| The release of phosphorus(P)in the sediment will aggravate the deterioration of the qualities of water bodies,controlling the release of phosphorus from the sediment is an important measure to remediate the black-odor water.Based on natural soil,funtional soil is modified for the practional need.In situ capping is a commonly used technique for in situ control of phosphorus release from the sediments.This paper studied on the use of the modified soil as the capping materials,using chemical oxidants or passivator as the modifier,improvingthe qualities of oxidation and fixing to pollutants,which can explore a cost-effective pollution in situ active coating technology.In this paper,the black sediment in Chengdu Shilling river was used as the research object,the pollution conditions and the distribution of phosphorus fractions in the Shiling River,the influence of environmental conditions on the release of phosphorus from sediments and the influence of modified soil capping to control the phosphorus release from sediment were analyzed,the results are as follows:(1)In this paper,the sediment physical-chemical qualities were analyzed according to standard method,phosphorus fractions in the sediments are investigated by using the method “SMT protocol”.The total phosphorus(TP),inorganic phosphorus(IP),organic phosphorus(OP),NH4Cl-extracted phosphorus(Ex-P),NaOH extracted phosphorus(Fe/Al-P)and HCl extracted phosphorus(Ca-P)are studied,the correlation analysis on the sediment qualities and different phosphorus fractions was studied according to Pearson.The result shows that the sediment has a high content of organic matter,and is under anaerobic.the contents of the phosphorus fractions are:Ca-P > Fe/Al-P > Org-P > Ex-P.There was a significant negative correlation between pH and Ex-P,Org-P,a significant negative correlation between ORP and Fe/Al-P,there was a positive correlation between organic matter and all forms of phosphorus,TP was positively correlated with IP,Fe/Al-P and Ca-P.(2)The sediment release experiment under different environmental conditions show that pH,temperature,dissolved oxygen and the intensity of disturbance all have great impacts on sediment release.Alkaline `or acidic conditions,elevate temperature and anaerobic will promote phosphorus release.The release pattern of phosphorus showed "U" curve under the condition of pH,and the release rate was the smallest under neutral condition.Anaerobic condition will promote the release of phosphorus,especially the fraction Fe/Al-P,the TP concentration of the overlying water is 7.41 times higher than aerobic condition.When the temperature is 35?,the maximum TP concentration in the overlying water is 4.05 mg/L,which is 4.26 times higher than that of 15?,and the higher the temperature,the faster the phosphorus release rate.The disturbance will lead to the resuspension of the sediment,so that the phosphorus concentration of the overlying water increases,but when the disturbance intensity increases to a certain extent,the disturbance can promote the increase of dissolved oxygen,which is beneficial to the adsorption of phosphorus to the sedimen.(3)The effect of red soil,kaolin,calcite and bentonite on the release of phosphorus from sediments was studied by static simulation test,and the influence of cover layer thickness and particle size was analyzed.The result showed that red soil,kaolin and calcite and bentonite can effectively inhibit the release of phosphorus in the sediments,the best effect of red soil,followed by kaolin.The calcite particle size and the thickness of the cover layer have a greater effect on the control of phosphorus,and the smaller the particle size,the greater the thickness of the cover layer and the better the control effect.The increase of the flow velocity promotes the oxygenation of the water body,the adsorption of phosphorus and the phosphorus concentration of the iron oxide or hydroxide in the water.(4)Compared to the red soil,the modified soil with potassium permanganate,peroxidation Hydrogen,calcium nitrate and iron salt on the water TP concentration decreased by 51%,23%,54%,12%.Modified soil cappingcan promote the weak adsorption state,iron and aluminum combined with unstable forms into more stablephosphorus fractions.It can be seen that the modified soil prepared by the combination of passivation and covering technology can enhance the effect on the release of phosphorus from sediments.(5)Modified soil as an environmentally friendly high oxidation and reduction potential material,can effectively control the release of phosphorus from the sediment,improve the water environment,which has application prospectsin the black and black water treatment.In practical engineering applications,the functional soil can be used as a black and black water treatment assistant technology,to carry out the operation,to improve the oxidation and reduction potential of the sediment,remove hydrogen sulfide and other odorous pollutants to deal with sudden water black. |
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