Browsing by Author "Reguyal, Febelyn"

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Fouling Elimination of PTFE Membrane under Precoagulation Process Combined with Ultrasound Irradiation
(2012-03-01)
Wan, Meng-Wei
;
Yang, Hui-Ling
;
Chang, Cheng-Hung
;
Reguyal, Febelyn
;
Kan, Chi-Chuan
Precoagulation is one of the effective pretreatments in membrane filtration. This process mitigates membrane fouling, which is the major drawback of membrane technology in drinking water and wastewater treatment. This study investigated the effects of precoagulation under different coagulation mechanisms on membrane fouling. Use of ultrasound in polytetrafluoroethylene (PTFE) membrane cleaning was also evaluated. In precoagulation, synthetic raw water was precoagulated using aluminum sulfate at different coagulation mechanisms, named electrostatic patch effect (EPE), charge neutralization (CN), and sweep flocculation (SW). Flocs produced from different coagulation mechanisms exhibited different sizes, structures, and strengths. Likewise, the fouling type generated from each mechanism was demonstrated as pore blocking for EPE, cake formation for SW, and combination phenomenon for CN. Moreover, this study indicated that the membrane flux was enhanced in the sequence of EPE > CN > SW. The flux recovery rate after ultrasonic cleaning was in the sequence of SW > CN > EPE. Finally, this study evidenced that the floc characteristics from various coagulation mechanisms affected membrane performance, fouling types, and ultrasonic cleaning efficiency. DOI: 10.1061/(ASCE)EE.1943-7870.0000406. (C) 2012 American Society of Civil Engineers.
Ultrasound irradiation combined with hydraulic cleaning on fouled polyethersulfone and polyvinylidene fluoride membranes
(2013)
Wan, Meng-Wei
;
Reguyal, Febelyn
;
Futalan, Cybelle
;
Yang, Hui-Ling
;
Kan, Chi-Chuan
In this study, an ultrasonic irradiation technique was utilized to mitigate the fouling of polyethersulfone (PES) and polyvinylidene fluoride ( PVDF) membranes. The use of ultrasound at 20 kHz was applied to a dead-end microfiltration cell in order to mitigate fouling caused by the presence of colloidal bentonite particles. The effect of ultrasonic power and pulse duration on the permeate flux recovery was examined. Measurements indicate that an increase in ultrasonic power and longer pulse duration results to a higher permeate flux recovery. In order to reduce power consumption, a low to high power shift (LHPS) and pulsation method, were investigated. Methods of cleaning such as ultrasonic irradiation, ultrasonic cleaning with forward flushing and ultrasonic cleaning with backwashing were utilized and their cleaning efficiencies were examined. The cleaning performance was assessed using the clean water flux method and scanning electron microscope analysis of the cleaned membranes. Results showed that LHPS and pulsation method both improve the permeate flux recovery but were not able to attain the 93.97 and 74.88% flux recovery for PES and PVDF that was achieved by constant-15 W ultrasonic cleaning. In addition, forward flushing and backwashing may enhance the performance of ultrasonic cleaning at 9 W but could become disadvantageous at 15 W.