Assessing the Fuel Potential of Fecal Sludge and Coal Through Co-combustion: Fid-Bau Portal

Assessing the Fuel Potential of Fecal Sludge and Coal Through Co-combustion

Saha, R. P. / Raaz, T. S. / Badruzzaman, A. B. M.

On-site sanitation facilities meet the sanitation needs of a major portion of the population of Bangladesh. However, the generated fecal sludge (FS) is not properly handled and is instead discharged in low-lying areas, posing a significant risk to human health and the environment. There are many examples from the United States, Europe, Japan, and China, where industries use sewage sludge as fuel. This strategy of generating energy from sludge through thermal combustion, if applied in Bangladesh, could be a sustainable solution that provides two simultaneous benefits of energy generation and sludge management. This study aims to evaluate the possibility of recovering energy from fecal sludge for use in energy generation through co-combustion with coal. Hence, for this study, the fecal sludge sample was collected from WSUP (Water and Sanitation for the Urban Poor)’s sludge collection chamber (located in Dhaka) and tested in the laboratory. The samples were subjected to proximate and ultimate analysis, in order to determine the properties of the FS. To determine the effect of sludge addition on calorific value, the sludge samples were mixed with different percent (by weight) of coal and combusted in bomb calorimeter. From the experiment, the gross energy content of the dried sludge sample was found to be 5.9 MJ/kg which had a moisture content in the range of 67–70% as determined through proximate analysis. After deducting the amount of heat required to evaporate the moisture from the sample, the net energy content of the dried FS sample was estimated to be 4.13 MJ/kg. For a sample containing sludge-coal mix in the ratio 1:1 (by weight), the gross and net energy contents were found to be 17.2 and 15.4 MJ/kg respectively, which exhibits acceptable capacity for extraction of energy. Although there are scopes of energy generation through co-combustion of fecal sludge with other fuels, the commercial viability of this study depends on identifying sustainable and cost-effective methods of dewatering and energy recovery technologies.