ceramic diffuser home | lakes
& ponds home
The Dryden Aqua ceramic oxygen diffusers are used to supply oxygen to lakes, ponds, rivers and for waste water treatment. Pure (or 90%) oxygen is used in
situations where the oxygen demand is too high for an aeration system, or if is not practical to fit and aeration system. Some examples are
presented below.
- Shallow rivers that suffer from pollution
- Emergency systems for immediate drop in to polluted rivers and water systems
- If no power is available, the diffusers operate directly from the compressed oxygen gas pressure
- Lakes and ponds that are seriously polluted or where there is high eutrophication
- Industrial emergency treatment systems.
The oxygenation systems can be connected to our oxygen monitoring equipment to provide a fully automatic control, treatment and alarm system
sizing a system
Sizing a system is relatively simple. As a guide the amount of oxygen dissolved in to the water should equate with the COD (Chemical
Oxidation Demand) of the water. Therefore if the COD of the water is 100mg/l and the water flowrate is 10 cubic meters per hour, the actual
weight of COD will be 1000 grammes per hour. Simply match the weight of COD to the weight of oxygen, then go to the
oxygen generator section to determine the size of oxygen generator,
alternatively you may use compressed or liquid oxygen.
Calculation example.
1000 g of oxygen
volume of 1000g = (1000/32) x 22.4 = 700 litres at standard temperature and pressure
1 x DAD6 diffuser will pass approx. 6 l/min = 360 litres per hour.
Therefore in order to dissolved 1000g of oxygen into water in 1 hour, you will need 2 x DAD6 diffusers.
The above calculation does not take into account the transfer efficiency of the oxygen into solution, this will be a variable depending upon the
water chemistry, quality and physical conditions, e.g. depth of the diffusers and water flowrates.
example.
When the oxygen bubble is expelled from our ceramic diffuser, initially the bubble will contain 100% oxygen. As the bubble ascends to the surface,
oxygen will be diffusing out of the bubble, and nitrogen will be diffusing into the bubble. If the depth of the tank is greater than 1 meter, or
if there is a current in the tank/river or lake which makes the passage of the bubble to the surface, loner than 1 meter, then by the time the bubble
reaches the surface, the partial pressure of the gases in the bubble will be within approximately 5% of the partial pressure of the gases in solution.
If we assume that the water is at 100% saturation, the water will contain approx. 75% nitrogen and 22% oxygen, the gas bubble will have
approx. 27% oxygen and 70% nitrogen, by the time it reaches the surface. The transfer efficiency of the diffuser is close to 100%, however once you
take into account the physical chemistry aspect of the transfer, then you are down to around a 70% efficiency factor. If the oxygen
content of the water is lower, then the transfer factor will be higher.
To conclude; in order to dissolved 1000g of oxygen into the water you will need 1400 g of oxygen, or 1000 litres of oxygen ( 1g in solution
requires 1 litres to be diffused), and 3 to 4 of our DAD 6 diffusers.
