Abstrakt

Humic substances impose substantial effect on the aquatic environment as well as the water organisms and human health. Among other features, the humic acids determine organoleptic properties of surface waters. Therefore explanation of the origin and properties of humic acids in surface waters is one of the priorities of water technology.Recently it was pointed out that in the wastewater treatment process organic compounds characterized by properties similar to humic acids are formed. The chemical features of wastewater indicate that they can influence the form of trace metals, the salts concentrations as well as concentrations of organic substances, including humic acids. The concentrations of these substances are higher in sewage than in surface waters. Moreover, the complexing abilities of the humic acids originating in wastewater treatment process are stronger than the naturally occurring humic substances. The humic acids formed in wastewater treatment process can be also responsible for trace metals transport and increase of their bioavailability in the ecosystem.Usually, the performance of WWTP is evaluated on the basis of organics and nutrients elimination efficiency. The influence of wastewater treatment technology on presence of hardly-biodegradable organic complexes has not been investigated yet. The sewage treated both in conventional WWTPs and CWs contain mostly organic substance resistant to biochemical transformation, however there is hardly any information about the properties of these substances.The objective of this paper is quantitative and qualitative comparison of humic acids formed during conventional and natural (CW) wastewater treatment. The quality of effluent from three highly-effective WWTPs (Jamno near Koszalin, Unieście and "Wschód" Gdańsk and two CWs (Darżlubie and Wiklino) was investigated and compared to the quality of humic acids present in the water of Vistula river (in the section near Gdańsk). Humic substances were isolated from treated sewage in order to analyze their properties: elemental composition, absorption spectrum in the visible light (VIS), ultraviolet (UV) and infrared (IR).

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