N. Sh. El-Gendy

Enhancing Biodegradation of Dibenzothiophene by Bacillus sphaericus HN1 Using Factorial Design and Response Surface Optimization of Medium Components

Abstract Based on four levels of full factorial design, a statistical design of experiments is used to investigate two cases of dibenzothiophene biodegradation in batch processes using Bacillus sphaericus HN1, involving as factors, yeast extract and dimethylsulfoxide or magnesium sulfate for first and second cases, respectively. Predictive models have been correlated finding out how significant the effects of these variables (factors) and their interactions are in practice. Also, response surface methodology has been applied to visualize the effect of the studied factors and LINGO software was used to find out the optimum values of the variables for enhancing the process.

Factorial Design and Response Surface Optimization for Enhancing a Biodesulfurization Process

Based on five levels of full factorial design, response surface methodology was used for modeling, optimization, and studying the interactive effects of two variables, nitrogen source and carbon co-substrate, in a batch process for dibenzothiophene biodesulfurization, using a new Gram-positive bacterial isolate R. erythropolis HN2 (accession no. KF018282). The optimum operating conditions were found to be 0.35 g/L yeast extract and 0.09 M glycerol.

The Biotreatment of Oil-Polluted Seawater by Biosurfactant Producer Halotolerant Pseudomonas aeruginosa Asph2

In this study, a halotolerant Pseudomonas aeruginosa Asph2 was used to bioremediate oil polluted seawater with total petroleum hydrocarbon content of 5 g/L in a batch system using a local, readily available, and commercial nutrient, corn steep liquor. P. aeruginosa Asph2 expressed good biodegradation capabilities for different petroleum hydrocarbon components, recording ≈ 58, 64, 56, 55, and 53% for total petroleum hydrocarbon, saturates, aromatics, asphaltenes, and resins, respectively, within 21 days of incubation at 30°C, pH 7, and 150 rpm. P. aeruginosa Asph2 proved good uptake of crude oil with high production of rhamnolipid biosurfactant. The produced biosurfactant exhibited low surface tension of 36 dyne/cm, low critical micelle concentration of 20 mg/L, and good emulsification index E24 of 55%.

The Biosorption of Phenol from Petroleum Refinery Wastewater Using Spent Waste Biomass

This work investigates the potentiality of application of spent waste biomass (yeast Saccharomyces cerevisiae, rice straw, and sugarcane bagasse) from bioethanol production process as low-cost biosorbents for removal of phenol from petroleum refinery wastewater. Batch adsorption studies were carried out under varying experimental conditions of contact time, initial phenol concentration, and operational temperature. Rice straw showed better affinity towards phenol than sugarcane bagasse, while S. cerevisiae did not express any biosorption capacity. The biosorption process on rice straw or sugarcane bagasse was fast and the time to reach equilibrium was found to be 150 min. Kinetic studies showed that biosorption follows the pseudo-second order rate expression. The results were better described by the Langmuir isotherm model than the Freundlich and Temkin isotherm models. The calculated heat of adsorption indicated that the biosorption process is taking place by chemical adsorption and has an endothermic nature.

The Optimization of Biodiesel Production from Waste Frying Corn Oil Using Snails Shells as a Catalyst

In this study, calcium oxide as a heterogeneous catalyst for biodiesel production was prepared by a simple calcination process at 800°C for snails shells collected from Egyptian shorelines. D-optimal design of experiments and response surface methodology was applied to analyze the influence of four process variables; methanol:oil (M:O) molar ratio, catalyst concentration (wt%), reaction time (min), and mixing rate (rpm) on biodiesel production through transesterification of waste frying corn oil at 60°C using the prepared biocatalyst. A second order quadratic model was obtained to predict the % biodiesel yield and it adequately described the studied experimental range. Based on the experimental analysis and response surface methodology study, the most suitable operational conditions for this process were: M:O, 6:1 molar ratio; catalyst concentration, 3 wt%; reaction time, 60 min; and mixing rate, 200 rpm. The corresponding predicted % yield of biodiesel was 96.76% and the experimental one was 96%. The activity of the produced green catalyst was comparable to that of chemical CaO and immobilized enzyme Novozym 435.

The Evaluation of Different Bioremediation Processes for Egyptian Oily Sludge Polluted Soil on a Microcosm Level

In this study, bioremediation of an Egyptian oily sludge polluted soil with total petroleum hydrocarbon content of 53,100 mg kg−1 was achieved on a microcosm level at 30°C over a 180-day period. The analysis of variance revealed that soil microcosms biostimulated with corn steep liquor and bioaugmented with Micrococcus lutes RM showed significant removal of total petroleum hydrocarbon relative to natural attenuation microcosms; recording total petroleum hydrocarbon removal of 44 and 54% with p = 0.004 and p = 7.69e-5, respectively. Kinetic study revealed that the degradation processes followed the first-order model. Bioaugmentation microcosms showed also the highest biodegradation efficiencies on different total petroleum hydrocarbon fractions: saturates, aromatics, resins, asphaltene, and the highest soil heterotrophic activity as measured by accumulative evaluation of CO2.

Kinetic Modeling of the Bioremediation of Diesel Oil Polluted Seawater Using Pseudomonas aeruginosa NH1

In this study, the marine diesel oil-degrading bacterium strain NH1 was isolated and identified with respect to its 16S rDNA sequence as Pseudomonas aeruginosa with accession number KM267644. The ability of NH1 immobilized by entrapment in Ca-alginate gel to degrade different components of diesel oil contaminating seawater was examined in a batch system. The biodegradation rate of different components of diesel oil in free and immobilized cell systems can be ranked in the following decreasing order: total resolvable peaks (normal- and iso-alkanes) > the 16 polyaromatic hydrocarbons listed by the United States Environmental Protection Agency as priority pollutants > polyaromatic sulfur heterocyclic compounds > unresolved complex mixture (naphthenes, cyclo-alkanes, and aromatics). Kinetic modeling was performed to estimate the rate of biodegradation of each hydrocarbon type component. The biodegradation of diesel oil, total resolvable peaks and unresolved complex mixture was found to be best fitted with the second-order, while that of polyaromatic sulfur heterocyclic compounds and polyaromatic hydrocarbons followed the first-order kinetic model equations. The biodegradation rate of different components of diesel oil: aliphatics, polyaromatic sulfur heterocyclic compounds, and biomarkers (pristane, phytane, and 4,6-dimethyldibenzothiophene) was enhanced by immobilization, indicating the improved tolerance of the immobilized cells towards different toxic components of diesel oil. Storage stability and reusability tests revealed that the diesel oil degradation ability of the immobilized cells was stable after storage at 4°C for 30 d and can be effectively reused for two batches of 56 d.

Application of D-optimal Design and RSM to Optimize the Transesterification of Waste Cooking Oil Using a Biocatalyst Derived from Waste Animal Bones and Novozym 435

This study was performed to investigate the applicability of the basic heterogeneous fluorapatite catalyst prepared from waste animal bones in the transesterification of waste cooking oil with methanol for production of biodiesel. Response surface methodology based on D-optimal design of experiments was employed to study the significance and interactive effect of methanol to oil (M:O) molar ratio, catalyst concentration, reaction time, and mixing rate on biodiesel yield using the prepared fluorapatite and Novozym 435. Quadratic model equations were obtained describing the interrelationships between dependent and independent variables to maximize the response variable (biodiesel yield) and the validity of the predicted models were confirmed. The optimum combination for transesterification were determined to be 7.35:1 and 6:1 M:O, 4.35 and 8.8 catalyst wt%, 91 and 96 min, and 331 and 394 rpm at 60°C, for prepared fluorapatite and Novozym 435, respectively, with maximum biodiesel yield of ≈ 96 and 62%, respectively. Fuel properties of the produced biodiesel and its blends with petro-diesel were measured and compared with those of Egyptian petro-diesel and international biodiesel standards. Acceptable agreement was observed, encouraging application of fluorapatite prepared from waste animal bones for production of biodiesel as an alternative or complementary to petro-diesel.

Waste Eggshells for Production of Biodiesel from Different Types of Waste Cooking Oil as Waste Recycling and a Renewable Energy Process

Based on 3-levels-D-optimal design, involving as factors: methanol:oil, molar ratio; catalyst concentration, wt%; reaction time, min; and type of waste cooking oil, a statistical design of experiments strategy was performed to evaluate and investigate the biodiesel production process from different types of waste cooking oil using CaO prepared from waste eggshells. MATLAB software was employed for experimental design and data analysis. An empirical quadratic regression equation model was obtained describing the interrelationships between dependent and independent variables to maximize the response variable (biodiesel yield). The optimum values of the selected predictor variables were obtained by solving the quadratic model equation using LINGO software. They were found to be: methanol:oil, 9.15:1 molar ratio; catalyst concentration, 7.728 wt%; and reaction time, 75 min, regardless of the type of waste cooking oil used as the feedstock. The qualification and yield of biodiesel were comparable to those prepared using chemical CaO and immobilized standard enzyme Novozym 435.

Applying Factorial Design and Response Surface Methodology to Enhance Microbial Denitrogenation by Tween 80 and Yeast Extract

In this study the effect of yeast extract as a conitrogen source and Tween 80 as a commercial and available nonionic surfactant on microbial denitrogenation MDN of carbazole by Bacillus clausii BS1 was investigated. The central composite design matrix and response surface methodology were applied in designing the batch experiments to evaluate the interactive effects of these two parameters on MDN. Quadratic model equations have been predicted finding out how significant the effects of these variables (factors) and their interactions are in practice. The validity of the predicted models was confirmed. The MDN efficiency increased from ≈88% without yeast extract or Tween 80 to ≈95% in presence of optimum concentration of 0.868 g/L yeast extract and 0.861% (v:v) Tween 80, which would represent a major economic improvement in low-margin, high-volume refining processes.