Study On The Effect Of Exogenous Additives On Reducing Nitrogen Loss During Aerobic Composting

The aerobic composting technology of sludge has the advantages of high degree of resource utilization and low operating cost.At the same time,it could achieve the purpose of reduction,harmlessness and resource utilization of sludge.However,traditional aerobic composting presents some drawbacks such as nitrogen loss,low quality of final product and low humification.Therefore,in this study,waste activated sludge and corn straw were used as raw materials,while nitrilotriacetic acid was used as additive and study on the effects of nitrilotriacetic acid on nitrogen loss,organic matter degradation and compost maturity in aerobic composting process;secondly,in order to solve the low quality of final product,that caused by addition of nitrilotriacetic acid,lignite was used as additive to study its effect of nitrogen conservation during aerobic composting.Thirdly,in order to solve the limitation of single additive on aerobic composting,the effect of compound additive on reducing nitrogen loss during aerobic composting was studied by adding nitrilotriacetic acid and lignite.Finally,the agricultural effect of composting products was evaluated by pot experiment.The results provide a useful reference for optimization of aerobic composting and the way to use compost products in china.The main results are as follows:（1）Effect of nitrilotriacetic acid on reducing nitrogen loss during aerobic composting.The dosage of nitrilotriacetic acid added was 2.5%（Dry weight of raw materials）could effectively reduce the nitrogen loss during aerobic composting by adjusting the initial p H value of compost.Compared with the control,the cumulative volatilization of NH₃was decreased by 15.20%.Meanwhile,the quality of final compost products was reduced,GI value of compost products was more than 80%,EC value was less than 4.0 m S/cm,but compared withthe control,GI value was decreased by 21.60%,EC value was increased by9.84%.（2）Effect of lignite on reducing nitrogen loss and improving quality of compost.The dosage of lignite added was 2.5%（Dry weight of raw materials）could effectively reduce nitrogen loss and improve the quality of the compost product.Under the adsorption of lignite,the cumulative NH₃volatilization amount was 0.75 g,which was 261.86%less than the control.At the end of composting,compared with the control,the GI value of the compost product increased by 15.43%,the EC value decreased by 21.11%,and the HS content increased by 57.92%.However,due to its large amount of addition,the TKN content of the compost product was relatively low,which was not conducive to the increase of the nutrient content of the compost product.（3）Effect of compound additives on reducing nitrogen loss during aerobic composting.The thermophilic stage of the pile with compound additives（2.5%（Dry weight of raw materials）nitrilotriacetic acid+45%（Dry weight of raw materials）lignite）was extended to 9days,and the high temperature was 63.3℃.At the end of composting,the GI value of the compost product was 133.77%,the EC value was 2.31 m S/cm,the E4/E6 was 3.57,the nitrification index was 2.85,NH₄⁺-N content of the pile remained low at 3.57 mg/g,and the TOC dropped by 13.89%,TKN increased by 50.32%,and the cumulative amount of NH₃volatilization was reduced by 48.66%and 14.65%,respectively,compared with the addition of nitrilotriacetic acid and lignite alone.（4）Evaluation of agricultural effect of compost products.The application of bio-organic fertilizer with compound additives could reduce the loss of soil inorganic salts and nutrients,and promote the growth of green vegetables.At the end of the pot experiment,the EC Value of the tested soil was decreased by 4.17%,the emergence rate of three consecutive cropping of small green vegetables was ranged from 78%to 90%,the plant height was ranged from13.98 to 15.06 cm,the root length was ranged from 4.16 to 4.41 cm,and the chlorophyll content was ranged from 0.74 to 0.77 mg/g.The results showed that the compost with compound additives was a good slow-release fertilizer,which could promote the growth of green vegetables and had good agricultural value.