Anaerobic Co-Digestion of Food Waste with Livestock Manure at Ambient Temperature: A Biogas Based Circular Economy and Sustainable Development Goals

Abstract

A shift from a linear economy to a circular economy of resource consumption is vital for diverting the value from lost resources to resource-efficient products towards developing a sustainable system. Household digesters provide one opportunity to create a biogas-based circular economy. Because household digesters are typically fed a wide and variable range of substrates, it is important to determine the ideal mixing ratios for them. In this study, an anaerobic digester startup process was analyzed and an assessment of anaerobic co-digestion of food waste with different livestock manures was carried out at ambient temperatures. Food waste (FW), cow manure (CM), poultry litter (PL) and goat manure (GM) were co-digested at mixing ratios (FW:PL:CM) of 2:1:1, 2:2:1, 1:1:2, 1:1:1 (wt/wt) and FW:PL:GM at mixing ratios of 2:1:1 and 1:1:2, at an organic loading rate of 1 g volatile solid (VS)/L/day, and 8% total solids. A maximum methane yield was obtained from co-digestion of FW:PL:GM at a mixing ratio of 2:1:1 in autumn-to-winter conditions, 21–10 °C, while the mixing ratio of FW:PL:CM at 2:2:1, showed negligible methane production under the same temperature condition. This study suggests that co-digestion of food waste and poultry litter with goat manure yields more biogas than other substrate combinations. Therefore, selecting suitable co-substrates with an optimized mixing ratio can promote several key indicators of a biogas-based circular economy towards achieving sustainable development goals 2, 3, 5, 6, 7, 9, 13 and 15.

Characterizing Chemistry and Microbiomes During Continuous Anaerobic Codigestion of Organics and Cattle Manure Digestate

“…The BMPs of IO and CMD at C:N 15, 25, and 35 were 0.23 ± 0.01, 0.31 ± 0.009, and 0.38 ± 0.009 L gVS –1 , respectively (Figure B, C:N 15 not shown). These data align with previous research demonstrating the BMPs of various combinations of food waste and cattle manure to be between 0.3 and 0.6 L gVS –1 . − The BMP results demonstrated that digestate from the current Amana digester could potentially be used to supplement external industrial organic waste digestion, and C:N 35 yielded the most methane of the combinations tested.…”

Treatment of Agricultural Waste Using a Combination of Anaerobic, Aerobic, and Adsorption Processes

“…The normalized biogas and methane production rate can be expressed in relation to the quantity of the volatile solids in the influent of the reactor, which are 651.0 ± 91.1 mL g −1 VS added and 433.8 ± 58.2 mL g −1 VS added , respectively. Similar results have been reported for the specific methane rate in other studies for mixtures containing food waste [24][25][26]. For example, food waste with pig manure resulted in a methane generation of 388 mL g −1 VS added , food and garden waste in 490 mL g −1 VS added , and food waste, goat manure, and cow manure in 264 mL g −1 VS added , respectively.…”

Microbial Community Structures in Family Anaerobic Digesters Reveal Potentially Differing Waste Conversion Pathways

“…For rural regions, the BSP-Nepal program established over 430,000 domestic digesters as of 2019 (Lohani et al, 2021a). They aim to provide economic benefits for rural families due to reduced expenditure on cooking and lighting fuels, as well as environmental benefits such as improved soil fertility by use of bio-slurry, improved local air quality due to cooking with biogas rather than dung or firewood, lower greenhouse gas emissions, and a reduction in deforestation (Dhungana et al, 2022). The motivations mirror the goals in many under-served locations.…”