Research On Separating Suspended Solid In Combined Drainage System

In the traditional wastewater treatment process, suspended solids in sewage deposit on the bottom of primary sedimentation tank and thus formed a kind of sludge removal system. At the same time plenty of organic matters are removed, resulting in the necessity of adding carbon on the following-up biological treatment process. However, if the primary sedimentation tanks are canceled, a large number of inorganic matters will enter into the biological treatment process and result in the decreasing of effective pool capacity and sewage treatment efficiency.Two model primary sedimentation tanks are made and imitate actual primary sedimentation tank in order to carry on parallel experiment. The composition of the primary sedimentation tanks are reform by the application of impellers and raw water is adopt in the test. With adjusting impellers’rotate speed, availability water level, HRT and sludge altitude and comparing with operational data of actual tank, the influence degree to model tanks by those different parameter combination is analyzed.The result shows that through the impellers’rotating, the granulation of the sludge becomes smaller and smaller by shearing strength until they turns into powders. Then the organic matters and the inorganic ones are separated. As long as impellers maintain a speed of 3.5r/min, the quantity of organic matters in sewage and the carbon in bio-treatment process could be increased. Meanwhile the sludge and bacteria can be made full contact, then the hydrolyzation and acidification reactions are speeded up to produce volatile fatty acids. VSS/SS value of sewage of simulation primary sedimentation tank is higher than that in the raw sewage. Thus the compositions of the primary sedimentation tank are reformed.