Study On The Application Of Straw Soil Permeability Improvement Technology In Sponge City Construction

In recent years,the concept of sponge city has been put forward and developed in China.The rainwater resources have been fully optimized and analyzed to improve the ecological environment of the city.Concave green space is an important part of sponge city construction.At present,the research on the sunken green space mainly focuses on the infiltration and storage capacity of natural sunken green space for rainwater,the ability to reduce rainwater flood peak,the ability to intercept runoff pollution and so on.There is little research on how to improve the infiltration and purification capacity of sunken green space.This paper mainly focuses on how to improve the infiltration capacity,water purification capacity and straw decomposition rate of the soil on the concave green underground bedding surface.The research content is to reuse straw resources as soil culture raw materials,and explore straw improvement soil technology,mainly from straw decomposition efficiency,soil water permeability improvement and soil purification effect on runoff It is feasible to use straw to improve the soil as a concave green underlay,and through the comparison of conditions,the best cultivation mode is obtained to improve the functionality of the concave green space.In the study of straw decomposition efficiency,firstly,the experiment of adding straw to soil according to different weight ratio was carried out.According to the results,the more straw was added,the faster the decomposition efficiency was improved.The best dosage in the experiment was that the weight ratio of soil to straw was 20:1,and the highest cellulase activity value was 0.0115mg/g.Then the experiment of applying different rotten bacteria to straw soil was carried out In the experiment of ripening bacteria,straw was added with the weight ratio of 20:1 of soil and straw,which was divided into three groups.Aspergillus oryzae,Trichoderma and Bacillus subtilis were added to each group respectively.In the three groups,the maximum enzyme activity values of cellulase were 0.0425 mg/g,0.0339 mg/g and0.0172 mg/g respectively Mg/g,under the condition of the same proportion of straw,the application of rotten bacteria can improve the decomposition efficiency of straw.Among different kinds of rotted bacteria,Aspergillus oryzae experimental group produces the most cellulase,and the effect of straw decomposition is better.At last,there are two ways to add straw:straw mulching and straw mixing.The cellulase activity value of straw mulching adding experiment group is almost no higher than that of native soil.Straw mixing adding should be used in fast decomposition straw.In the study of straw permeability,according to the experiment of different weight ratio of soil and straw,according to the stable permeability rate measured in the experiment,the more straw is added,the greater the permeability rate of the experimental group is.In terms of soil penetration rate,all the experimental groups with mature bacteria were higher than those without mature bacteria.Among the different mature bacteria,the stable penetration rate of Aspergillus oryzae was the highest,reaching 3.72mm/min.The soil porosity of Aspergillus oryzae group was55%and the average bulk density was 1.26g/cm3.In the research of straw soil degradation of rainwater pollutants,the removal rate of COD,NH₃-N and TP are mainly studied.According to the experimental results of different weight ratio of soil and straw,the addition of straw can improve the removal rate of soil pollutants compared with the original soil,and the improvement effect is better with the increase of straw addition,of which soil and straw 20:1.In the weight ratio experiment group,the maximum removal rate of COD was 72.2%,the average removal rate was 64.6%,the maximum removal rate of NH₃-N was 72.3%,the average removal rate was 56.8%,the maximum removal rate of TP was 77.6%,and the average removal rate was 60.49%.The results showed that the highest removal rate of COD was 91.8%,the average removal rate was 84.91%,which was about 1.6 times higher than that of the original soil.The highest removal rate of NH₃-N was 84.5%,the average removal rate was 71.83%,the highest removal rate of TP was 88.72%,the average removal rate was 81.86%.In this study,the best way to improve soil culture was to add Aspergillus oryzae in the ratio of 20:1 weight of soil and straw,which could improve the infiltration and purification ability of soil to rainwater.It provides a theoretical basis for the construction of concave green space cushion.