垃圾焚化飛灰水萃廢水處理之研究

Evaluation on the treatment process of wastewater from water extraction of MSWI fly ash

何欣怡(Hsin-Yi Ho)

指導教授 ： 高思懷

淡江大學/工學院/水資源及環境工程學系碩士班/碩士(2006年)

https://doi.org/10.6846/TKU.2006.00411

摘要

都市垃圾焚化飛灰中含有大量的氯鹽、重金屬及有機污染物質等，造成在處理上許多的問題。水萃是飛灰處理中大家所熟知的一種方法，能洗出干擾後續處理之有害污染物質。然而水萃廢水之成分複雜，含有重金屬、高濃度鹽類，難以利用傳統方法將其妥善處理電聚法是一項新穎的水處理技術，已經應用於許多不同種類廢水的處理，其能在不受高濃度氯鹽的影響下將污染物去除。另外利用水萃配合磷酸鹽穩定處理為眾所熟知的可行方法，能洗出干擾後續處理的氯鹽，並可將重金屬穩定於殘灰中，降低環境污染。研究目的在於瞭解電聚法應用於處理都市垃圾焚化飛灰水萃廢水之可行性探討並與傳統處理方式進行比較，及處理廢水後產生的污泥穩定化探討。
此研究主要是在降低廢水中之重金屬，經由飛灰水萃產生廢液進入電聚系統進行處理，針對液固比、pH、作電壓及停留時間來探討各操作參數對重金屬去除效率之關聯，以找出最佳操作條件。
實驗指出最佳之操作條件為pH 9、停留時間40秒。結果顯示操作電壓在處理過程中為一重要因子，且會隨導電度增加，最佳操作電壓隨之下降，於液固比5時選擇2模式（上“－” 下“＋”），各種污染物之去除效率分別為SS 85%、Cu 97%、Pb 98~100%、Zn 100％及Cd 100%。與傳統處理法比較在化學混凝法的對照實驗中發現，水萃廢液在L/S 5時，其氯化鐵的最佳加藥量300 mg/L時，才可達到放流水標準。磷酸鹽穩定之部分，在操作電壓100、75 V，停留時間40 sec時，廢液經電聚系統處理後，115和220 mg/LNaH2PO4其鉛去除率分別為可達95、100％、和99、100％，污泥中的重金屬也無再溶出。硫化物穩定之部分，污泥中重金屬幾乎會再溶出無法達穩定之效果。

關鍵字

焚化飛灰 ； 電聚法 ； 水萃 ； 重金屬 ； 磷酸鹽 ； 硫化物

並列摘要

Municipal solid waste incinerator (MSWI) fly ash contains a lot of chloride, heavy metals and organic pollutants, et al., many problems has raised in the procedure of treatment and recovery. Water extraction is a well-known process for the ashes pre-treatment, which washes out the harmful pollutants in the residues. Nevertheless, elements in extracted wastewater are complex; it contains heavy metals, COD, and high concentration of chloride, which is difficult to be treated by the conventional methods. Electro-aggregation is a novel process, which has been studied in many wastewater treatment processes. It has the ability to remove these pollutants and not interfered by the high concentration chloride. This study explored the feasibility of application on the treatment of MSWI fly ash extraction wastewater and compare with conventional method, and assessed the stabilization ability of heavy metals in the sludge.This study was aimed to remove the heavy metals in the wastewater produced by the washing of fly ash, and adopted an electro-aggregation system for treatment. Discussing of the relationship between the parameters of the operation voltage, hydraulic retention time (HRT), pH, liquid-to-solid ratio (L/S) extraction, different electrode connection mode. The chemical coagulation and flocculation experiments were executed as the comparison.The results showed that, optimum operating condition for electro-aggregation was pH 9, 40 sec HRT. The results indicate that the operation voltage is the majority, and the optimal voltage is decreasing with the increasing of the conductivity of raw water. The proper electrode connection mode for the L/S 5 extraction wastewater is mode A. The removal efficiency of SS, Cu, Pb and Zn were around 85%, 97%, 97%, 98~100% and 100%, respectively. The comparison with coagulation and flocculation, FeCl3 dosage up to 700 mg/L could meet the effluent standards. 220 mg/L of NaH2PO4 dosing before entering the electro-aggregation, 100% Pb could be removed under 100 V, 40 sec HRT, and the heavy metals in the sludge could be stabilize safely. Nevertheless, sulfide dosing didn’t satisfy the stabilization ability for the sludge.

並列關鍵字

fly ash ； electro-aggregation ； water extraction ； phosphoric acid ； stabilization ； heavy metals

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“Stabilisation of heavy metal containing dusts by reaction with phosphoric