Browsing by Author "Shao, Hsin"

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Application of TiO(2) photocatalytic oxidation and non-woven membrane filtration hybrid system for degradation of 4-chlorophenol
(2009-09-15)
Horng, Ren-Yang
;
Huang, Chihpin
;
Chang, Min-Chao
;
Shao, Hsin
;
Shiau, Be-Lain
A system coupling photocatalytic oxidation of titanium dioxide particles separated by non-woven membrane for the degradation of 4-chlorophenol in an aqueous solution was studied. Non-woven membranes with three different pore sizes were applied to compare their specific flux and permeate turbidity. The results showed that when the pore size was slightly smaller than secondary particles of photocatalyst, higher specific flux and lower turbidity permeate were obtained. Four different applied fluxes, 0.25, 0.5, 1.0 and 2.0 m(3)/m(2)/d, were used with a 2.0 mu m pore size non-woven membrane in a continuous system. The results revealed that the transmembrane pressure (TMP) was less than 10 kPa in all applied fluxes, due to the formation of a porous dynamic cake layer on the surface of the membrane. Based on the filtration characteristics of non-woven membranes, we found that cake formation, rather than pore blocking or pore narrowing, was the dominant factor. This phenomenon also resulted in permeate turbidity ranging from 0.5 to 1.5 NTU and non-detectable concentration of TiO(2) in the permeate. At the same time the experimental results indicated that the concentrations of TOC and 4-chlorophenol decreased with decreasing applied flux, and that the concentration of chloride ions increased with decreasing applied flux in a 4-chlorophenol photodegradation test. It showed that 4-chlorophenol could be effectively degraded by this hybrid system with lower TMP and stable applied flux.
Enhancement of membrane filtration ability by pretreatment of secondary effluent using a new photocatalytic oxidation system
(2009-06-01)
Horng, Ren-Yang
;
Huang, Chih-Pin
;
Chang, Min-Chao
;
Shao, Hsin
;
Ernst, Mathias
Secondary effluent including different kinds of foulants, e.g. extracellar polymeric substances (EPS), soluble microbial products (SMP), and humic acids was considered as a major barrier for wastewater reuse and reclamation when a membrane was applied to obtain high quality treated water. A new hybrid system of photocatalytic oxidation and non-woven membrane separation was studied for treating secondary effluent. Initially, the foulant properties, such as polysaccharide, protein, and biopolymer, etc., were examined in a batch test. The experimental results revealed that foulants in secondary effluent could be photodegraded. Then, a continuous experiment with this new hybrid system, three applied fluxes of 16.6, 33.3, and 50.0 L/m(2) A (LMH), was applied to investigate the photodegradation ability and the filtration behavior. The results revealed that the concentration of foulants in permeate increased with increasing applied flux, due to the reduction of hydraulic retention time (HRT). In comparison with the system using microfiltration (MF) or ultrafiltration (UF) membrane, larger specific flux was obtained in our non-woven membrane system. In addition, a batch-stirred cell test using UF membrane was performed to compare filtration performance before and after photodegradation in secondary effluent. Such results proved that this new hybrid system was an effective treatment process for foulant removal in secondary effluent.