以高分子調理鋁鹽污泥對其脫水性影響之研究

Abstract

本文主要在探討高分子調理劑對鋁鹽污泥脫水特性之影響。探討內容則針對調理時高分 子之劑量、電性及攪拌強度等變化對污泥脫水效能、水份分佈及污泥結構等之影響及其間 之相關性分析。此外對污泥結合水分析方法與定義亦同時進行研究探討，並對污泥脫水性 試驗之濾葉試驗測值、布氏漏斗試驗測值及CST試驗測值等對最佳加藥量判斷之差異亦一 併予以分析。研究中以膨脹計(Dilatometer)進行污泥結合水(Bound Water)含量分析，並 應用自由沈降(Free Settling)、影像分析(Image Analysis)及碎形維度分析(Fractal Di mension Analysis)等技術進行污泥結構變化研究。 經由膨脹計分析試驗結果顯示， 選用不同之濾液膨脹係數、降溫速率及測體固含量下所求得的結合水計算值有明顯差異。 另試驗時氣泡之干擾則可經由膨脹計上之液位指示管來量測其氣泡體積並加以修正之。以 -20℃作為降溫終點所定義出之結合水其水結合強度值約為24.5 KJ/Kg接近於一般的物理 吸附之鍵結能。濾葉試驗中不同之過濾筒擺放位置明顯造成不同之比阻抗值。但過濾筒位 置不同（指上、下吸而言）對於最佳加藥量之選取並不造成明顯差異。布氏漏斗試驗無攪 拌時之比阻抗值較有攪拌時為高。布氏漏斗及CST試驗最佳加藥量之劑量判斷與濾葉試驗 並不符合。高分子調理結果顯示過量高分子會造成脫水效率降低及結合水含量增高。污泥 結合水含量變化應與其表面電位變化有一定之關係。本研究亦指出結合水含量降低乃因高 分子附著於污泥顆粒表面後將表面水分子取代及高分子聚集顆粒引生污泥顆粒間之擠壓所 致。而結合水含量增高則主要是因高分子加入後，小顆粒大量聚集增加顆粒間之間隙水大 量形成所致。而調理後結合水之增減即為此二作用之競爭結果所致。此外調理過程中污泥 結合水量增加乃來自污泥顆粒粒徑變大、有效密度降低之故。而污泥碎形維度值隨劑量之 增加而增高乃顯示膠羽聚集時之構型改變（Configuration）而由調理攪拌強度之實驗結 果則證實在同一攪拌強度下但不同G/t比值及在不同攪拌強度與不同攪拌機制下之調理攪 拌會影響污泥調理後之脫水性效能、結合水值與污泥顆粒結構。 The major objective of the study reported herein was focused on the effects o f polymer dosing onto the dewatering characteristics of alum sludge. In this s tudy, the moisture distribution, dewatering characteristics and flocs structur e of alum sludge were investigated and correlated with the polymer charge type and dose as well as the mixing intensity being used during the conditioning. A study on methodology and physical definition of bound water in sludge and th e determination of optimal conditioning dose The measured bound water content was affected by the solid concentration of sludge, the expansion coefficient o f sludge filtrate and the cooling rate in the dilatometric test. The interfere nce due to the presence of the bubbles during the test could be corrected by m easuring the volume of bubbles indicated by the reading of the liquid level ab ove the dilatometer. The binding strength of bound water at -20*C was calculat ed as 24.5 kJ/kg, which is close to that of the normal physico-adsorption proc ess. In Leaf test, different position of the filter placed in the mixing tank could significantly affect the SRF values (specific resistance of filtration) of sludge samples. However, the determination of optimal polymer dosage was th e same with the change of filter position. In Bucher test, SRF measured withou t stirring were higher than that with stirring. The optimal polymer dose deter mined in Bucher test and CST test were not in agreement with that in Leaf test . From the results of polymer conditioning test, the poor performance in dewat ering and the increasing in bound water content were the result of over dosage . Two phenomena, bound water depletion, which was caused by the polymer replac ing adsorbed molecular water on particles surfaces and the inter-particles agg regation squeezing water trapped in the interstitial space and interstitial wa ter formation, which produced by the enlargement of the interstitial spaces re sult in the change of bound water content afteIt was found that the dewatering performance, bound water content and flocs structure of sludge would affected by the different G/t value with the same mixing intensity, similar for differ ent mixing intensity and mechanisms.