| 摘要: | 國內污水處理廠所產出之脫水污泥，一般雖經濃縮、脫水等處理程序，但產出之脫水污泥含水率仍高達85%~89%，未能有效減積減容，且近年來經廢水處理後之污泥處理與處置問題日漸嚴峻，不僅面臨現有最終處置容量近趨飽和，更需支應日益高漲之污泥清運處理龐大支出成本，如何更有效疏緩污泥處理困境亦為污水處理廠的重要課題。
本研究主要探討，利用聚合硫酸鐵(polyferric sulfate, PFS)對於污泥酸化調理脫水之影響。藉由添加PFS及不同pH值之調理實驗，經毛細汲取時間(CST)、過濾比阻抗(SRF)、含水率等評估指標，來探究其經酸化調理後是否有利於污泥脫水，以降低清運處理之成本。
綜合實驗結果，藉由硫酸及PFS進行污泥酸化調理脫水試驗，以添加PFS調理至pH值為5時，可得最適之調理效果，亦即能對污泥調理脫水之性質有大幅度的改變。如CST、SRF、含水率等評估項目，都相較優於採用添加硫酸調理所得結果，尤其濃縮污泥在添加PFS調理後，其濾餅厚度顯著降低約57 %，表示其脫水效率提升能形成易脫水的污泥形態，進而大幅減少污泥體積，提升機械脫水設備之運作效率。
以新竹某工業區污水處理廠為例進行成本評估，110年度脫水污泥濾餅產生量約3,808公噸(以含水率85%估算)，總費用約為31,929,124元/年。若於機械脫水處理前，改以PFS進行酸化調理至pH值為5時，推估經機械脫水設備後之污泥濾餅含水率可降低至80 %，進而推算出年度脫水後污泥濾餅產生量約為2,856公噸，亦即每月平均約可減少79.3公噸之污泥產出量。不僅每年可降低約25 %的污泥產出量，亦可減少約9.58 %之相關成本支出。;Most of the dewatered sludge produced by industrial wastewater treatment plants contains moisture as high as 85% to 89%. Since sludge disposal regulations become strict in recent years, and the existing final disposal capacity is approaching saturation. How to effective alleviate the predicament of sludge treatment is an important issue.
The purpose of this study is to discuss the effect of chemical conditioning, and specifically the use of polyferric sulfate (PFS) for sludge conditioning and dehydration. The capillary extraction times (CST), specific filtration resistances (SRF), and moisture content are indexes to evaluate the sludge dewatering performance.
According to the results, when sludge conditioning and dehydrated with PFS at a pH of 5, the conditioning and dewatering properties are changed substantially. For example, the values of CST, SRF, moisture content, etc. are better than those obtained by using sulfuric acid, and the thickness of the sludge filter cake after adding PFS conditioning is reduced about 57%. This means that it can improve the efficiency of the dewatering process to produce a form of sludge that is easier to dewater, as well as reduce the volume of sludge and improve the machine′s efficiency.
The estimated annual dewatered sludge production of this study case is approximately 3,808 metric tons (85% moisture content), with a total annual cost of approximately NT31,929,124 based on the cost assessment. If PFS is used for acidification and conditioning, the pH is adjusted to 5, it is estimated that the moisture content of the sludge after mechanical dehydration can be reduce to 80%. The disposal sludge was reduced to 2,856 metric tons, which equates to an average reduction of about 79.3 metric tons per month. Not only reduce sludge amount by about 25% every year, but also reduce related costs by about 9.58%. |
