To study the functions of activated carbon and activated coke adsorption for the treatment of highly contaminated discolored industrial wastewater with a wide molecular size distribution of organic compounds, the deposited lignite pyrolysis wastewater from a filled open-cast coal mine was used for continuous and discontinuous experiments.

The investigations were performed using water samples taken from various depths of the deposit pond. These differently loaded water samples, with various spectra of humic-like macromolecules in sizes from >1 kDa up to the μm-range, were used untreated as well as treated by flocculation prior to the experiments. The results show that, in principle, decolorization connected with TOC (total organic carbon) removal is possible for each of the water samples. The treated waters from the bottom of the deposit contain about 100 mg/l consisting mainly of hydrophilic compounds. In contrast, the organic compounds of the completely autoxidized surface water were almost nearly completely adsorbed (94%).

The adsorption processes were influenced by fouling and secondary sequential loading of the organic substances with various molecular sizes in the range up to 100 kDa. Further, secondary adsorption effects of low molecular-weight compounds were observed.

A comparison of the capacities of the adsorption materials used showed, that because of its large number of macro- and mesopores, activated coke is more suitable for wastewater treatment and in addition cheaper than activated carbon.