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Hydrodynamic and kinetic study of a hybrid detoxification process with zero liquid discharge system in an industrial wastewater treatment.

Abid MF, Abdulrahman AA, Hamza NH - J Environ Health Sci Eng (2014)

Bottom Line: The analysis results confirmed that the water from the Hybrid-System could be safely recycled and reuse.It was found that the kinetics of dye degradation was first order with respect to dye concentration and could be well described by Langmuir-Hinshelwood model.A power-law based empirical correlation was developed for the photocatalysis system, related the dye degradation (R) with studied operating conditions.

View Article: PubMed Central - PubMed

Affiliation: Chemical Engineering Department, University of Technology, Baghdad, Iraq.

ABSTRACT
This work focused on the degradation of toxic organic compounds such as methyl violet dye (MV) in water, using a combined photocatalysis/low pressure reverse osmosis (LPRO) system. The performance of the hybrid system was investigated in terms of the degradation efficiency of MV, COD and membrane separation of TiO2. The aim of the present study was to design a novel solar reactor and analyze its performance for removal of MV from water with titanium dioxide as the photocatalyst. Various operating parameters were studied to investigate the behavior of the designed reactor like initial dye concentration (C = 10-50 mg/L), loading of catalyst (CTiO2 = 200-800 mg/L), suspension flow rate (QL = 0.3-1.5 L/min), pH of suspension (5-10), and H2O2 concentration (CH2O2 = 200-1000 mg/L). The operating parameters were optimized to give higher efficiency to the reactor performance. Optimum parameters of the photocatalysis process were loading of catalyst (400 mg/L), suspension flow rate (0.5 L/min), H2O2 concentration (400 mg/L), and pH = 5. The designed reactor when operating at optimum conditions offered a degradation of MV up to 0.9527 within one hours of operation time, while a conversion of 0.9995 was obtained in three hours. The effluent from the photocatalytic reactor was fed to a LPRO separation system which produced permeate of turbidity value of 0.09 NTU which is closed to that of drinking water (i.e., 0.08 NTU). The product water was analyzed using UV-spectrophotometer and FTIR. The analysis results confirmed that the water from the Hybrid-System could be safely recycled and reuse. It was found that the kinetics of dye degradation was first order with respect to dye concentration and could be well described by Langmuir-Hinshelwood model. A power-law based empirical correlation was developed for the photocatalysis system, related the dye degradation (R) with studied operating conditions.

No MeSH data available.


Related in: MedlinePlus

Variation of dye degradation with illuminated time at different liquid flow rate (CMV = 30 mg/L, CTiO2 = 400 mg/L, pH = 5, and CH2O2 = 400 mg/L).
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Fig10: Variation of dye degradation with illuminated time at different liquid flow rate (CMV = 30 mg/L, CTiO2 = 400 mg/L, pH = 5, and CH2O2 = 400 mg/L).

Mentions: Falling–film reactors characterized by a high ratio of exposure (surface area to liquid volume), which positively impact the performance of such type of reactors. Flow rate of synthetic wastewater is another important parameter which must be considered. Effect of liquid flow rate on the dye degradation and COD removal was tested by taking various flow rates from (0.3 to 1.5 L/min) keeping all other parameters unchanged at (CMV = 30 mg/L, = 400 mg/L, = 400 mg/L, and pH = 5). Figure 10 illustrates the variation of the dye degradation against illuminated time. As can be seen from Figure 10 that liquid flow rate has negative impact on degradation rate. This may be explained from the view point of shorter contact time of aqueous suspension with illumination source as the recirculation rate increased. Figure 11 illustrates the influence of liquid flow rate on the COD of the reactor effluent. It can be concluded from the graph that effluent with 0.5 L/min has undergone almost complete degradation at 180 min of solar exposure which indicated that resulted water could be recycled in the process. When the liquid flow rate increased to 1.5 L/min, COD of the reactor effluent has dropped to 241 mg/L which indicates the necessity for further light exposure. This could be firstly due to the limitation of the solar light penetration because of rise in the liquid thickness and secondly to the reduction of the residence time of substrate which lead to reduce the surface reaction efficiency. Figure 12 shows dye degradation against Reynolds number of the liquid falling–film. The liquid Reynolds number NRe can be calculated from equation (3) [33].3\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$ {\mathrm{N}}_{\mathrm{Re}}=4{\mathrm{Q}}_{\mathrm{L}}{\uprho}_{\mathrm{L}}/{\mathrm{W}\upmu}_{\mathrm{L}} \cos \upbeta $$ \end{document}NRe=4QLρL/WμLcosβwhere QL = Liquid flow rate (m3/s), ρL = Density of water (kg/m3), W = Width of reactor, μL = Dynamic viscosity of water (kg/m. s), and β = altitude angle. As can be seen, the impact of liquid Reynolds number on dye degradation shows a positively increasing trend to a point where all the surface of the photocataytic reactor was covered with a thin falling–film of synthetic wastewater, where dye degradation reported 99.95% at NRe = 69.2 after then dye degradation started to decrease with further increasing of liquid flow rate at NRe = 138.4, NRe = 207.6, and NRe = 276.6 the dye degradation were 82.3%, 64.4%, and 40.32%, respectively. This may be attributed to decreasing the residence time of reactants as the liquid flow rate increased.Figure 10


Hydrodynamic and kinetic study of a hybrid detoxification process with zero liquid discharge system in an industrial wastewater treatment.

Abid MF, Abdulrahman AA, Hamza NH - J Environ Health Sci Eng (2014)

Variation of dye degradation with illuminated time at different liquid flow rate (CMV = 30 mg/L, CTiO2 = 400 mg/L, pH = 5, and CH2O2 = 400 mg/L).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4308886&req=5

Fig10: Variation of dye degradation with illuminated time at different liquid flow rate (CMV = 30 mg/L, CTiO2 = 400 mg/L, pH = 5, and CH2O2 = 400 mg/L).
Mentions: Falling–film reactors characterized by a high ratio of exposure (surface area to liquid volume), which positively impact the performance of such type of reactors. Flow rate of synthetic wastewater is another important parameter which must be considered. Effect of liquid flow rate on the dye degradation and COD removal was tested by taking various flow rates from (0.3 to 1.5 L/min) keeping all other parameters unchanged at (CMV = 30 mg/L, = 400 mg/L, = 400 mg/L, and pH = 5). Figure 10 illustrates the variation of the dye degradation against illuminated time. As can be seen from Figure 10 that liquid flow rate has negative impact on degradation rate. This may be explained from the view point of shorter contact time of aqueous suspension with illumination source as the recirculation rate increased. Figure 11 illustrates the influence of liquid flow rate on the COD of the reactor effluent. It can be concluded from the graph that effluent with 0.5 L/min has undergone almost complete degradation at 180 min of solar exposure which indicated that resulted water could be recycled in the process. When the liquid flow rate increased to 1.5 L/min, COD of the reactor effluent has dropped to 241 mg/L which indicates the necessity for further light exposure. This could be firstly due to the limitation of the solar light penetration because of rise in the liquid thickness and secondly to the reduction of the residence time of substrate which lead to reduce the surface reaction efficiency. Figure 12 shows dye degradation against Reynolds number of the liquid falling–film. The liquid Reynolds number NRe can be calculated from equation (3) [33].3\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$ {\mathrm{N}}_{\mathrm{Re}}=4{\mathrm{Q}}_{\mathrm{L}}{\uprho}_{\mathrm{L}}/{\mathrm{W}\upmu}_{\mathrm{L}} \cos \upbeta $$ \end{document}NRe=4QLρL/WμLcosβwhere QL = Liquid flow rate (m3/s), ρL = Density of water (kg/m3), W = Width of reactor, μL = Dynamic viscosity of water (kg/m. s), and β = altitude angle. As can be seen, the impact of liquid Reynolds number on dye degradation shows a positively increasing trend to a point where all the surface of the photocataytic reactor was covered with a thin falling–film of synthetic wastewater, where dye degradation reported 99.95% at NRe = 69.2 after then dye degradation started to decrease with further increasing of liquid flow rate at NRe = 138.4, NRe = 207.6, and NRe = 276.6 the dye degradation were 82.3%, 64.4%, and 40.32%, respectively. This may be attributed to decreasing the residence time of reactants as the liquid flow rate increased.Figure 10

Bottom Line: The analysis results confirmed that the water from the Hybrid-System could be safely recycled and reuse.It was found that the kinetics of dye degradation was first order with respect to dye concentration and could be well described by Langmuir-Hinshelwood model.A power-law based empirical correlation was developed for the photocatalysis system, related the dye degradation (R) with studied operating conditions.

View Article: PubMed Central - PubMed

Affiliation: Chemical Engineering Department, University of Technology, Baghdad, Iraq.

ABSTRACT
This work focused on the degradation of toxic organic compounds such as methyl violet dye (MV) in water, using a combined photocatalysis/low pressure reverse osmosis (LPRO) system. The performance of the hybrid system was investigated in terms of the degradation efficiency of MV, COD and membrane separation of TiO2. The aim of the present study was to design a novel solar reactor and analyze its performance for removal of MV from water with titanium dioxide as the photocatalyst. Various operating parameters were studied to investigate the behavior of the designed reactor like initial dye concentration (C = 10-50 mg/L), loading of catalyst (CTiO2 = 200-800 mg/L), suspension flow rate (QL = 0.3-1.5 L/min), pH of suspension (5-10), and H2O2 concentration (CH2O2 = 200-1000 mg/L). The operating parameters were optimized to give higher efficiency to the reactor performance. Optimum parameters of the photocatalysis process were loading of catalyst (400 mg/L), suspension flow rate (0.5 L/min), H2O2 concentration (400 mg/L), and pH = 5. The designed reactor when operating at optimum conditions offered a degradation of MV up to 0.9527 within one hours of operation time, while a conversion of 0.9995 was obtained in three hours. The effluent from the photocatalytic reactor was fed to a LPRO separation system which produced permeate of turbidity value of 0.09 NTU which is closed to that of drinking water (i.e., 0.08 NTU). The product water was analyzed using UV-spectrophotometer and FTIR. The analysis results confirmed that the water from the Hybrid-System could be safely recycled and reuse. It was found that the kinetics of dye degradation was first order with respect to dye concentration and could be well described by Langmuir-Hinshelwood model. A power-law based empirical correlation was developed for the photocatalysis system, related the dye degradation (R) with studied operating conditions.

No MeSH data available.


Related in: MedlinePlus