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Tawfik A.,Egypt Japan University of Science and Technology st | Zaki D.,Center for Monitoring Research | Zahran M.,Helwan University
Sustainable Environment Research | Year: 2014

Decolorization of reactive dyes wastewater in an up-flow anaerobic sludge blanket (UASB) coupled with down-flow hanging sponge (DHS) was investigated with a total hydraulic retention time of 8 h. The UASB and DHS achieved color removal efficiencies of 64 ± 17 and 41 ± 13% respectively, while the overall removal efficiency of the combined system was reached up to 78 ± 12%. For enhancement of the decolourization of the combined system, reactive dye wastewater was supplemented with either 1 mg L-1 cationic or 1 mg L-1 anionic polymer. Results indicated, the overall removal efficiency of color was slightly improved (80 ± 12%) in case of addition of cationic polymer to the influent wastewater. In contrast, the addition of anionic polymer reduced the decolourization process (25 ± 13%). However, the UASB/DHS system achieved similar removals of 65 ± 6, 90 ± 9, 84 ± 7 and 99 ± 1% for chemical oxygen demand, biochemical oxygen demand, total suspended solids and turbidity, respectively. Source

Gar Alalm M.,Egypt Japan University of Science and Technology st | Tawfik A.,Egypt Japan University of Science and Technology st | Ookawara S.,Tokyo Institute of Technology
Desalination and Water Treatment | Year: 2014

Solar photocatalytic degradation of phenol by TiO2 (p25), which was immobilized on powdered activated carbon (TiO2/AC) by temperature impregnation method, was investigated. Solar compound parabolic collectors reactor with a capacity of 4.0 L was used. Characterization of TiO2/AC by Brunauer–Emmett–Teller analysis, Fourier transform infrared spectroscopy, and scanning electron microscope revealed successful impregnation of TiO2 particles on activated carbon (AC). Fifty three percent degradation of phenol was recorded at irradiation time of 30 min and increased up to 80% after 150 min using TiO2. This was not the case for TiO2/AC, where the phenol was rapidly removed by a value of 40% within 15 min and complete degradation of phenol was attained at illumination time of 120 min. This indicates that immobilization of TiO2 on AC is very effective for phenol degradation. Moreover, in TiO2/AC photocatalysis, the presence of aromatic intermediates (catechol, hydroquinone, and p-benzoquinone) was relatively lower as compared to TiO2 photocatalysis. However, TiO2/AC photocatalysis of phenol degradation is strongly affected by pH values and dosage of the catalyst, i.e. complete degradation of phenol was occurred at pH value of 5.3 and dosage of 1.2 g/L. The photocatalytic degradation of phenol by TiO2/AC followed the pseudo-first-order kinetic according to Langmuir–Hinshelwood model. Costs estimation of full-scale solar oxidation plant with life time of 20 years was assessed. The results showed that complete removal of phenol using TiO2/AC costs 3.19 €/m3. © 2014 Balaban Desalination Publications. All rights reserved. Source

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