低碱性环保固化剂调理淤泥的板框压滤脱水试验研究

Experimental Study on Dewatering of Plate-and-Frame Filter Press for Sludge Treatment with a Low-Alkaline Environmental Modifier

常规药剂用于疏浚淤泥调理效果较好,但存在板框压滤脱水尾水、泥饼的高碱性问题。在室内淤泥调理试验的基础上,研究了低碱性环保固化剂与聚合氯化铝(PAC)、聚丙烯酰胺(PAM)组合调理淤泥的板框压滤脱水过程,对尾水、泥饼的特性进行了分析。结果表明:低碱固化剂与PAC、阴离子聚丙烯酰胺(APAM)联用,在达到同等调理效果的同时,可降低PAC、APAM加药量;在2.5%的低碱固化剂和2.5%、0.12%的PAC、APAM的组合调理下,脱水尾水和泥饼的pH值分别为7.4、7.6,脱水效率比不加药剂时的脱水效率提升42.2%。粒径分析表明:低碱固化剂的加入,提高了泥饼内大颗粒比例,改善了脱水性能。对泥饼的X射线能谱分析(EDS)和X射线衍射(XRD)分析发现:低碱固化剂与淤泥中的黏土矿物反应,生成硅酸盐矿物骨架,有利于降低淤泥的比阻,改善板框压滤脱水性能;低碱固化剂脱水泥饼pH值随时间会缓慢下降,直至稳定,加药量越大,泥饼pH值下降幅度也越大。研究成果为探究新型药剂对淤泥的调理性能及在板框压滤设备上的工艺特性提供了科学依据。

Despite good performance in conditioning dredging sludge,conventional chemicals generate highly alkaline tail water and mud cake from plate and frame pressure filtration dehydration.Based on laboratory sludge conditioning test,we researched the process of plate and frame pressure filtration dehydration of sludge conditioned with low-alkaline environmental modifier,PAC and PAM,and further analyzed the characteristics of tail water and mud cake.Results demonstrate that low-alkaline modifier combined with PAC and PAM could reduce the dosage of PAC and APAM while achieving an equivalent conditioning effect.With 0.12%APAM,2.5%PAC and 2.5%low-alkaline modifier,the pH value of tail water and mud cake is 7.4 and 7.6,respectively,and the dehydration efficiency is 42.2%higher than that without dosing.Particle size analysis shows that the low-alkaline modifier increases the proportion of large particles in mud cake and improves the dehydration performance.EDS and XRD analysis reveals that low-alkaline modifier reacts with clay minerals in sludge and generates silicate mineral skeleton,which is favourable to reducing the specific resistance and the dewaterability.The pH value of the mud cake treated from the modifier declines slowly until finally stablizes,and such decline gets more intensive in the presence of high dosage.The research findings provide a scientific basis for exploring the sludge conditioning performance of new agents and the technical features of plate and frame filter press equipment.