Interaction of ozone and organic matter in coagulation with inorganic polymer flocculant-PACl: Role of organic components

Abstract

a b s t r a c t a r t i c l e i n f oIn this study, two model waters were used to evaluate the ozone effect on aquatic organic matter (AOM) removal by coagulation with inorganic polymer flocculant (IPF)-polyaluminum chloride (PACl). Flocs formation during coagulation processes were detected by using PDA (Photometric Dispersion Analyzer). Apparent molecular weight distribution (AMWD) and resin fractionation (RF) were also performed to characterize the change of AOM as a result of pre-ozonation. The experimental results show that the dosage of O 3 , characteristics and composition of AOM are the most important factors on the behavior of coagulation. Great differences have been found between the two model waters. Coagulation in model water 1 (MW1) (composed of humic acids) is impaired markedly by pre-ozonation, as more DOC (Dissolved Organic Carbon) is produced with increasing O 3 dosage. Floc formation, as exhibited from decreasing of the slopes of FI (Flocculation Index), is retarded gradually during coagulation process. Although residual turbidity is reduced with 1.15 mg/L O 3 , removals of DOC and UV 254 all decreased. As for model water 2 (MW2) (composed of salicylic acid), FI is retarded also, but turbidity and DOC removals of coagulation after pre-ozonation are improved to a certain extent. Coagulation performance judged from removal of DOC is improved distinctly by pre-ozonation. Fractionation results show that molecular weight of organic matter (OM) of MW1 is converted from higher to lower; and OM becomes from more hydrophobic to more hydrophilic, which might be one of the mechanisms involved in the impairment of ozonation on coagulation effect. OM in MW2 is oxidized and mineralized to a greater extent, thus its impairment on coagulation is released. Finally, according to water properties, some proposed applications were provided for application of ozone in water treatment process.

Impact of ozonation on particle aggregation in mature fine tailings

“…This effect may be caused by desorption of the organic compounds coating the MFT surfaces and/or conversion of high molecular weight matter to lower molecular weight compounds with hydroxyl and carboxylic groups. This finding is consistent with the findings from previous studies (Edwards et al, 1993;Jekel, 1991;Liu et al, 2009). Since the high molecular weight fractions are degraded and compounds of higher polarity are formed by ozonation, the resulting organic matter is less adsorbable on mineral particles such as silicon dioxide and kaolinite (Bonneville and Smith, 2001;Farvardin and Collins, 1989;Jekel, 1991).…”

Biological Pre-treatment of Poultry Slaughterhouse Wastewater

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