Study On The Multi-layer Cross Flow Infiltration Bed For Treatment Of Turbid Landscape Waters

In recent years,with the urbanization speed up the development and improvement of living standards,an increasing number of landscape water bodies were constructed in order to improve the living environment.However,the landscape for more than a static body of water or poor mobility of the closure of slow-flow water bodies,the general area of water with a small,easy to pollution,water environmental capacity of small water bodies and low self-purification ability,together with the residents living in water and fish Impact on the landscape vulnerable to suspended solids in the water increased,increased turbidity,and has seriously affected water bodies beautiful landscape.When apply the conventional water treatment technology to turbid landscape waters,it had the disadvantage of low operation load?large area occupied?easily blocked and so on.Therefore it needed to develop an efficient and stable turbid landscape water treatment technology,to treat a lot of turbid landscape water in limited space.In this research,the cross-flow infiltration bed was discussed for treating turbid landscape water.Finished the preliminary design and research of the infiltration bed,and explained removal characteristics of filter bed and operation stability.The results showed:Finished the preliminary design of the Multi-layer Cross Flow Infiltration Bed,through the vertical stratification and multipoint inflow,the water production could be increased significantly by the same surface area of infiltration bed under the same surface loading,it could be up to 2.7 times.The Multi-layer Cross Flow Infiltration Bed test results showed that:Although the water production increased dramatically,infiltration bed still had a high efficiency in turbidity removal,and also had a good removal effect for other pollutants.When the surface hydraulic loading rate was 0.5 m³/?m²·d?,the infiltration bed with different sizes of particle?10-30,5-10 and 2-5mm?on the turbidity removal efficiency were85.09%,95.34%and 97.41%,respectively.The average effluent turbidity of infiltration beds with small and medium particle size were under 10NTU,the effluent was clear and transparent.The removal rate of colloidal COD came up to 31.42%?34.27%?38.80%respectively,the removal rate of ammonia nitrogen were 49.52%?60.58%?68.21%,the TP were 20.91%?34.37%?40.25%.After five months,the infiltration bed enhanced the microbial action.The enzyme activity is mainly in the surface,the distribution showed the same trend in the vertical direction of enzyme activity,and the surface is best.There was positive correlation between activities of dehydrogenase in the substrate and removal rate of NH₄⁺-N?TP.And the removal rate of COD showed significant positive correlation.There was positive correlation between activities of urease in the substrate and removal rate of COD.The percentage decline of porosity were 4.2%?5.0%?5.3%·month^-1 in infiltration beds with different particle sizes?10-30,5-10 and 2-5mm?.Considering the advantages in running stability and turbidity removal,it was suggested that 5-10mm diameter of gravel should be as the main filler in the practical work.Analyzed the change of porosity and turbidity interception in each layer of infiltration beds,its surface area,close to the water entry was efficient intercept zone.Through the vertical stratification and multipoint inflow,made the second and third layers become effective intercept zone,and effectively shared the blocking risk of the surface layer like that occurred in common filter,and prolong the operation duration of infiltration bed.