正渗透污泥脱水工艺的影响因素研究

Study on influencing factors of forward osmosis sludge dewatering process

将正渗透技术应用于污泥浓缩脱水，对孔径更大、机械强度更高的低压过滤膜应用于正渗透污泥脱水工艺的可行性及影响因素进行了探索。对比试验证明低压过滤膜由于膜厚度方面的劣势带来的严重浓差极化现象而无法获得良好的水通量，不能满足用于正渗透污泥脱水的要求。对正渗透污泥脱水过程中盐离子反向传质情况的监测分析发现，这一过程受污泥侧盐累积量与污泥含水率两个因素影响，污泥侧盐浓度最终根据试验条件不同而稳定在0．1～0．2 mol/L 内。污泥中混入盐对污泥极限脱水性能存在不利影响而应加以控制。试验用的3种常用污泥絮凝剂使正渗透污泥脱水效果有所提高。

The forward osmosis process was applied for sludge dewatering.The feasibility of low-pressure filter membranes with larger pores and higher mechanical strength used in the forward osmosis sludge dewatering process and its influencing factors were investigated.The results show that a low water flux was resulted by a more severe concentration polarization due to the disadvantages of the film thickness of low-pressure filter membrane.Therefore,the low-pressure filtration membrane is not suitable for the forward osmosis sludge dewatering process.The reverse salt transfer in the forward osmosis sludge dewatering process is affected by two factors including the salt accumulation of sludge side and the sludge moisture content.The salt concentration of sludge side keeps finally between 0.1 and 0.2 mol/L no matter experimental conditions.Salt dissolved in sludge was proved to have negative effects on sludge dewatering.As a result,the reverse salt transfer in the forward osmosis sludge dewatering process should be minimized as possible.The performance of forward osmosis sludge dewatering process is improved by the three kinds of common sludge coagulants.