NQA

Aeration & Oxygenation systems

 

Environmental & sustainable water treatment

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Dryden Aqua fine bubble Air Diffusers.... Aeration efficiency

Aeration index

 

1 x diffuser code 6.2.10, 3m long 10 cubm/hr will support 100PE population equivalent is sewage effluent treatment
1 x diffusers code 6.2.10, 3m long running at 10 cubm/hr will dissolved into the water between 20kg and 50 kg of oxygen per day
Transfer efficiency,  for 1 kw of energy expended  2kg to 5 kg of oxygen will be dissolved into the water

 

  The Dryden Aqua diffusers are usually twice as efficient as any other diffuser on the market and up to 4 times more efficient than surface aerators that can waste a huger amount of energy as kinetic energy simply throwing the water up into the air.

 

Typical Oxygen Transfer Efficiencies at Different water depths against the partial pressure of oxygen in solution

 

% oxygen saturation  1m depth2m depth3m depth4m depth6m depth30m depth
5%20%35%50%65%73%80%
10%15%20%40%55%65%75%
20%10%18%28%45%60%70%
30%8%15%20%30%50%65%
40%6%12%14%23%35%55%
60%4%7%8%15%20%45%
80%2%5%7%9%12%30%

 

Dryden Aqua Advantage

 

Dryden Aqua air diffusers do not need to be secured to the base of the lagoon or aeration tank, the air ring main goes around the perimeter of the tank, 1/2" hose  connects the air ring main to the diffusers, and the diffusers are simply dropped in to the tank. The Dryden diffusers are a very fine bubble diffuser with low pressure drop which makes them the most efficient diffuser available for water treatment and mixing application. However the diffusers do need to be cleaned for  time to time to maintain the performance, but this is very easy to accomplish. Cleaning, just pull the 1/2" hose to lift the diffuser out of the water, give it a quick brush or pressure wash and then drop back into the tank. Cleaning takes about 2 minutes per diffuser, you do not need to turn off the air blower and you do not need to empty the tank.

 
Table  Relationship between Ammonium, BOD, Phosphate and alkalinity

Kg of component required

Ammonium nitrogen 1kgCOD/BOD 1 kgPhosphate 1kg
Oxygen required =

5 Kg

2 Kg

***
Ammonium nitrogen consumed =

***

0.1 Kg

10 Kg

COD/BOD consumed =

10 Kg

***

100 Kg

Phosphate required =

0.1 Kg

0.01 Kg

***

Alkalinity required

Sodium hydroxide =

4 kg

Sodium bicarbonate =

12 kg

Calcium carbonate =

7 kg

Magnesium oxide =

2 kg

 

The algae factor in shallow tank lagoon systems

 

When a leachate treatment system matures,  there will not only be a healthy population of bacteria,  but the algae levels will also be quite high.  In order for their to be an input from algae the treatment system should be open to direct sunlight.  The algae will metabolize the ammonium and in the process they will also produce oxygen.  In system that have a high ammonium,  it is best to use two or more lagoons or open tanks.  Once the algae become established they will reduce the ammonium levels very quickly and in the process produce oxygen. 

 

Algae will grow heterotrophically in the absence of sunlight,  while they are still beneficial in system,  the algae will consume oxygen and they are more difficult to cultivate.

 

Algae level in a 4 x lagoon system

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Raw leachate
5-10,000mg/l COD
1000-14000 mg/l ammonium
lagoon 1

50% reduction in COD and ammonium, water becomes quite clear, little to no algae present

lagoon 2

Algae bloom develops and water turns green.

lagoon 3

Daphnia and zooplankton bloom crops the algae and reduces the green colour

lagoon 4

Stable algae level and biological system. Newts, frogs, and some fish now living in treatment system

BOD < 5mg/l
COD < 100mg/l
Ammonium < 5mg/l