The impact of algal properties and pre-oxidation on solid–liquid separation of algae

• Published in: Water research (Oxford) Vol. 42; no. 8; pp. 1827 - 1845
• Main Authors: Henderson, Rita, Parsons, Simon A., Jefferson, Bruce
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.04.2008; Elsevier Science
• Subjects: Algae; algae and seaweeds; Applied sciences; cell motility; coagulants; Coagulation; dissolved air flotation; Eukaryota - isolation & purification; Eukaryota - physiology; Exact sciences and technology; Filtration; flocculation; Flotation; literature reviews; organic matter; Other industrial wastes. Sewage sludge; oxidation; Oxidation-Reduction; physical properties; plant morphology; Pollution; population density; processing stages; Sedimentation; solid-liquid separation; surface active properties; surface area; surface charge; Wastes; water treatment; Water treatment and pollution; Flotation; Filtration; Sedimentation; Algae; Coagulation; Water treatment; Surface charge; Organic matter; Motility; Algae,Coagulation,Filtration,Flotation,Sedimentation; Optimization; Solid liquid separation; Flocculation reagent; Flocculation; Morphology; Physicochemical purification; Oxidation
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2007.11.039

Algae are traditionally classified according to biological descriptors which do not give information on surface characteristics that are important with respect to removal by water treatment processes. This review examines the character of freshwater algal populations from a water treatment perspective and evaluates the impact of their varying properties and the use of pre-oxidation on their removal by solid–liquid separation processes.. The characteristics shown to impact on treatment were morphology, motility, surface charge, cell density and the extracellular organic matter (EOM) composition and concentration. With the exception of density, these are not phyla specific. It was also shown that dissolved air flotation (DAF) was the most robust clarification method, where up to 99.8% removal was achieved compared to 94% for sedimentation when using metal coagulants. However, successful clarification relied heavily on the optimisation of preceding coagulation and flocculation and coagulant demand was important in this respect. Comparison of all available data reveals a relationship between cell surface area and coagulant demand. It is thus suggested that cell surface area would provide a basis for regrouping algae such that the classification is informative with respect to water treatment. However, the absolute coagulant demand is a result of both surface area and EOM influences. The latter are relatively poorly understood in comparison to natural organic matter (NOM) systems and this remains a limit in current knowledge.