Municipal Solid Waste Management in a Low Income Economy Through Biogas and Bioethanol Production

The biodegradable fraction of municipal solid wastes generated from households in Ghana has favourable characteristics worth considering for bioenergy production. The suitability of this biodegradable portion for biogas and bioethanol production was assessed in this study. The assessment was performed on both untreated and hydrothermally treated unsorted and sorted fractions of the waste using standard methods for biomass conversion to bioenergy.

Compositional analysis of the waste indicated that unsorted biodegradable municipal solid wastes (BMSW) consisted of 38.7 % dry matter (DM) glucan, 8.3 % DM hemicellulose, 10.1 % DM lignin and 7.6 % DM ash. The sorted fractions with the highest glucan but least lignin and hemicellulose were the pool of cassava, yam and plantain peeling wastes (CYPPW) with 84 % DM glucan much of which was starch, 5.6 % DM lignin and 0.5 % DM hemicellulose.

The highest ethanol yield of 0.29 l/kg DM was measured from this same CYPPW while fruit wastes (FW) had the highest biomethane potential of 408 ml CH4/g VS. The BMSW had ethanol yield of 0.17 l/kg DM and biogas 369 ml CH4/g VS. The hydrothermally pretreated wastes had marginal increases in glucose and ethanol yield except the treated yard waste which significantly increased by 54 % in glucose over the untreated waste.

The most promising waste fractions were FW, CYPPW and mixed paper wastes. Careful selection of these fractions in feedstock for biofuel production would reduce generation of the waste, improve the quality and effectively lead to higher yield of biofuel over the unsorted form.