Occurrence Of Steroidal Estrogens In Aquatic Environment Of Hefei City And Their Removal During Biological Treatment Process

Natural steroidal estrogens are typical endocrine disrupting chemicals, which showstrong ecological and genetic toxicity even at ng/L concentration. In this paper, theconcentration of steroidal estrogens in sewage, dairy farm waste and surface water inHefei city were investigated using trace analysis technic. And biodegradation andtransformation of steroid estrogens under anaerobic and aerobic conditions were alsostudied using batch and pilot scale experiments. Related conclusions were asfollows:The concentration of estrone (E1),17α-estradiol (17α-E2) and17β-estradiol(17β-E2) in cow manure were between61.95~439.87μg/kg DW,31.97~940.54μg/kg DW and56.5~277.7μg/kg DW respectively. The influent water of wastewatertreatment plants in hefei contains E1(180.62~339.35ng/L),17β-E2(65.46~556.95ng/L), estriol(E3)(208.96~454.43ng/L) and slight17α-E2.Although the removal of E1and E3was higher than17β-E2in sewagetreatment plants, the different treatment processes have different remove effectof estrogens. There were still contains high concentration of estrogens, totalestrogens between101.58to721.14ng/L in effluent of wastewater treatmentplants, resulting in the concentration of estrogens increased in receiving water.The results of anaerobic batch experimental showed that the removal rate of17β-E2was more than95%in surface and synthetic wastewater after375days,and the anaerobic degradation of17β-E2followed first-order reaction kineticmodel. It also showed that the decrease of17β-E2was accompanied by theaccumulation of E1and then converted to another product, such as17α-E2, butthere were no significant impacts on total estrogens. In Fe(III)-DIRB anaerobicsystem, the presence of Fe(III) had slighter promotion on the degradation ofestrogens, but there are no significant impacts in long term.Under aerobic conditions, the removal rate of17β-E2in water samplesreached98.3%within5hours, while under anoxic condition it only reached87.6%in24hours. The adsorption of sludge caused the increasing of E1, untilachieve stability, but the concentration of17β-E2changed smaller. Theactivated sludge was acclimated using sequencing batch reactor (SBR) mode,after40days of acclimation, the performance of activated sludge was stabilized.When the mixed liquid suspended solid (MLSS) was3000mg/L, operation cycle was six hours, the removal effect of COD and ammonia was the best.Under this condition, the removal rate of17β-E2was90.6%and the totalestrogens was just59.7%in one cycle. The residue estrogens was adsorbed insludge, and just reduced15.8%in15days when the influent did not containestrogens. It was clear that the aerobic biological treatment processes for theremoval of estrogens is still very limited.