High generation of fecal sludge without proper treatment is a major sanitation problem. A key step in curbing this problem is producing value-added resources such as vermicompost from fecal sludge through substrate enrichment. Substrate enrichment is a vermicomposting technique that involves augmenting vermibed substrates with organic rich materials to provide additional nutrients, as well as underlying layers needed for microcosm development to produce desirable vermicompost. The aim of this study was to investigate effects of substrate enrichment with organic soils (black soil, red laterite soil and sandy soil) combined with coconut coir as bulking material, on the fecal sludge vermicomposting process and quality of the end-product. The purpose of the study was to promote the development of highly nutritive vermicompost from fecal sludge using substrate enrichment as a low-cost innovative vermicomposting technique. The enriched substrates were prepared with 160g of coconut coir, 120g of fecal matter (65–70% dry matter) and 80g of organic soil. The treatments were labelled T1, T2 and T3 representing systems containing black soil, red laterite soil and sandy soil respectively. The control treatment (T4) contained no soil. Triplicate treatments were setup and about 20 3-week old clitellated earthworms of the species Eisenia. fetida with live weights ranging from 255 to 275mg, released into each system for vermicomposting over a period of 12 weeks. Physicochemical parameters such as pH, Organic Carbon (Corg), Total Nitrogen (Ntot), Available Phosphorus (Pavail), Exchangeable Calcium (Caexch), Iron (Fe), Lead (Pb) and Aluminium (Al) were determined for both the fecal sludge and the vermicompost. The vermicompost in the setup with black soil (T1) showed the highest Corg mineralization and Ntot, Pavail and Caexch enhancement followed by T2, T3 and T4. Treatment T1 also resulted in the lowest concentration of Fe, Pb and Al in the vermicompost. Concentrations of these heavy metals were found to be higher in the other treatments in increasing order of T2, T3 and T4. Less than 16% earthworm mortality was recorded in all treatments except T4, in which the mortality was about 38% (38.33 ± 13.74). The enriched substrates were therefore found to provide a more suitable microclimate for earthworm development and produced vermicompost with high nutrient content. However, a more comprehensive study on metal accumulation in the earthworm tissues as a potential metal contaminant is needed to establish a strong hypothesis in the safe use of earthworms for this vermicomposting technique.

The criminal act of fuel (gasoline) adulteration still remains a global worry due to its environmental, health and economic effect. Current methods for the detection of fuel adulteration have not been effective in most developing countries due to the associated cost of implementation. Therefore, there is the need for a fast, reliable and cheaper approach for screening of adulterants in fuel. This study combined FTIR analyses with Chemometric (multivariate) techniques for qualitative and quantitative determination of four possible adulterants: kerosene, diesel, naphtha and premix in gasoline. Synthetic admixtures prepared by mixing the gasoline with varying proportions of the adulterants were obtained and used for the model calibration. Soft Independent Modeling Class Analogy (SIMCA) classification and Partial Least Square (PLS) regression methods were the Chemometric techniques employed. The SIMCA classification model developed predicted the type of adulterant present at an error rate of 6.25% for Kerosene and naphtha, and 12.5% for premix. However, no prediction error was recorded for classifying samples contaminated with diesel. The PLS regression model was able to predict the concentrations of adulterant with prediction errors lower than 5% for all adulterants considered. Applying the models to commercial gasoline samples collected from a Metropolis in Ghana revealed 7% gasoline adulteration with kerosene (4%), premix (2%) or diesel (1%). No adulteration with naphtha was detected. The FTIR-Chemometric approach proved a fast and cheaper method for detection of adulteration which can be adopted by quality assurance and monitoring laboratories for forensic screening of gasoline in Ghana

The use of fermenters at large scale is usually hampered by sub-optimal conditions in terms of yield and productivity, along with the low tolerance of strains to process stresses, such as substrate and product toxicity, and other fermentation inhibitors. Attempts to improve the industrial efficacy of fermenters have been in the areas of genetic engineering to improve strain tolerance, but this usually involves detailed and unfeasible mechanistic studies. Statistical designs of experiments have also been used to optimize industrial fermenters but this again often results in local optima due to the relatively small-dimensional space covered by the experiments. Mathematical techniques have recorded great successes and regarding ethanol fermentation with sorghum extracts, previous work has modeled and established the presence of product inhibition, however, did not consider other degrees of freedom (temperature and pH) that minimize the effect of such inhibitions. This paper includes the description of a batch alcohol fermentation process that has been optimized using a technique based on the application of mathematical modeling and optimal control. Calculus of variation is introduced as a valuable tool to derive and solve the necessary conditions for optimality, and the obtained results show the optimal temperature and pH profiles for the fermentation of sorghum extracts. A Simulink model of the fermentation process shows that using the proposed control strategy increases ethanol yield by 14.18%, cell growth by 71.96% decreases the residual substrate by 84.77%.

Unlike high-rate anaerobic digesters that employ some mechanism to retain microbial sludge mass, low-rate systems use sufficiently long hydraulic retention times to ensure process stability, which becomes economically unattractive for treating large quantities of waste. This study presents the use of attainable region to develop a new strategy to enhance the stability of low-rate digesters. By considering three digestion cases, diary manure only (batch 1) or diary manure with granular (batch 2) or lagoon (batch) sludge as innoculum, the following findings were obtained. (1) For a given concentration of volatile acids in an anaerobic digester, higher concentrations of methanogenic archae can be attained using a digester structure (combination of different digesters) as opposed to single digester. (2) For a given digested substrate, a change in the source of inoculum results in a change in the limits of achievability by the system (attainable limits for batches 1, 2 and 3 were 46.486(g/L)², 5.562(g/L)² and 0.551(g/L)², which resulted in performance improvements of 118.604%,175.627% and 200.436% respectively), and hence optimal digester structure. The evidence from this study suggests that the technique can be used to simultaneously improve process stability, define performance targets and propose digester structures required to achieve a given target.

The study presents the economic feasibility assessment of converting the produced biogas from water hyacinth biomass into electricity. Approximately, 0.3793 m³CH₄/kgVS was generated from the water hyacinth biomass. The research indicated that the available water hyacinth population on the Lower Volta River in the year 2020 could potentially generate a methane yield of 53.676 × 10⁶m³. The volume of methane gas generated had the potential to produce an annual electricity output of 110.792 × 10⁶ kWh, which could be integrated into the national grid. The economic analysis indicated positive results with an initial total investment cost of $67,273,700. The project showed a positive net present value (NPV) of $8,923,769 and a levelized cost of 0.172 $/kWh. The simple payback and equity payback periods were determined to be 5.5 and 11.3 years, respectively. Furthermore, a sensitivity analysis conducted showed that the project’s NPV remained positive when variations in input parameters such as initial cost, operations, and maintenance cost were less than 15% sensitive range. However, a 30% reduction in the feed-in tariff cost resulted in a negative NPV. In conclusion, biogas production from water hyacinth biomass in Ghana can make a significant contribution to the country’s energy mix and help alleviate the energy shortfall in rural areas.

Recently ethanol production involved the processing and fermentation of sorghum and maize extracts. Sorghum and maize are cheaper, locally available and a substitute to imported barley malt. Large scale ethanol fermentation systems are usually hampered by instability, in the form of oscillations resulting from ethanol inhibition and the lag response of yeast cells to this inhibition. There is limited information regarding the mathematical nature of such inhibitions in the fermentation of sorghum and maize extracts. In the present work, mathematical models are developed to determine the nature of ethanol inhibition during the fermentation of sorghum and maize extracts. The models were sets of coupled ordinary differential equations based on a Monod type cell growth kinetic model that accounts for product inhibition. The Inhibition patterns considered were; Linear, Sudden Growth Stop and Exponential. The results obtained showed that there is product inhibition during ethanol fermentation using sorghum extracts, with inhibition patterns being Linear and Exponential. However, the results obtained from ethanol fermentation of maize extract also showed that there is product inhibition during ethanol fermentation using maize extracts, with inhibition patterns being Linear and Sudden Growth Stop. The obtained models described with high accuracy, 99% Confidence Interval the dynamics of substrate utilization, product formation and cell growth. These inhibitions which affect the high ethanol yields can be minimized by setting up an optimal control problem using the developed models and solved to determine the control variables that minimize the effect of such inhibitions during the fermentation of sorghum and maize extracts.