The removal of pathogenic microorganisms in a biological system with floating islands

Pathogenic microorganisms in water pose a great risk to human health.Therefore, it is necessary to find an efficient, environmentally friendly, and economicallyacceptable solution for their removal from polluted and wastewater. This paper presentsthe efficiency of a biological system with floating islands in the removal of pathogenicmicroorganisms from the water of a polluted urban river. The modified floating treatmentwetland consisted of a collection tank, 4 calls with floating islands and 1 cell with algae,which enabled additional water polishing. The results of the research showed that thebiological system constructed on the bank of this river had a high efficiency in reducing thenumber of various groups of pathogenic microorganisms. Within the cells with the floatingislands, 100% efficiency in the removal of coliform bacteria of faecal origin was achieved,and the reduction of pathogens was continued within the cell with algae. The realisedefficiency of removal of total coliform bacteria was 100% in all cells, except in the cell 4with decorative aquatic macrophytes, in which the efficiency was 97%. The number ofintestinal enterococci was reduced in the range of 92 to 97% in cells with plants, and up to98% in the cells with algae. The floating islands and algae also enabled a high reduction inthe number of aerobic heterotrophs and facultative oligotrophs. In addition, the ratio ofthese microorganisms had a value above 1 during the entire period of water treatment,which indicated that natural processes of self-purification of polluted water ran smoothly in the floating treatment wetland. Due to the reduction of pathogenic microorganisms, waterthat belonged to class V, i.e., III, after the discharge from the biological system, had thecharacteristics of water with excellent ecological status (class I)