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Advanced treatment of Membrane Bioreactor (MBR) effluents for effective wastewater reclamation
Sarp, Sarper,Chon, Kangmin,Kim, In S.,Cho, Jaeweon IWA Publishing 2011 Water Science & Technology Vol.63 No.2
<P>One of the two main objectives of this work is to oxidize MBR effluents with ozone/peroxide in high pH conditions in order to improve oxidation of pharmaceuticals, which could efficiently be rejected by the nanofiltration (NF) stage. The other main objective is to effectively oxidize of dissolved organic carbon (DOC) in MBR effluents in order to decrease fouling in the filtration stage. In this work, ozone/peroxide oxidation was applied to the MBR effluents in high pH conditions in order to improve the formation of OH radicals, and oxidized effluents were filtered by the NF membrane (NE90) in order to investigate fouling potentials and the removal of pharmaceuticals. Natural and synthetic wastewater samples were used as feed solutions for the MBR system, which was equipped with a U-shaped hollow fiber membrane module. The flux decline was decreased from 29% to 15% when 9 mg/L of ozone was used, the same decline was also observed when 6 mg/L ozone and hydrogen peroxide (1/1 ozone/peroxide mol ratio) were used. A further decrease in flux decline was observed when pH was adjusted to 9.00 (29% to 9%) prior to the ozone/peroxide oxidation. In most cases, the increase in the ozone dose, the addition of hydrogen peroxide and the adjustment of the pH level led to an increase in the removal of pharmaceuticals. Iopromide, TCEP and Naproxen were found to be more resistant to the oxidation when pH was increased.</P>
Time-series image analysis for investigating SWRO fouling mechanism
Monruedee, Moonkhum,Sarp, Sarper,Lee, Young Geun,Kim, Joon Ha Balaban Publishers 2012 Desalination and Water Treatment Vol.43 No.1
<P> The fouling behavior of seawater reverse osmosis membranes has yet to be definitively investigated due to the complexity of seawater compositions. In this study, a time-series image analysis (TSIA) was performed to investigate the fouling mechanism using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The fouling experiments were conducted with synthetic seawater (SS) and SS mixed with humic acid substances (SHA). The effect of operational time was investigated for 2, 4, 6, 8, 12, and 20 h. According to the TSIA results, different fouling characteristics between SS and SHA experiments were observed. In the SS case, the fouling mechanism is the interaction between inorganic particles and the membrane surface as well as interaction between inorganic particles and the deposited foulants. Then, increased accumulation of deposited foulants was observed with respect to the operational time. However, in the presence of humic acid, the fouling mechanism was significantly influenced by the adsorption of humic acid onto the membrane surface at the initial stage (first 2 h). This organic layer traps inorganic particles and organic substances, and accelerates the fouling formation on the membrane surface, thereby leading to a greater flux decline compared to the SS experiment. </P>