• 2025-07-09

Activated sludge

Activated Sludge System Function

The activated sludge process achieves the following core functions through aerobic microbial communities:

Efficient pollutant degradation

Organic matter mineralization

Remove BOD₅ > 95% (bacterial floc oxygen uptake rate 1.2 kgO₂/kgVSS·d)

Oxidize organic matter to generate CO₂/H₂O and new biomass

Nutrient salt transformation

Nitrification: NH₄⁺→NO₂⁻→NO₃⁻ (ammonia oxidation rate 0.8 gN/kgVSS·h)

Phosphorus Removal by Biology: Polyphosphate-accumulating organisms (PAOs) accumulate 3-7% of their dry weight in phosphorus

Enhanced Solid-Liquid Separation

■ Floc Formation

Secretion of extracellular polymeric substances (EPS) to form settleable flocs (SVI < 150 mL/g)

Sedimentation tank SS removal rate >99% (effluent SS < 30 mg/L)

■ Dissolved Substance Control

Colloidal substance adsorption retention (zeta potential -15 mV → 0 mV)

Gas component regulation

Inhibit H₂S/CH₄ production (DO maintained at 2mg/L)

Reduce CO₂ by 40-60% through carbonation reaction