Study On The Coupling Process Of Straw Degradation And Soil Pollution Bioremediation

The utilization of straw resources and the treatment of soil pollution are two maj or environmental problems in our country.As an important resource utilization method,straw mulching still has problems such as long degradation cycles and low efficiency.Bioremediation of soil pollution has good development prospects for its good effect and low cost.In this paper,straw degradation and the bioremediation of soil pollution were organically coupled by straw decomposing agent.The degradation of soil organic pollutants was achieved while the straw was rapidly degraded.The main results are as follows:The results of the straw degradation process showed that the straw decomposing agent had good adaptability of temperature(20-35?),water content(60-75%),and pH(4-6).Under the conditions of 25?,substrate moisture content 75%and substrate pH 5,the degradation rate of straw was up to 56.55%on the 10th day.On the 16th day the activities of laccase,filter paper activity(total cellulase activity)and xylanase were up to 23.13 IU/g,230.91 IU/g and 4222.61 IU/g,the degradation rate of cellulose,hemicellulose and lignin were up to 72.27%,65.69%and 34.25%,and the degradation rate of straw was 63.21%.The koji obtained by straw solid-state fermentation was applied to the bioremediation of soil contaminated by chlorpyrifos.The results showed that the degradation effect of koji is better than enzyme solution,and the degradation rate differs by more than 20%under the same conditions.Under the conditions of koji dosage 3 IU/g,temperature 30?,pH 3.0 and soil moisture content 40%,the degradation rate of chlorpyrifos in soil was up to 56.11%after 8 days.The coupling process of straw degradation and soil pollution bioremediation was studied.The results indicated:Daily water supply should be adjusted according to the ambient temperature;the best straw degradation effect could be achieved when the substrate moisture content was maintained at about 75%.the degradation rate of chlorpyrifos could be improved by increasing the water supply in an appropriate range.In the process of simultaneous fermentation,the water content of the substrate is more stable and the remediation effect of soil was better.Under the conditions of 30?,daily water supply 80%,synchronous fermentation,the activity of laccase in the matrix could reach 24.75 IU/g,and the degradation rate of straw could reach 54.23%on the 10th day of the coupling process.And the degradation rate of chlorpyrifos could reach 65.6%on the 16th day.The coupling process had a good bioremediation effect on the soil contaminated by 2,4,5-trichlorophenol,oxytetracycline,bisphenol A and isoproturon.On the 16th day of the coupling process,the degradation rate of 2,4,5-trichlorophenol,oxytetracycline and bisphenol A in the soil reached 74.93%,92.13%and 79.13%respectively.The degradation rate of isoprouron reached 38.05%,which was comparatively low.The results of this paper have good application prospects in the field of straw utilization and soil pollution bioremediation.