Difficulties of access to public water distribution sources in the suburbs of the sixth district of Cotonou create more resorts to the traditional water sources (wells). To assess the degree of chemical pollution of those waters, a study was conducted during the long rainy season of 2015 on thirty (30) traditional wells. Concentration of nitrogenous pollutants (nitrates and nitrites) was analyzed by cadmium reduction method and diazotization method, respectively. Micropollutants (lead and mercury) were respectively determined by the rapid extraction method of LeadTrak ™ column and by pre-concentration at cold vapor method. The results show that waters have a high level of nitrate and mercury pollution which are respectively 26.67%, (16.38 mg/l to 349.85 mg/l) and 13.33% (0.10 mg/l to 1.50 mg/l) and a low level of nitrite (0.02 mg/l to 2.63 mg/l) and lead (1 mg/l to 5mg/l). The Principal Component analysis helped to identify four groups (I-IV) of well waters: water with high degree of nitrogen pollution (NO3-) and high toxic metal and toxic metal (I: 20%); with low degree of nitrogen and toxic metal (II: 30%);water with high mineralization (III: 20%) and water rich in nitric pollutant (NO2-) (IV: 6.67%).The water pollution may be related to the low sanitation level and the improper conditions of well installation. Consumption of well waters may expose humans to health risks.
In developing countries, institutions that have to operate continuously during daylight hours consume relatively large amounts of electrical energy for lighting and air conditioning, leading to high bills. Untimely power cuts lead to a fluctuation in the voltage delivered by the conventional network, which induces the malfunctioning of electrical equipment and the discontinuity of judicial work. The use of photovoltaic solar energy makes it possible, on the one hand, to ensure continuity of service in the event of damage, and on the other hand to stem greenhouse gas emissions through the sustainable nature of this energy. Solar installations also make it possible to maintain the permanent power supply in the event of instability of the electrical network and to correct the voltage variations undergone by the energy equipment. Thus, this (case) study is based on the energy balances evaluated on the buildings of the jurisdiction of the city of Kandi (Benin) to propose effective solutions of electrification according to six (6) technical scenarii. Each component of the back up system has been sized considering technical requirements and an economic and environmental study has been carried out. The results indicate that the integrated scenario 6 of a "back-up" system with a solar fraction of up to 37% (49.5 kWc) seems to be the most suitable conf iguration for the current needs of the Kandi jurisdiction due to the shortest time to return on investment (5.1 years) and the maximum annual savings generated (33,674 USD). The environmental impact study has made it possible to determine the CO2 emissions avoided as well as the contribution of Carbon credits that this jurisdiction would reap has been evaluated at 115.8 tCO2 equivalent, or 10.6 hectares of forest carbon preserved over the life of the project. This configuration is therefore strongly recommended for a sustainable energy mix in the jurisdictions of Benin as well as for administrative or similar sites where electricity consumption is maximum during the day.
The research concerns energy saving issues at refrigeration plants in warm tropical areas. The object is to optimize operating cost of the cold stores for food industries by calculating the energy consumption of refrigeration systems for different outside temperatures. The compressor energy consumption decreases as compression ratio becomes low for colder outside temperatures. The determined energy consumption of the fans shows a very small increase when outdoor temperature increases, thus it can be considered to be constant. The floating HP operating mode shows a better COP than the fixed HP one. The calculation for several refrigerants i.e. R717, R404A and R22 having been made, the results show that the COP is better for ammonia than for R22 and R404A. The annual energy gain is at least 600kWh/kW of cooling capacity compared to the fixed HP operating mode. In terms of energy consumption the refrigerant R404A gives the best gain (17 %), and ammonia does 13 %. Although temperature does not change a lot over the year in the humid tropical areas concerned, 15 % energy saving can be predicted with floating condensation pressure control. For industrial refrigerating plant, the method appears to be very promising and competitive in terms of energy saving, with investment being very small. It can also permit the design and the management of more environmentally sustainable industrial refrigeration plants.
A small-scale maize harvester was designed and fabricated for developing countries and is composed of a harvester header, a chain conveyor, a drive power unit and a five-wheel tricycle. Fabrication of components was made and assembling of the devices on the tricycle was done. The performance evaluation of the small-scale maize harvester was done at 15% kernels moisture content (wet basis). Three rotational speeds of the engine, 1347, 1521 and 1937 rpm were used, while the forward velocity of the harvester was kept at an average of 0.617 km.hr-1. The testing experiment revealed significant effect of physical properties of maize (p<0,05). The highest machine capacity was obtained at 0.05 ha.hr-1, while the highest driving efficiency was 97.30% and the highest picking and conveying efficiencies were 84.11% and 98.21%, respectively. However, it was observed that the machine noise level decreased with increase in engine speed. Also, the engine speed affected both picking and conveying efficiencies. The designed machine is found suitable for most smallholder farms.
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