Study On Odour Reduction And Inhibitor Of Nitrogen Losses During Pig Manure Composting

With intensive and scale development of livestock and poultry industry,how to reasonably and scientificly disposal the livestock and poultry wastes has become one of the research hots in the area of environmental science.Aerobic composting was one of the most effective ways to transform livestock and poultry wastes to high-quality organic fertilizer.Whereas it generally produced odours(such as NH₃ and H₂S) during the period of composting,which not only caused the environmental contamination and seriously impact on human health and animal growth but also the loss of nitrogen reduced the agricultural value during mature composting.Pig manure was used as research material,the ordour reduction and inhibitor of nitrogen losses effect of different physical amendments,physical and chemical amendments and biology amendments were studied by high temperature oxygen method during pig manure compost,in order to select good amendments and its appending proportion.The results are showed as follows:1.Odour production of compost and nitrogen losses can be reduced by physical measures(such as adding different physical amendments) during pig manure composting process.Results indicated that the better effects of odour reduction and nitrogen preservation were showed in treatment 5(72.98%fresh pig manure + 20% rice brain) and treatment 8(72.98%fresh pig manure + 20%straw).Compared with CK,the two treatments have been reduced the time of odour removing with 9 days, the duration time of above Ms4 degree were reduced 9 days and 6 days respectively, volatilized amount of NH₃ were reduced by 49.76%and 51.53%,Volatilized amount of H₂S were reduced by 24.46%and 20.50%,the decline rate of total nitrogen content were reduced by 43.46%and 56.65%,the loss of nitrogen were reduced by 21.33% and 26.21%respectively.2.Physical and chemical methods(certain amount of conditioner was based on treatment 5 and treatment 8) have been used during pig manure composting process were good for odour reduction and nitrogen losses inhibitant of compost.Results indicated that the better effect of odour reduction and nitrogen preservation were showed in treatment H(pig manure-straw-10%CaCl₂) and treatmentâ… (pig manure-straw-15%CaCl₂).Odour reduction of two treatments were reduced 3 days with 18 days,compared with CK.The volatilized amount of NH₃ in treatment H was reduced by 62.42%and 60.13%respectively,compared with CK1(pig manure-straw) and CK2(pig manure-rice bran),and the volatilized amount of NH₃ in treatmentâ… were reduced by 65.45%and 63.34%,few H₂S were produced in treatment H and treatmentâ… during compost processing,which effectively reduced the odour. Compared with CK1 and CK2,the content of total nitrogen in treatment H has been increased by 285.52%and 322.63%respectively after composting,and the content of total nitrogen in treatmentâ… has been increased by 282.65%and 319.18%.The lowest amount of total nitrogen loss are treatment H and treatmentâ… with 12.76%and 13.06%respectively,compared with CK1,it has been decreased by 51.57%and 50.44%respectively,it has been decreased by 51.01%and 49.88%,compared with CK2.The values of solid-phase C/N in every treatment are under 20 at the end of compost,the index of seed germination(GI) had been reached 80%,which indicated that the composting reached maturity level.3.The production of odour was controlled and the loss of nitrogen was reduced by physical,chemical and biological measures(such as adding biological amendments into treatment H) during mature composting.Results indicated that treatmentâ…¡(pig manure-straw-10%CaCl₂-curing bacteria),treatmentâ…£(pig manure-straw-10% CaCl₂-curing and nitrifying bacteria) and treatmentâ…¤(pig manure-straw-10% CaCl₂-mixed bacteria) had the best effects on odour reduction and nitrogen preservation.Compared with CK(pig manure-straw-10%CaCl₂),these treatments were 3 days earlier for no odour,and reduced the sustainable days in Ms4 degree by 3 days.All treatments had almost no H₂S release,which effectively reduced the odour. The volatilized amount of NH₃ in treatmentâ…¡,treatmentâ…£and treatmentâ…¤were fallen to 50 mg / L on the 18^th day,with 3 days earilier than CK.Compared with CK, treatmentâ…¡,treatmentâ…£and treatmentâ…¤increased the total nitrogen content by 29.45%,27.21%and 14.26%,and increased the water-soluble TN by 31.47%,8.39% and 3.85%,and by 7.12%,3.02%and 2.01%for water-soluble NH₄⁺-N,and by 44.32%,34.84%and 37.88%for water-soluble NO₃^--N,respectively.The values of water-soluble C/N had fallen to 5 below,and values of solid-phase C/N were under 17 at the end of compost,the index of seed germination(GI) had been reached 80%, which indicated that the composting reached maturity level.All of above results were showed that,adding curing bacteria,nitrifying-curing bacteria and mixed bacteria(the initial value of C/N was modified about 25) on the basis of 20%straw(physical amendment) and 10%CaCl₂(chemical amendment) during pig manure composting,degradate speed of fermentations was faster,and the effect of odour reduction and nitrogen preservation was better,it was suited to be applied in composting.