周进式二沉池配水槽的模拟研究及改进

THE SIMULATION STUDY AND IMPROVEMENT OF WATER DISTRIBUTION CHANNEL OF PERIPHERAL-FEED SECONDARY CLARIFIERS

根据某城市污水处理厂周进式二沉池运行中出现的问题,利用计算流体力学模拟技术、采用3维、稳态、k-ε两方程紊流模型,对其配水槽和挡板高度的变化对流态的影响进行了考查。模拟结果和实际情况吻合,配水槽内部水流速度过小,后1/3段出现了明显的泥水分层;各个挡板高度下均出现不同程度的泥水分层,主要症结在于配水槽内部流速过小。提出了改进方案,挡板高度改为0.5 m,并安设1台水下推进器。改进后的模拟结果表明,泥水分层问题得到解决,配水槽内水流流速增加至0.2 m.s-1左右,配水均匀性得到了改善。这种改进方法用于实际运行后,二沉池出水SS含量降低、去除率升高,去除效果更加稳定。

In accordance with the problems in operating the peripheral-feed secondary clarifiers of a certain wastewater treatment plant,with the adoption of the three-dimensional,steady and k-ε turbulent model,the water distribution channel of a secondary clarifier was simulated by using Computational Fluid Dynamics（CFD） simulation technique.The results which fit the reality well showed that the water velocity in the distribution channel was low and the obvious layering of water and sludge appears in the last 1/3 part of the channel.The effects of different height of the baffle to the flow state were examined,of which the results showed that layering of water and sludge still appeared with each height of the wall and the key problem was the low velocity in the channel.An improvement program was proposed in accordance with the results,that was,changing the height of the baffle to 0.5 m and installing an underwater propeller.The simulation results of the improvement program showed that the layering water and sludge disappeared;the water velocity in the distribution channel increases,which kept around 0.2 m·s-1;the uniformity of water distribution was improved as well.After the improvement program was carried into effect in the plant,the suspended substance concentration in effluent decreased;the suspended substance removal rate increased;the removal effect was much more stable.