- 學位論文
堆肥製作過程二氧化碳及甲烷排放量測
Flux of Carbon Dioxide and Methane during Compost Preparation
摘要
為了解堆肥場二氧化碳及甲烷釋出，選擇桃園及彰化地區堆肥場作為研究對象。本論文的研究包括：1. 建立堆肥場溫室氣體採樣方法，並探討翻堆處理、堆積時間、堆積高度及不同資材對溫室氣體排放量影響。2. 於不同資材堆肥場進行二氧化碳及甲烷釋放量量測，並推估畜牧產業溫室氣體之排放量。3. 以開放式氣態傅立葉轉換紅外線分光儀 (Fourier Transform Infra Red，FTIR)，進行堆肥場內溫室氣體濃度量測，並與傳統點偵測以氣相層析儀分析法比較。4.於實驗室中進行有系統探討堆肥化之模擬試驗，了解溫度及水分對二氧化碳及甲烷生成之影響。5. 探討堆肥過程中，總菌數及纖維分解菌與二氧化碳及甲烷釋放量相關性。6. 進行水田、旱田、濕地及掩埋場等二氧化碳及甲烷釋放源量測。 堆肥過程中溫度快速上升，而後漸降至末期趨於腐熟，水分、總有機碳及碳氮比亦隨著堆肥過程漸降，但pH、灰分、總氮和發芽率則呈現上升的趨勢。以採樣罩進行採樣時，當覆蓋時間較長，二氧化碳濃度增加率下降，此情形於高釋量處較為顯著，覆蓋15分鐘後二氧化碳增加速率降低。若以一般採集樣品之覆蓋時間30分鐘，則測得之釋放量將較覆蓋15分鐘減低約10%。而覆蓋5及10分鐘之採樣時間，則因覆蓋時間較短，堆肥場內環境及採樣時間控制不易造成實驗誤差，故高溫高釋放量樣品採集時間以15分鐘較佳。 堆肥槽中間二氧化碳釋放量大於兩側，溫度中間處亦大於兩側，由於堆肥樣品於同一醱酵時期為同一批資材，成分相類似，故中間及左右兩側之釋放量差異遠小於不同醱酵時期，左右兩側二氧化碳釋放量則以右側略大於左側，此則為右側與另一堆肥槽相鄰，雖無通風之優點，但有助於醱酵熱之保存，甲烷釋放量兩側較中間高。而不同高度堆肥二氧化碳釋放量與堆肥高度相關係數0.972，甲烷則高達0.999，堆肥成品溫室氣體釋放量與堆肥高度成正相關。比較體積為104公升壓克力採樣罩及18公升圓桶採樣罩採樣情形，小型採樣罩罩內氣體濃度初期上升較快，覆蓋30分鐘後，溫室氣體濃度與壓克力採樣罩相近。 翻堆後溫度上升至16小時後趨緩，甲烷釋放量於翻堆第19小時後與翻堆前略同，而二氧化碳釋放量於翻堆後10小時最高。翻堆供氣使微生物有氧呼吸作用提高，二氧化碳釋出量上升而甲烷下降，翻堆時將堆肥中蓄積之二氧化碳及甲烷釋出，使得場內濃度提高，翻堆後初期因溫度及氣體蓄積，使得釋放量下降。 二氧化碳釋放速率與堆肥溫度、pH、水分含量及纖維性分解菌相關性較甲烷釋放速率為高，上層 (10 cm)之相關性最高，中層 (30 cm)較低，而下層 (50 cm)最低，二氧化碳及甲烷釋放速率可做為堆肥腐熟指標。 除了量測堆肥場溫室氣體釋放源外，亦選取同為廢棄物處理之台灣北部掩埋場進行溫室氣體排放量測；彰化地區水稻田及毛豆、花生、大白菜、甘藍菜、花椰菜、蔥、萵苣、洋蔥及西瓜等植物種植地點，進行溫室氣體採集；以及濕地溫室氣體釋放源進行量測。 本研究成功的建立槽式堆肥密閉式壓克力罩採樣法，進行甲烷及二氧化碳排放量測，並對不同堆肥資材、醱酵槽不同醱酵位置及翻堆影響進行分析。首次以FTIR遙測儀進行堆肥場即時且長距之溫室氣體測量，採樣罩覆蓋後最佳採樣時間為15分鐘，翻堆能縮短腐熟時間，降低堆肥過程中甲烷排放。每公噸堆肥於60天的堆積過程中，甲烷及二氧化碳平均釋放量分別為0.34和23.87 kg。本研究所得溫室氣體排放與堆肥化過程中成分變化和環境因子關係，可以提供農政單位、環保機構、產業界和國人參考，研擬堆肥化過程溫室氣體排放減量之可行策略。
並列摘要
To investigate the GHGs production/emission from compost plant, Tao-yuan and Chang-hua compost plants were choosen to analyze carbon dioxide (CO2) and methane (CH4) emission. Present thesis includes: 1. Establish greenhouse gases (GHGs) sampling method from compost plant and analyze the effect of turning operation, composting period and different raw materials. 2. Measuring emission rate of CO2 and CH4 in compost plants with different raw materials and estimate annual emission from compost. 3. Measuring GHG using open type FTIR (Fourier Transform Infra Red) in compost plants, and compare the results with the traditional gas chromatography method. 4. Carry out systematic experiment in the laboratory to understand the effect of temperature and moisture content on CO2 and CH4 emission during composting. 5. Discuss the role of total bacteria and cellulolytic microbes on CO2 and CH4 emission. 6. Measurement of CO2 and CH4 emission from different sources such as paddy field, upland, wetland and landfill. During composting, temperature increased rapidly and decreased gradually. Moisture content, total organic carbon and C/N ratio also have the same tendency, but pH, ash, total nitrogen and germination index increased during the composting. During sampling, when the gas collection chambers placed on the compost for longtime the emission rates were low. Similarly, if the collection time was short the differences between replicates were very high. Hence, the gas collection time of 15 min was optimum. The CO2 emission rate was higher in the middle of the trough than the edges which correlates with the highest temperature observed in the middle than in the edges. When comparing the two edges, the edge with an adjacent compost trough had higher emission than the edge with out adjacent compost trough. But the CH4 emission rate was low in the middle of the trough. High correlation coefficient between compost height and emission rates of CO2 and CH4 was observed. The correlation coefficients between compost height and emission rates were 0.972 and 0.999 for CO2 and CH4, respectively. When comparing two sampling chambers of different size, 18 L and 104 L, the concentration was rapidly increased in the small chamber during the initial period; however after 30 minutes the concentration was similar in both the sampling chambers. After turning the compost, temperature rose up to 16 hours and then stable for sometime and decreased. CH4 emission rate after 19 hours of turning was the same as before turning. But CO2 emission rate was highest after 10 hours of turning. Turning supply air to microbes, which through aerobic respiration produce CO2 and hence the CO2 emission rate increased but CH4 emission dropped. The correlation coefficients between CO2 emission rate and substrate pH, moisture content, compost temperature, and populations of cellulolytic microbes were higher than those with CH4 emission rate. The upper layer (10 cm depth) had the highest correlation coefficient, followed by the middle layer (30 cm depth), and the bottom layer (50 cm depth) was the least. The CO2 and CH4 emission rates could be used as the parameters of compost maturity. The greenhouse gas emission were measured from different sources: landfill in northern Taiwan; paddy field, uplands with young soy beans, peanut, chinese cabbage, cabbage, cauliflower, green onion, lettuce, onion and watermelon plants in Chang-hua. A wetland was also studied in the perspective of greenhouse gas emission. This study successfully established the sampling method and parameters for compost plant using closed acrylic chamber. Simultaneously, for the first time, the emission rates were successfully determined using FTIR. Since, in FTIR, the concentrations were measured for long distance, the values reflect the actual conditions. Turning reduced the compost production time and CH4 emission. In a total period of 60 days, each ton of compost produced 0.34 and 23.87 kg of CH4 and CO2, respectively. The result of GHGs emission from compost and other sources deliver potential information to the environmental protection agencies and policy makers to formulate the strategy to mitigate the greenhouse gas emission.