INTEGRATED HEAT ENERGY AND NUTRIENTS RECOVERY IN SUGARCANE WASTES

Abstract

Sugarcane processing industry produces bagasse, molasses and press mud as wastes. Both bagasse and press mud have high energy content while press mud is rich in nutrients phosphates, calcium and nitrates. However, when bagasse is abandoned in heaps and left to decompose, it creates negative environmental conditions and often leads to fires owing to formation of alcohol after fermenting. Attempts have been made to make bagasse briquettes using clay (usually from swamps) as a binder. Clay has low heat energy value and its excavation in turn leads to land degradation. Sugar mill wastes comprise of bagasse, press mud and molasses, and usually the latter is used economically. This study endeavored to find ways of enhancing heat energy and nutrients recovery from bagasse and press mud by incorporating press mud and molasses as binders in the making of bagasse briquettes. Optimum bagasse, press mud and molasses formulation ratios for maximum heat energy recovery were determined. From the trial experiments, the formulation with 52.6% bagasse, 26.3% press mud and 21.05% molasses was found to be the best formulation with 3.75 kCal/g. After complete combustion of the briquettes, the ashes of the briquettes were acid digested and nutrient content determined. Nutrient levels in the resultant ash from the briquettes formulation of 40% bagasse, 20% press mud and 40% molasses were highest with 15.97% Nitrogen, 23.66% Phosphorous, 3.19% Potassium, 1.68% Sodium, 0.28% Calcium, 0.25% Magnesium, 1.38 % Manganese and 0.1% Iron respectively. Calorific value and presence of nutrients in the briquettes, is a possible indicator of the viability of adoption of this form of waste management of integrated heat energy and nutrient recovery. When adopted, it can makes a positive contribution to environmental conservation, energy access and food security.