焚化爐灰燼作為掩埋場滲出液處理之混凝劑利用研究

Study of MSWI Ashes as Coagulant on Landfill Leachate Treatment

吳冠中(Kuan-Chung Wu)

指導教授 ： 羅煌木

朝陽科技大學/理工學院/環境工程與管理系/碩士(2009年)

摘要

台灣由於地狹人稠，垃圾處理已由掩埋為主轉為焚化處理為主。但垃圾經焚化處理後，仍產生將近原來重量或體積之十分之一或十五分之一之灰燼。此剩餘灰燼仍需妥善處理以避免二次污染。灰燼包含底灰、集塵灰、鍋爐灰與反應灰等。底灰之處理以作為骨材、填土、土壤改良與掩埋覆土等，飛灰雖有部份作為骨材，但大部份仍以固化與穩定化為主。目前灰燼之處理如上所述，以資源化為主。但因灰燼含有大量鋁鹽與鐵鹽，且飛灰具有小粒徑及其比表面積之特性，作為去除垃圾場滲出水中溶解物之主要吸附劑，適於作為混凝劑潛勢。因此，本研究乃探討如上述以外之其它利用管道，如作為水與污水混凝劑之可行性研究，尤其是最難處理之掩埋場滲出液。因此若滲出液處理可行，則其它污水處理之利用可行性亦相對提高。因此，本研究擬利用瓶杯試驗（Jar-test）進行灰燼作為混凝劑之可行性。水質分析指標有酸鹼度（pH）、氧化還原電位（ORP）、導電度（EC）、化學需氧量（COD）、氨氮（NH4-N）、磷酸鹽（PO4-3）、色度（Color）、懸浮微粒（SS）、金屬分析（ICP-OES）等。實驗所採操作參數計灰燼添加量（0、2、4、8、16、32、64 g/0.1L）、pH調整（1、3、5、7、9、11、13）、攪拌時間（0、5、10、20、40、60 min）、轉速控制（0、20、40、80、120、200 rpm）。實驗結果顯示，底灰組最佳條件為添加2g/0.1L、pH 7、80 rpm、溫度25。C、20 min，去除能力COD>Color >SS分別為30%、24%及11%；飛灰組最佳條件為2 g/0.1L、pH 7、40 rpm、25℃、5 min，去除能力Color>COD分別為70%、54%。以灰燼最佳條件搭配混凝劑硫酸鋁（700、1400、2800、5600、8000、12000 mg/L）與氯化鐵（30、130、430、830、1000、2000 mg/L）不同添加比例，並調整pH = 7與未調整pH做比較。硫酸鋁1400 mg/L與飛灰6 g（未調整pH），對於去除PO4-3與Color都可達到80%以上，重金屬去除率為Zn>Cu>Pb；氯化鐵430mg/L與飛灰16g(未調整pH)，對於PO4-3、Color去除率都有75%以上，COD去除率40%，重金屬之去除能力分別為Zn>Cu>Ni。經由實驗設計與參數分析，可獲得不同滲出液之可能最佳灰燼添加量與環境操作條件，可作為污水處理如滲出液處理之利用，並解決部份灰燼處理問題。

關鍵字

灰燼 ； 混凝 ； 瓶杯試驗 ； 滲出液 ； 重金屬

並列摘要

Municipal solid waste (MSW) has been treated in major by incineration and in part by landfilling due to the scarce land in Taiwan. However, ashes such as bottom ash (BA) and fly ash (FA) generated from MSW incinerator (MSWI) still account for about 10-15% of original MSW. Thus, they need to be treated carefully to prevent the secondary pollution. In general, BA has been mostly used as aggregate, backfill, soil amendment and landfill cover. FA has also been used as additive aggregate or cement partly. However, it has been treated by solidification and stabilization in most case. Generally, BA and FA have been treated for utilization purpose. BA and FA contain large amount of Al and Fe oxide and have high specific surface. Therefore, they have the potential to be used as adsorbent and coagulant for landfill leachate treatment. In this study, jar test was used to test the suitability of FA and BA as a coagulant for leachate treatment. Water parameters analysis includes pH, ORP, EC, COD, NH4-N, PO4-3, color, SS and metals. Experimental operational conditions contained BA or FA/leachate ratios (0, 2, 4, 8, 16, 32, 64 g/0.1 L), pHs (1, 3, 5, 7, 9, 11, 13), agitation time (0, 5, 10, 20, 40, 60 min), and rotation speed (0, 20, 40, 80, 120, 200 rpm). After optimal test of operation parameters, BA was found to have the high treatment efficiency at the conditions of 2 g/0.1 L ratio, pH 7, 80 rpm, 25℃, 20 min. The removal efficiency was found to be in the order of COD (30%) > Color (24%) > SS (11%). Similarly, FA was found to have the high treatment efficiency at the conditions of 2 g/0.1 L ratio, pH 7, 40 rpm, 25℃, 5 min. The removal efficiency was found to be in the order of Color (70%) > COD (54%) > SS (42%). Using the optimal conditions of BA and FA, Al2(SO4)3 (700, 1400, 2800, 5600, 8000, 12000 mg l-1) and FeCl3 (30, 130, 430, 830, 1000, 2000 mg l-1) coagulants with different amounts were used to test their removal efficiency of leachate pollutants. In addition, pH adjusted to 7 and pH without adjustment after coagulants addition was conducted for comparison. Results showed that removal efficiency of PO4-3 and color could be reached as higher than 75% at the conditions of Al2(SO4)3 (1400 mg l-1) plus FA (16 g), FeCl3 (430 mg l-1) plus FA (16 g) and Al2(SO4)3 (1400 mg l-1) plus FA (4 g) plus FeCl3 (430 mg l-1) plus FA (4 g) without pH adjustment. It is also noted that removal efficiency of heavy metals higher than 65% was observed in most case. This phenomenon indicates that suitable amounts of combination of BA, FA, Al2(SO4)3 and FeCl3 can enhance the PO4-3, color and metals removal efficiency than any of them with only individual treatment test.

並列關鍵字

Coagulant ； Heavy metals ； Jar test ； Leachate ； Ashes

參考文獻

52. 行政院環境保護署， http://www.epa.gov.tw，（2005）。

1. Adin, A. and Asano T., “The Role of Physical-Chemical Treatment in Wastewater Reclamation and Reuse”, Water Science and Technology, Vol. 37, No.10, pp.79-90 (1998).

2. Amirtharajah, A. and Mills, K. M., “Rapid-Mix Design for Mechanism of Alum Coagulation”, Journal American Water Works Association, Vol.74, No., pp.201-216 (1980).

3. Amokrane, A., Comel, C. and Veron, J., “Landfill Leachates Pretreatment by Coagulation–Flocculation”, Water Research, Vol.31, No.11, pp.2775-2782 (1997).

4. Annadurai, G., Sung, S. S. and Lee D. J., “Floc Characteristics and Removal of Turbidity and Humic Acid from High-Turbidity Storm Water”, Journal of Environmental Engineering, Vol.129, No.6, pp.571-575 (2003).