Emission Characteristics Of Estrogen In Dairy Cow Manure And The Effect Of Additives On Its Degradation In Aerobic Compostin

Estrogen is a kind of endocrine disruptor.At trace concentration（ng/L）in the environment,estrogen can interfere with the endocrine system of organisms and further hreaten the health and safety of animals and human beings.Livestock and poultry feces are one of the main sources of environmental estrogens,studying the emission characteristics and removal technology of estrogens in livestock and poultry feces was of great significance to reduce the environmental risk of returning livestock and poultry feces to the cropland.In this study,the content of 6 estrogens（Estrone（E1）,17α-estradiol（17α-E2）,17β-estradiol（17β-E2）,estriol（E3）,diethylstilbestrol（DES）,17α-ethinylestradiol（EE2））in dairy cow feces was studied through the positioning bar experiment,and the emission characteristics of estrogens in dairy cow feces at different growth stages and seasons were revealed.The effects of different conditioners and exogenous microbial inoculants on estrogen degradation in dairy cow manure composting were studied by simulated composting experiment.Redundancy analysis（RDA）was used to analyze the correlation between environmental factors,estrogen contents and bacterial community composition,in order to reveal the main factors affecting estrogen degradation in dairy cow feces aerobic composting.The main conclusions are as follows:（1）The estrogens in fresh dairy cow feces are mainly E1,17β-E2,and 17α-E2,of which E1 the detection frequency and detection concentration were the highest.The median total concentrations of estrogens in the faces of lactating,calves,and bred cattle were 79.21,47.20,25.72μg/kg（DW）,respectively,and there was significant seasonal variation in the estrogen content in the feces of dairy cows,and the estrogen contents was observed higher in winter and spring than in summer and autumn.（2）The total daily excretion of 6 estrogens by per lactating cattle,breds,and calves was356.02,113.00,and 12.44μg/（d·cow）,respectively.The number of estrogens excreted by dairy cows through feces at different growth stages varied significantly,and the effects of the different growth stages of cows should be considered when calculating the emission load of estrogen in cow feces.（3）After 30 days of composting,the concentration of ammonia nitrogen（NH₄⁺-N）,p H,Electrical conductivity（EC）,and Seed germination index（GI）of each treatment met the requirements of composting products.The comprehensive evaluation of the indicators showed that the composting treatment（except SD-BF）reached maturity after 30 days of composting;The total estrogens degradation rate of each treatment ranged from 95.34%to99.44%,indicating that each treatment in this study could effectively remove most of the estrogens and reduce estrogens activity.（4）Compared with sawdust,mushroom residue,the oyster shell powder,and rice hull biochar can greatly accelerate the degradation rate of estrogens in the process of cow faces composting,and the half-life of the sum of 17β-estradiol equivalent concentrations（ΣEEQ）for 6 estrogens in the treatment with oyster shell powder,rice hull biochar,sawdust,and the mushroom residue was 2.25,1.78,6.00 and 7.44 d,respectively.The addition of commercial microbial inoculants accelerated the degradation of estrogens.The promoting effects of the three kinds of microbial inoculants on estrogen degradation were in order:EM microbial inoculants>fecal starter cultures>bio-fertilizer starter cultures.（5）Ten genera of estrogens degradation-related genera with high relative abundance（>1%）were found in compost samples.In the compost treatments with different conditioners,the degradation of estrogen in the composting process was significantly related to the genera of Acinetobacter,Bacillus,and Pseudomonas.In the compost treatments with the addition of exogenous microbial inoculants,the degradation of estrogens was significantly correlated with Acinetobacter during composting.（6）p H was the main environmental factor that affected the composition of estrogen-degrading bacteria in composts with different conditioners.The addition of rice hull biochar and oyster shell powder increased the p H and temperature rapidly in the early stage of composting,increased the microbial activity,and promoted rapid degradation of estrogens.In composts with different microbial inoculants,EC was the main environmental factor that affected the composition of estrogen-degrading bacteria,EC was positively correlated with Bacteroides and negatively correlated with Pseudoxanthomonas,Sphingobacterium.The addition of composting additive promoted the change of biological community structure related to estrogen degradation by changing p H,EC,and other physicochemical parameters of the heap material,thus improving the ability of estrogen degradation.