Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei City 106, Taiwan, ROC.
Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei City 106, Taiwan, ROC; Agricultural Net-Zero Carbon Technology and Management Innovation Research Center, National Taiwan University, Taipei City 106, Taiwan, ROC.
Sci Total Environ. 2023 Sep 15;891:164612. doi: 10.1016/j.scitotenv.2023.164612. Epub 2023 Jun 5.
An electricity-assisted anaerobic co-digestion (EAAD) process was developed and compared with conventional anaerobic co-digestion (AD) using piggery wastewater and rice husk as feedstocks. Various methodologies, including kinetic models, microbial community analyses, life-cycle carbon footprints, and preliminary economic analysis, were integrated to comprehensively evaluate the performance of the two processes. The results demonstrated that EAAD exhibited a positive improvement of 2.6 % to 14.5 % in biogas production compared to AD. The suitable wastewater-to-husk ratio for EAAD was found to be 3:1, which corresponded to a carbon-to‑nitrogen ratio of approximately 14. This ratio demonstrated positive co-digestion effects and electrical enhancements in the process. According to the modified Gompertz kinetics, the biogas production rate in EAAD ranged from 1.87 to 5.23 mL/g-VS/d, significantly higher than the range of 1.19 to 3.74 mL/g-VS/d observed in AD. The study also investigated the contributions of acetoclastic and hydrogenotrophic methanogens to biomethane formation, revealing that acetoclastic methanogens accounted for 56.6 % ± 0.6 % of the methane production, while hydrogenotrophic methanogens contributed to 43.4 % ± 0.6 %. No significant difference in the methanogenic reaction pathways was observed between AD and EAAD, indicating that the introduction of an external electric field did not alter the predominant pathways (p > 0.05, two-sample t-test). Furthermore, retrofitting existing AD plants with EAAD units can reduce the carbon intensity of piggery wastewater treatment by 17.6 % to 21.7 %. The preliminary economic analysis indicated a benefit-cost ratio of 1.33 for EAAD, confirming the feasibility of implementing EAAD for wastewater treatment while simultaneously producing bioenergy. Overall, this study provides valuable insights into upgrading the performance of existing AD plants by introducing an external electric field. It demonstrates that EAAD can achieve higher and cost-effective biogas production with a lower life-cycle carbon footprint, thus enhancing the sustainability and efficiency of the biogas production process.
开发了一种电辅助厌氧共消化（EAAD）工艺，并将其与使用猪场废水和稻壳作为原料的传统厌氧共消化（AD）进行了比较。综合运用了各种方法，包括动力学模型、微生物群落分析、生命周期碳足迹和初步经济分析，全面评估了两种工艺的性能。结果表明，与 AD 相比，EAAD 沼气产量提高了 2.6%至 14.5%。发现 EAAD 的适宜废水与稻壳比为 3:1，对应于大约 14 的碳氮比。该比值在共消化过程中表现出了积极的协同作用和电增强效果。根据修正的 Gompertz 动力学，EAAD 中的沼气产率范围为 1.87 至 5.23 mL/g-VS/d，明显高于 AD 中 1.19 至 3.74 mL/g-VS/d 的范围。该研究还调查了乙酸营养型和氢营养型产甲烷菌对生物甲烷形成的贡献，结果表明，乙酸营养型产甲烷菌占甲烷产量的 56.6%±0.6%，而氢营养型产甲烷菌的贡献为 43.4%±0.6%。AD 和 EAAD 之间的产甲烷反应途径没有显著差异，表明引入外部电场并没有改变主要途径（p>0.05，双样本 t 检验）。此外，通过在现有的 AD 工厂中 retrofit EAAD 单元，可以将猪场废水处理的碳强度降低 17.6%至 21.7%。初步经济分析表明，EAAD 的效益成本比为 1.33，证实了在处理废水的同时生产生物能源的情况下，实施 EAAD 的可行性。总的来说，这项研究为通过引入外部电场来提高现有 AD 工厂的性能提供了有价值的见解。它表明，EAAD 可以实现更高的、具有成本效益的沼气生产，同时生命周期碳足迹更低，从而提高沼气生产过程的可持续性和效率。
