REGENERATION OF ACTIVATED-SLUDGE UNDER OXIC AND ANOXIC CONDITIONS

Regeneration of biomass cultivated by synthetic soluble organic substrate under oxic and anoxic conditions was studied by following the maximum substrate removal rates r(X,m) during the endogenous phase. Two semicontinuously operated units simulating contact stabilization process were operated. In one of the units endogenous anoxic period was established after nitrification was completed. The regeneration process was connected with an increase in r(X,m) values. The increase was very similar under both oxic and anoxic conditions. The comparison of the contact stabilization process with oxic and combined oxic-anoxic endogenous phase has shown the following: rates of exogenous substrate removal and nitrification were the same, in ox-anox system nitrogen was completely eliminated and oxygen consumption was reduced, the rate of regeneration was the same in both systems. Combined oxic-anoxic regeneration phase can be used as a modification of the contact stabilization process for soluble organic substrate. In addition, during the endogenous phase kinetic constants r(X,m), saturation coefficient K(s) and biomass yield coefficient Y have significantly increased. The problem of actual Y value determination is discussed.