Department of Smart-city Engineering, Inha University, 100 Inha-ro, Michuhol-gu, Incheon 22212, Republic of Korea.
Department of Smart-city Engineering, Inha University, 100 Inha-ro, Michuhol-gu, Incheon 22212, Republic of Korea; Department of Environmental Health, Daejeon Health Institute of Technology, 21 Chungjeong-ro, Dong-gu, Daejeon 34504, Republic of Korea.
Water Res. 2021 Apr 15;194:116920. doi: 10.1016/j.watres.2021.116920. Epub 2021 Feb 10.
Auto-generative high pressure digestion (AHPD) and hydrogen-injecting digestion (HID) have been introduced to directly produce high CH-content biogas from anaerobic digester. However, each approach has its own technical difficulties (pH changes), and practical issues (high cost of H) to obtain > 90% CH containing biogas, particularly, from the high-strength waste like food waste (FW). To overcome this problem, in this study, AHPD and HID were integrated, which can offset each drawback but maximize its benefit. Substrate concentration of FW tested here was 200 g COD/L, the highest ever applied in AHPD and HID studies. At first, the reactor was operated by elevating the autogenerative pressure from 1 to 3, 5, and 7 bar without H injection. With the pressure increase, the CH content in the biogas gradually increased from 52.4% at 1 bar to 77.4% at 7 bar. However, a drop of CH production yield (MPY) was observed at 7 bar, due to the pH drop down to 6.7 by excess CO dissolution. At further operation, H injection began at 5 bar, with increasing its amount. The injection was effective to increase the CH content to 82.8%, 87.2%, and 90.6% at 0.09, 0.13, and 0.18 L H/g COD of H injection amount, respectively. At 0.25 L H/g COD, there was a further increase of CH content to 92.1%, but the MPY was dropped with pH increase to 8.7 with residual H being detected (4% in the biogas). Microbial community analysis showed the increased abundance of piezo-tolerant microbe with pressure increase, and direct interspecies electron transfer contributors after H injection. In conclusion, the integration of two approaches enabled to directly produce high calorific biogas (90% > CH, 180 MJ/m biogas) from high-strength FW at the lowest requirement of H (0.18 L H/g COD) ever reported.
自生高压消化（AHPD）和注氢消化（HID）已被引入，以直接从厌氧消化器中生产高 CH 含量的沼气。然而，每种方法都有其自身的技术难题（pH 值变化）和实际问题（H 的高成本），难以获得 >90% CH 含量的沼气，特别是从高强度废物（如食物废物（FW））中获得。为了克服这个问题，在本研究中，AHPD 和 HID 进行了集成，这可以抵消彼此的缺点，但最大限度地发挥其优势。此处测试的 FW 底物浓度为 200g COD/L，这是 AHPD 和 HID 研究中应用的最高浓度。首先，在不注氢的情况下，通过将自生压力从 1 升高到 3、5 和 7 bar，来操作反应器。随着压力的增加，沼气中的 CH 含量逐渐从 1 巴时的 52.4%增加到 7 巴时的 77.4%。然而，在 7 巴时观察到 CH 产量（MPY）下降，这是由于 CO 溶解过多导致 pH 值下降到 6.7。在进一步的操作中，在 5 巴时开始注氢，并增加注氢量。注氢有效将 CH 含量提高到 0.09、0.13 和 0.18 L H/g COD 注氢量时的 82.8%、87.2%和 90.6%。当注氢量为 0.25 L H/g COD 时，CH 含量进一步增加到 92.1%，但随着 pH 值升高到 8.7 和检测到残留 H（沼气中 4%），MPY 下降。微生物群落分析表明，随着压力的增加，压电耐受微生物的丰度增加，注氢后直接种间电子转移贡献者增加。总之，两种方法的结合使得能够以最低的 H 要求（报告的最低值为 0.18 L H/g COD）直接从高强度 FW 中生产高热值沼气（90%>CH，180 MJ/m 沼气）。
