Activated sludge: oxygen demand and aeration

Description

Total oxygen demand (carbon removal plus nitrification, less the oxygen recovered by denitrification), multiplied by the peak factor:

$RO = RO_c + RO_n - RO_{dn}$

$AOR = F_p \, RO$

Conversion from field to standard conditions:

$SOR = \frac{AOR \, C_{s,20}}{\alpha \, \theta^{(T-20)} \, (\beta f_H C_{s,T} - C_L)}$

$f_H = 1 - \frac{z}{9450}$

Oxygen saturation is calculated by the Benson-Krause equation (Standard Methods) unless given.

Air flow for diffused aeration, with 0.2791 kg O₂ per normal m³ of air:

$Q_{ar} = \frac{SOR}{SOTE \cdot 0.2791}$

Power for mechanical aeration, from the standard oxygenation efficiency $EO$ in kg O₂/kWh:

$P = \frac{SOR}{EO}$

Air flow and power are calculated only when SOTE and $EO$, respectively, are given.

Reference

VON SPERLING, M. Lodos ativados. Princípios do tratamento biológico de águas residuárias, v. 4. Belo Horizonte: DESA/UFMG.