集約養豬場已知對於環境有極大的衝擊，原因在於豬廢水中的氮和磷若沒有經過適當的處理，將會汙染土壤及水源，然而，這些被視為汙染物的物質卻可以是培養微藻極好的營養源。本研究的目標為評估結合微藻處理豬隻廢水之養豬場的環境衝擊，利用質量平衡、能量平衡以及環境衝擊評估的方法，考慮的系統包括利用微藻處理豬隻廢水的高效率養藻池、豬隻廢水與微藻的共消化、厭氧消化產生沼氣之汽電共生以及利用微藻取代豬隻飼料。而厭氧消化後剩餘的沼渣可作為堆肥使用。本研究比較了四種情境所產生的環境衝擊，分別為 (1)傳統情境；(2)厭氧消化；(3)厭氧消化與高效率養藻池；(4)厭氧共消化與高效率養藻池。結果顯示出在所有情境當中，豬飼料生產都為環境衝擊最大的部分，而以整個系統的觀點而言，比起情境1，本研究所提出的系統(情境3與情境4)有效降低ReCiPe方法當中，中端指標大多數的環境衝擊類別，亦分別降低了終端指標40% 和29% 的環境衝擊。雖然情境2產生最多的淨能量，但營養足跡分析顯示出本研究提出之系統能有效提高營養回收率。
此外，本研究針對飼料、厭氧消化以及高效率養藻池三個面向執行靈敏度分析，結果顯示出飼料取代的比率，為最有效改善環境衝擊之變因。總結而言，結合微藻處理豬隻廢水擁有產生淨能量、提高營養回收率以及降低環境衝擊的優點。

The pig manure generated from intensive pig farming is known to have significant impacts on the environment. The nitrogen and phosphorus compounds in the piggery wastewater contaminate the soil and bodies of water. However, these nutrients can also become a good source to cultivate microalgae. The present work aimed to evaluate the environmental impact of microalgae-based pig production system using high-rate algal pond (HRAP) through mass balances, energy balances and life cycle assessment. The system involved simultaneous treatment of piggery wastewater using microalgae, co-anaerobic digestion of pig manure and microalgal biomass, biogas cogeneration, and substitution of pig feed. The organic residues after the anaerobic digestion could be applied as fertilizers to farmland and replace mineral fertilizers. The environmental performances of four scenarios including (1) conventional application; (2) anaerobic digestion (AD) only; (3) AD and HRAP; and (4) co-AD and HRAP were compared. As shown in the results, pig feed production contributed to the most environmental impact in all scenarios. For the overall system, the ReCiPe midpoint indicators of proposed systems (scenario 3 and 4) decreased in most of the categories and ReCiPe endpoint indicators were also saved by 40%, and 29% respectively compared to scenario 1. Although scenario 2 generated the most net energy, the nutrient footprint revealed that proposed systems significantly improved the nutrient recovery.
Additionally, the sensitivity analysis was implemented in three aspects: feedstuff, anaerobic digestion, and HRAP for proposed systems. The results indicated that the feed conversion rate was the main factor in improving environmental performance. In summary, combining microalgae-based wastewater treatment into pig farming system has advantages of net energy production, better nutrient recovery and better performance concerning environmental impacts.

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