This document summarizes technologies for removing nitrogen and phosphorus from wastewater. It discusses the problems caused by nutrient pollution in waterways and outlines biological and chemical solutions. Key points include: nitrification and denitrification can remove nitrogen through autotrophic and heterotrophic bacteria; enhanced biological phosphorus removal uses phosphorus-accumulating organisms; and chemical precipitation uses metal salts like aluminum and iron to remove phosphorus by forming insoluble phosphates. The document also provides details on nitrogen and phosphorus levels in domestic sewage and the nitrogen transformation process in biological treatment systems.

1. Wastewater Treatment
Technologies for
the Removal of Nitrogen &
Phosphorus
- Akshay More,
M.Sc. Biotechnology-1.,
Modern College, Ganeshkhind, Pune.

2. Outline
• Problem-
Nutrient Pollution (Eutrophication)
• Solutions-
1. Nitrogen Removal:
Nitrification and denitrification
2. Phosphorus Removal:
- Enhanced Biological Phosphorus Removal.
- Chemical Treatment.

3. Eutrophication
• Nutrient enrichment
• Algal growth
• Decay of algae
• Oxygen consumption
Oberlin, OH (before) Oberlin, OH (after)

4. Nitrogen and Phosphorus Concentrations
in Domestic Sewage:
• Total Nitrogen (25 to 50 mg/L)
– Ammonium Nitrogen (15 to 35 mg/L)
– Organic Nitrogen (10 to 20 mg/L)
(Most organic nitrogen hydrolyzes to ammonia).
• Phosphorus (4 to 8 mg/L)

5. Nitrogen Transformation in
Biological Treatment:
A. Nitrification By Autotrophic Bacteria

6. B. Denitrification by Heterotrophic Bacteria
NO3 + BOD N2 + CO2 + H2O + OH- + CELLS
Occurs under anoxic conditions.
Required mixing and nitrate recycle.
For 1 gram of NO3-N Denitrified:
a. ~ 3.0 g BOD are consumed
b. ~ 0.45 g new cells are produced
c. 3.57 g of alkalinity are formed (~50% recovery of
alkalinity consumed in nitrification)

7. Other Nitrogen Removal Processes
(Industrial & Municipal)
Initial species Process Ultimate species
Organic-N Ammonification
• Biological conversion to NH3(g)
• Biological nitrification
• Ammonia, NH4+- N
• Nitrate, NO3—N
Ammonia
(NH4+ - N)
• Biological uptake during
bacterial growth
• Breakpoint chlorination
• Ion-Exchange will exchange
ammonia for another cation
• Organic-N
Nitrate
(NO3 -N)
• Biological nitrification
• Ion-Exchange will
exchange nitrate another anion
• N2(g)
• Resin

8. Phosphorus Removal
• Enhanced Biological Phosphorus Removal (EBPR).
• Chemical Precipitation.

9. What is Enhanced Biological Phosphorus
Removal (EBPR)?
• Biological Process that promotes the growth of phosphorous accumulating
organisms (PAOs) that are able to take up and store high concentrations of
phosphorus.
• Normally bacteria in activated sludge contain 1-1.5 % P
• In the EBPR process, bacteria that store phosphorus are selectively retained
in the biological process and they contain 20-30% P
• Need an anaerobic/aerobic process to select for these PAOs (phosphorus
accumulating organisms)
• PAOs require readily biodegradable COD (rbCOD) as volatile fatty acids
(VFAs)
• Denitrification bacteria out compete PAOs for rbCOD. Need anoxic zones
for denitrification if nitrates are present.
• Supplemental carbon or fermentation may be needed of wastewater is
carbon deficient.
• Phosphorus is removed by wasting PAOs.

11. Chemical Treatment
Phosphorus Removal Mechanism
• Metal salt precipitate at stoichiometric dose but …..
• For very low P concentration metal-hydroxide formed.
• Al2(SO4)3.18H2O+ 2H3(PO4) 2Al(PO4) + 3H2SO4 +18H2O
• FeCl3 + H3(PO4) Fe(PO4) + 3HCl3
• Chemical treatment will deplete alkalinity, decrease pH and increase
TDS

12. Primary
Clarifier
Aerobic
Zone
Final
Clarifier
Chemical
Coagulant
P Removal
RAS WAS
Effl
Q

13. Treatment Of Effluent
Influent
Wastewater
Treated
Effluent
• Treated Effluent
Possible mechanisms:
• ion exchange
• adsorption
• precipitation

14. THANK
YOU