研發畜牧場沼氣純化生物反應器及發電系統整合

Abstract

灣現有畜牧場廢棄物衍生出龐大沼氣，是為快速可用之再生能 源，然而受限於沼氣純度與後端發電技術，使得此生質能源無法被高 度利用。我們在 96 與 97 年度「農業生物國家型計畫」中所研發的嗜 酸自營菌生物除硫反應器，已完成高效能菌種篩選、模場規模除硫測試 (可將 2000 ppm 硫化氫在 2 分鐘滯留時間下去除 98% 以上)，以及實場 200 倍放大初步除硫測試 (可將 4000 ppm 硫化氫在 2 分鐘滯留時間下 去除 96% 以上)。此生物反應器無一般除硫法衍生之硫沉澱物堵塞困擾， 但會隨著硫酸根累積而導致系統酸化，因此在本計劃中將針對硫酸根排放 或回收再利用進行研究。再者將提昇系統運作穩定性，並藉由反應器改良， 使沼氣處理速率由目前的 100 L /min 大幅提高到 200 L /min 以上 (或氣 體滯留時間縮短一半為 1 分鐘)。 此外，本實驗過去執行國科會個人與跨領域整合計畫，亦發展出改良 型化學-生物串聯反應器，目前已完成模場規模除硫測試(可將 2500 ppm 硫化氫在 1 分鐘滯留時間下達 100% 去除率)及5 倍實場放大測試 (可將 5000 ppm 硫化氫在 1 分鐘氣體滯留時間與 20 L/min 處理速率下達 95% 以上去除率)。此化學-生物串聯除硫法之缺點為生物反應速度過慢，因此在 本年度創新計畫中另一目標是使用已篩選到之 10 倍活性菌種，取代實場 反應器中的原始菌株來提昇反應速率。另外藉由反應器改良進行硫沈澱回 收，並經由 10 倍放大，可將處理速率由 20 L/min 提昇至 200 L/min 以 上。在沼氣純化及發電的整合方面，本年度計畫也將進行各種不同參數的 長期監測，由結果歸納出最佳操作條件，以及建構自動化控制設備，提昇 操作安全性及穩定性。期望此二項除硫發電系統在本年度計畫結束後，已 達到量產化之雛形（沼氣純化速率達 500 L/min），適用於 3000 頭猪隻規 模之養猪場。

The utilization of renewable energy and development of new energy sources are government policy. A large amount of biogas derived from wastes is an excellent resource at present. However, the application of bioconversion energy is restricted by low purity of biogas and the techniques of power generation. In the former projects, we isolated an acidophile autotrophic strain with high H2S removal efficiency. The results of bench-scale biofilter reactor could remove 98% of 2000 ppm H2S in 2 minutes GRT (gas retaintion time). The pilot scale of 200-fold scale-up reactor was constructed, and the H2S removal efficiency was 96% in 2 minutes GRT (4000 ppm). In this project, we will focus on sulfide recovery due to the sulfide accumulation, which caused pH vaule dropping dramatically. Furthermore, the gas flow rate will be improved and elevated from 100 L/min to 200 L/min after improvement of the reactor in this project (or shorten half of GRT to 1 minute). We have designed a combined chemical-biological reactor in the former project. The bench scale reactor which eliminated 100% of 2500 ppm H2S in 1 minute GRT. The 5-fold scale up pilot scale reactor eliminated 95% of 5000 ppm H2S in 1 minute GRT. In this project, the high efficiency mutant strain will be applied to system for better H2S elimination performance. Also, the reactor will be 10-fold scaled up to elevate gas flow rate from 20 L/min to 200 L/min. After that, we will optimize the operating parameters. The automatic control system will also be constructed in this system for better security, stability performance and easier to operate. We expect our system is suitable to use in all piggeries with 3000 pigs and reach electrical self-sufficiency.