下水污泥堆肥程序質能平衡之研究

Abstract

由於台灣生活水準的提升與工商業高度的發達，國內生活污水及工廠所排放之污水量逐漸增加，造成了環境品質惡化；因此，政府將逐年提升都市下水道普及率 3%，來改善這個日益嚴重的環境問題，但污水處理後衍生出的龐大污泥量，將是一個潛在的棘手問題。因應未來龐大都市下水道污泥量，以及滿足民眾因環保意識型態的提升，而對環境品質要求愈趨嚴格的情況下，污泥堆肥化即為一套既環保又符合經濟效益的解決之道。 本研究將建立設計堆肥實廠所需的質能平衡數學模式，推導堆肥化過程中各種機制質能消長之量值，再用污泥堆肥化之實驗數據驗證此模式的適當性及精確度，以供未來設計堆肥實廠之參考，減少污泥的處理成本、加速堆肥化反應和改進腐熟堆肥成品的品質。 堆肥實驗以民生污水處理廠之污泥餅為基質，並以木屑和腐熟之堆肥成品做不同水分之調配；兩槽 110 公升實驗室規模反應槽 (Lab-Scale)，分為密閉式和開放式，進行三批次共六組實驗，每批次初始污泥堆肥含水率調整各為 55%、60% 和 65%。一槽 13 立方公尺模廠規模實驗廠 (Pilot-Scale) 建置於八里污水處理廠內，進行一批次一組實驗，初始污泥堆肥含水率調整為 65%。110 公升實驗室規模反應槽所進行的六組污泥堆肥化實驗，結果顯示以開放系統之堆肥化反應較佳，溫度高於密閉系統約 3-5oC，顯示堆肥物與大氣接觸面積越多，堆肥化反應效果越佳。另外，因氣候因素以開放式初始含水率 55% 的堆肥化反應最佳，共減少 9.6 kg，其次為 60% 及 65%。13 立方公尺模廠式規模實驗廠所進行的六組污泥堆肥化實驗，總共減重 4.59 公噸，溫度維持 55oC 超過 15 天以上，已達到 U.S. EPA 305 法規的標準。將七組的實驗數據帶入質能平衡模式，其質量平衡與能量平衡之最大平均誤差值各為 46% 與 9.6%。另外，取高雄第一科技大學所進行的蔬菜堆肥數據一組，帶入質能平衡模式，其質量平衡與能量平衡之平均誤差值各為 34.7% 與 6.2%。

In order to correspond with the promotion of living standard in Taiwan, as a result the industry, and commerce are highly prosperous. Then the quantity of sewage sludge which is discharged by families and factories is increasing gradually, and that causes the decrease of the environment quality. Therefore, the government is going to raise the rate of drainage for 3% per year to improve this actual environmental problem. However, the huge sludge comes into being due to the sewage disposal, which will be a potential troublesome problem as well. In order to dispose of the huge sewage sludge quantity that increases year by year, and to satisfy the residents who strictly request a better environment due to the raise of environmental protection consciousness, sludge compost process will be the profitable solution that fits hygienic and economic. This study constructs the mathematical formula of mass and energy balance, which is required for a design of a compost plant. It is necessary to: 1) infer and set up the energy and mass growth and decline the conditions during the composting process. 2) apply these data to estimate the suitability and accuracy of this formula, so as to be the reference for designing compost plant in the future, 3) decrease the sludge treatment and disposal costs, 4) accelerates the compost reaction and improve the quality of maturity compost. The compost experiment uses the sludge cake made by Ming-Sheng sewage disposal plant as a source; then mix the wood dust and compost products with different water content. Two 110 L capacity Lab-Scales differentiate into shut type and open type. Three lots, totally six experiments are conducted. In the beginning, the moisture percentage of the sludge compost in each lot is modified to 55%, 60% and 65% each. One 13 m3 capacity Pilot-Scale is located inside the sewage disposal plant in Pa-Li, and one batch experiment is proceeded there. The moisture percentage of the sludge compost is changed to 65% in the beginning. Six sludge compost experiments are started off in the 110 升 capacity Lab-Scale. The outcome indicates the compost process runs better in the open system. The temperature is 3° to 5° hotter than the shut system, which proves the more compost touches with atmosphere, the better reaction compost process reveals. Furthermore, in the open system, the compost process reacts the best when the moisture possesses 55% in the beginning. It decreases 9.6 Kg in total. Secondly comes 60% and 65%. During the six sludge compost experiments proceeded in 13 m3 capacity Pilot-Scale, it totally decreases 4.59 ton. The temperature remains 55oC for over 15 days, which has already achieved the standard of U.S.EPA 305 regulation. To calculate 7 sets experiment data based on mass and energy balance, the average peak error in mass energy balance and energy balance is 46% and 9.62% each. In addition, to quote one set of vegetable compost data conducted by Kaohsiung First Science and Technology University into mass and energy balance. The average peak error in mass energy balance and energy balance appears 34.7% and 6.24%.