Chapter 4: Activated Sludge Modelling - IqTMA-UVa

Solids production rateP MLVSS = r g V (active X) + r d V (debris) + QX 0,I (nbVSS) = [kgVSS/d]r g = µX = X/SRT with X= (SRT/HRT)Y(S 0 – S)/(1+ k d SRT)r d = cell debris production rate = f d k d XQX 0,i = amount of nbVSS introducedP MLVSS = QY(S 0 – S)/(1 + k d SRT) + f d k d XV + QX 0,iRemember the solid fraction in made of active biomass, cell debris andan inert VSS introduced from the influent. The last 2 fractions willimpact process efficiency because larger settler and reactor tank willbe needed.During wastewater treatment, one must also add the solid fraction dueto inorganics.31