The aim of this work is to study the influence of the physicochemical characteristics of neem seeds, according to their mass and oil content, on the production of biodiesel. After the physical characterization of the seeds and extraction of the oil (triglycerides), biodiesel was produced from crude neem seed oil by transesterification with ethanol in the presence of sodium hydroxide. This study shows that the physicochemical characteristics of these seeds vary according to the origin of the samples. The seeds from Zidim, with a mass average of 200 seeds evaluated at 141.36 g and an almond content of 40.70%, have better characteristics compared to those collected in the city of Maroua, with average values evaluated at 128.00 g and 36.05%, respectively. Almonds have an average lipid content of 53.98 and 56.75% for the Maroua and Zidim samples, respectively. This study also reveals that neem oil, by its physicochemical characteristics, has a satisfactory quality for a valorization in the production of biodiesel. However, its relatively high free fatty acid content is a major drawback, which leads to a low yield of biodiesel, evaluated on average at 89.02%, and requires a desacidification operation to improve this yield. The analysis of biodiesel indicates physicochemical characteristics close and comparable to those of petrodiesel, particularly in terms of calorific value, density, kinematic viscosity, acid value, evaluated at 41.00 MJ/kg, 0.803, 4.42 cSt, and 0.130 mg/g, respectively.

Tigernut tubers (Cyperus esculentus) are used for the production of vegetable milk, commonly known as “Horchata de chufa” in Spain. The presence of starch in the tuber limits the yield of the milk, since this carbohydrate gelatinizes during the pasteurization of the milk and leads to the considerable solidification of this drink. The present work aims to improve the yields and extraction practice of the milk by an in situ hydrolysis of starch, using exogenous amylases of industrial or vegetable origin. The obtained results show that sprouting improves the extraction yields of tigernut milk, which goes from 50% to about 70%. This improvement in milk yield corresponds to a hydrolysis of about 35% of the starch in the tuber. The use of exogenous amylases leads to starch hydrolysis rates of 45% and 70%, respectively, for amylolytic extracts from sprouted tigernut tubers and amylase, with the corollary of a natural increase in the sweetness of milk. This technical approach makes it possible to produce a naturally sweetened tigernut milk which easily lends itself to pasteurization without a significant increase in viscosity.

The global energy trends are currently dominated by a massive use of fossil non-renewable energy sources which are progressively depleting. In this way, the production of second-generation biogas production from organic wastes by the dark fermentation process offers, therefore, an attractive solution to diversify the present energy mix. The development of biogas production units has led to an increase in the quantity of biomethane, but it contains impurities. A biomethane purification and storage system was developed in this work to improve the quality of this biofuel. Solutions were first developed to capture carbon dioxide, hydrogen sulfide, water, and volatile organic compounds found in the initial biogas. These solutions were based on a system of purification made up of water absorption reactions and iron oxide, activated charcoal, and steel wool adsorption. Thus, the biomethane obtained after purification has been stored in an inflatable balloon before being compressed into a refrigerant bottle of R134a. The treatment system was used to release a biogas with 95 % biomethane and a law heating value (LHV) of 54 MJ/kg after purification. It also emerges that purification of 2 m³ of biogas requires 0.15 m³ of water at 20oC to produce 1.4 m³ of biomethane. This biomethane can meet an energy demand of 1624 Wh or 0.2 m³ of daily biomethane requirements. The system as a whole can allow customers with a biodigester to produce their own energy (cooking or electric) while reducing the production of green-house gases in the atmosphere.