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Bazri M.M.,University of British Columbia | Martijn B.,PWN Technologies andijk | Kroesbergen J.,Het Waterlaboratorium | Mohseni M.,University of British Columbia
Chemosphere | Year: 2016

The formation potential of carbonaceous and nitrogenous disinfection by-products (C-DBPs, N-DBPs) after ion exchange treatment (IEX) of three different water types in multiple consecutive loading cycles was investigated. Liquid chromatography with organic carbon detector (LC-OCD) was employed to gauge the impact of IEX on different natural organic matter (NOM) fractions and data obtained were used to correlate these changes to DBPs Formation Potential (FP) under chlorination. Humic (-like) substances fractions of NOM were mainly targeted by ion exchange resins (40-67% removal), whereas hydrophilic, non-ionic fractions such as neutrals and building blocks were poorly removed during the treatment (12-33% removal). Application of ion exchange resins removed 13-20% of total carbonaceous DBPs FP and 3-50% of total nitrogenous DBPs FP. Effect of the inorganic nitrogen (i.e., Nitrate) presence on N-DBPs FP was insignificant while the presence of dissolved organic nitrogen (DON) was found to be a key parameter affecting the formation of N-DBPs. DON especially the portion affiliated with humic substances fraction, was reduced effectively (~77%) as a result of IEX treatment. © 2015 Elsevier Ltd. Source

Galjaard G.,PWN Technologies andijk | Clement J.,PWN Technologies andijk | Ang W.S.,Singapores National Water Agency | Lim M.H.,Singapores National Water Agency
Water Practice and Technology | Year: 2012

Ceramic membrane technology is used in water treatment due to the robustness of ceramic membranes, but ceramic membrane systems are costly as each membrane module is housed in individual casing. PWNT has developed a ceramic membrane system called the CeraMac which greatly reduced the capital cost of installing the system by housing up to 200 modules in a single stainless steel vessel. PWNT and PUB have jointly started a 18-month operation at Choa Chu Kang Waterworks (CCKWW). In this paper, the results of the optimization runs using settled water as feed has shown that membrane operation at flux of 200 lmh can be sustained with stable transmembrane pressure (TMP) and permeability, and the proposal to apply 0.5 mg/L residual ozone to the feed to investigate the effect of ozonated feed on membrane operational performance and fouling will be discussed. © IWA Publishing 2012. Source

Zheng J.,PWN Technologies andijk | Galjaard G.,PWN Technologies andijk | Shorney-Darby H.,PWN Technologies andijk
Water Practice and Technology | Year: 2015

A sustainable membrane operation often requires pretreatment of the feed liquor to improve its technical and economic feasibility. This paper reports the impact of pretreatment on the performance of ceramic microfiltration for several pilot studies at different locations. Four different pretreatment processes were investigated: (1) in-line coagulation (to remove high molecular weight, HMW, dissolved organic carbon, DOC); (2) ion exchange (to remove low molecular weight, LMW, DOC); (3) ozone (for disinfection, taste and odor control, and modifying the character of DOC) (4) ion exchange followed by in-line coagulation (for almost complete removal of DOC). Pretreatment in all cases was needed to control membrane fouling, to establish a technically and economically feasible process. These studies seem to show that the DOC’s HMW (which includes biopolymers) and LMW fractions (the latter includes humics/acids), are primarily responsible for the TMP increase after filtration followed by backwashing (irreversible fouling). Removing one of these organic fractions often results in more stable operation. Ozonation in all cases led to better operation, but is not always economically feasible. The feasibility of ozone as pre-treatment depends largely on the initial ozone demand, and whether or not there are secondary treatment targets (e.g., higher virus removal, taste, and/or odor). © IWA Publishing 2015. Source

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