Wood fuels are a major source of energy in the developing world whose sustainability is diminishing in forest cover and production increases in demand due to rising population. Alternative environmentally friendly accessible sources of energy for households are therefore a necessity. These include faecal matter, forest and agricultural residues that are convertible into briquettes. There source will depend on availability, impact on environment, renewability and energy content. The benefit of briquettes arises from near equal mass balance of carbon dioxide demand by photosynthesis in the atmosphere to the amount released during combustion. Briquetting thus need designed agglomeration machines and understanding of the engineering properties. The parameters density and shape have effect on combustion and performance characteristics hence should be determined. The research thus focused on spherical, triangular and cylindrical shapes and densities of 600 kg/m 3 , 700 kg/m 3 and 800 kg/m 3 on ignition and burning time. Carbonization of faecal matter and sawdust with binders was the activities. There was significant difference on ignition time on shapes and densities and none on burning times with shapes and binders. The average ignition time ranged from 2.7 to 3.7minutes irrespective of shapes and binders. The average burning time ranged from 18 to 26 minutes for molasses and starch bonded cylindrical briquettes. The spherical briquettes had the least ignition time of 2.7 minutes. Packing ratio, evenly distributed air spaces, higher volatile matter in binder, porosity due density advantaged the spherical briquettes.

Energy availability at domestic level is a challenge across the world and especially in Africa. Firewood is the major source of energy for cooking for households in Kenya and there is need for a friendly sustainable environmental fuel. Carbonized biomass materials (briquettes) are considered a substitute. This study thus evaluated effect of selected briquetting techniques on briquettes' performance properties. Milled charcoal dusts mixed in a ratio of 1:1:1 (Rice husk, maize cob, and sugarcane bagasse) with molasses binder in the ratio of 6:1 was hence ready for densification and agglomeration. The Water Boiling Test was used in determination of the briquette's performance characteristics for various parameters. High (screw press); and low (drum agglomerator and hand making) pressure briquetting techniques were distinctly different in ignition time (minutes), time to boil (minutes) burning rate (g/min), specific fuel consumption (g/ml) and power output (kW) values as (4, 3, 3; 14, 12, 11: 0.8, 1.1, 1.3; 0.11, 0.13, 0.15; and 1.8, 1.4, 0.75). Diversified briquetting techniques, number and type of feedstocks are thus factors that influence performance characteristics of briquettes in converting the agricultural and or other wastes for useful energy application. This knowledge should enable users to make choices on techniques for optimum efficiency towards realization of Sustainable Development Goal Number #7 on affordable and clean energy.

Biogas production can be greatly affected by inoculum addition and total solids. The effect of substrate to inoculum ratios and total solids of chicken, goat and cow manure on biogas production was studied using a 0.15m3 laboratory scale batch digester at a constant temperature of 35°C. Feed stocks were mechanically minced to 3 mm effective particle sizes prior to co-digesting with untreated cow manure from a free-range dairy rearing system. Different amounts of cow substrate inoculum were used at ratios of 2:1, 3:1, 4:1, 5:1 and 6:1, while total solid levels between (7.5% and 10.5%) at intervals of 0.5% were used to study their effects on biogas production. Increasing inoculums and total solids resulted in increased biogas production with peaks at a substrate to inoculum ratio of 4:1 (20% inoculum addition) and 9% total solids. Biogas production rates of 0.61 and 0.63m3/m3d were realized respectively. Keywords: Biogas Production, Chicken-Goat-Cow Manure, Substrate to Inoculum Ratios, Total Solids

Biogas production can be greatly affected by inoculum addition and total solids. The effect of the substrate to inoculum ratios and total solids of chicken, goat and cow manure on biogas production was studied using a 0.15m3 laboratory-scale batch digester at a constant temperature of 35°C. Feedstocks were mechanically minced to 3 mm effective particle sizes prior to co-digesting with untreated cow manure from a free-range dairy rearing system. Different amounts of cow substrate inoculum were used at ratios of 2:1, 3:1, 4:1, 5:1 and 6:1, while total solid levels between (7.5% and 10.5%) at intervals of 0.5% were used to study their effects on biogas production. Increasing inoculums and total solids resulted in increased biogas production with peaks at a substrate to inoculum ratio of 4:1 (20% inoculum addition) and 9% total solids. Biogas production rates of 0.61 and 0.63m3/m3d were realized respectively. Keywords: Biogas Production, Chicken-Goat-Cow Manure, Substrate to Inoculum Ratios, Total Solids

The effect of hydro, mechanical and thermal pretreatment of chicken and goat manure on biogas production was done using a 0.15m3 laboratory scale batch digester. The feedstocks were subjected to 6, 12 and 18 hours of soaking, 2 mm, 3 mm and 4 mm of mechanical mincing, and 60˚C, 80˚C and 100˚C of heating. Pretreated feed stocks were co-digested with untreated cow manure from an extensive dairy rearing system. Experiments were done at 8 % substrate total solids and a constant temperature of 35°C. Averagely, mechanical pretreatment resulted in the highest increase in mean biogas production rate with 11.11%, over the co-digestion control (0.54 m3/m3d), followed by thermal and hydro by 5.56% and1.85%. Maximal increase in production for each pretreatment was at 6 hour soaking time (9.30%), 3 mm effective feed stock particle sizes (18.52%) and 80˚C of heating (14.81%). Co-digestion increased mean biogas production rate over mono-digestion by 68.97% (chicken), 81.84% (goat) and 8.8% (cow manure). Superior outer cell wall and cover disruption of feed stocks for easy hydrolysis advantaged mechanical pretreatment.