TRANSFORMATION OF ORGANIC-MATTER AND BANK FILTRATION FROM A POLLUTED STREAM

A case study of the examination of the changes of organic matter in a small, highly polluted stream and the adjacent alluvial aquifer is pre sented. The investigated stream was actually a collector of effluents from baker's yeast and pharmaceutical industries. The stream was chara cterized by a COD of several thousands of mg O-2 l(-1), most of which was biodegradable organic matter. Biodegradation processes took place in the surface water, with consequent oxygen depletion in the stream. The organic matter content of the river sediment was more than 10% of its dry weight. Bank filtration of organic substances was investigated in a number of observation wells at distances of 5-150 m from the riv er (under different hydrological conditions). The infiltration of orga nic matter from the polluted stream into the aquifer was found to be s ignificant only at hydrological conditions where the water level excee ds the altitude of the stream bed. The organic matter present in groun dwater samples was mainly a humic/fulvic type, and was not degraded du ring the 64 days of the laboratory biodegradation experiment. Copyrigh t (C) 1996 Elsevier Science Ltd