藉由溫相式厭氧消化 (TPAD) 系統將農牧廢棄物轉化製造生質肥料

Abstract

本研究結合溫相式厭氧消化(TPAD)及厭氧共消化之概念來處理農牧廢棄物 (豬糞和稻稈)，並探討TPAD系統之效能、厭氧生物產能和製備生物肥料等目的。豬糞和稻稈在臺灣為主要的農牧廢棄物，且污染量和強度相對於其他農牧廢棄物高。一般而言，單一廢棄物經厭氧消化處理常有反應槽效能不佳或是微生物抑制問題產生，導致厭氧處理在應用上受限；消化二種或二種以上不同來源之廢棄物，有效提高厭氧效能並減少操作問題產生。 TPAD 系統是由前段高溫反應槽及後段中溫反應槽所組成，藉由高溫段提升整體系統之處理效能如揮發性固體物(VS)去除、產生大量生物沼氣及致病菌消滅，而中溫階段則負責洗鍊高溫出流，提升TPAD出流水品質及強化整體系統之穩定性。由於本研究在實驗設備上的問題導致TPAD系統在整個馴養期間受到相當大的影響，本研究之最大揮發性固體物濃度控制在20 g VS/L，為避免阻塞問題發生。 擬穩態階段之數據顯示二個PM及RS比例(PM:RS=80:20和 90:10)皆可達到Class A biosolids 對於VS和致病菌的規範；進料大部分有機氮被轉化為氨氮，然而消化後污泥中有機磷略微增加。從重金屬結果得知，本實驗之二比例在銅和鋅二金屬濃度遠高於其他金屬，且超出臺灣對液態肥料之標準，此外鉻和鎳也有超出規範的可能，這表示豬糞和稻稈比例在本實驗中仍未達到最佳比例。

This study combined with temperature-phased anaerobic digestion (TPAD) and the concept of anaerobic co-digestion to treat agriculture and live stock wastes (pig manure and rice straw) and investigated the performances of TPAD system, anaerobic bioenergy production as well as biofertilizer production. Pig manure (PM) and rice straw (RS) are the main this type waste in Taiwan and the amount and strength compared to other agro-wastes are much high. In general, single source waste treated with anaerobic digestion often has poor reactor performances or microbial inhibition problems and results in a limitation of anaerobic treatment; co-digestion with two or more different sources wastes can effectively improve anaerobic performances and reduce operational problems. TPAD system, which includes the first thermophilic stage and the second mesophilic stage reactors, takes the thermophilic stage to improve the system performance, volatile solid (VS) removal, producing a large amount of biogas as well as pathogens elimination; while the mesophilic stage is responsible for polishing thermophilc effluent and strengthening the stability of whole system. Because the problem of laboratory equipments in this study caused a considerable impact in overall accumulation periods, the maximum VS concentration was 20 g VS/L in this research to avoid occurring obstruction problem. The data of pseudo-steady-state conditions showed that two ratios of PM and RS (PM:RS=80:20 and 90:10) could meet the Class A biosolids for the specifications of the VS removal and pathogens reduction. Organic nitrogen in the substrate was converted to ammonium, however organic phosphorus in the effluent sludge slightly increased after digesting. From the result of heavy metals, the concentrations of copper and zinc were much higher than other metals and exceeded Taiwanese standards for liquid fertilizers, moreover the concentrations of chromium and nickel were also likely to exceed the standards, indicating both the ratios of PM and RS in this study didn’t yet reach the optimum ratio.