Abstract
Food waste (FW) is a global issue due to the increasing rates of waste generation and the subsequent economic, social, and environmental consequences it presents. The household sector has been identified as a major contributor to food waste across the food supply chain. Anaerobic digestion (AD) is a promising technique that has the potential to provide a sustainable solution for diverting organic food waste from landfills while generating biofuels that can be used as an energy source. This study investigates the potential for waste-to-energy conversion of household organic waste at the University of Bahrain’s campus. The research aims to quantify and characterize household food waste (HFW) and evaluate its potential as a feedstock for anaerobic digestion.
The methodology includes a cross-sectional study design involving food waste sampling and analysis, characterization, and anaerobic digestion operation. The waste collection was done using a direct-measurement approach, collecting food waste from the household’s doorstep. Characterization of the food waste was based on the total (TS) and volatile solids (VS) analysis as well as the chemical characteristics of the food waste. Anaerobic digestion was performed in a 10 L lab-scale continuous-stirred tank reactor (CSTR) under mesophilic conditions (37 ⁰C), a mixing speed of 100 rpm, and organic loading rates (OLR) varying from 2 to 4 g VS L-1 d-1. The experiments were conducted for fruit and vegetables waste (FVW) and cooked food waste (CFW) to evaluate their digestion performance and determine the methane potential.
The research findings show that the average food waste generation rate was 3.99 ± 0.54 kg/household/week, of which 63.3% was considered avoidable food waste. Analysis of the quantities and compositions has shown a significant increase in household food waste generation rates and the avoidable food waste composition during Ramadan. The collected food waste had a high organic matter with 94.2% and 95.2% VS for FVW and CFW, which makes it suitable as a feedstock for anaerobic digestion. The methane potential was 370.9 and 380.6 mL/g VS at optimal OLRs of 3 and 4 g VS L-1 d-1 for FVW and CFW, respectively. Overall, cooked food waste had a better digestion performance than fruit and vegetable, indicated by the higher efficiency in VS and COD reduction and the process stability parameters such as pH, intermediate alkalinity to partial alkalinity ratio, and ammonium nitrogen.
The study concludes that household food waste has a high potential for anaerobic digestion and the technology can be applied in Bahrain to reduce greenhouse gas emissions, minimize waste disposal, and generate renewable energy. In addition, the research contributes to the limited literature on household food waste management and anaerobic digestion technology in Bahrain and provides the basis for future research.