Locust beam pod solution (LBPS) was prepared by extraction from the outer leathery cover of the pod soaked in water for twenty four hours in ten different concentrations of known weight of dried locust bean pod cover in 20 litres of clean water. Using ten levels of these concentrations, five sandcrete blocks of size 150mm cube were produced for each concentration, making a total of fifty blocks and the compressive strengths at 28 days were determined. Using a concentration of 50g/l, twenty blocks were produced with 0, 5, 10, 15, 20, 25, 30, 35 and 40% respectively by weight of cement reduced making a total of 180 blocks. They were subjected to compressive strength test on 7, 14, 21 and 28 days respectively, crushing five blocks in each day to determine their average compressive strength. In order to investigate the effect of duration of soaking the locust bean pod cover in water on the compressive strength of the sandcrete blocks, five blocks were produced using the same concentration of 50g/l but soaked in water for 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 days respectively and their compressive strengths were determined at 28 days. It was found that the higher the concentration of the LBPS, the more the compressive strength and soaking the locust bean pod cover for more than 24 hours is not necessary as the compressive strength tends to decrease. In conclusion, up to 25% by weight of cement can be saved by using locust bean pod solution in moulding the sandcrete blocks.

A response surface methodology (RSM) was utilized in this study for optimisation of biogas production process. The optimal values of process parameter capable of giving a high yield of biogas were established. A biodigester of 20 liters capacity capable of producing biogas from rural household domestic waste was designed, constructed and used in the study. Its major units are the anaerobic and gas collecting units. The process parameters investigated are the pH of the substrate, detention time and ratio of substrate to water while the yield of biogas was used as performance characteristics. The experiment was based on a central composite rotatable design (CCRD). The results revealed that the highest yield of biogas was obtained from a combination of detention time of 30 days, ratio of substrate to water of 1:1 and pH of 7, while the least yield of biogas of 11 cm3 was obtained from combination of detention time of 30 days, ratio of substrate to water of 1:3 and pH of 2. Numerical optimization carried out with the goal of maximizing the biogas yield revealed optimum values of detention time of 40 days, the ratio of substrate and water used; 1:2 and pH of 6.71 for biogas of 771.77 cm3 with the desirability of 0.9850. The detention time had the highest significant effects on the yield of biogas. The results of this study provided standard input process variables capable of yielding the optimum yield of biogas for the rural community.

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This study focused on the isolation of microorganisms associated with biodegradation of domestic wastes in three rural communities (Gbadagbadzu (A), Ndawangwa (B), and Kuchiworo (C)) in Lavun Local Government Area of Niger State, Nigeria, for biogas production. The biogas was produced by anaerobic microbial degradation of different biodegradable household domestic waste aided by fresh rumen of cow. The anaerobic microbial degradation was carried out in a temperature range of 250C to 320C for a detention time of 39 days for rural biogas production. The results showed the presence of the following bacteria: Bacillus cereus, Sphingobacterium yamdrokense, Clostridium perfringens, Salmonella typhi, Alkaligenes faecalis, Pseudomonas aeruginosa, Staphylococcus epidermidis, Klebsiella pneumoniae and Bacillus licheniformis while fungi isolated were Muccor pusillus and Aspergillus flavus. The research therefore shows that household domestic wastes have the potential to produce biogas with or without the addition of inoculum.