Papers by Youssouf Touhami
Process Biochemistry, 2004
This study compares the performance of anaerobic digestion of fruit and vegetable waste (FVW) in ... more This study compares the performance of anaerobic digestion of fruit and vegetable waste (FVW) in the thermophilic (55 • C) process with those under psychrophilic (20 • C) and mesophilic (35 • C) conditions in a tubular anaerobic digesters on a laboratory scale. The hydraulic retention time (HRT) ranged from 10 to 20 days, and raw fruit and vegetable waste was supplied in a semi-continuous mode at various concentrations of total solids (TS) (4, 6, 8 and 10% on dry weight). Biogas production from the experimental thermophilic digester was higher on average than from psychrophilic and mesophilic digesters by 144 and 41%, respectively. The net energy production in the thermophilic digester was 195.7 and 49.07 kJ per day higher than that for the psychrophilic and mesophilic digesters, respectively. The relation between the daily production of biogas and the temperature indicates that for the same produced quantity of biogas, the size of the thermophilic digester can be reduced with regard to that of the psychrophilic and the mesophilic digesters.
Process Biochemistry, 2005
This work reviews the potential of anaerobic digestion for material recovery and energy productio... more This work reviews the potential of anaerobic digestion for material recovery and energy production from fruit and vegetable wastes (FVW). These wastes contain 8-18% total solids (TS), with a total volatile solids (VS) content of 86-92%. The organic fraction includes about 75% easy biodegradable matter (sugars and hemicellulose), 9% cellulose and 5% lignin. Anaerobic digestion of FVW was studied under different operating conditions using different types of bioreactors. It permits the conversion of 70-95% of organic matter to methane, with a volumetric organic loading rate (OLR) o f 1-6.8 g versatile solids (VS)/l day. A major limitation of anaerobic digestion of FVW is a rapid acidification of these wastes decreasing the pH in the reactor, and a larger volatile fatty acids production (VFA), which stress and inhibit the activity of methanogenic bacteria. Continuous two-phase systems appear as more highly efficient technologies for anaerobic digestion of FVW. Their greatest advantage lies in the buffering of the organic loading rate taking place in the first stage, allowing a more constant feeding rate of the methanogenic second stage. Using a two-stage system involving a thermophilic liquefaction reactor and a mesophilic anaerobic filter, over 95% volatile solids were converted to methane at a volumetric loading rate of 5.65 g VS/l d. The average methane production yield was about 420 l/kg added VS.
Journal of Colloid and Interface Science, 2001
The effects of a ready-made surfactant (sodium dodecyl sulfate) on the dynamic interfacial tensio... more The effects of a ready-made surfactant (sodium dodecyl sulfate) on the dynamic interfacial tension between a model acidic oil (linoleic acid dissolved in paraffin oil) and various aqueous alkaline (NaOH) systems have been studied using pendant drop tensiometry at surfactant concentrations both below and above the critical micelle concentration (CMC). Below the CMC the added surfactant contributes significantly to a further reduction of interfacial tension of the reacting acid/alkaline system, whereas above the CMC the added surfactant plays an important role in damping the dynamic trends observed for the reactive system alone. C 2001 Academic Press
Desalination and Water Treatment, 2012
Two bacterial strains, Bacillus cereus and Bacillus pumilus, were isolated from the sludge of an ... more Two bacterial strains, Bacillus cereus and Bacillus pumilus, were isolated from the sludge of an aerobic reactor treating textile wastewater containing indigo dye. These strains were chosen as augmented decolourizers which were mixed in various ratios with the activated sludge and the effect of their concerted metabolism on the decolourization and the biodegradation efficiencies were studied. Results showed that there
Biotechnology Letters, 2000
Microbial consortia in a two-phase, anaerobic bioreactor using a mixture of fruit and vegetable w... more Microbial consortia in a two-phase, anaerobic bioreactor using a mixture of fruit and vegetable wastes were established. Bacterial and archaeal communities obtained by a culture-independent approach based on single strand conformation polymorphism analysis of total 16S rDNA showed the adaptation of the microflora to the process parameters. Throughout the 90 d of the study, the species composition of the bacterial community changed significantly. Bacterial 16S rDNA showed at least 7 different major species with a very prominent one corresponding to a Megasphaera elsdenii whereas bacterial 16S rDNA of a methanization bioreactor showed 10 different major species. After two weeks, Prevotella ruminicola became major and its dominance increased continuously until day 50. After an acid shock at pH 5, the 16S rDNA archaeal patterns in the acidogenic reactor showed two major prominent species corresponding to Methanosphaera stadtmanii and Methanobrevibacter wolinii, a hydrogenotrophic bacterium.
Bioresource Technology, 2008
Anaerobic digestion of cheese whey wastewaters (CW) was investigated in a system consisting of an... more Anaerobic digestion of cheese whey wastewaters (CW) was investigated in a system consisting of an ecological pretreatment followed by upflow anaerobic filter (UAF). The pretreatment was conducted to solve the inhibition problems during anaerobic treatment of CW caused by the amounts of fats, proteins and carbohydrates and to avoid the major problems of clogging in the reactor. The optimized ecological pretreatment of diluted CW induce removal yields of 50% of chemical oxygen demand (COD) and 60% of total suspended solids (TSS) after acidification by Lactobacillus paracasei at 32°C during 20 h and neutralization with lime. The pretreated CW was used to feed UAF (35°C). The effects of organic loading rate (OLR) and hydraulic retention time (HRT) on the pretreated CW anaerobic degradation were examined. The average total COD removals achieved was 80-90%. The performance of the reactor was depressed by increasing the COD concentration to 20 g/l (OLR = 4 g COD/l d) and the COD removal efficiency was reduced to 72%. Significant methane yield (280 l/kg COD removal) was obtained at an HRT of 2 days.
Biochemical Engineering Journal, 2004
The two-phase anaerobic digestion of a mixture of fruit and vegetable wastes (FVW) was studied, u... more The two-phase anaerobic digestion of a mixture of fruit and vegetable wastes (FVW) was studied, using two coupled anaerobic sequencing batch reactors (ASBR) operated at mesophilic temperature. The effect of increasing loading rates on the acidification step was ...
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Papers by Youssouf Touhami