Mass balance-based plant-wide wastewater treatment plant models – Part 2: Tracking the influent inorganic suspended solids

  • GA Ekama
  • MC Wentzel
  • SW Sötemann
  • SW Sötemann


From an experimental and theoretical investigation of the continuity of influent inorganic suspended solids (ISS) along the links connecting the primary settling tank, fully aerobic or N removal activated sludge and anaerobic and aerobic digestion unit operations, it was found that the influent wastewater (fixed) ISS concentration is conserved through activated sludge and aerobic digestion unit operations. However, the measured ISS flux at different stages through a series of wastewater treatment plant unit operations is not equal to the influent ISS flux, because the ordinary heterotrophic organism (OHO) biomass contributes to the ISS flux by differing amounts depending on the active (OHO) fraction of the Volatile Suspended Solids (VSS) at that stage. Literature data indicated that conservation of influent ISS through primary sludge anaerobic digestion was within 10%, which is too wide to be conclusive.

Water SA Vol.32 (3) 2006: pp.277-285

Journal Identifiers

eISSN: 0378-4738