Aspects of drinking water supply in areas of humic water

Sammanfattning: The thesis investigated several aspects that are important for drinking water supply from waters with high amounts of humic substance (humic water). The results showed that the composition of humic substances is important in their sorption to aquifer material during surface water artificial recharge through infiltration basins to groundwater. The more acidic fraction of humic substances was less effectively sorbed than the more hydrophobic fraction. The removal of the former fraction from the recharged groundwater was effective using weak base anion exchange resin. A high total number of bacteria in presence of cyanobacteria in the subsurface below the infiltration indicated that significant decrease of biodegradation of organic matter, during water passage from blooming humic lake to groundwater, is not likely. Because of high amounts of microbially assimilable organic carbon in humic water and its low reduction during chemical treatment, bacterial growth in drinking water distribution systems was dependent on the phosphorus concentration. In the distributed water bacteria were forming biofilm on the pipe surfaces. To reduce the biofilm growth fairly high doses of chlorine were needed. The anion exchange resin was successfully used to determine concentrations of iron-humic complexes in humic groundwater. According to this analysis a significant part of iron in drinking water, produced by artificial recharge from a humic lake, was bound to humic substances.