Department of Civil Engineering, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada.
Department of Civil Engineering, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada.
J Environ Manage. 2018 Jul 1;217:416-428. doi: 10.1016/j.jenvman.2018.03.123. Epub 2018 Apr 5.
This paper investigates the feasibility and advantages of using a dual-stage hyper-thermophilic/thermophilic semi-continuous reactor system for the co-digestion of Thickened Waste Activated Sludge (TWAS) and Fat, Oil and Grease (FOG) to produce biogas in high quantity and quality. The performance of the dual-stage hyper-thermophilic (70°C)/thermophilic (55°C) anaerobic co-digestion system is evaluated and compared to the performance of a single-stage thermophilic (55°C) reactor that was used to co-digest the same FOG-TWAS mixtures. Both co-digestion reactors were compared to a control reactor (the control reactor was a single-stage thermophilic reactor that only digested TWAS). The effect of FOG% in the co-digestion mixture (based on total volatile solids) and the reactor hydraulic retention time (HRT) on the biogas/methane production and the reactors' performance were thoroughly investigated. The FOG% that led to the maximum methane yield with a stable reactor performance was determined for both reactors. The maximum FOG% obtained for the single-stage thermophilic reactor at 15 days HRT was found to be 65%. This 65% FOG resulted in 88.3% higher methane yield compared to the control reactor. However, the dual-stage hyper-thermophilic/thermophilic co-digestion reactor proved to be more efficient than the single-stage thermophilic co-digestion reactor, as it was able to digest up to 70% FOG with a stable reactor performance. The 70% FOG in the co-digestion mixture resulted in 148.2% higher methane yield compared to the control at 15 days HRT. 70% FOG (based on total volatile solids) is so far the highest FOG% that has been proved to be useful and safe for semi-continuous reactor application in the open literature. Finally, the dual-stage hyper-thermophilic/thermophilic co-digestion reactor also proved to be efficient and stable in co-digesting 40% FOG mixtures at lower HRTs (i.e., 9 and 12 days) and still produce high methane yields and Class A effluents.
本文研究了使用两段式超高温/高温半连续反应器系统对浓缩剩余活性污泥（TWAS）和脂肪、油和油脂（FOG）进行共消化以高产气量和高质量生产沼气的可行性和优势。评估和比较了两段式超高温（70°C）/高温（55°C）厌氧共消化系统的性能与用于共消化相同 FOG-TWAS 混合物的单段高温（55°C）反应器的性能。将两个共消化反应器与一个对照反应器（对照反应器是仅消化 TWAS 的单段高温反应器）进行了比较。彻底研究了 FOG%在共消化混合物中的比例（基于总挥发性固体）和反应器水力停留时间（HRT）对沼气/甲烷产量和反应器性能的影响。确定了两个反应器在稳定的反应器性能下获得最大甲烷产量的最大 FOG%。在 15 天 HRT 下，单段高温反应器获得的最大 FOG%为 65%。与对照反应器相比，该 65%FOG 导致甲烷产量提高了 88.3%。然而，两段式超高温/高温共消化反应器被证明比单段高温共消化反应器更有效，因为它能够在稳定的反应器性能下消化高达 70%的 FOG。共消化混合物中 70%的 FOG 在 15 天 HRT 下与对照相比，甲烷产量提高了 148.2%。到目前为止，70%的 FOG（基于总挥发性固体）是已被证明在开放文献中对半连续反应器应用有用且安全的最高 FOG%。最后，两段式超高温/高温共消化反应器在较低 HRT（即 9 天和 12 天）下共消化 40%FOG 混合物时也表现出高效和稳定，仍能产生高甲烷产量和 A 级出水。
