Effect of Process Variables on the Transesterification Process of Palm Oil Sludge to Biodiesel

In this research work, the optimum process variables (catalyst, methanol to oil ratio and reaction time) for transesterification of palm oil sludge (POS) to biodiesel were studied. The transesterification process was carried by mixture of palm oil sludge, methanol and catalyst with the help of magnetic stirrer at 300 rpm and at temperature of 60ºC. The catalyst used for the process was potassium hydroxide (KOH). One-Factor-at-A-Time was used to select the possible optimum levels of process variable that gives high biodiesel yield. The study was evaluated by five levels of methanol-to-oil ratio (1:1 – 12:1), catalyst (0.1- 2%) and reaction time (30 – 150 min).The optimum process variables for transesterification of palm oil sludge (POS) to achieved maximum biodiesel yield were found to be methanol to oil molar ratio of 12:1, catalyst loading of 1.5wt% and reaction time of 30 min. At this optimum conditions the maximum biodiesel yield was 61.2%. The biodiesel produced from transesterification of palm oil sludge was characterized in order to determine the properties of the product. The density of POS is 857.0 kg/m3, kinematic viscosity of 5.38 mm2/s, flash point of 180°C, pour point of -5°C, and Acid value of 0.17 mgKOH/g. The biodiesel produced from transesterification of palm oil sludge meets the EN 14214 and ASTM 6751 standard. Thus, this study will be helpful to determine an efficient and economical procedure for biodiesel production from non-edible raw materials with high free fatty acid.

Bioremediation of atrazine herbicide contaminated soil using different bioremediation strategies

ABSTRACT: This study evaluated the bioremediation of atrazine herbicide contaminated agricultural soil under different bioremediation strategies using indigenous Pseudomonas aeruginosa, Bacillus subtilis and Aspergillus niger as bioaugmentation agents and poultry droppings as biostimulation agent. The results showed that bioaugmentation with Pseudomonas aeruginosa, bioaugmentation with Bacillus subtilis, bioaugmentation with Aspergillus niger, bioaugmentation with bacterial-fungal consortium (Pseudomonas aeruginosa, Bacillus subtilis and Aspergillus niger), biostimulation with poultry droppings, and combined biougmentation and biostimulation (Pseudomonas aeruginosa, Bacillus subtilis, Aspergillus niger and poultry droppings) resulted in maximum atrazine biodegradation of about 97%, 95%, 84%, 99%, 100% and 100%, respectively. The kinetics of atrazine biodegradation in the soil were modelled using first-order kinetic model and the biodegradation half-life estimated. The first order kinetic model adequately described the kinetics of atrazine biodegradation in soil under the different bioremediation strategies. The rate constants ( k1 ) of atrazine biodegradation in soil subjected to bioaugmentations with Pseudomonas aeruginosa, Bacillus subtilis, Aspergillus niger, and bacterial-fungal consortium ranges between 0.059 day-1 and 0.191 day-1 while for that subjected to natural bioattenuation, biostimulation and combined bioaugmentation and biostimulation are 0.026 day-1, 0.164 day- 1 and 0.279 day-1, respectively. The half-life ( 2 t1/ ) of atrazine biodegradation in soil under natural bioattenuation was obtained to be 26.7 days. This was reduced to between 2.5 and 11.7 days under the application of bioaugmentation, biostimulation and combined bioaugmentation and biostimulation strategies. The bioremediation efficiencies of the different bioremediation strategies in influencing atrazine biodegradation or removal is of the following order: Combined bioaugmentation and biostimulation > Bioaugmentation with bacterial-fungal consortium > Biostimulation with poultry droppings > Bioaugmentation with Pseudomonas aeruginosa > Bioaugmentation with Bacillus subtilis > Bioaugmentation with Aspergillus niger > Natural bioattenuation

Optimization of Operating Conditions Affecting Microbiologically Influenced Corrosion of Mild Steel Exposed to Crude Oil Environments Using Response Surface Methodology.

In this study, the influence of four operating parameters (pH, salinity, nitrate concentration and immersion time) and their interactions on the microbiologically influenced corrosion (MIC) rate of mild steel in simulated crude oil environments were investigated by response surface methodology (RSM). 4-level historical data design: pH (A) at 4, 6, 8, 10, salinity (B) at 25, 50, 75 and 100 g/l, nitrate (C) at 25, 50, 75 and 100 g/l and immersion time (D) at 168, 336, 504 and 672 h, was employed to correlate the factors with the corrosion rate as response. A polynomial regression model was developed and validated prior to optimization studies. The result showed that pH has the most influential effect on the response and that the predicted data had a reasonable agreement with the experimental data with the values of R2 = 0.9660 and Adj-R2 = 0.9516. The optimum conditions of the crude oil environments were observed at: pH (9.37), salinity (94.73 g/l), nitrate concentration (37.97 g/l) and immersion time of mild steel (168 h) in order to achieve minimum corrosion rate of 0.155196 mpy. The study has revealed that the historical data RSM design is an efficient statistical technique for predicting the optimum operating conditions of crude oil environments required to minimize mild steel corrosion in oil pipelines by incorporating all factors under consideration.

Statistical Optimization of Process Variables for Biodiesel Production from Waste Cooking Oil Using Heterogeneous Base Catalyst.

In this study, the effects of methanol-to-oil molar ratio, catalyst amount and reaction time on the transesterification of waste cooking oil (WCO) to biodiesel were investigated. Methanol with calcium oxide as a heterogeneous catalyst was used for the transesterification process at a temperature of 60oC and 3000 rpm stirring speed. Response surface methodology (RSM) with central composite rotable design (CCRD) was used at five levels of oil-to-methanol molar ratio (9:1 – 14:1), catalyst (1- 5 %) and reaction time (30 – 90 min) as independent variables and WCO biodiesel yield as dependent variable (response). A statistically significant (P < 0.0001) second-order quadratic polynomial regression model with a coefficient of determination, R (= 0.9964) was obtained for biodiesel production (using Design-Expert Statistical program (v. 6.0.8)) and verification experiment confirmed the validity of the predicted model. Numerical optimization technique based on desirability function was carried out to optimize the WCO conversion to biodiesel. The optimum combinations for transesterification to achieve a predicted maximum biodiesel yield of 94.15 percent were found to be: oil-to-methanol molar ratio, 9.14:1; catalyst amount, 3.49 % and reaction time, 60.49 min. At this optimum condition, the observed biodiesel yield was found to be 94.10 percent. In addition, the fuel properties of the produced biodiesel were in the acceptable ranges according to international standards for biodiesel specifications. The statistical analyses and the closeness of the experimental results to model predictions show the reliability of the regression model and thus, the results will be helpful in selecting an efficient and economical method for biodiesel production from cheap raw materials with high free fatty acid.

Batch Equilibrium and Kinetic Studies of Simultaneous Adsorption and Biodegradation of Phenol by Pineapple Peels Immobilized Pseudomonas aeruginosa NCIB 950.

This study was aimed to investigate the use of pineapple as a cheap, eco-friendly adsorbent and support matrix for the immobilization of microbial cell and for subsequent removal of phenol from waste water. The effects of initial phenol concentration, pH and adsorbent particle size on the simultaneous adsorption-biodegradation (SAB) of phenol were studied. The batch simultaneous adsorption and biodegradation (SAB) of phenol in simulated phenol waste water by pineapple peels immobilized Pseudomonas aeruginosa NCIB 950 has been studied with the use of glass bottles as bioreactors placed in a rotary mechanical shaker for 72 h. The results of the batch equilibrium adsorption-biodegradation studies showed that adsorption-biodegradation capacity decreased with increase in particle size. The equilibrium adsorption-biodegradation data were analyzed by the Langmuir, Freundlich and Redlich-Peterson models of adsorption. The results showed that the equilibrium data for phenol degradation sorbent systems were well fitted to the three adsorption models with Langmuir and Redlich-Peterson adsorption isotherms having the best fit. The adsorption-biodegradation kinetic data obtained at different initial phenol concentrations and pH showed that the adsorption-biodegradation capacity of the pineapple peels immobilized P. aeruginosa generally increased with increase in initial phenol concentration and pH. The kinetic data were analyzed using Lagergren pseudo-first order, pseudo second-order, Elovich and intraparticle diffusion rate equations. The rate equations fitting showed that the adsorption-biodegradation kinetic data generally fitted the four rate equations tested from which the rate constants and diffusion rate constants were estimated. However, the Lagergren pseudo first-order rate equation gave the best fit and, thus the process followed first-order rate kinetics. Therefore, pineapple peels being an agricultural waste product have the potential to be used as low-cost adsorbent and support matrix for microbial culture immobilization for the removal of organic pollutant from waste water.