評估施用養豬廢水厭氧消化沼液土壤重金屬污染與風險

經濟起飛對於動物性蛋白質的需求增加，這也使得畜牧產業的蓬勃發展。雖然滿足了人類對動物性蛋白的需求，也在過程中對環境造成污染。畜牧產業產生之畜牧廢水若未經處理被排放至水體中，很容易造成水體之污染。為了防止廢水污染，在農作物種植過程施用畜牧廢水所含的營養源(氮磷鉀)取代作物生長需要的化學肥料。畜牧廢水經過廢水程序處理，放流水部分含有微量重金屬，若直接施灌於農地可能會對農地的土壤造成重金屬含量增加的風險。本研究探討養豬場厭氧發酵的沼渣與沼液中重金屬濃度與評估施用農地可能的重金屬風險。同時利用BCR序列萃取法探討沼渣重金屬之結合狀態，以及評估潛在的重金屬風險。環境污染與風險指標含地質累積指標(Igeo)、潛在生態風險指標(PERI)、全量風險指數(GRI)等指標。結果顯示沼液中部分重金屬對環境是具有嚴重風險與污染程度，但沼液施灌之土壤，短期土壤重金屬仍屬於低風險與污染。然而將沼液長期施灌於土壤，仍需評估對土壤造成之風險。

關鍵字

沼液； BCR序列萃取法；重金屬風險評估；地質累積指標(Igeo) ；潛在生態風險指標(PERI)

並列摘要

With the economic development and the rapid population growth, the demand for animal protein has also increased, leading to the vigorous development of the animal husbandry industry. However, it meets the human need for animal protein, it also causes a little pollution to the environment. If the livestock wastewater produced is discharged into the water body without treatment, it will easily cause water pollution. To avoid severe water pollution of livestock wastewater, which is used to replace the chemical fertilizers required for crop growth. The treated livestock wastewaters containing nitrogen, phosphorus, and potassium are applied to farmlands. Although the treated livestock wastewater has decomposed the organic matter, it may still contain trace heavy metals in the discharge water. Therefore, if it is directly irrigated on farmland, it may cause the risk of increased heavy metal content in farmland soil. This study investigated the concentration of heavy metals in biogas residue and biogas slurry from anaerobic digestion of pig wastes. It is intended to evaluate the possible risk of heavy metals in agricultural land. At the same time, the BCR sequence extraction method was used to explore the binding state of heavy metals in biogas residues and evaluate the potential risk of heavy metals. Some environmental pollution and risk indicators are used to assess the risk of applied biogas slurry on farmland, such as geoaccumulation index (Igeo), potential ecological risk index (PERI), and global risk index (GRI). The results show that some heavy metals in biogas slurry have severe risks and pollution to the environment. However, in the soil where biogas slurry is irrigated, these heavy metals in short-term soil have remained at low risk and pollution. However, the biogas slurry is applied to the farmland soil for a long time; it still needs to assess the possible risk caused the heavy metal risk in the slurry.