电解浮选用于活性污泥固液分离的研究

Electro-Flotation Using in Solid-Liquid Separation of Activated Sludge

在装有Ti／RuO2—IrO2-TiO2阳极、Ti阴极的电解浮选槽中进行了活性污泥固液分离的研究．考察了影响电解浮选性能的操作参数，这些参数包括水力停留时间、电流密度、进水SS浓度和进水pH值．研究表明，电解浮选是高效的固液分离单元，水力停留时间和电流密度是主要的影响因素．SS的去除率随着水力停留时间和电流密度的增加而增大；污泥负荷增加，SS的去除率下降；pH值影响电解产生微气泡的尺寸和污泥性质，但对SS的去除影响不大，实际应用中可以不调节pH值．进水SS约1000mg／L时，当水力停留时间为20min，接触室电流密度为5mA／cm^2，分离区电流密度为2．5mA／cm^2，SS的去除率可达97％以上，此时的能耗为0．4～0．5（kW·h）／m^2废水．电解浮选产生的浮渣含水率为95．9％，低于溶气气浮和二沉池的污泥含水率，对污泥减量化及其最终处置有较大的意义．

The separation of suspended solids （SS） from activated sludge was carried out in an electro-flotation cell which has two sets of electrodes,three Ti/RuO2-IrO2-TiO2 anodes and three Ti screen cathodes. The effect of operating parameters on the performance of the electro-flotation system was examined. The parameters investigated were hydraulic retention time （ HRT）, current density, initial SS concentration and initial pH. The results show that electro-flotation cell is a unit of high performance in solid-liquid separation. HRT and current density are the main affecting factors. The removal ratio of SS increases with increment of HRT and current density; and it decreases with the increment of sludge loading. The pH value affects the size of tiny bubbles generated from water electrolysis and the character of sludge, but it has little effect on the removal of SS. The pH value is not need to be adjusted during the electro-flotation. Under the conditions with initial SS about 1 000mg/L, HRT 20min, a current density 5 mA/cm^2 in contacting zone, a current density 2.5 mA/cm^2 in separating zone, the removal ratio of SS can reach up to 97 %, at this point, the electrolysis energy consumption is 0.4- 0.5 （kW· h）/m^3 wastewater. The water content of the sludge from electro-flotation is much lower than that from dissolved air flotation and secondary sedimentation tank, which has significant in the decrement and final disposal of the sludge.