1. Subdivision of Total Influent P Influent TP (P ti ) Organically bound P (P ti - P bi ) 70 ~ 90% 10 ~ 30% 100% 10 ~ 20% in the activated sludge process Sol. PO 4 - (P si ) 1 Source: human body waste, food waste, various household detergents Phosphorus

2.  Algae: Derive energy from sunlight  H & O  H 2 O; C  CO 2 N, P, S, etc.  dissolved salts Not readily soluble Eutrophic (life-giving) substances  N  NH 4 + & NO 3 - ; from natural and manmade sources  P  PO 4 -3 ; from human body waste, food waste, various household detergents  Presence of excess P: algal bloom Photo-Synthetic Autotrophs 2

3. 3 Old Now Forms 54Orthophosphate 30Tripolyphosphate (detergents) 10Pyrophosphate (breakdown of tri-P) 11Organic phosphates 0?Hexametaphosphate (corrosion inhibitor) 105Total mg/L Why? Ban of phosphate-based detergents

4. Addition to water Corrosion (and scale) control in drinking water Industrial water softening Boiler waters Cleaning compounds Sewage 1.2 lb/capita/yr from human and food waste 4

5. Aerobic mg/L Time Poly-β- hydroxybutyrate (PHB) (Storage) PHB Poly-P 5 Biomass Acetate Ortho-P Waste P removal Anaerobic  Aerobic Anaerobic

6. Anaerobic condition (no oxygen and nitrate/nitrite) Phosphate-accumulating organisms (PAOs) take up substrate under anaerobic conditions in the form of acetate or other volatile fatty acids (VFAs) and convert it into a carbon-containing storage product, such as poly- β-hydroxybutyrate (PHB). The energy needed for the substrate uptake and conversion comes from the splitting of the stored polyphosphate. Aerobic condition The energy used by oxidizing stored PHB is used by PAOs to take up the ortho-P from the wastewater. P is removed by wasting PAO-containing activated sludge from the biological treatment system. 6

7. Anaerobic/Oxic Process Excess sludge Better SRT control Readily biodegradable soluble COD Vital for P Uptake SRT: Solid retention time, sludge age, or mean cell residence time (MCRT); total biomass in the system/biomass wasted/loss 7