Résumé :
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Some of the main factors affecting the biological removal of nutrients in wastewater treatment plant have been investigated. The influence of low concentration of oxygen and the redox potential on the denitrification, activity of activated sludge was studied in batchwise experiments. Oxygen was found to have a negative effect on denitrification even when present at concentration lower than could be measured with conventional oxygen probes. A linear relationship was found between the denitrification activity and the redox potential. Furthermore, denitrification with ethanol and methanol as carbon sources was studied in two parallel chemostats, as well in batch cultivations of pure denitrifying strains. A simple method to determine the volatile fatty acid (VFA) potential, a measure of the readily fermentable organic fraction in domestic wastewater, was developed. This fraction is considered to be of crucial importance for the performance of enhanced biological phosphorus removal (EBPR).
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