Effect of ozone on EOM and coagulation

Abstract

Extracellular organic matter from algae affects particle coagulation, depending on the type of algae and the concentration of the extracellular matter. Ozonation of drinking water containing algae sometimes produces beneficial effects on coagulation. These benefits are often attributed to the extracellular organic matter (EOM) from the algae. This study focused on the properties of extracted EOM from three species of algae. Ozonation of EOM reduced its apparent molecular size and hydrophobicity. Ozonation also increased the functional group charge of EOM compounds but decreased the charge as measured by the colloid charge titration. Coagulation experiments with extracted EOM indicated that only small amounts were necessary to neutralize positively charged latex particles. Ozone produced no significant effect on EOM and thus did not affect coagulation of these particles. Alginic acid, a model EOM compound, was compared with the extracted EOM and behaved similarly to the high‐molecular‐size extracted EOM.

Enhanced removal of intracellular organic matters (IOM) from Microcystic aeruginosa by aluminum coagulation

“…Tomoko et al (2007) reported that both EOM and cellular organic matter (COM) disturbed the flocculation of suspended kaolin with polymer aluminum chloride (PACl), and the non-proteinous substances within EOM may play an important role [12]. Additionally, EOM mainly acts as non-ionic polymers or anionic polyelectrolytes and shows effects thereafter [13,14]. Basically, the effects of AOM on coagulation may include two aspects.…”

Algae Removal Characteristics by Light Irradiation Using Natural Coagulants

“…In case EOM emissions due to the algae increase during summer months and the target material of the coagulant covers the surface, the induced stabilization of the particles leads to an increase in the coagulant dosage. In addition, the reduction of carbon dioxide in water due to the photosynthesis of algae raises the pH and increases the solubility of the coagulant, thus inhibiting floc formation [4].…”

Mn(VII)–Fe(II) pre-treatment for Microcystis aeruginosa removal by Al coagulation: Simultaneous enhanced cyanobacterium removal and residual coagulant control

“…The improved algae removal by pre-oxidation has been mainly attributed to the alteration in external cell membrane (Ma et al, 2012a), the impeded motion of cells (Steynberg et al, 1996) and the release of intracellular organics (Ma et al, 2012a;Chen et al, 2009). However, the oxidation of algae, if extensive, can yield cell lysis, and the subsequent massive release and degradation of intracellular organics might negatively affect the coagulation (Ma et al, 2012a;Paralkar and Edzwald, 1996). Moreover, water quality can be deteriorated by organics such as taste and odor substances, toxins, and precursors of disinfection by-products (DBPs) (Daly et al, 2007;Wert et al, 2014;Li et al, 2014;Zhou et al, 2014).…”

“…Because AOM consists of organics released from cells naturally and by artificial processes such as oxidation, it is highly valuable to achieve 'moderate pre-oxidation' of algae cells, i.e., to inactivate algae cells but avoid the extensive oxidation of algae that might lead to not only extensive increase in the concentration of DOM but the decrease in the MW of it (Ma et al, 2012a;Paralkar and Edzwald, 1996). Lower MW organics resulted from extensive oxidation were reported to be more easily biodegradable and associated with an increasing risk of DBPs formation (Bose and Reckhow, 2007;Bond et al, 2009).…”

“…The effect that DOM has on the coagulation depends on its concentration and molecular weight (MW). Organics with relatively low level and/or high MW are regarded to enhance the coagulation (Chen et al, 2009;Paralkar and Edzwald, 1996;Bernhardt et al, 1985).…”