• High SS levels (>500 mg/L) can:
  • Clog air release nozzles
  • Form dense sludge layers reducing bubble-particle contact
  • Cause premature settling of coarse solids
• Very low SS (<50 mg/L) makes floc formation difficult, requiring chemical coagulants

Optimal SS range ensures proper bubble attachment without system overload.

• Free-Floating Oils:
  • Easy to remove but high concentrations (>100 mg/L) form thick layers that hinder skimmers
• Emulsified Oils:
  • Require chemical de-emulsifiers (e.g., coagulants)
  • Without treatment, they bypass bubbles reducing removal efficiency
• Dissolved Oils:
  • Require advanced pre-treatment (e.g., activated carbon)
  • DAF alone cannot remove dissolved compounds

• pH Level:
  • Impacts particle surface charge and coagulant efficacy
  • Aluminum-based coagulants work best at pH 5-7
  • Iron salts prefer pH 7-9
• Ionic Strength:
  • High calcium/magnesium/salts alter water chemistry
  • May cause scaling in air saturation tank/nozzles

• High Temperature (>40°C):
  • Reduces air solubility in saturation tank
  • Decreases bubble production
• Low Temperature (<10°C):
  • Increases water viscosity, slowing bubble rise
  • May cause biological foaming in warmer water

Temperature control optimizes both bubble production and flotation kinetics.

• Stabilize emulsions and prevent floc formation
• Require higher coagulant dosages
• Can coat bubble surfaces, reducing contaminant attachment

Chemicals like heavy metals, solvents, or biocides can:

• Disrupt bubble formation (e.g., surfactants lowering surface tension)
• Inhibit coagulant reactions (e.g., heavy metals complexing with coagulants)
• Corrode DAF components, reducing equipment lifespan

Pre-treatment is essential for waters containing toxic compounds to protect DAF efficiency.