Treatment Plants for Nitrification
Total tank volume
3000 m'
2000
1000
o ._____._ _ _._____. _ __.__......___._ _ _.__• COD/TN in the influent of
o
5
nitrification tank
Fig 6.18 The total tank volume and its distribution on the two tanks of a two sludge system, as
a function of the composition of the wastewater. Raw wastewater to tank 1 is assumed
to contain 1,000 kg COD and 100 kg TN/d.
nitrification stage. It will be seen that the minimum total volume will be achieved
when the overall part of the organic matter is removed in stage 1. This plant type is
often used when extending existing plants in which nitrification is required. The
oldest parts of the plant, including the sludge treatment parts, often with anaerobic
digestion, can continue their usual operation, while the new part of the plant will be
based on nitrification and aerobic sludge stabilization. In practice, the sludge properties
in the second stage of the plant often turn out to be poor due to the low sludge
production by nitrification. However, it will often be possible to solve the problem
by applying a certain (small) amount of raw wastewater into the nitrification stage.
6.2.4 Nitrification plants with separate sludge in
filters
Biological wastewater treatment plants solely intended for oxidation of ammonium are
always designed as filters, as the adhesion of the bacteria is so good that a sufficient
biomass can be maintained in such a plant in spite of the small sludge production.
Normally no settling is needed after the filter due to the small sludge production.
6.2.5 Two sludge nitrification plants in filters
Biofilters in which both organic material and ammonium are to be oxidated should
be regarded as two sludge treatment systems. The tanks resemble tanks with plug
flow, and as suggested in connection with the criterion for nitrification, Expression
(6.8), there will be no nitrification at the inlet of the plant, as the Sooo/Soz ratio is
high, but the decreasing concentration of organic matter through the tank means
that nitrification will be possible after a certain point in the tank.
215
Total tank volume
3000 m'
2000
1000
o ._____._ _ _._____. _ __.__......___._ _ _.__• COD/TN in the influent of
o
5
nitrification tank
Fig 6.18 The total tank volume and its distribution on the two tanks of a two sludge system, as
a function of the composition of the wastewater. Raw wastewater to tank 1 is assumed
to contain 1,000 kg COD and 100 kg TN/d.
nitrification stage. It will be seen that the minimum total volume will be achieved
when the overall part of the organic matter is removed in stage 1. This plant type is
often used when extending existing plants in which nitrification is required. The
oldest parts of the plant, including the sludge treatment parts, often with anaerobic
digestion, can continue their usual operation, while the new part of the plant will be
based on nitrification and aerobic sludge stabilization. In practice, the sludge properties
in the second stage of the plant often turn out to be poor due to the low sludge
production by nitrification. However, it will often be possible to solve the problem
by applying a certain (small) amount of raw wastewater into the nitrification stage.
6.2.4 Nitrification plants with separate sludge in
filters
Biological wastewater treatment plants solely intended for oxidation of ammonium are
always designed as filters, as the adhesion of the bacteria is so good that a sufficient
biomass can be maintained in such a plant in spite of the small sludge production.
Normally no settling is needed after the filter due to the small sludge production.
6.2.5 Two sludge nitrification plants in filters
Biofilters in which both organic material and ammonium are to be oxidated should
be regarded as two sludge treatment systems. The tanks resemble tanks with plug
flow, and as suggested in connection with the criterion for nitrification, Expression
(6.8), there will be no nitrification at the inlet of the plant, as the Sooo/Soz ratio is
high, but the decreasing concentration of organic matter through the tank means
that nitrification will be possible after a certain point in the tank.
215