Evaluating fecal sludge supplemented with other biomass for use as fuel briquettes

Abstract

In Uganda much of fecal sludge is under-utilized and poorly disposed in many slum areas for example Bwaise. Market wastes such as empty bean pods and pineapple peelings are usually or never utilized. They are mainly disposed off as cabbage in many market centers and around home steads. The study explored the potential and possibility of improving utilization of fecal sludge, pineapple peelings, charcoal dust and empty bean pods. This was by producing biomass briquettes made of fecal sludge and supplementing them with pineapple peelings, empty bean pods and charcoal dust. A mixing ratio of 1:2 (binder: biomass) was used when making all the four batches of briquettes with red soil as a binder. These included; fecal sludge (FS) + red soil (RS), fecal sludge + pineapple peelings (PP) + red soil, fecal + charcoal dust (CD) + red soil, fecal sludge + empty bean pods (BP) + red soil. The four batches of briquette (FS+RS, FS+PP+RS, FS+CD+ RS, FS+BP+RS) were tested for different fuel properties. Physical, thermal chemical and combustion characteristics of the briquette batches that were determined. These included moisture content (%), density (g/cm3), compressive strength (N/mm2), maximum force (N), ash content (%), volatile matter (%), calorific value (kcal/g), ignition time (min), burning rate (min) and thermal efficiency (%). Data was analyzed using MicroSoft Excel software. The results were compared using one-way analysis of variance (ANOVA-single factor) to determine if there was a significant difference among the different briquette parameters. Briquettes made of FS+PP+RS had the highest calorific value (1.24Kcal/g). Briquettes made of FS +RS had the lowest calorific value (0.49Kcal/g). Density was highest in briquettes made of FS+RS (1.122g/cm3) and lowest in briquettes made of FS+BP+RS (0.847g/cm3). Compressive strength was highest in briquettes made of FS+BP+RS (48.01N/mm2) and was lowest in briquettes made of FS+PP+RS (31.269N/mm2). Briquettes made of FS+PP+RS had the highest moisture content with average of 4.2%. Volatile matter was highest in briquettes made of FS+PP+RS (38.99%) and was lowest in briquettes of FS+RS (25.72%). Highest burning rate of was recorded in briquettes of FS+CD+RS (8g/min) and was recorded lowest in briquettes of FS+PP+RS (4g/min). It was noted that FS+PP+RS briquettes had better chemical properties (volatile matter, ash content, calorific value) compared to other types of briquette while FS+CD+RS briquettes had better physical properties ( compressive strength, moisture content, density) compared to the other briquettes types. Further studies should be done to determine the emission rates of briquettes made of fecal sludge supplemented with other biomass.