Tag Archives: advanced oxidation

UV-light emitting diodes for advanced oxidation processes

Olivier Autin, Christophe Romelot, Lena Rust, Julie Hart, Peter Jarvis, Jitka MacAdam, Simon A. Parsons. Evaluation of a UV-light emitting diodes unit for the removal of micropollutants in water for low energy advanced oxidation processes. Chemosphere, Volume 92, Issue, July 2013, Pages 745–751.

There is growing interest in using light emitting diodes (LEDs) as alternative to traditional mercury lamps for the removal of micropollutants by advanced oxidation processes due to their low energy consumption and potential for high efficiency and long lifetime. This study investigates the penetration and coverage of the light emitted by LEDs in order to build an optimised LED collimated beam apparatus. From the experimental data, cost analysis was conducted in order to identify when LEDs will become economically viable. It was observed that if their development follows the predictions, LEDs should be a viable alternative to traditional lamps within 7 yr for both UV/H2O2 and UV/TiO2 processes. However, parameters such as wall plug efficiency and input power need to improve for LEDs to become competitive.

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Wang et al 2011: Effects of advanced oxidation pretreatment on residual aluminum control in high humic acid water purification

W. Wang, H. Li, Z. Ding, and X. Wang. Effects of advanced oxidation pretreatment on residual aluminum control in high humic acid water purification. J Environ Sci (China). 2011;23(7):1079-85.

School of Environmental and Municipal Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, China. wwd@xauat.edu.cn

Due to the formation of disinfection by-products and high concentrations of Al residue in drinking water purification, humic substances are a major component of organic matter in natural waters and have therefore received a great deal of attention in recent years. We investigated the effects of advanced oxidation pretreatment methods usually applied for removing dissolved organic matters on residual Al control. Results showed that the presence of humic acid increased residual Al concentration notably. With 15 mg/L of humic acid in raw water, the concentrations of soluble aluminum and total aluminum in the treated water were close to the quantity of Al addition. After increasing coagulant dosage from 12 to 120 mg/L, the total-Al in the treated water was controlled to below 0.2 mg/L. Purification systems with ozonation, chlorination, or potassium permanganate oxidation pretreatment units had little effects on residual Al control; while UV radiation decreased Al concentration notably. Combined with ozonation, the effects of UV radiation were enhanced. Optimal dosages were 0.5 mg O3/mg C and 3 hr for raw water with 15 mg/L of humic acid. Under UV light radiation, the combined forces or bonds that existed among humic acid molecules were destroyed; adsorption sites increased positively with radiation time, which promoted adsorption of humic acid onto polymeric aluminum and Al(OH)3(s). This work provides a new solution for humic acid coagulation and residual Al control for raw water with humic acid purification.