Activité cellulolytique in vitro de sols de deux steppes à alfa (Stipa tenacissima L.) d’Algérie

Cellulose represents an important part of the organic matter returned to soil with the litter of alfa. Thus cellulolytic activity is a good indicator of the soil microbial activity. Different experiments in vitro compared the influence of different conditions, particularly the gradient of aridity, corresponding to two sites : arid alfa steppe and semi-arid alfa steppe. Soil samples were collected underneath and between tufts of vegetation. Different temperature and humidity were chosen in function of climatic data. Two levels soil depth were studied. From our results, it can be concluded that cellulolytic activity in the arid alfa steppe soils is less intense than in the semi-arid ones, as determined in vitro.La cellulose constitue une part importante de la matière organique apportée par les litières d’alfa. L’activité cellulolytique étant un bon indicateur de l’activité microbiologique des sols, différentes expériences in vitro ont été effectuées afin de comparer l’influence des conditions stationnelles et en particulier du gradient d’aridité dans deux stations : une steppe d’alfa aride et une steppe d’alfa semi-aride. Des prélèvements ont été effectués sous les touffes d’alfa et entre les touffes. Différents taux d’humidité et températures ont été choisis en fonction des conditions climatiques. Deux niveaux de sol ont été étudiés. Il apparaît que l’activité cellulolytique in vitro est moins intense dans la station la plus aride. Les sols de la station aride sont proportionnellement plus actifs aux fortes températures et humidités faibles que ceux de la station semi-aride.Bessah Rahma, Rozé Françoise, Nedjraoui Dalila. Activité cellulolytique in vitro de sols de deux steppes à alfa (Stipa tenacissima L.) d’Algérie. In: Ecologia mediterranea, tome 25 n°2, 1999. pp. 185-192

Optimization and kinetic study of the bioethanol production by a locally isolated strain using response surface methodology

International audienc

Experimental optimization of Waste Cooking Oil ethanolysis for biodiesel production using Response Surface Methodology (RSM)

Biodiesel production from Waste Cooking Oil (WCO) is the most suitable diesel fuel substitute, due to its cleaner emissions, engine lubricity, nontoxic properties, and renewable sources. This study mainly focused on improving biodiesel experimental production using ethanol and investigating the influence of main operating parameters (ethanol–oil molar ratio, catalyst concentration and stirring speed) on biodiesel yield using Response Surface Methodology (RSM). The problem with using ethanol at the expense of the toxicity of methanol as an alcohol is mainly the separation of glycerol from biodiesel at the end of the transesterification reaction. However, the addition of 5% (v/v) glycerol and 1% (v/v) water at the end of the reaction has been found to aid this separation and improve oil conversion. The optimization of the produced biodiesel is carried out through three factors: Face-Centered-Composite Design (FCCD), building a mathematical model, and statistical analysis, shows that the experimental results agree with the predicted values; they are close to unity with the R2 value (0.9924), indicating the correctness of the model. The optimal conditions of catalyst concentration (1.62 wt%), stirring speed (200 rpm) and molar ratio of ethanol to oil (12.9:1) were obtained, resulting in a biodiesel efficiency of 89.75%. The model was also experimentally validated, achieving about 90% biodiesel yield. The fuel properties of the ethyl ester were investigated and compared successfully with the EN and ASTM standards and with baseline local diesel (NA 8110)

Experimental study and kinetic modelling of bioethanol production from industrial potato waste

International audienceThe potato wastes constitute a major environmental concern due to their significant production in the potato processing industry. Due to their high organic content, this waste can constitute a very interesting Algerian resource for biofuel production. The objective of this study is the energy recovery of an industrial agro-food waste to produce bioethanol. This waste is a solid residue of chips manufacturing and mainly consists of potato starch. The conversion of this biomass was achieved using a chemical pretreatment with hydrochloric acid. The acid hydrolysis of potato starch with a ratio of material to acid solution of 1:2 (w/v) was enough to liberate a high amount of fermentable reducing sugar (159.3 g/l) contained in the potato waste. The hydrolysate obtained at the end was fermented using Saccharomyces cerevisiae yeast under the following conditions (pH 5, 30 degrees C, 100 rpm). The maximum yield of bioethanol (54.12 g/l) was achieved after 116 h. Thus, operating conditions used for the sugar fermentation were favorable and did not exhibit any sort of process inhibition. The Gompertz model was applied to experimental data, and kinetic fermentation parameters such as maximum ethanol concentration (P-m = 49.81 g/l), production rate (r(pm) = 0.87 g/(l h)), and lag phase (t(L) = 5.29 h) were accurately estimated. Those parameters can be used to investigate the economical feasibility for such industry. The results demonstrate that potato starch (by-product of the potato industry) has a great potential for bioethanol production

Heat transfer and fluid flow of Biodiesel at a backward-Facing step

You should Three-dimensional simulation of a biodiesel fluid flow within a rectangular duct over a backward-facing step is investigated in the present paper. The fluid, which obeys to the Newtonian rheological behavior, is obtained by transformation of Algerian waste cooking oil into a biodiesel. Flow through a rectangular channel subjected to a constant wall temperature or constant heat flux as boundary conditions. The partial differential equations governing fluid flow and heat transfer are solved by the Fluent CFD computational code based on the Finite Volume Method. The numerical experiments are carried out to examine the effect of the Reynolds number by fluid inlet velocity variation for the two boundary conditions. The results are analyzed through the distribution of the temperature and the velocity contours. The variation of the Reynolds number and boundary conditions affects greatly the heat transfer and the fluid flow, in particular near the step region

Heat transfer and fluid flow of Biodiesel at a backward-Facing step

You should Three-dimensional simulation of a biodiesel fluid flow within a rectangular duct over a backward-facing step is investigated in the present paper. The fluid, which obeys to the Newtonian rheological behavior, is obtained by transformation of Algerian waste cooking oil into a biodiesel. Flow through a rectangular channel subjected to a constant wall temperature or constant heat flux as boundary conditions. The partial differential equations governing fluid flow and heat transfer are solved by the Fluent CFD computational code based on the Finite Volume Method. The numerical experiments are carried out to examine the effect of the Reynolds number by fluid inlet velocity variation for the two boundary conditions. The results are analyzed through the distribution of the temperature and the velocity contours. The variation of the Reynolds number and boundary conditions affects greatly the heat transfer and the fluid flow, in particular near the step region