No abstract

The Water Framework Directive 2000/60/EC [1] has been in force in the EU since 2000. Its main aim is to ensure the protection of waters and help them to obtain the socalled "good" status until 2015. Accomplishing these tasks requires identifying the threat and evaluating its influence on the environment. When necessary, it also means undertaking some remedy procedures to achieve the environmental aims in the assumed range and time concerning the "good" chemical status of waters. Discharging industrial and municipal wastewater (rich in metal and metalloid ions) into rivers and streams is one of the many factors affecting environmental water quality.

Sorption capacities of low-moor peats and Neogene clays from the overburden of lignite beds in Central Poland for Cr(III) ions as chloride and metalorganic complex ions have been investigated. The binding mechanisms and sorption parameters were determined based on the Freundlich and Langmuir nonlinear sorption isotherms. The sorption capacities of studied materials for Cr(III) ions depended on their properties (porosity, average pore diameters, specific surface area and content of Fe hydroxyoxides) as well as charge of Cr(III) ions, functional groups and their diagonal lengths. Cr(III) ions from chlorides were bound onto sorbents via Coulomb attraction and by Fe hydroxyoxides. However the complex Cr(III) ions were bound to the sorbent surface via hydrogen bonds between the dye -OH groups and =O of the sorbent functional groups. The equation parameters of sorption isotherms indicate cooperative heterogeneous adsorption at low Cr(III) concentrations and chemisorption at high Cr(III) concentrations.