RATE-CAPACITY CHARACTERIZATION OF WASTE-WATER FOR NUTRIENT REMOVAL PROCESSES

The detailed composition of wastewater has significant impact on the b iological wastewater treatment processes. The carbon sources present g overn the oxygen uptake rate, the rate of denitrification and the biol ogical phosphorus uptake rate. In this paper, the respiration rate det erminations used for the bi- or tri-substrate determinations are coupl ed to removal capacity in order to develop rate-capacity diagrams, tha t gives a fuller picture of the wastewater and its influence on the bi ological processes. The directly degradable carbon source gives high r eaction rates, but the concentration and thus the capacity can be very limited. In such a case the overall obtainable removal rate is of mor e interest than the peak rate. The rate-capacity diagrams are shown fo r raw, primary settled and primary precipitated wastewater, characteri zed by detailed investigations of the respiration rates obtainable. It shows the effect of pretreatment not only on the total concentrations in the pretreated wastewater, but also in the rate-capacity curves fo r biological denitrification. The rate-capacity curves are in practice coupled to the design and operation of the treatment plant. These two factors determine whether the carbon sources in the influent wastewat er are used for denitrification (or biological phosphorus removal), fo r oxidation with oxygen or for sludge production.