Ww- Nutrient Removal

Front 1

what is the source of ammonia in the fresh wastewater?

Back 1

It comes from the cleaving of mainly urea and a little bit protein in the sewer system through hydrolysis

Front 2

Amount of Nitrogen in the fresh ww.. and the req. amount in the effluent

Back 2

Originally, it is roughly 100 mg/l..... and then.. 13 mg/l N or 10 mg NH4- N

Front 3

The steps in the removal of Nitrogen and the responsible MO groups. Also, an elaboration of nitrification.

Back 3

Nitrification and denitrification. Nitrificaiton occurs in an aerobic zone, during which, two groups of Autotrophs, known as Nitrifiers, obtain carbon from inorganic carbon forms and oxidize ammonia in a two step process:
Nitrosomonas oxidize NH 4 to No2, and Nitrobacter oxidize No2 to No3.
NH4 + 1.5O2 -- No2 + 2H + H2O
No2 + 0.5 O2--- No3

Front 4

An elaboration of the denitrification process.

Back 4

During denitrification, nitrate is converted into Nitrogen gas by facultative heterotrophic bacteria under anoxic condition. it takes place in an anoxic zone, during which nitrate serves as the electron acceptor in energy metabolism and is converted to N2. Nitrate requires an electron donor, which can be an external carbon source or influent ww BOD.

Front 5

chemical formula of nitrification

Back 5

NH4 + 1.5O2---nitrosomonas---> No2 + 2H + H2O
NO2 + 0.5 O2 --Nitrobactor-----> No3

Front 6

types of denitrification systems

Back 6

There are three types of denitrification systems depending on the location of the anoxic zone: Predinitrificaiton, Postdenitrification, Simultaneous dinitrification

Front 7

Anoxic zone of Predinitrification or Preanoxic

Back 7

Anoxic zone is at the begining.
BOD is automatically used up and serves as electron donor (is not depleted though)
NH4 will slightly go up due to the degradatio of the protein in the BOD.
No3, on the other hand decreases becasue it is used as electone source (The anoxic zone should bed designed so that No3 is completely depleted)
4 parts of the Recycled ww from the aerobic zone, which serves as a source of No3, is mixed with 1 part of the raw clarified ww which surves as a source of carbon.

Front 8

Oxic.. or aerated zone of Predinitrification or Preanoxic

Back 8

The remaining BOD is copletely degraded (1/4 the way)
Nh4 builts up due to the degradation of the protein in the BOD, and reaches its peak at about halfway and then goes down.
NO3 goes up once BOD is completely depleted as a result of nitrification.

Front 9

Postdenitrification aerated zone

Back 9

Bod is degraded in the first quarter of the tank.
Nh4 goes up due to the degradation of the protein in the BOD, and reaches its peak at about halfway and then goes down due to nitrification.
NO3 goes up once BOD is completely depleted as a result of nitrification as well.
Recycling is in this case done just to maintain the 4kg / m3 of TS which are mainly bacteria.

Front 10

Postdenitrification anoxic zone

Back 10

NO3 is completely depleted starting from the high level that it gained in the aerated zone. (design criteria)
External carbon source (CH3OH) is degraded proportional to NO3.

Front 11

Postdenitrification vs. Predinitrification

Back 11

The recirculated wastewater is relatively small in the case of Postdenitrification, than Predinitrifcation. Predinitrification requires more pumping as more sludge is used as a carbon source. But again, Postdenitrification incurrs extra cost for a carbon source.

Front 12

Anammox

Back 12

NH4+ + NO2 ---> N 2+ + H2O
The Anammox® process (for: Anaerobic ammonium oxidation) removes ammonium without oxygen and with nitrite as the electron acceptor. Aeration is also not needed, thus the associated cost is removed. Also, the emission of greenhouse gases is enormously reduced using the Anammox® process. The overall CO2 emission of a wastewater treatment plant is reduced.

Front 13

The use of an external Carbon souce (benefits and consequences)

Back 13

The use of methanol or any other artificial carbon source should be avoided as it adds to the cost of the treatment and also some operation difficulties may arise from dosing rate of methanol. If it is too much, unnecessary BOD is introduced into the system, and If it is too little, denitrification will be compromised.

Front 14

What happens if fat is not removed early on?

Back 14

Aeration in the AS forces the fat to form a layer and float, just like it would in the floatation tank. Thus, the fat although a source of energy for bacteria, becomes inaccessible to the fat degrading enzymes within the 12-16 HRT of the AS

Front 15

What is the purpose of removing sand

Back 15

to avoid the abrasive nature of sand

Front 16

Phosphurus removal.... and what is the purpose of early dosing

Back 16

Fe+++ + Po4-- ---- FePo4, Al+++ + Po4-- ---- AlPo4
Early dosage gives the precipitation more time, and also facilitates the sedimentation of organic material in the primary sedimentation tank. Compared to the organic material, the precipitants are heavy, and if they are formed early on, the organic material adsorbs onto them.

Front 17

Treatment of surplus sludge

Back 17

Anaerobic digestor: CSTR; UASB; .... systems
Soluble Bod5(COD)-Fermentation/ acidogenesis---
H2,Co2, acetate, VFA, lactate, Alcohol.

H2,Co2, acetate,---->Methanogenesis-->co2 + ch4
Vfa, lactate, alcohol--->.acetogenesis---> Ac,co2,h2,--Methanogenesis--->co2 + ch4

Paticulate BOD5(COD9---Hyerolysis--->monomer--> same as above