Determination of parameters affecting kinetic and thermodynamic values for lead removal Using wastewater treatment plant sewage sludge ash

ABSTRACT. In this study, treatment of lead containing wastewater using sewage sludge ash obtained from the incineration unit in the domestic wastewater treatment plant in Gaziantep province in Turkey was investigated. The main purpose of the study is to determine the potential of using the treatment sludge ash, which comes out as waste in the treatment plant, in the treatment of wastewater of another industry. As a result of this study, the most suitable adsorption conditions were determined and focused on the kinetics of adsorption. In the experiments, the lead adsorption capacity of sewage sludge ash was determined as 122 mg g-1 at 0.5 g L-1 adsorbent concentration in wastewater containing 100 mg L-1 Pb2+ under optimum conditions. As a result of the research, it was determined that the adsorption reaction proceeds according to the pseudo second degree reaction and is suitable for the Langmuir isotherm. As thermodynamic constants, ΔH° = 7.407 kJ mol-1 and ΔS° = 33.25 J mol-1 were determined. As a result of this, it was determined that the adsorption reaction was endothermic, spontaneous and random, and adsorption was physical adsorption. The results show that sewage sludge ash can be used in the treatment of water containing high concentrations of Pb2+.     KEY WORDS: Adsorption, Heavy metal, Lead removal, Sewage sludge ash Bull. Chem. Soc. Ethiop. 2022, 36(4), 935-948.                                                               DOI: https://dx.doi.org/10.4314/bcse.v36i4.18                                                     &nbsp

STOCHASTIC ENVIRONMENTAL RESEARCH AND RISK ASSESSMENT

In this study, the removal of nitrate ions from aqueous solutions with liquid membrane technique has been investigated for different organic solvent types in which solubilized tetradecyl trimethyl ammonium bromide (TDTMABr) as carrier. n-butyl alcohol, chloroform, and mixture of chloroform + n-hexane (n-hexane 85% + chloroform 15%) were used as organic solvent. Kinetic parameters (k(1d), k(2m), k(2a), t(max), R-m(max), J(m)(max), J(a)(max)) were calculated from obtained data. time R-a values of mixture, butyl alcohol, and chloroform are 0.81, 0.78, and 0.55, respectively. Similarly R-d, R-m, and t(max) values of the mixture equal to 0.14, 0.04, and 87.92 min, respectively. This behavior of the system shows the organic solvent type is an effective parameter on separation yield. It can be concluded that the mixture is the most effective organic solvent type among the investigated ones, because liquid membrane systems should be operated within the range of having the R-m, R-d, and t(max) values are minimum while R-a values are maximum

Optimization of specific energy consumption for Bomaplex Red CR-L dye removal from aqueous solution by electrocoagulation using Taguchi-neural method

In this investigation, firstly, Taguchi method was applied to determine the optimum specific energy consumption (SEC) for dye removal from aqueous solution by electrocoagulation using aluminum electrodes. An orthogonal array (OA(16)) experimental design that allows to investigate the simultaneous variations of five parameters (Initial dye concentration, Initial pH of the solution, Supporting electrolyte concentration, Supporting electrolyte type and Current density) having four levels was employed to evaluate the effects of experimental parameters with two replicates. According to Taguchi-neural method, while the optimum conditions that dye removal efficiency equals to 62.71 % were found to be initial dye concentration 600 mg/L, initial pH of the solution 6, supporting electrolyte concentration 7.0 mM, supporting electrolyte type NaCl, and current density 0.10 mA/cm(2). Under these optimum conditions, energy consumption is 0.38 kW h/m(3). Alternatively, it can be said that optimum conditions can be modified as follows supporting electrolyte concentration of 10.0 mM and supporting electrolyte type CaCl2, for 600 mg/L, initial dye concentration initial pH of the solution 6, and current density 0.10 mA/cm(2). Under these optimum conditions, SEC and dye removal efficiency are 0.45 kW h/m(3) and 69.18 %, respectively. In this investigation, firstly, Taguchi method was applied to determine the optimum specific energy consumption (SEC) for dye removal from aqueous solution by electrocoagulation using aluminum electrodes. An orthogonal array (OA16) experimental design that allows to investigate the simultaneous variations of five parameters (Initial dye concentration, Initial pH of the solution, Supporting electrolyte concentration, Supporting electrolyte type and Current density) having four levels was employed to evaluate the effects of experimental parameters with two replicates. According to Taguchi-neural method, while the optimum conditions that dye removal efficiency equals to 62.71 %were found to be initial dye concentration 600 mg/L, initial pH of the solution 6, supporting electrolyte concentration 7.0 mM, supporting electrolyte type NaCl, and current density 0.10 mA/cm2. Under these optimum conditions, energy consumption is 0.38 kW h/m3. Alternatively, it can be said that optimum conditions can be modified as follows supporting electrolyte concentration of 10.0 mM and supporting electrolyte type CaCl2, for 600 mg/L, initial dye concentration initial pH of the solution 6, and current density 0.10 mA/cm2. Under these optimum conditions, SEC and dye removal efficiency are 0.45 kW h/m3 and 69.18 %, respectively.</p

The effects of pH on phosphate removal from wastewater by electrocoagulation with iron plate electrodes

In this study, the effect of pH on phosphate removal from wastewater by electrocoagulation with iron plate electrodes has been investigated. For this aim, experiments have been carried out controlled initial pH values within the range of 3-9. Effects of initial pH have been analyzed on efficiencies of phosphate removal and energy consumptions. From obtained results, it was found that optimal initial pH is 3. Besides, experiments have been carried out controlled system pH. Effects of system variables have been analyzed on constant pH. From obtained results in these experiments, it was found that optimal system pH is 7. (c) 2006 Elsevier B.V. All rights reserved

Optimization of phosphate removal from wastewater by electrocoagulation with aluminum plate electrodes

The Taguchi method was used to determine the optimum conditions for the phosphate removal from wastewater by electrocoagulation with aluminum plate electrodes. The experimental parameters investigated were initial phosphate concentration, initial pH of the wastewater, supporting electrolyte concentration, supporting electrolyte type and current density. The ranges of experimental parameters were between 50 and 500 mg/L (as PO4-P), 4-7 for initial pH, 0-10 mM, NaCl, NaNO3, Na2SO4 and CaCl2 and 0.25-1.00 mA/cm(2) mm for initial phosphate concentration, initial pH of the wastewater, supporting electrolyte concentration, supporting electrolyte type and current density, respectively. Reaction period was kept constant in 25 min for statistical analysis. The optimum conditions for these parameters were found to be 50 mg/L, 4,5 mM, NaCl and 1.00 mA/cm(2), respectively. Under these conditions, the predicted and experimental removal efficiency of phosphate from wastewater by electrocoagulation with aluminum plate electrodes were 99.9 and 100.0%, respectively. A statistical analysis of variance (ANOVA) was performed to see whether the process parameters were statistically significant or not. According to the F-test results, it can be concluded that the degrees of the influences of parameters on the removal efficiency is initial phosphate concentration, current density and initial pH of the solution. (c) 2006 Elsevier B.V. All rights reserved

Organic and inorganic matter removal from tannery wastewater using the electrocoagulation process

In this study, the effect of current density and stirring speed on treatment of tannery wastewaters by the electrocoagulation process using aluminum electrodes was investigated. In the studies, it was determined that the stirring speed did not have much effect on the removal efficiency, but increased the reaction rate. While the second degree reaction rate constant is k(2) = 0.0444 L g(-1) min(-1) at 100 rpm stirring speed, this value increases to k(2) = 0.1261 L g(-1) min(-1) when the stirring speed is increased to 400 rpm. Although the COD removal efficiencies at 0.6 and 1.2 mA cm(-2) current densities were almost the same, the COD removal efficiencies decreased at 1.8 and 2.4 mA cm(-2) current densities. However, while the treatment time was approximately 50 min at 0.6 mA cm(-2) current density, this time decreased to 25 min at 1.2 mA cm(-2) current density. At the end of 60 min of retention time under the determined optimum conditions, 84% COD, 98% turbidity, 97% oil-grease, 98% chromium, 68% total nitrogen, 100% phosphate and 79% sulfate removal efficiencies were obtained. The energy consumption of the system was calculated as 2.37 kWh m(-3). In the cost analysis studies, it was concluded that the increase in current intensity did not have much effect on the treatment efficiency, but increased the treatment cost. While the electricity and electrode cost of the system at 0.6 A current intensity was 0.239 $m(-3), this cost was obtained as 0.8817$ m(-3) for 2.4 A

Effect of organic solvent type on the removal of nitrate ion using liquid membrane technique

In this study, the removal of nitrate ions from aqueous solutions with liquid membrane technique has been investigated for different organic solvent types in which solubilized tetradecyl trimethyl ammonium bromide (TDTMABr) as carrier. n-butyl alcohol, chloroform, and mixture of chloroform + n-hexane (n-hexane 85% + chloroform 15%) were used as organic solvent. Kinetic parameters (k(1d), k(2m), k(2a), t(max), R-m(max), J(m)(max), J(a)(max)) were calculated from obtained data. time R-a values of mixture, butyl alcohol, and chloroform are 0.81, 0.78, and 0.55, respectively. Similarly R-d, R-m, and t(max) values of the mixture equal to 0.14, 0.04, and 87.92 min, respectively. This behavior of the system shows the organic solvent type is an effective parameter on separation yield. It can be concluded that the mixture is the most effective organic solvent type among the investigated ones, because liquid membrane systems should be operated within the range of having the R-m, R-d, and t(max) values are minimum while R-a values are maximum

The effects of current density and phosphate concentration on phosphate removal from wastewater by electrocoagulation using aluminum and iron plate electrodes

In this study, effects of initial phosphate concentrations and current densities on the phosphate removal by electrocoagulation using either aluminum or iron plate as electrodes were investigated