ABSTRACT
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.
ABSTRACT
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
Subject(s)
Atrazine , Biodegradation, Environmental/methods , NigeriaABSTRACT
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.