超声-生物沥浸-氧化钙联合超高压压滤系统实现市政污泥深度脱水及其泥饼的毒性评估

本研究采用超声-生物沥浸-氧化钙调理联合超高压压滤系统对市政污泥进行深度脱水试验，探讨了其调理过程对污泥脱水效率的影响，并对调理后的脱水污泥的重金属含量及植物毒性进行评估.结果表明，经超声-生物沥浸-氧化钙调理后，比阻（SRF）去除率和结合水去除率分别达到90.12%和72.21%.经预调理联合超高压压滤系统处理后，泥饼含水率降低至49.94%，泥饼中Cr 、Cu、Cd、 Zn、As 和Pb的去除率分别为42.41%、36.50%、30.92%、27.97%、25.94%、22.11%，白菜发芽指数大于80%.通过分析污泥理化性质及滤液有机物含量，阐明该联合技术的作用机理.首先，超声预处理后，污泥结构被破坏，造成污泥粒径d_0.5减小、zeta电位上升，污泥中多糖和蛋白质被释放，从而改善脱水性能，促进污泥中重金属释放，植物毒性降低；经超声-生物沥浸调理后，污泥粒径d_0.5进一步减小、zeta电位趋近于中性，滤液中酪氨酸/色氨酸类氨基酸类有机物和酪氨酸/色氨酸类蛋白有机物被降解且疏水性的腐殖酸和富里酸类有机物含量升高，污泥脱水性能进一步提高，泥饼重金属含量进一步下降，但植物毒性反而加强；最后添加氧化钙后，污泥颗粒被重新絮凝，形成刚性骨架，增加了污泥的可压缩性能，在高压压滤过程释放出更多有机物，最终实现了污泥深度脱水，重金属总量减少，植物毒性显著降低.此外，经济分析表明该联合工艺具有一定潜在推广应用价值.

Deep dewatering of sewage sludge by ultrasonic-bioleaching-lime conditioning combined with ultrahigh pressure filtration system and its toxicity evaluation

The ultrasonic-bioleaching-lime conditioning combined with ultrahigh pressure filtration system was explored for sludge dewatering. Moreover, the heavy metals content and the phytotoxicity in the dewatered sludge were evaluated. The results show that the removal rates of specific resistance to filtration (SRF) and bound water were 90.12% and 72.21%, respectively, by ultrasonic-bioleaching-lime conditioning. After ultrahigh pressure filtration system treatment, the water content of sludge cake decreased to 49.94%. Moreover, the removal rates of Cr, Cu, Cd, Zn, As and Pb were 42.41%, 36.50%, 30.92%, 27.97%, 25.94%, 22.11%, respectively, and germination index of cabbage was higher than 80% in the dewatered sludge. From the sludge physicochemical characteristics and the organic contents in the filtrate, the mechanism of the combined ultrasonic-bioleaching-lime treatment was illuminated. First, after the ultrasonic pretreatment, the sludge structure was destroyed, leading to the decrease in particle size (d_0.5) and the increase of zeta potential. Moreover, the polysaccharides and proteins of the sludge released from the inner to outer layers, which improved the sludge dewaterability, promoted release of the heavy metal and slightly decreased the phytotoxicity of the dewatered sludge. Second, after ultrasonic-bioleaching treatment, d_0.5 further decreased and the zeta potential of sludge was close to zero. Furthermore, tyrosine/tryptophan amino acid and protein compounds in the filtrate were degraded while the hydrophobic humic acid and fulvic acid compounds increased, which further enhanced the sludge dewatering. The heavy metals content further decreased while the phytotoxicity increased for dewatered sludge. Lastly, with the addition of lime, the shattered sludge particles were re-flocculated and form a rigid skeleton, which elevated the compressibility of the sludge. Meanwhile more organic matters released to the filtrate in the process of ultrahigh pressure filtration. As a result, the sludge after deep dewatering, heavy metal content and phytotoxicity declined. In addition, the result of economic analysis shows that this combined process has a great potential for application.