This study concerns the utility of the coagulation process in removing humic substances and its dependence on the properties of these substances and their concentrations. The coagulation process was performed on model solutions of natural humic acids. Polyaluminum chloride (PAX XL3) and aluminum sulfate were used for this study, which allowed for a comparison of the effectiveness of pre-hydrolyzed and hydrolyzing coagulants. The coagulant dosages were determined as gram aluminum per gram carbon, thanks to which it was possible to compare the process effectiveness for different initial organic carbon concentrations, whose values were in the range of 5.51-21.23 gC/m 3. The obtained values of reductions in organic carbon concentrations point to a significant process effectiveness (37.2-59.4% and 20.0-41.5% for pre-hydrolyzed and hydrolyzing coagulants, respectively), which increased with increasing molecular mass of the humic substances present in water. These results are analogous to those found for coagulation of surface waters and point to a greater effectiveness of pre-hydrolyzed coagulant in removing humic substances (at the same coagulant dosage). The effectiveness in removing organic substances increased with coagulant dosage and the initial total organic carbon concentration. The coagulation process most effectively removed aromatic substances absorbing UV light. The content of substances absorbing UV light in raw and post-coagulation water was proportional to the dissolved organic carbon content.

The results of optimizing the coagulant choice for surface water treatment for human consumption have been presented. This optimization included not only elimination of organic matter from water with low contamination levels but also determining the cost of the process. Ten coagulants differing in aluminum content and in preliminary hydrolysis have been examined. The costs were calculated for four most effective coagulants.

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This study concerns an evaluation of humic substance removal during an adsorption process on three sorbents: two consisting of carbon nanotubes embedded on a polymer (polypropylene and polyethylene) and granulated active carbon as a reference. The results that were obtained show a significantly lower organic substance removal effectiveness in the case of sorbents containing carbon nanotubes, with an insignificantly lower unit effectiveness (mg/g) of the nanosorbents during first two hours of adsorption. Unfortunately, nanosorbents only allow removing substances with a low molecular weight and high aromaticity, which significantly reduces the possibility of its use in technical conditions for naturally occurring water and the sorption capacity nanotubes were significantly lower in comparison to the GAC.