The rate at which feedstock is added to the anaerobic digester (AD) reactor has to be adjusted for the growth rate of methanogens bacteria. Increase in biogas yield is as a result of improved mathanogens forming bacteria. Under loading and over loading of feedstock in the AD reactor has effect on methanogens forming bacteria. If more feedstock is added than the bacteria are able to degrade, the process will become acidic. Feedstock has to been fed to the reactor at a uniform rate and volume. If feeding pattern has to change, this must be done gradually so that bacteria can adapt to the new conditions. For optimum biogas yield, required amount of feedstock must be added to the AD reactor. The aim of this research work is to determine the effect of organic loading rate (OLR) on biogas yield from food waste, water hyacinth, cow dung, waste water from abattoir, poultry dropping and pig dung. The experimental set up comprises of single stage and three-stage continuous AD reactors. The same quantity and composition of feedstock were used and this was subjected to a variation of OLR 0.5 kg/m3(1.5 kg/m3, 2 kg/m3, 2.5 kg/m3, and 3 kg/m3). The experiment was conducted within a mesophilic temperature range of 36°C-37°C, percentage total solid (%TS) of 9.98% and percentage volatile solid (%VS) of 78%. pH meter was used to monitored the daily pH reading of the slurry. It was observed that the quantity of biogas yield from the feedstock increases with increasing organic load rate to the optimum value of 1.5 kg/m3and started decreasing above the optimum value for a single stage AD reactor but this was not the case for the three-stages continuous AD reactors that experienced continuous increase in biogas yield with a successive increase in OLR from 1-5 kg/m3-3.0 kg/m3.
A novel cassava peeling machine that operates on the principle of the lathe was designed, fabricated and tested. The unique peeling principle uses a self-loading, self-adjusting single point cutting tool that can follow the contour of the cut cassava tuber sections or sized lots. The single point cutting tool allows the peeler to peel both freshly harvested cassava tubers and cassava tubers that are up to four days old effectively and efficiently. Test results show a peeling efficiency of over 70% for all categories of tubers and a minimal loss of flesh.
In this study, the principles underlying the energy involved during cracking in a vertical centrifugal nut cracker was analyzed. This will help to elucidate the relationship between various parameters that are relevant to the design and operation of the centrifugal nut cracker for the Tenera and Dura varieties. Experimental analysis was then carried out for each of the two varieties. Each variety was classified into size ranges based on their geometric mean diameter (GMD). Technical analysis revealed that the revolution per minute required by the rotor disc of a centrifugal nut for effective nut cracking is influenced by rotor disc radius (r) and nut dimensions (d1, d2, d3).The modeled equation developed could be used for predicting nut translational kinetic energy required to crack dried nut of the Dura and Tenera varieties to release high percentage of whole kernel.
In Nigeria Arable land covers approximately 745,000km2 of the total land area and at present organic farming is not prevalent, encouraged or facilitated despite its sustainability advantages. The anaerobic digestion process produces two main outputs (biogas and digestate). The digestate when properly harnessed can be used as a substitute for inorganic fertilizer. The digestate retains a high content of organic matter such as Nitrogen, Phosphorous and Potassium (K), as well as a range of other macro-and micronutrients like Calcium, Magnesium, Iron, Manganese, Zinc and ammonium. In this research work, a developed grass shredding machine for the composting of a digestate was evaluated for performance. Preliminary studies were undertaken to determine the liquid absorbability of non-shredded grass vise-visa dry shredded grass, the moisture content of fresh elephant and spear grass. An internal combustion powered shredding machine was developed to shred dry and sieve crushed grasses to be used as absorbent of digestate. The machine was evaluated for performance using different samples of properly dried elephant and spear grass. The shredded grasses samples were mixed with discharge digestate collected from a bio-digester to produce organic fertilizer. The shredding time, machine throughout capacity efficiency, mass of fibre and liquor were determined. The results of performance evaluation with elephant grass sample revealed that an average value of efficiency (90.97%), machine through put capacity (1.225g/sec), shredding time (126.54seconds), percentage loss (8.393%), fibre (288.58g) and liquor (119.83g) were established. Similar result were obtained with spear grass; efficiency (90.50%), machine through-put capacity (1.225g/sec), shredding time 126.54 seconds), percentage loss (8.32%), fibre (294.12g), and liquor (118.85g). The outcome of the results revealed that both solid fertilizer (fibre) and liquid fertilizer (liquor) were extracted from the digestate, and an average mass of 138.86g dried grass can absorb 269.55g of liquid digestate to produce organic fertilizer.
Breaking of cocoa pods in order to release the beans presently constitutes a difficult task for Nigerian cocoa farmers. The traditional method of using wood and machete to break the pods is not only laborious and time consuming but also uneconomical. An electrically operated cocoa pod breaking machine has been designed, fabricated and tested. The machine which utilizes roller mechanisms was fabricated using locally sourced materials. Cocoa pods were categorized as big, medium and small based on their mid diameter sizes. The mid diameter size of the small category was most useful in determining the size of the breaking chamber. Pod breaking efficiency of over 95% was achieved during testing. Bean damage, a common feature of traditional methods and existing hand operated cocoa pod breaking machines was reduced to negligible proportions.
An experimental organic waste to biogas conversion mini-plant that works by anaerobic digestion has been designed, fabricated and tested. The demonstration involved the use of primarily, a biodigester and few other components. The organic waste was made into slurry and digested anaerobically for 14 days at an ambient temperature range of 28 to 32°C. The flame of biogas generated burnt with smokeless blue flame, indicating the presence of a colourless odourless gas called methane. The biodigester achieved a conversion efficiency of 64 percent. This equipment can be used to meet a good percentage of the fuel needs in Nigeria.
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