農畜產廢棄物利用及堆肥製造之現況

Abstract

依1993年禽畜飼養頭數估計臺灣地區主要禽畜糞排泄量約12,773,800公噸，而每年主要農產廢棄物稻殼、甘蔗渣、廢棄菇類木屑總量為2,009,950公噸，以禽畜糞生產自給肥料為l,371,190公噸，農產廢棄物由政府輔導設立之農業廢棄物處理中心用來製造堆肥及當做燃料計約有1,277,276公噸，其餘之農畜產廢棄物有待加強技術輔導，擴大推廣堆肥製造及處理，讓農業廢棄物資源能被有效利用且使生態、環境受到維護。在堆肥化過程中需要有良好的發酵條件，如適當的含水率、碳氮比例、充分的通氣等。禽畜糞的碳氮比值皆小於30，故可直接逕行發酵製造堆肥，堆肥完熟所需的時間較短，雞糞約2星期，牛、豬糞約3星期，但混合木屑、蔗渣、稻殼等材料以增加通氣性及減少臭氣時，發酵完熟所需的時間要延長。一般農產廢棄物的碳氮比值較高，分解速度較緩慢，氮磷含量比禽畜糞低，須添加氮源、磷源使腐熟加速，以廢棄菇類木屑、蔗渣為主材料製造堆肥，發酵完熟所需要時間分別為8星期、5個月。堆肥腐熟度可用發芽率、圓形濾紙圖形判斷法等方法測定。目前製造堆肥方式已驅向於機械化，並附設送風系統，俾於減少人力、縮短發酵完熟所需要的時間，農產廢棄物於製造堆肥發酵過程，若管理適當則可以幾乎沒有臭味，但禽畜糞於製造堆肥發酵過程則仍須要考慮除臭的問題。堆肥場臭氣之脫臭技術，以木屑脫臭及土壤脫臭法為主，其對氨氣的脫臭效率可達100%，較水洗法之脫臭效率16.7%~79.5％為佳。 The quantity of livestock feces was estimated about 12,773,800 tons, and agricultural waste, including rice hull, processed sugarcane residue, wasted mushroom sawdust, was about 2,009,950 tons, 1993, in Taiwan. Now, goverment is trying to solve the agricultural waste and livestock feces problems by providing farmer with finance and technique to make compost. So, strengthening consult of technique, enlarging extension work of making and utilizing compost become very important. Maintaining good fermentation conditions, during composting process necessaried for producing good quality compost, were suitable moisture content, C/N ratio, enough air flux. The C/N ratios of livestock feces were smaller than 30:1, and they could be composted directly. But the C/N ratios of agricultural wastes were always larger than 30:1, So, they must be adjusted C/N ratio below 30:1 with nitrogen sources before composting. Generally speaking, The time durations, needed for composting, were followed in the sequence processed sugarcane residue (5 months) > wasted mushroom sawdust (8 weeks) > cattle feces, swine feces (3 weeks) > chicken feces (2 weeks). Composting processes now are improved to be automatic systems, for saving labor and reducing composting period. Two methods, germination rate test and paper chromatograph test, were used to assess compost maturity degree, in the paper. Experimental data showed that the second method was more reliable than the first one. When agricultural wastes were used for composting, the odors were hardly presented in the process. But the odors of composted livestock feces were strong. Currently, the odors were removed by sawdust adsorption method, soil adsorption method, and water washing tower method. The former two methods removed ammonia gas completely from composted materials, and the third method only removed 16.7%~79.5% ammonia gas.