Study On Phosphorus Release From Sediment And Application In Constructed Wetland

In recent years,with the continuous development and progress of China’s industry,the gradual increase in the amount of sewage discharge,eutrophication of lakes and rivers has become increasingly serious,has become a very serious environmental problems.The main cause of eutrophication of water body is the excessive discharge of nitrogen,phosphorus and other nutrients,most of which are restricted by phosphorus.Therefore,how to reduce the phosphorus concentration in water becomes an urgent problem.As a big province of iron and steel in Hebei Province,the annual output of steel slag is in the forefront of the country,but as a kind of solid waste,steel slag has not been effectively utilized.Therefore,this study uses the steel slag as the phosphorus fixation agent and the application of steel slag in the two kinds of artificial wetland substrate.Specific research contents and results are as follows:(1)The adsorption capacity of steel slag was studied.The adsorption properties of three kinds of steel slag were analyzed and compared by the adsorption kinetics experiment of steel slag and the adsorption isotherm of steel slag.The results showed that the adsorption of phosphorus on steel slag was in accordance with the Langmuir adsorption isotherm model,and the pseudo two order kinetic equation was fitted.The results showed that the adsorption of phosphorus slag belongs to chemical adsorption and molecular layer adsorption.Among the three kinds of steel slag,the phosphorus adsorption capacity of steel slag No.two was the best,and the maximum adsorption capacity was 6.8 mg/g.(2)The law of phosphorus release from sediments was studied.Through the simulation experiment of four kinds of sediment phosphorus release,the release curve of each sediment drawing experiments show that different sediment phosphorus release rules are not the same,but the release rate was increased first and then decreased,and reached the peak in 10-20 days,the maximum release amount of water sediment phosphorus four sediment test in the peak,the highest total phosphorus concentration in the overlying water can reach a maximum of 0.74mg/L.(3)The effect of the addition of steel slag on phosphorus release from sediments was studied.Steel slag was added to the sediment phosphorus release simulation device to test thevariation of total phosphorus concentration in the overlying water.The smaller the particle size of steel slag,the better the effect of steel slag on the release of phosphorus from the sediment.The more the amount of steel slag,the better the inhibition effect of phosphorus release.(4)The steel slag as substrate,the design experiment in constructed wetland,the experimental design of 45 cm zeolite,adding middle 45 cm converter steel slag,steel slag and gravel,40 cm 10cm 40 cm and 10 cm four groups of steel slag zeolite parallel experiment,the experimental results show that the combination of steel slag and steel slag and the concentration adding zeolite can reduce the total phosphorus into the water,to ensure the total phosphorus removal rate reached more than 97% of artificial wetland.