淨水污泥高分子調理機構之研究

Abstract

淨水場淨水污泥在日趨嚴格的環保法令下, 以往未經處理即予排放的做法 已不可為，污泥的處理已刻不容緩。本研究係利用台北自來水事業處長興 淨水場沉澱池污泥分別以分子量相似之中性、高電荷密度陽離子性、低電 荷密度陽離子性、高電荷密度陰離子性、低電荷密度陰離子性等五種高分 子調理劑調理之。並以改變高分子調理劑劑量、攪拌G 值、攪拌時間等實 驗方法，並藉布氏漏斗所測之平均過濾比阻、界達電位儀（ Zeta Meter ）所測之 EM 值、流導電流儀（Streaming Current Detector ）所測之 SC值等數據，了解高分子調理劑與污泥粒子間之反應機構，期能作為日後 實場操作時選擇高分子調理劑之依據。污泥性質隨時間改變之老化現象， 由本研究之實驗結果顯示，污泥老化現象對污泥的調理機構沒有顯著影響 。由實驗結果可知，陽離子性高分子調理劑之調理機構為：高分子調理劑 帶陽離子活化位置可取代氫氧化鋁微粒而與帶負電之污泥粒子進行電性中 和作用，而不帶電部位亦可行架橋作用；陰離子性高分子調理劑之調理機 構為：高分子調理劑帶陰離子活化位置可將帶負電污泥粒子與其外圍之氫 氧化鋁微粒整個包覆起來發生電性中和作用，而不帶電部位亦可行架橋作 用；中性高分子調理劑之調理機構則僅有架橋作用。攪拌 G 值與攪拌時 間在污泥調理過程中亦為重要影響因子， 過高之 G 值或過長之攪拌時間 皆有將已形成之污泥團打碎的現象。另一項影響調理機構之因子為 pH， 實驗結果顯示，陽離子性高分子調理劑在 pH 為 7 或小於 7 時，其調理 效果較 pH 大於 7時為佳；對陰離子性高分子調理劑而言，pH 在 7 - 8 之間有較佳之調理效果。而中性高分子調理劑則在 pH 5 - 7 時調理效果 較佳。 Five polymers with similar molecular weight,including nonionic, high electron density cationic, low electron density cationic, high electron density anionic and low electron density anionic polymers, were used in this study to condition the sludge of the sedimentation basin from Chiang-Hsin treatment plant,Taipei Water Department. Experiments were conducted with different polymer dosages, G values and mixing times. Average filtration specific resistance,EM value and SC value were determined by Buchner funnels, Zeta Meter and Streaming Current Detector, respectively. Reactions between polymers and sludge particles derived from these data are expected to be a reference for selecting ploymers with appropriate dosage in the field operations. Results indicate that the aging of sludge has insignificant effect on the conditioning. This study proposes conditioning mechanisms for polymers as (1)cationic polymer: Cationic reactive sites can substitute for aluminum hydroxide particles and undergo electric neutralization with negatively charged colloid particles. The interparticle bridging can occur on uncharged sites. (2)anionic polymer: Anionic reactive sites can cover nagtively charged sludge particles and surrounding aluminum hydroxide particles that the neutralization can be brought about. Uncharged site can also conduct the bridging reaction. (3)nonionic polymer: The only mechanism is an interparticle bridging.