Conversion of Biogas from Municipal Solid Waste of Kaduna State to Bio-methane

Abstract

The uncontrolled hazardous wastes from industries mixing up with municipal wastes create potential risks to human health. A major environmental concern is gas released by decomposing garbage which increases the concentration of atmospheric greenhouse gases. This study was aimed to convert biogas to bio-methane from municipal solid wastes (MSW) in Kaduna State, Nigeria. The segregates of the wastes were immersed in sodium hydroxide (NaOH) solution for 5days to reduce the lignocellulosic content and was further homogenized in a propeller mixer. Proximate composition, physical and chemical and properties were analyzed. The mean values for moisture, ash, pH, temperature, total solids, volatile solids, BOD and COD were 65.10%, 1.10%, 5.49, 230C (initial), 6560mg/L, 84.53%, 205mg/L and 540mg/L respectively. The lignocellulosic content of the waste were of 34%, 33%, 33% for hemicellulose, lignin and celluloses, and nutrient values of 32:1 for carbon-to-nitrogen ratio, 0.48% and 1.16% for total sodium and phosphorous which indicate the MSW as potential substrates for biogas production. The waste fractions were assessed for a total hydraulic retention period of 35days and ambient temperature (370C) with neutral pH (7.35 to 8.0). The maximum gas yield was between 1070 and 1402cm3 within 20-30 days retention time. There was substantial decrease in biogas yield that correlated with temperature fluctuation within 10-15 days retention time, obtaining a value from 868 to 589cm3 at 33 to 310C. The biogas produced were characterized as 68.57% CH4, 30.21% CO2, 1.31% H2S and 1.50% O2 (25-30days), which significantly increased with regards to CH4 (87.52%) and significantly decreased to CO2, H2S and O2 (9.58, 0.38 and 0.01%) respectively. Municipal solid wastes (MSW) can be utilized for biogas production thereby solving the waste disposal problem.