Subdivision of Total Influent PInfluent TP

(Pti)

Organicallybound P (Pti - Pbi)

70 ~ 90% 10 ~ 30%

100%

10 ~ 20%in the activatedsludge process

Sol. PO4- (Psi)

1

Source: human body waste, food waste, various household detergents

Phosphorus

Algae: Derive energy from sunlightH & O H2O; C CO2

N, P, S, etc. dissolved salts Not readily soluble Eutrophic (life-giving) substancesN NH4

+ & NO3-; from natural and

manmade sourcesP PO4

-3; from human body waste, food waste, various household detergents

Presence of excess P: algal bloom

Photo-Synthetic Autotrophs

2

Forms of Phosphate

3

Old Now Forms5 4 Orthophosphate3 0 Tripolyphosphate (detergents)1 0 Pyrophosphate (breakdown of tri-

P)1 1 Organic phosphates0 ? Hexametaphosphate (corrosion

inhibitor)10 5 Total

mg/L

Why? Ban of phosphate-based detergents

Phosphorus in Wastewater

Addition to waterCorrosion (and scale) control in drinking water

Industrial water softeningBoiler watersCleaning compounds

Sewage1.2 lb/capita/yr from human and food waste

4

Biological Phosphorus Removal (BPR) Mechanism

Aerobic

mg

/L

TimePoly-β-hydroxybutyrate (PHB)(Storage)

PHB Poly-P

Poly-P 5

Biomass Biomass

Acetate

Ortho-P

Waste

P removal

Anaerobic Aerobic

Anaerobic

6

BPR MechanismAnaerobic 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 conditionThe 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.

Anaerobic/Oxic Process

Excess sludgeBetter SRT control

Readily biodegradablesoluble 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