Effect of co-digestion of food waste and cow dung on biogas yield

Makhura Emmanuel Pax,Edison Muzenda,Tumeletso Lekgoba,D Ta-Wei Lin

doi:10.1051/e3sconf/202018101005

Makhura Emmanuel Pax, Edison Muzenda + Show 2 more

Open Access

https://doi.org/10.1051/e3sconf/202018101005

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Abstract

This paper aims at finding the effect of co-digestion of cow dung and food waste on total biogas yield. Biogas production was improved through co-digestion of cow dung and food waste (FW) containing a small fraction of inoculum under mesophilic temperature (37ºC) over a retention time of 24 days. Co-digestion ratios of 1:1, 2:1 and 3:1 for cowdung/foodwaste were used for the study on anaerobic digestion on the co digested matter. Tests were carried out starting with the preparation of substrates, substrate characterization to determine the moisture content (MC), total solids (TS), volatile solids (VS) and ultimately batch anaerobic digestion experiments under thermophilic conditions (370C). The moisture content, volatile solids and total solids for food waste were 78, 22 and 90.7% respectively while the characteristics for cow dung were 67.2, 32.8 and 96.0 % respectively. From the study, a mixing ratio of cow dung: food waste of 1:2 was found to be the optimum substrate mixture for biogas production at 25595.7 Nml. The accumulated gas volumes of 18756.6, 14042.5, 13940.8 and 13839.1 Nml were recorded for cow dung: food waste ratios of 2:1, 1:1, 1:3 and 3:1 respectively. For a co-digestion containing more of the food waste than cow dung, a higher volume of biogas is produce.

Highlights

Anaerobic digestion is a multistep chemical and biological process where organic matter is broken down in the absence of oxygen and coonverted into biogas via complex interactions of microorganisms [1]
When different feedstocks are used for anaerobic digestion, this is known as co-digestion
Food waste (FW) as well as cow dung were used in this study as substrates for anaerobic digestion

Summary

Introduction

Anaerobic digestion is a multistep chemical and biological process where organic matter (food waste, cow dung, human excreta etc) is broken down in the absence of oxygen and coonverted into biogas via complex interactions of microorganisms [1]. Many feedstocks in Botswana such as cow dung, food waste, agricultural biomass have been identified as feedstock for biogas generation. Biogas is a combustible mixture of gases produced through anaerobic digestion of organic matter. Hydrogen sulphide makes less than 2% of the gas and with other gases in small traces. Biogas offers benefits such as; used as an energy source, environmental protection etc.

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