Characterization of Different Livestock Dropping Mixtures to Assess their Potential for Biogas Production Godfrey M. N. Ngunjiri Department of Agricultural Engineering, Egerton University, Kenya Peter M. Ndungu Department of Industrial & Energy Engineering, Egerton University, Kenya Daudi M. Nyaanga Department of Agricultural Engineering, Egerton University, Kenya Raphael M. Wambua Department of Agricultural Engineering, Egerton University, Kenya Abstract-This research was conducted at Egerton University, Njoro, Kenya. The main objective of the research was to characterize different livestock droppings mixtures at various ratios to establish their potential for biogas production. Substrate parameters which were total and volatile solids, pH, temperature and density were determined using standard procedures. The mean influent percent total solids (TS) for the ratios (9:1, 7:3, 1:1, 3:7 and 1:9) of Cowdung to Chicken droppings (CC) and cow dung to Sheep droppings (CS) were respectively 9.70% and 10.52%. That of cowdung alone (CA) was 9.52%. The corresponding total solids for CC and CS effluents were 7.71% and 8.55%; while that of CA was 9.09%. These values were within what is established to be appropriate for biogas production. The highest and lowest daily ambient temperatures during the research period were 24.7oC and 20.6oC, respectively. This was within the mesophilic region for biogas production. The pH for all influent and effluent substrate mixtures and ratios averaged 6.94 and 7.44 respectively. These values were within the levels which are appropriate for the growth of methane generating micro-organisms. The respective densities for influent and effluent averaged 1.05g cm-3 and 0.97g cm-3. The reduction in density from influent to effluent could be attributed to decrease in total solids due to bacteria activity and biogas production. This provides a preliminary indication of bio-degradability of the substrates and their potential to produce Methane. Key words; Substrate, total and volatile solids, anaerobic digestion, Livestock droppings 1. INTRODUCTION Potential of biogas plants as a source of both energy and fertilizer has been recognized by several authors [9], [6], [16], [7], [17]. Unfortunately these benefits have not been fully exploited in Kenya because of a number of constraints. Studies by [13] on technological constraints to adoption and sustainability of biogas technology reported that, the adoption rate in Nakuru County was 150 out of 9,446 (1.6%). She also found that plant design was significant in the sustainability of the technology. Another study by [19] noted that, properties of substrates and environmental parameters such as pH and temperature also play a pivotal role in biogas production and must be determined and optimized. According to [8], anaerobic digestion is widely accepted as a sound technology for waste treatment applications. Municipal waste water treatment plants play a significant role in treatment of anaerobically digestible sludge than land disposal strategies [4]. Bio-digesters can be fed with animal and human waste. Biogas plants help to reduce the population of insects like flies and mosquitoes [2], resulting in a healthier environment. The most convincing evidence that biogas production from feedstocks was feasible came from Chinese experience. Chinese family size digester have had as their major carbon source; grass, leaves and crop residues and as their major nitrogen source, human and animal wastes [5]. The C/N ratio under these conditions varies between 1:15 and 1:20; and in most cases the mode of charge of household units is intermediate between batch and semi-continuous [5]. A study by [11] suggested that, if fibrous residues were used, then the bacteria population needed time to adjust before they are able to degrade the fibre component efficiently; and [14] found that the quantity and quality of International Journal of Innovations in Engineering and Technology (IJIET) Volume 4 Issue 3 October 2014 44 ISSN: 2319 – 1058