Study On Adsorption And Microbial Biodegradation Of 17 Beta-estradiol On Soil Colloid

Environmental estrogens are a kind of pollutants with hormone effect.When the concentration of water is greater than 1 ng/L,the growth of organisms will be affected.Estradiol is a highly active pollutant in estrogens.The estradiol entering the natural environment is mainly attenuated by two ways:adsorption and microbial degradation.In this paper,the adsorption behavior of colloid on estradiol was studied with the characteristics of a high level of ammonia nitrogen and high estradiol content in livestock farms in Shenyang.The degradation mechanism of estradiol and the effect of colloid adsorption on the degradation of the estradiol by the highly efficient degrading Gordon strain R9 were studied.The results of the study are as follows:?1?This paper successfully prepared the soil colloid which was combined with the characteristics of the contaminated site of livestock and poultry farms.The adsorption mechanism of estradiol was studied.The results showed that the adsorption kinetics of the estradiol was in accordance with the pseudo two order reaction kinetics,and the speed limited step of estradiol on the colloid was internal particle diffusion.With the increase of ionic strength,the adsorption of the estradiol on colloid increased and the adsorption amount increased.The adsorption equation was in accordance with the Langmuir phase.The colloid turbidity,temperature,pH and ionic strength were selected as four factors for the response surface to analyze the adsorption of 17beta-estradiol on the colloid.The results showed that the estradiol was adsorbed by the colloid most at20 NTU,pH 5.5,temperature 4?,and NH₄NO₃ 0.01 mol/L,and the adsorption capacity was 191.94 mg/g.?2?Through the study of the degradation performance of the strain R9 of Gordon's strain,it is known that it has a wide range of adaptation to pH,temperature and substrate concentration.The whole genome test analysis shows that the genome of Gordon's R9strain is ring,1 Scaffold,a total of 6033879 BP,and the content of GC is 66.90%,and5613 genes are encoded.Through the whole genome analysis,a complete sterol degradation pathway,as well as 50 genes involved in steroid hormone degradation,were obtained,and the degradation pathway of estradiol was speculated.9 genes involved in the degradation of estrogen were successfully amplified from the R9 R9,and were successfully expressed and purified to the tetracycline promoter protein,the3 beta-dehydrogenase protein,the 3-ketosterol-1-dehydrogenase protein,and the acyl dehydrogenase protein.?3?The adsorption of colloid on estradiol affects the mass transfer process of estradiol to microbes,thus affecting the degradation rate of estradiol.This study conducted experiments on microorganism estradiol and colloid microorganism estradiol system respectively.The presence of colloid could slow the degradation rate of estradiol.The microorganism needs 24 h to degrade 92%,while under the condition of colloid,the microorganism needs 120 h to degrade more than 90%.The study shows that the degradation kinetics of estradiol in the colloid-microorganism-estradiol system and the estradiol in the microorganism conforms to the kinetic equation of the double exponential decay.By comparing the attenuation constants,it is known that the phase of the estradiol degradation is the fast degradation stage.