Comparative Study of Effluent from Anaerobic Digesters for Human and Fruit Waste

Thumbnail Image
Journal Title
Journal ISSN
Volume Title
The study examined comparatively the levels of macronutrients, pollution monitoring parameters, metals and pathogenic indicator organisms from effluent of two anaerobic digesters for human waste and fruit waste with respect to the influent. Both digesters were operated within mesophilic conditions at very short hydraulic retention time. Laboratory analysis of these parameters (macronutrients, pollution monitoring indicators and pathogenic indicator organisms) was therefore important to ensure that utilisation of the effluent was environmentally friendly and acceptable to farmers, the food industry, consumers, the environmental protection agency and the World Health Organisation (WHO). Results of this study found that, pH and macronutrients (NH4-N, P2O5 and K2O) were higher in the effluent than in the influent for both human and fruit waste. For instance, ammonium-N was about 25.1% higher in the effluent with respect to the influent for human waste and 19.1% higher in the effluent of fruit waste. Total Solids (TS), Volatile Solids (VS), BOD and COD were lower in the effluent than in the influent for both wastes (human and fruit wastes). Reduction of 51.6% Total Coliforms (TC), 53.4% Faecal Coliform (FC) and 58.9% E. coli were found in the digested effluent of fruit waste. 62.8% TC, 64.4% FC and 60.6% E.coli were found in the digested effluent of the human excreta. Heavy metals in the respective effluents were within tolerable limits that are acceptable to the Ghana Environmental Protection Agency (GEPA). The results of this study therefore join other studies to show that the process of anaerobic digestion causes reduction in pollution indicators, destruction of pathogenic organisms and increases the availability of macronutrients. Keywords: Anaerobic digestion, Influent, Effluent, Macronutrients, Metals, Pathogens, Pollution indicators.
A thesis submitted to the Department of Agricultural Engineering,Kwame Nkrumah University of Science and Technology in partial fulfilment of the requirements for the degree of Master of Science in Agro- Environmental Engineering, 2011