Diploma Thesis Defense by Mrs. Stylianos Hamatzolas
Thesis Title: «Inactivation of faecal contamination markers in water by chlorination and photocatalysis translation»
Friday 25 September 2020, at: 10:00, Venue: https://tuc-gr.zoom.us/j/91969976207?pwd=V0R5c1kvbStKZjdwNzVTOWN3dWtyZz09
Examination Committee
- Associate Professor Danae Venieri (advisor)
- Professor Evan Diamadopoulos
- Professor Mihalis Lazaridis
Abstract
The present dissertation focuses on testing the effectiveness of two water disinfection methods for inactivating markers of faecal contamination, namely the bacteria Escherichiacoli (Gram negative bacterium) and Enterococcusfaecalis (Gram positive bacterium). The methods applied are photocatalysis with UVA radiation using TiO2 as a catalyst and chlorination. As part of the work, an attempt was made to evaluate the two methods for inactivation of bacterial markers, the control of which is required by current legislation. According to the experiments performed, differences were observed, which were related to the functional parameters of the two methods, but also to the type of bacterium that was tested each time.
Photocatalysis efficiency was improved by increasing the catalyst concentration by one degree.
The optimal TiO2 concentration under the given experimental conditions was 25 mg / L, as there was a decrease in bacterial populations of 6-7 Log within 20 min. Further increase in catalyst concentration did not lead to improved efficiency. In contrast, the population of each bacterium remained high.
Regarding chlorination, the efficiency of the method was quite satisfactory for the case of E. coli, while Enterococcus showed high resistance. However, the dose of chlorine used was low (3 mg / L), while at the same time, the initial bacterial concentration was of the order of 107CFU / mL.
In general, among the two indicators of faecal infection, E. faecalis was more resistant to the "adverse conditions" induced by either method.
Based on the results of the present work, it becomes apparent that the efficiency of photocatalysis and chlorination as disinfection methods is influenced by the functional parameters, as well as by the type of bacterium examined in each case.
