Key Laboratory for City Cluster Environmental Safety and Green Development of the Ministry of Education, School of Ecology, Environment and Resources, Guangdong University of Technology, Guangzhou 510006, China; Environmental Research Institute, National University of Singapore, 1 Create Way, 138602, Singapore; Energy and Environmental Sustainability for Megacities (E2S2) Phase II, Campus for Research Excellence and Technological Enterprise (CREATE), 1 Create Way, Singapore 138602, Singapore.
Environmental Research Institute, National University of Singapore, 1 Create Way, 138602, Singapore; Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China.
Sci Total Environ. 2023 Nov 15;899:165783. doi: 10.1016/j.scitotenv.2023.165783. Epub 2023 Jul 24.
Food waste (FW) has become a worldwide issue, while anaerobic digestion (AD) has appeared as a widely adopted technology to recover energy and resources from FW. Compared to many existing case studies of centralized AD system, the comprehensive study of decentralized micro-AD system from both system energy efficiency and carbon emission perspective is still scanty, particularly system operated under ambient temperature conditions. In this study, an actual decentralized micro-AD system with treating capacity of 300 kg FW/d for a local hawker center in Singapore was reported and evaluated. The results showed that 1894.5 kg of FW was treated and 173 m biogas with methane content of 53 % was produced during the experimental period of 75 days. The methane yield results showed a high FW degradation efficiency (87.87 %). However, net energy consumption and net carbon emission were observed during the experimental period. Nevertheless, energy self-efficiency and carbon neutrality, even net energy output and carbon reduction, can be achieved by increasing daily FW loading and biogas engine efficiency. Specifically, the FW loading for system energy self-efficiency was identified as 159 kg/d for engine efficiency of 35 % at a high kitchen waste/table waste ratio (63 %/37 %, with covid-19 dine-in restrictions); while they were 112 and 58 kg/d for engine efficiency of 25 % and 35 %, respective, at a low kitchen waste/table waste ratio (31 %/69 %, without covid-19 dine-in restrictions). The carbon emission ranged from 156.08 kg CO-eq/t FW to -77.35 kg CO-eq/t FW depending on the FW loading quantity and engine efficiency. Moreover, the sensitivity analysis also showed that the used electricity source for substitution influenced the carbon emission performance significantly. The obtained results imply that the decentralized micro-AD system could be a feasible FW management solution for energy generation and carbon reduction when the FW loading and engine electrical efficiency are carefully addressed.
食物垃圾（FW）已成为全球性问题，而厌氧消化（AD）已成为从 FW 中回收能源和资源的广泛采用的技术。与许多现有的集中式 AD 系统案例研究相比，从系统能源效率和碳排放角度对分散式微型 AD 系统的综合研究仍然很少，特别是在环境温度条件下运行的系统。在这项研究中，报告并评估了一个实际的、处理能力为 300 公斤 FW/d 的分散式微型 AD 系统，该系统位于新加坡的一个当地小贩中心。结果表明，在 75 天的实验期间，处理了 1894.5 公斤 FW，并产生了 173 立方米甲烷含量为 53%的沼气。甲烷产率结果表明 FW 降解效率很高（87.87%）。然而，在实验期间观察到净能量消耗和净碳排放。尽管如此，通过增加每日 FW 负荷和沼气发动机效率，可以实现能源自给自足和碳中和，甚至实现净能量输出和碳减排。具体而言，确定系统能源自给自足的 FW 负荷为 159 公斤/天，发动机效率为 35%，厨房垃圾/餐桌垃圾比例高（63%/37%，有 COVID-19 堂食限制）；而当厨房垃圾/餐桌垃圾比例低（31%/69%，无 COVID-19 堂食限制），发动机效率分别为 25%和 35%时，它们分别为 112 公斤/天和 58 公斤/天。根据 FW 负荷量和发动机效率，碳排放量范围为 156.08 公斤 CO-eq/t FW 至-77.35 公斤 CO-eq/t FW。此外，敏感性分析还表明，替代用电来源对碳排放性能有显著影响。研究结果表明，当仔细考虑 FW 负荷和发动机电效率时，分散式微型 AD 系统可以成为一种可行的 FW 管理解决方案，用于发电和减少碳排放。
