ACIDOBASIC BALANCES IN THE COURSE OF HETEROTROPHIC DENITRIFICATION

Acidobasic balances are discussed to define the influence of organic s ubstrate composition on CO2, HCO3-, CO32- production and pH value chan ges in the course of heterotrophic denitrification. The decisive param eter for these balances for undissociated substrates is average oxidat ion number of carbon (AONC). For dissociated substrates the balances a re influenced by the composition of organic compounds (the number of C , H, O atoms and the oxidation number). The rules for determination of pH value changes according to substrate composition are discussed bot h for dissimilative and assimilative reactions. The theoretical conclu sions are verified in kinetic denitrification tests with selected orga nic compounds (glucose, glycerine, ethanol, methanol, acetate, endogen ous substrate). Furthermore, indication of nitrates and nitrites remov al (the end of denitrification) by continuously measured pH is describ ed (when denitrification has been finished, pH value begins to decreas e).