Exo-pectinase production by Bacillus pumilus using different agricultural wastes and optimizing of medium components using response surface methodology.

In this research, the production of exo-pectinase by Bacillus pumilus using different agricultural wastes was studied. Agricultural wastes containing pectin such as wheat bran, sugar beet pulp, sunflower plate, orange peel, banana peel, apple pomace and grape pomace were tested as substrates, and activity of exo-pectinase was determined only in the mediums containing sugar beet pulp and wheat bran. Then, effects of parameters such as concentrations of solid substrate (wheat bran and sugar beet pulp) (A), ammonium sulphate (B) and yeast extract (C) on the production of exo-pectinase were investigated by response surface methodology. First, wheat bran was used as solid substrate, and it was determined that exo-pectinase activity increased when relatively low concentrations of ammonium sulphate (0.12-0.21% w/v) and yeast extract (0.12-0.3% w/v) and relatively high wheat bran (~5-6% w/v) were used. Then, exo-pectinase production was optimized by response surface methodology using sugar beet pulp as a solid substrate. In comparison to P values of the coefficients, values of not greater than 0.05 of A and B (2) showed that the effect of these process variables in exo-pectinase production was important and that changes done in these variables will alter the enzyme activity.

Kinetics of Remazol Black B adsorption onto carbon prepared from sugar beet pulp.

Dried sugar beet pulp, an agricultural solid waste, was used for the production of carbon. Carbonised beet pulp was tested in the adsorption of Remazol Black B dye, and adsorption studies with real textile wastewater were also performed. Batch kinetic studies showed that an equilibrium time of 180 min was needed for the adsorption. The maximum dye adsorption capacity was obtained as 80.0 mg g(-1) at the temperature of 25 °C at pH = 1.0. The Langmuir and Freundlich adsorption models were used for the mathematical description of the adsorption equilibrium, and it was reported that experimental data fitted very well to the Langmuir model. Mass transfer and kinetic models were applied to the experimental data to examine the mechanisms of adsorption and potential rate-controlling steps. It was found that both external mass transfer and intraparticle diffusion played an important role in the adsorption mechanisms of dye, and adsorption kinetics followed the pseudo-second-order type kinetic model. The thermodynamic analysis indicated that the sorption process was exothermic and spontaneous in nature.

Use of carbonised beet pulp carbon for removal of Remazol Turquoise Blue-G 133 from aqueous solution.

Carbonised beet pulp (BPC) produced from agricultural solid waste by-product in sugar industry was used as adsorbent for the removal of Remazol Turquoise Blue-G 133 (RTB-G 133) dye in this study. The kinetics and equilibrium of sorption process were investigated with respect to pH, temperature and initial dye concentration. Adsorption studies with real textile wastewater were also performed. The results showed that adsorption was a strongly pH-dependent process, and optimum pH was determined as 1.0. The maximum dye adsorption capacity was obtained as 47.0 mg g(-1)at the temperature of 25 °C at this pH value. The Freundlich and Langmuir adsorption models were used for describing the adsorption equilibrium data of the dye, and isotherm constants were evaluated depending on sorption temperature. Equilibrium data of RTB-G 133 sorption fitted very well to the Freundlich isotherm. Mass transfer and kinetic models were applied to the experimental data to examine the mechanisms of adsorption and potential rate-controlling steps. It was found that both external mass transfer and intra-particle diffusion played an important role in the adsorption mechanisms of dye and adsorption kinetics followed the pseudo second-order type kinetic model. The thermodynamic analysis indicated that the sorption process was exothermic and spontaneous in nature.

Removal of Chemazol Reactive Red 195 from aqueous solution by dehydrated beet pulp carbon.

An agricultural low-cost by-product, dehydrated beet pulp carbon (DBPC) was used as an adsorbent for removal of Chemazol Reactive Red 195 (CRR 195) from aqueous solution. The surface area of DBPC was measured as 9.5m(2)g(-1) by using BET method. The results indicated that adsorption was strongly pH-dependent and optimum pH was determined as 1.0. The maximum dye adsorption capacity was obtained as 58.0 mg g(-1)at the temperature of 50°C at this pH value. The Freundlich and Langmuir adsorption models were used for the mathematical description of the adsorption equilibrium and it was reported that, experimental data fitted very well to Freundlich model. Mass transfer and kinetic models were applied to the experimental data to examine the mechanisms of adsorption and potential rate-controlling steps. It was found that both external mass transfer and intra-particle diffusion played an important role in the adsorption mechanisms of dye and adsorption kinetics followed the pseudo-first-order type kinetic model. The thermodynamic parameters such as, Gibbs free energy changes (ΔG°), standard enthalpy change (ΔH°) and standard entropy change (ΔS°) had been determined. The results show that adsorption of CRR 195 on DBPC is endothermic and spontaneous in nature.

Combined effects of external mass transfer and biodegradation rates on removal of phenol by immobilized Ralstonia eutropha in a packed bed reactor.

Biodegradation of phenol by calcium-alginate immobilized Ralstonia eutropha was carried out in a batch stirred and a packed bed reactor. In the batch system studies, the effect of initial phenol concentration on biodegradation was investigated at 30 degrees C and pH 7 while in the continuous system studies, the effects of flow rate and inlet phenol concentration on biodegradation were tested at the same temperature and pH. The observed biodegradation rate constant was calculated at different flow rates with the assumption of first-order biodegradation kinetics. Various external mass transfer correlations were evaluated and a new correlation of the type JD=K(NRe)(-(n-1)) was developed with the values of K=1.34 and n=0.65. The intrinsic first-order biodegradation rate constants and the external mass transfer coefficients were calculated then the combined effects of these rates on the observed first-order biodegradation rate constants were also investigated.

Internal mass transfer effect on biodegradation of phenol by Ca-alginate immobilized Ralstonia eutropha.

Phenol biodegradation by free and Ca-alginate immobilized Ralstonia eutropha was performed in batch system. Optimum initial pH and temperature were determined as 7 and 30 degrees C, respectively for free cells, while a wide pH and temperature range were obtained for immobilized cells. Phenol had a strong inhibitory effect on the microbial growth and Haldane model was used to describe the substrate inhibition. Model parameters were determined as mumax=0.89 h(-1), KS=55.11 mg dm(-3) and KI=257.94 mg dm(-3) by non-linear regression analysis. The effective diffusion coefficient of phenol in immobilized particles was calculated. For this purpose, using biodegradation rates experimental effectiveness factors were determined for different sized immobilized particles. The Thiele modulus was evaluated from experimental effectiveness factors. Then the average effective diffusion coefficient was calculated as 1.21 x 10(-7)cm2 s(-1). These results showed that intraparticle diffusion resistance was important for this system and could not be ignored.