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ABSTRACT:The present study investigated the phenol utilization kinetics of a pure culture of an indigenousPseudomonas fluorescence under steady state and non-steady state (washout) conditions. Steady states of a continuous culture with an inhibitory substrate was used to estimate kinetic parameters under substrate limitation (chemo stat operation) Pure cultures of an indigenous Pseudomonas fluorescence were grown in continuous culture on phenol as the sole source of carbon and energy at dilution rates of 0.010 -0.20/h. Using different dilution rates, several steady states were investigated and the specific phenol consumption rates were calculated. In addition, phenol degradation was investigated by increasing the dilution rate above the critical dilution rate (washout cultivation). The results showed that the specific phenol consumption rate increased with increased dilution rate at steady state and phenol degradation by Pseudomonas fluorescence can be described by simple substrate inhibition kinetics under substrate limitation but cannot be described by simple substrate inhibition kinetics under washout cultivation. Fitting of the steady state data from continuous cultivation to various inhibition models resulted in the best fit for Haldane, Yano and Koga (2), Aiba and Teissier kinetic inhibition models. The r smax value of 0.229 mg/mg/h obtained from the inhibition model equations was comparable to the experimentally calculated r smax value of 0.246 mg/mg/h obtained under washout cultivation. Therefore, the biokinetic constants evaluated using these models showed good tolerance and growth of the indigenous organism.

The present investigation was undertaken to compare the adsorption efficiency of a low cost adsorbent, periwinkle shell-based granular activated carbon (PSC) with the adsorption efficiency of the commercial activated carbon (CAC) and a ratio 1:1 mixture of PSC and CAC (PSC/CAC) with respect to uptake of the organic components responsible for the chemical oxygen demand (COD) of industrial wastewater. The influence of treatment time, adsorbent dose, pH of the media, agitation speed and adsorbent particle size on the rate of percent COD removal is evaluated. PSC has shown quite effective adsorbent capacity for COD removal with 77.5% efficiency. Though its capacity is slightly lower than that of CAC with 79% efficiency, however the low material cost makes it an attractive option for the treatment of COD. The equilibrium adsorption study can be described by the Linear, Langmuir and Freundlich models. The mechanisms of the rate of adsorption of COD were analysed using the Elovich equation and a pseudo-second-order model. The models provided a very high degree of correlation of the experimental adsorption rate data suggesting either model could be used in design applications.La présenteétude aété menée dans le but de comparer l'efficacité d'adsorption d'un adsorbant bon marché, du carbone activé granulaire (PSC) venant de la coque de bigorneau, avec l'efficacité d'adsorption du carbone activé commercial (CAC) et d'un mélange de rapport 1:1 de PSC et CAC (PSC:CAC), en tenant compte de l'absorption en composés organiques responsables de la demande chimique en oxygène (COD) des eaux usées industrielles. L'influence du temps de traitement, de la dose d'adsorbant, du pH des milieux, de la vitesse d'agitation et de la taille de particule de l'adsorbant sur la vitesse de retrait de COD en pourcentage estévaluée. Le PSC montre une capacité d'adsorption assez efficace pour le retrait de COD avec une efficacité de 77,5%. Bien que sa capacité soit légèrement inférieureà celle du CAC qui est de 79%, le faible coût du matériau en fait un choix intéressant pour le traitement du COD. L'étude d'adsorptionà l'équilibre peutêtre décrite par les modèles linéaires de Langmuir et de Freundlich. Les mécanismes de la vitesse d'adsorption de COD ontété analysésà l'aide de l'équation d'Elovich et d'un modèle de pseudo second ordre. Les modèles fournissent un très haut degré de corrélation des données de vitesse d'adsorption expérimentales, ce qui permet de penser qu'ils pourraient servirà des applications de conception.

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The world is confronted with the twin crisis of fossil fuel depletion and environmental degradation caused by fossil fuel usage. Biodiesel produced from renewable feedstocks such as Jatropha seed oil or animal fats by transesterification offers a solution. Although biodiesel has been produced from various vegetable oils such as Jatropha seed oil, the reaction kinetics studies are very few in literature, hence the need for this study. Jatropha curcas seed oil was extracted and analyzed to determine its free fatty acid and fatty acid composition. The oil was transesterified with methanol at a molar ratio of methanol to oil 8:1, using 1% sodium hydroxide catalyst, at different temperatures ranging from 32oC to 65oC, at atmospheric pressure. The order of the reactions with respect to the triglyceride's disappearance in the forward reaction at the chosen temperatures was found to be pseudo-first-order and found to be first-order for the reaction at 32oC. The rate constants of the three consecutive reaction steps at 65oC, namely, triglyceride to diglyceride, diglyceride to monoglyceride, and monoglyceride to glycerol, were found to be 0.422 min-1 0.117 min-1, and 0.037min-1, respectively. Their corresponding activation energies in J/mol were 22.165, 3.136, and 19.770, respectively.

The potential of various organisms to metabolise organic compounds has been observed to be a potentially effective means in disposing of hazardous and toxic wastes. Phenolic compounds have long been recognised as one of the most recalcitrant and persistent organic chemicals in the environment. The bioremediation potential of an indigenous binary mixed culture of Pseudomonas aeruginosa and Pseudomonas fluorescens was studied in batch culture using synthetic phenol in water in the concentration range of 100-500 mg/litre as a model limiting substrate. The effect of initial phenol concentration on the degradation process was investigated. Phenol was completely degraded at different cultivation times for the different initial phenol concentrations. Increasing the initial phenol concentration from 100 mg/litre to 500 mg/litre increased the lag phase from 0 h to 18 h and correspondingly prolonged the degradation process from 24 h to 96 h. There was decrease in biodegradation rate as initial phenol concentration increased. Fitting data into three different kinetic models (Monod, Haldane, and Yano and Koga) showed that the difference in fit between the models was very small and thus statistically insignificant. Thus, the Yano and Koga model has been used to 178 interpret the free cell data on phenol biodegradation. The kinetic parameters have been estimated up to initial phenol concentration of 500 mg/litre. The r smax decreased, K s and K i increased with higher concentration of phenol. The r smax has been found to be a strong function of initial phenol concentration.

Transesterification is a chemical reaction which produces biodiesel from vegetable oils or animal fats.Transesterification of Jatropha seed oil and methanol with sodium hydroxide as a catalyst was carried out in an improvised batch reactor at different temperatures ranging from 32 65 degrees Celsius for 120minutes each. Molar ratio of methanol to oil used is 8:1.Aliquots of the reaction mixture were withdrawn at every 15 minutes interval of time from the time reaction starts for Gas Chromatographic analysis to determine percentage fatty acid methyl ester formed. The optimum percentage conversion, temperature and reaction time were found to be 99.9%, 65°C and 75minutes respectively. The fuel properties measured according to standard methods, were found to conform to International standard.

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