HOUSEHOLD SOLID WASTE GENERATION RATE AND CHARACTERIZATION OF ITS PHYSICO-CHEMICAL COMPOSITION IN HARAMAYA TOWN, EASTERN HARARGHE ZONE, ETHIOPIA

Abstract

Knowledge of quantity and composition of urban solid waste is required and considered as a basis for designing and operating appropriate solid waste management systems. Cognizant of this, a study was initiated to characterize the household solid waste generation rate and its physico-chemical composition based on a field survey and waste measurement in Haramaya town, Eastern Hararghe Zone, Ethiopia. For this study households were stratified into three groups based on level of their income: high, medium and low income. From each stratum, the households were randomly selected. A total of 136 households were incorporated for data collection and analysis. Solid wastes were weighed daily for one week and analyzed for the component composition and physicochemical properties over five days. Compostable organic components of wastes were analyzed for their physico-chemical compositions such as moisture content (MC), ash content (AC), pH, electrical conductivity (EC), total organic matter (TOM), total organic carbon (TOC), total NPK and carbon to nitrogen ratio (C:N) where as all waste types were analyzed for their bulk density (BD). The results of this study revealed that the average generation rate of solid waste in the town estimated to 0.274 kg/person/day and 1.50kg/HH/day. The average amount of wastes generated daily from households and the annual total from the town were about 10.55 and 3375.84 tons, respectively. The wastes from the residential sources were sorted and categorized into 12 various sub-types. The largest proportion of waste types was the yard waste which represents 31.68% followed by food waste which accounts 23.19%. In terms of waste biodegradability, biodegradable organic waste components (62.27%) had the largest proportion of waste stream, where as the remaining were the non-biodegradable inorganic waste and “others” waste categories which comprised of 31.5% and 6.38%, respectively. Results revealed that the mean values of MC, BD, pH, EC, TOM and C/N ratio of the waste composition were 59.43%, 377.44kg/m3, 6.74, 6.02 mS/cm, 63.95% and 29.62:1 respectively which indicates that the wastes are suitable for composting and biogas energy recovery. But, the wastes had high ash (36.05%) and potassium (0.58%) content; and low phosphorous (0.43%). The statistical analysis of the related socioeconomic parameters indicated that the household’s monthly income and family size were the main influential factors significantly affecting the amount of household waste generation of the study area. Finally, it is concluded that the RSW generations of Haramaya town is increasing in line with growth in socio-economic parameters, which is significantly affected by household family size and monthly income. The waste generated in the town is mainly biodegradable organic consisting of mostly yard and food waste materials. As a result, the more compostable organic content of the waste materials with optimum ranges of physico-chemical composition indicates an opportunity to give priority to the recovery of the waste materials through composting and biogas energy production, required for the appropriate waste management technology option in the town to reduce the current and future trends of waste generation while benefiting the local households