Abstract
The main transformation processes effected by the natural microbial consortium of upper Iskar River with predominant participation of sediment biofilm were simulated in the laboratory by the use of portable devices (chambers). The dynamics of real heterotrophic respiration, organic matter oxidation, denitrification and ammonification were analysed by oxygen depletion, reduction of chemical oxygen demand, nitrate uptake and ammonium accumulation, under the conditions prevailing during high and low flow periods. The experimental results showed fast oxygen consumption and high process rates – indicators for intensive respiration by a heterotrophic microbial consortium and good functioning of the ecosystemcomponent studied. The nitrogen transformations occurred at slower rates but in mutual dynamic balance and their simultaneous realisation was due to precise, adaptive division in time and space.
Highlights
Streams and rivers are important ecological components and drinking water sources but they are the main recipients of treated or raw wastewaters
To respond effectively to these heterogeneous needs requires specifying what transformation processes happen in river systems with hazardous substances; which of the variations in water parameters are natural modifications and which are results of anthropogenic influence? One area of interest is the study of the biological activity of aquatic organisms responsible for effecting the main nutrient transformations and for the development of the self-purification capacity of the aquatic system
The results reported here were focused on the microbial metabolism in stream-bed sediments
Summary
Streams and rivers are important ecological components and drinking water sources but they are the main recipients of treated or raw (crude) wastewaters. One area of interest is the study of the biological activity of aquatic organisms responsible for effecting the main nutrient transformations and for the development of the self-purification capacity of the aquatic system The understanding of these ecological processes provides insight into the functional and structural characteristics of river systems and brings a unifying framework to this area of investigation (Allan, 1995). A suitable approach to avoid these problems is simulation of natural transformation processes in the laboratory by the use of portable devices (chambers) These mini-bioreactors are analogous models of a river system and the results obtained can be used for modelling functional aspects of water quality (Dodds and Brock, 1998; Naegeli and Uehlinger, 1997; Uehlinger et al, 2002)
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