Application of activated carbon impregnated composite ceramic filters in cassava mill effluent treatment: prospects and limitations

Disposal of poorly managed cassava mill effluent often results in serious environmental degradation. A low-cost treatment option was developed to alleviate this rising concern prevalent among third world processors. Frustum-shaped ceramic filters produced by mixing different proportions of sawdust and activated carbon with equal amounts of clay, kaolin and sherds powder and sintered at 850°C was assessed in this study. The results indicated pollutant removal efficiency ranging from 6.5 to 98.1% with the best removal efficiency obtained for chemical oxygen demand (COD) [97.9 - 98.1%] closely followed by biochemical oxygen demand (BOD) [71.24 - 77.14%] while (24.13 - 30.72%) and (6.5 - 71.7%) were obtained for turbidity and hydrogen cyanide respectively. The filter with 12.8% of sawdust, 5.1% of activated carbon, 7.13% of kaolin, 3.6% of sherds powder and 71.3% of clay gave the best removal efficiency. A maximum flow rate of 0.0035 L/H (LPH) was recorded with a corresponding time of first drop of 216 minutes. The high removal efficiency observed for some parameters, locally available construction materials and wastewater reuse options makes this a viable option for cassava mill effluent treatment, however, further study is required to optimize this technique to meet wastewater permissible limits

PERFORMANCE EVALUATION OF A DE-FEATHERING MACHINE WITH SCALDING TANK

Studies have shown that mechanical means of de-feathering will lead to an increased poultry processing rate. This study evaluated a de-feathering machine with scalding tank. The machine was evaluated in terms of machine plucking time, machine capacity and machine efficiency. A  completely randomized experimental design was carried out using three poultry birds (broiler, cockerel and layer) and three scalding temperatures (60, 70 and 80 oC) at machine constant speed of 480 rpm and at three replicates. The average machine plucking time obtained were 21.0, 20.6 and 23.3 s for broiler, layer and cockerel respectively. The average machine capacities were 175, 179 and 159 birds/hr for broiler, layer and cockerel birds respectively while the average machine efficiencies were 95, 93 and 90% for broiler, layer and cockerel birds respectively. The machine plucking time reduced from 28 s to 19 s with an increase in scalding temperature from 60 to 80oC for the different poultry breeds. The highest machine efficiency obtained were 96, 94 and 95% for broiler, layer and cockerel birds respectively at 70oC temperature. The machine capacity increased from 131 to 197 birds/hr with an increase in temperature from 60 to 80oC for the different poultry breeds. The optimum machine capacity was obtained at 80oC with values 194, 197 and 180 birds/hr for broiler, layer and cockerel birds respectively

Adapting television satellite dish for low-temperature solar thermal application: Experimental evaluation

Digital television broadcasting is currently becoming popular and as a result, the purchase of television cable dishes and other accessories are on the rise. Abandoned television satellite dishes continue to litter our environment due to obsolescence. Finding alternative use stands as a control measure for this inevitable environmental degradation. This paper, therefore, investigates the adaptation for low temperature solar thermal application. The TV satellite dish selected for this study has a diameter of 33.9 cm, depth of 9 cm and a focal point of 31.2 cm. The components added to the dish include; a reflective surface, pot stand, adjustable chain, dish support stand and base, control arm. This system was used in carrying out stagnation test on three different types of pots (aluminium, iron and stainless steel pots) positioned at the focal point. Other performance parameters studied include; standard stagnation temperature (SST) and the rate of change of pot temperature. The maximum stagnation temperatures attained by the inside of the iron, aluminium and stainless steel pots were 68, 80 and 82 °C respectively after 10, 13 and 40 minutes respectively; while their respective maximum SST were 100, 57 and 50 oC. The maximum temperature change inside the iron, aluminium and stainless steel pots were above 9, 12 and 10 oC/min. The result gathered shows that this system will be suitable for lower temperature applications like pasteurization, sterilization, household water heating, etc

Design and Preliminary Evaluation of a Dry Cowpea Dehuller

Cowpea dehulling is an important operation in the processing of cowpea. Traditional cowpea dehulling methods recognize the soaking of cowpea in water for a significant amount of time before manual abrasion is carried out either through the use of mortar and pestle, hands, or legs. Existing mechanical alternatives also require prolonged soaking of cowpea before dehulling occurs in addition to being expensive and beyond the reach of many rural populations. This study designed and fabricated a dry cowpea dehulling machine using engineering principles and with locally available materials. Components of the machine include the hopper, power transmission drive, dehulling chamber, polishing chamber, sieves, discharge chute, and agitator. Dry cowpea varieties of Brown Drum (15%Mc dB) and Oloyin (17.5%Mc dB) cowpea weighing 500 g each were fed into the machine at a constant speed of 358 rpm. Preliminary tests showed the “Brown Drum” cowpea variety recorded a maximum dehulling efficiency of 97.44% in 7 minutes while the Oloyin variety was completely dehulled in 7 minutes at 98.75% efficiency. The throughput capacity recorded was 450kg/hr and this machine raises the possibility of producing dry dehulled cowpea for domestic and industrial end-users

Sero-epidemiological survey and risk factors associated with brucellosis in dogs in south-western Nigeria

Introduction: In Nigeria, there is limited information on brucellosis particularly in dogs, despite its public health implications. We undertook a sero-epidemiological survey of brucellosis in dogs to determine the prevalence of the disease and associated risk factors for its occurrence in Nigeria. Methods: A cross-sectional study was conducted to screen dogs in south-western Nigeria for antibodies to Brucella sp using the rapid slide agglutination test (RSA) and Rose Bengal test (RBT), with positive samples confirmed respectively by serum agglutination test (SAT) and competitive enzyme linked immunosorbent assay (cELISA). Data were analyzed with STATA-12. Results: From the 739 dog sera tested, 81 (10.96%) were positive by RSA and 94 (12.72%) by RBT; these were corroborated with SAT (4/81; 4.94%) and cELISA (1/94; 1.06%), respectively. Logistic regression identified location (OR=0.04; 95% CI: 0.02-0.09), breed (OR=1.71; 95% CI: 1.34-2.19), age (OR=0.10; 95% CI: 0.04- 0.30) and management system (OR=8.51; 95% CI: 1.07-68.05) as risk factors for Brucella infection by RSA. However, location (OR=10.83; 95% CI: 5.48-21.39) and history of infertility (OR=2.62; 95% CI: 1.41-4.84) were identified as risk factors using RBT. Conclusion: Given the 10.96% to 12.72% seroprevalence of brucellosis recorded in this study, we advocate control of the disease in dogs, and public health education for those at risk of infection. Again, further studies are required to elucidate the role of dogs in the epidemiology of brucellosis in Nigeria considering the conducive human-animal interface and ecological factors responsible for the transmission of the disease.Pan African Medical Journal 2016; 2

Application of the physical properties of local cowpea varieties in the development of a multi-variety cowpea cleaner

Cowpea, an annual legume widely grown and consumed in Nigeria, has been observed to contain between 27-33% impurities when freshly harvested and threshed. This poses a threat to humans when consumed and in large-scale agricultural processing. Therefore, this study is aimed at developing and evaluating the performance of a multi-variety cowpea cleaner (MVCC). Using standard methods, some selected engineering properties of the cowpea varieties were examined and used in the design of the MVCC. The cowpea had a moisture content of 8-14%, depending on the locations and varieties. Other properties investigated include the length, width, thickness, sphericity, geometric mean diameter, unit volume, arithmetic mean diameter, aspect ratio, surface area, unit weight, true density, terminal velocity, and angle of repose. The MVCC comprised the hopper, winnower, cleaning unit, fan assembly, and frame. The performance of the MVCC was also evaluated. The efficiency of separating good products of honey, drum, and Sokoto White beans was 95, 91, and 84%, respectively, while separating bad products was 87, 94, and 96%, respectively

Design and Preliminary Evaluation of a Snail Shelling Machine

Snail meat is an alternative source of rich protein in the tropics and an important part of many diets. Despite its wide popularity as a cheap source of dietary protein, very little investments have been made into the processing of snail meat in terms of processing equipment and other value addition technologies. Up till now, many farmers utilize manual methods in breaking snail shells which are very demanding and tiring.  Furthermore, existing technology of snail shellers are not only expensive but the technology is beyond the reach f many local farmers thereby discouraging many from exploring the abundant potentials of the processing value chain. Hence, this study designed and evaluated a snail shell cracking machine using standard engineering procedures and locally available materials that will specifically replace human efforts in snail shell removal. The components of the machine include: the hopper, cracking chamber, rollers, discharge chute transmission shaft, chain drive and a prime mover. Preliminary test of 20 mature snails at a constant speed of 410 rpm showed that the average cracking time for the snails was 1.73 seconds while a total of 34.65 seconds was spent in the process. A throughput achieved during testing translates to 330kg/hr and an efficiency of 96.03% was also recorded during the testing. The total cost of the machine. Hence, this study establishes that snail processing can be achieved using mechanical means at very reasonable cost and further processing opportunities can be explored using the technolog