DPP) was biodegraded on 28d. The degradation curves of 11 PAEs all obeyed typical first-order kinetics in aerobic sludge kinetics test, with the correlation coefficient r²>0.96, the degradation rate constant was between 0.021-1.11 h^-1, and the degradation half-life was between 0.625-32.7 h. In aerobic sludge simulation test, the removal rates of 10 PAEs were >80% at hydraulic detention time of 12h, except that DNPP was only 55%-70%. The removal rates of all PAEs reached 90% at hydraulic detention time of 24h. The relative high exposure in effluent for DMP, DEP, DIBP, DBP and DEHP was found by using GC/MS, with the residue concentrations of ND-44.0, ND-12.0, 60.4-594, 88.0-823 and 130-728 ng·L^-1, respectively. The results from STP model prediction showed that the removal in STP was mainly contributed by biodegradation, but for DPP, DNP and DEHP, the absorption removal was also an important removal way.