不同离子性质絮凝剂在淤泥脱水中的脱水作用特征

用几种不同高分子絮凝药剂对某湖底淤泥进行了絮凝脱水实验研究。通过应用相同离子性质不同离子度(阳离子度)和特征黏度、不同离子性质相近特征黏度的高分子絮凝药剂的不同加药量,对天然湖泊淤泥进行絮凝处理,考察了药剂用量对经处理后淤泥的絮团大小、滤饼含水率、滤液透过率、滤液CODcr值和ζ电位的影响。研究结果表明,特征黏度分别为14.4、10.4、13.5 dL/g的APAM(T-150)、20%阳离子度的自制阳离子型CPAM(PDA)、NPAM(351)3种聚丙烯酰胺在各自形成絮团最佳点时药剂用量依次为208.8、261.0、261.0 mg/L;絮凝处理后淤泥滤饼含水率依次为54.8%、53.2%、57.0%。经不同性质药剂絮凝处理后,淤泥上清液化学需氧量(CODcr值)随药剂用量递增的变化规律均呈先减后增趋势,对应的透过率T(%)则成锯齿折线状,先增后减;最佳絮凝点对应的CODcr值一般在曲线的最低点之后。随着药量变化,阳、非离子型药剂ζ电位递增,阴离子递减。由此可知,阴、阳、非离子药剂均可用于淤泥絮凝脱水;就形成较佳絮团的加药量而言,阴离子型絮凝剂有一定优势;从得到低含水率滤饼的效果上比较,某些自制阳离子型PDA有一定优势,能从较大程度上降低淤泥运输成本和堆放体积。此研究工作结果可为现代清淤工程中的淤泥,尤其是浮淤絮凝脱水工艺和絮凝剂选择问题提供一定的参考。

Dehydration Characteristics of Flocculants with Different Ionic Properties and Molecular Weights in the Processes of Sludge Dehydration

Dehydration characteristics of synthetic copolymers of acrylamide with cationic(CPAM),non-ionic(NPAM) and anionic(APAM) properties and different intrinsic viscosities in the dehydration processes of sludge from lake bottom was studied by jar tests.Experimental results indicated that,the dosages to form an optimum size of the flocculate for APAM(T-150),CPAM(20%PDA) and NPAM(351),whose intrinsic viscosities were 14.4 dL/g,10.4 dL/g and 13.5 dL/g respectively,were 208.8 mg/L,261.0 mg/L and 261.0 mg/L and the water-containing rates of cakes for them were 54.8%,53.2% and 57.0% respectively.After flocculation by APAM,PDA and NPAM,CODcr values of the filtrate decreased first and then increased with the increasing dosages,but the transmittion of supernatant T(%) increased first and then decreased.The CODcr value of forming optimum size of flocculate was behind the lowest point on the corresponding curve of CODcr values.The zeta potential increased with the dosage of PDA and NPAM,but decreased with the dosage of APAM.In general,APAM,PDA and NPAM could all be used in sludge dehydration.For forming optimum size of the flocculate and for obtaining lowest water-containing rates of the cake,APAM and CPAM(PDA) had their superiority respectively.Especially,low water-containing rates of cakes plays an important role in decreasing the cost of transportation and the stacking volume.