利用雞糞生產磷酸銨鎂之研究

Abstract

隨著全球人口持續攀升，糧食需求與日俱增，高效農業倚重大量化肥。而全球逾95 %的商業磷肥依賴有限的磷礦石，磷肥的永續供應面臨嚴峻挑戰。家禽產業每日產出的高氮、高磷雞糞若處置不當，易造成環境汙染及水體優養化。如何在處理家禽廢棄物的同時，妥善再利用磷資源，是刻不容緩的課題。厭氧消化技術不僅能將有機質轉化為沼氣，作為再生能源的燃料，同時也為禽畜廢棄物的磷回收提供了可行途徑。 玄武岩粉末富含鈣、鎂、鉀及多種礦物養分，施用於土壤不僅可供給礦物質養分同時調節土壤酸鹼值改善地力，亦能透過加速風化過程捕獲二氧化碳將之再礦化固定。然而，玄武岩施用後對土壤微生態系統的影響迄今瞭解有限。 本研究聚焦「磷回收」與「土壤碳固定」兩大主軸，將研究分為兩部分：其一，透過厭氧共消化高鈣雞糞與稻草，探討磷的釋放與磷酸銨鎂(struvite)回收；其二，評估玄武岩粉末施用對土壤菌相與固碳效益的影響。 第一部分結果顯示，高鈣雞糞的磷溶釋效率偏低且過量 Ca²⁺ 會干擾 struvite 結晶。透過添加稻草調整碳氮比增加微生物活性，5 日內磷釋放量提高 2–3 倍，瘤胃球菌科(Ruminococcaceae)成為優勢菌群，厭氧消化系統中的生物酸化有效降低 pH從而促進雞糞中的磷溶出，消化液再以草酸脫鈣並優化 pH，大幅降低 Ca²⁺ 的干擾並提高回收磷酸銨鎂晶體的純度及效率。隨後以上流式流體化結晶床的實廠試驗確認了反應系統及規模放大的可行性，畜牧廢水中的磷回收率可達 90% ，並且經X光繞射(XRD, X-ray diffraction)圖譜鑑定為磷酸銨鎂晶體。 第二部分顯示，玄武岩粉末添加明顯提升寡營養菌Acidobacteriota比例與微生物多樣性指標 (npShannon、Sobs)；相對地，有機質添加則促進富營養菌Bacillota、Actinomycetota、Pseudomonadota並提高 C/N 比。玄武岩可長期穩定土壤 pH，補充 Ca、Fe、Mg 等微量元素，強化土壤固碳潛力並降低環境風險。 綜上所述，本研究提出一套兼顧磷回收與礦物固碳的永續農業循環策略，既能減少化肥依賴、降低污染，又具經濟與生態雙重效益，為農業永續發展提供新的思路與實務指引。

With the continuous growth of the global population, the demand for food is steadily increasing, driving the reliance of intensive agriculture on large quantities of chemical fertilizers. However, more than 95% of commercial phosphate fertilizers worldwide are derived from finite phosphate rock resources, posing a significant challenge to the sustainability of phosphorus fertilizer supply. Simultaneously, the poultry industry's large volumes of nitrogen- and phosphorus-rich manure risk soil pollution and aquatic eutrophication if mismanaged. Anaerobic digestion offers a dual solution, converting organic matter to renewable biogas and enabling phosphorus recovery from livestock waste. Basalt powder, rich in Ca, Mg, K, and other minerals, can supply soil nutrients, buffer pH, and capture atmospheric CO₂ via accelerated weathering, though its microbial and carbon sequestration influences are less understood. This study addressed two issues: (i) recovering phosphorus as high-purity magnesium ammonium phosphate (struvite) through anaerobic co-digestion of high-calcium poultry manure with rice straw, and (ii) evaluating the impact of basalt powder addition on soil bacterial communities and carbon sequestration. In the first part, co-digesting manure with rice straw optimized the C/N ratio and stimulated microbial metabolism, resulting in a two- to three-fold increase in phosphate release within five days and promoting the dominance of Ruminococcaceae. Microbial acidification lowered pH, facilitating phosphate dissolution. Subsequent oxalic acid decalcification and pH optimization significantly reduced Ca²⁺ interference, leading to the precipitation of struvite with high yield and purity. A subsequent field study using an upflow fluidized bed crystallizer confirmed both the feasibility and scalability of the reaction system. The phosphorus recovery rate from livestock wastewater reached up to 90%, and X-ray diffraction (XRD) analysis identified the recovered product as magnesium ammonium phosphate crystals. In the second part, basalt amendment markedly enriched oligotrophic Acidobacteriota, and elevated microbial diversity indices (npShannon, Sobs), while organic amendments favored copiotrophic Bacillota, Actinomycetota, and Pseudomonadota, and raised the soil C/N ratio. Basalt also stabilized soil pH long-term and supplied Ca, Fe, and Mg, enhancing carbon-sequestration potential and mitigating environmental risks. In summary, this study proposes a sustainable agricultural circular strategy that integrates phosphorus recovery with mineral carbon sequestration. This approach not only reduces dependence on chemical fertilizers and mitigates environmental pollution but also offers both economic and ecological benefits, providing new insights and practical guidance for sustainable agricultural development.