Flocculation: Processes and Applications

0497263 - ÚH 2020 RIV US eng M - Monography Chapter
Pivokonský, Martin - Načeradská, Jana - Novotná, Kateřina - Čermáková, Lenka - Vašatová, Petra
Flocculation of AOM in Water Treatment.
Flocculation: Processes and Applications. New York: Nova Science, 2019 - (Vollan, E.), s. 107-142. Chemistry Research and Applications. ISBN 978-1-53614-339-3
R&D Projects: GA ČR(CZ) GA18-14445S
Institutional support: RVO:67985874
Keywords : algae * algal organic matter * AOM characterization * coagulation * coagulation mechanism * flocculation * floc properties * water treatment
OECD category: Environmental sciences (social aspects to be 5.7)

Global proliferation of algal blooms and subsequent deterioration of water quality by organic compounds that are being produced (algal organic matter - AOM) pose new challenges to water treatment technologies. Flocculation/coagulation using primarily Al- and Fe- based coagulants is widely employed as an essential process in removal of various impurities at drinking water treatment plants and is also irreplaceable in the case of AOM elimination. This review chapter discusses current knowledge on AOM flocculation, the impact of AOM on the removal of other compounds and links AOM composition and character to the efficiency of flocculation, the reaction conditions and mechanisms and finally, to the properties of flocs. In general, the removal efficiencies of dissolved AOM are lower compared to intact phytoplankton cells and usually reach maximum under slightly acidic pH values. The strong pH-dependence of flocculation is attributed to the fact that the involved mechanisms are to a great extent determined by the charge ratios in the coagulating system. Furthermore, substantial differences in flocculation behaviour were observed between diverse AOM constituents, i.e., between peptides/proteins versus non-proteinaceous matter and high versus low molecular weight organics. The latter (specifically AOM > 10 kDa) are reluctant to flocculate and would therefore require other treatment techniques. AOM has also been reported to influence flocculation of other common impurities, both of organic and inorganic nature. Mutual interactions have been proven, while their influence on flocculation efficiency can be either positive or negative, depending on the AOM character, pH conditions and on the ratio between AOM, the other polluting agents and coagulants. Finally, AOM also appeared to alter the properties of flocs, with an impact on the subsequent separation steps. In further research, a particular emphasis should be put on AOM components that are difficult to coagulate, the interactions of AOM with other impurities and on elucidation of the relationship between AOM and floc properties
Permanent Link: http://hdl.handle.net/11104/0292478