THE EFFECTS OF FILL STRATEGIES ON SBR PERFORMANCE UNDER NITROGEN DEFICIENCY AND RICH CONDITIONS

The effects of anoxic and oxic fill strategies on SBR performance unde r nitrogen (NH4Cl as the nitrogen source) deficiency and rich conditio ns are evaluated using glucose as the sole substrate. The performance is evaluated according to substrate removal, sludge settleability, sup ernatant suspended solids (SS), and reactor biomass concentration. Sub strate removal efficiencies are found to be independent of the fill st rategies adopted under all conditions tested. The incorporation of ano xic selector environment fails to prevent the development of bulking s ludge under nitrogen deficiency conditions thereby resulting in a grad ual depletion of reactor biomass. Under nitrogen rich conditions, on t he other hand, the sludge settleability improves significantly by adop ting the anoxic fill strategy. Furthermore, SS readings taken at the e nd of settling period are greater with anoxic fill than with oxic fill , indicating that the latter discourages the growth of dispersed bacte ria.