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Oxidation of compounds produced by cyanobacteria Microcystis aeruginosa and its impact on water treatment by coagulation
Štědrá, Karolína ; Načeradská, Jana (advisor) ; Kopecká, Ivana (referee)
Due to eutrophication of aquatic environment, massive growth of algae and cyanobacteria occurs and the seasonal algal bloom is formed. Drinking water treatment plants have to deal with the increased amount of cells as well as organic compounds produced by algae and cyanobacteria (so-called AOM). Moreover, the presence of AOM causes a reduction in the efficiency of coagulation, which is an essential process in drinking water treatment. To increase coagulation efficiency, supportive methods, such as ozone oxidation, are added usually prior to coagulation. While many studies focused on the ozonation of algal and cyanobacterial cells, little is known about the effect of ozonation on AOM. This diploma thesis focused on the evaluation of the effect of ozonation in combination with coagulation on the removal of cellular organic compounds (COM) produced by cyanobacteria Microcystis aeruginosa. The effect of ozonation before or after coagulation on COM removal was investigated. The degradation of microcystins, which are naturally contained in the COM sample, was also monitored. Various ozone doses (1 - 10 mg/L) were tested at three pH values - 5, 7 and 9. Two coagulants were utilized - aluminium sulphate and ferric sulphate. Ozonation removed COM negligibly. However, eliminated microcystins, the degradation...
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The impact of oxidation processes on AOM coagulation
Titov, Ivan ; Načeradská, Jana (advisor) ; Novotná, Kateřina (referee)
Due to anthropogenic impact, surface water sources are subject to intensive growth of phytoplankton communities. This poses a problem for water treatment, not only because water contains a large number of algae cells, but also because of the high concentrations of algal organic matter (AOM). These substances are characterized by low removability during the conventional water treatment process by coagulation, and therefore the increase in AOM removability is currently being researched. Oxidation pretreatment before coagulation is one of the methods that increase the effectiveness of algae and its excreted matter's removability. This work researches the influence of oxidation treatment on AOM removability by coagulation, and on treated water quality. The literary research has shown that pre-oxidation is rather ambiguous in terms of AOM coagulation. From one point of view, with the correct calibration of operation conditions, a right choice of oxidation process and the optimum oxidant dosage it is possible to achieve an effectiveness increase of partial AOM removal (e.g. cyanotoxins, taste and odour compounds and low molecular weight compounds with the help of mineralization). Pre-oxidation, however, can impair AOM coagulation by transforming high molecular weight compounds into low molecular weight...
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