Impact On Urban Pollution Black Smelly River Sediment Aeration And Bioremediation

The environmental issues of polluted urban rivers have become more important, the black-odor phenomenon of polluted rivers still has not yet been controlled while the governance funding increased, the impact of surrounding by polluted rivers is even more serious. So to study effective and environment-friendly management measures is particularly urgent and important.Using Indoor simulation method, the variation process of black-odor sediment physicochemical property and internal nitrogen fraction was investigated under aerating condition. At the same time, the variation process of black-odor sediment physicochemical property under the action of Vallisneria spiralis roots was explored. In this thesis, the main conclusions are as follows:(1) It’s obvious that the effect of aerating to sediment is better than aerating to overlying-water on decreasing black-odor phenomenon. The removal rate of FeS reached95%under aerating to sediment condition, which is1.8times of aerating to overlying-water condition, while the black-odor phenomenon of sediment significantly eliminated.(2) Under aerating to sediment condition, the inorganic nitrogen content decreased, organic nitrogen content increased, and the system total nitrogen decreased. The surface sediment pore-water dissolved and sediment adsorbed ammonia concentration was reduced by94.4%and75.6%, respectively. The pore-water and sediment organic nitrogen concentration were increased to6.82mg-L"1and2.78mg·kg-1, which is6.7times and12.1times of the initial value. The nitrogen removal rate was12.6%which is1.64times that of the control group, when aerating to sediment for15days.(3) Among the aeration effect factors, aeration time (6h·-1and12h·d-1) has no obvious influence on the sediment physicochemical properties and internal nitrogen changes, on the contrary, the initial pH of the overlying-water is affected. The overlying-water, pore-water and sediment adsorbed ammonia removal rates reached94.31%,84.07%and68.29%when the initial pH of the overlying-water is neutral, it’s significantly better than the initial pH of11.(4) It’s obvious that the roots of Vallisneria spiralis can significantly change the black-odor phenomenon of the sediment. During the experiment the Eh of surface sediment rose from-70mv to90mv. Ferrous content reduced by25%in experiment group while increased by38%in the control group; It decomposed organic matter effectively, prevented from natural decomposition to the smelly substances. There is3mm thick greyish yellow oxide layer after7days in the experimental group, and the oxide layer gradually thickened over time. The thickness of the oxide layer reaches to 11mm at the end of the experiment, and no significant odor was detected. On the contrary, there is only1mm oxide layer in the control group and thickness remains unchanged. Meanwhile, an obnoxious odor existed during the whole experiment.(5) The roots of Vallisneria spiralis have significant influence on the porosity of sediment. The porosity of surface sediment is3.72%lower than the control group. On one hand, the densification of sediment can be improved by Vallisneria spiralis. On the other hand, it has a positive ecological meaning by the Vallisneria spiralis to change the state of the surface sediment flows, reduce the erosion of river sediment and inhibit the transfer of black-odor substances.