Aeration

Aeration equipment is vital to the biological operation of aerobic waste water purification processes. There are several different methods of providing aeration.  All methods have the same basic purpose, namely to introduce oxygen into the treatment process in the most efficient manner possible. This oxygen is essential to sustain the beneficial bacteria that consume the pollutants. These organisms are known as activated sludge bacteria.

The pollution existing in the wastewater is measured as the Bio-chemical Oxygen Demand (BOD) and is typically about 250 mg/l in raw sewage. After aeration and settlement of the activated sludge BOD is reduced to about 15 mg/l.

In addition to providing oxygen, the aeration system also serves the important function of maintaining the mixed liquor solids in suspension.

Generally speaking the longer a bubble is retained in the liquid the greater will be the oxygen transfer. This concept naturally favours fine bubble diffusers. The advantage of the coarse bubble diffuser is that it is less susceptible to clogging. In simple terms any diffuser device with openings of less than 1.5mm  may be considered a fine bubble diffuser. 

Both fine and coarse bubble aeration systems have a role in wastewater treatment.

EPCO Australia is the source of the following aeration systems:

• Cast Iron Stainless Steel Coarse Bubble Diffusers
• Synthetic fine bubble membrane diffusers
• Mechanical Aerators

Cast Iron Stainless Steel Coarse Bubble Diffusers

Coarse bubble diffusers are a non-clog diffuser ideally suited for intermittent aeration systems and sewage streams that have had limited screening. Air quality required for the coarse bubble diffuser is not as critical as for the fine bubble type. 

The EPCO Australia range of coarse bubble diffusers are extremely reliable under arduous conditions. 

• Coarse bubble cast iron flap type are suitable for extended aeration plants.
• Ball type brass or 316SS diffuser suit small aeration systems or aerated grit chambers.

Cast Iron Coarse Bubble Diffuser

Synthetic medium bubble membrane diffusers

• high oxygen utilisation.
• suitable for intermittent operation.
• high temperature resistance.
• low susceptibility to encrustation.
• suitable for industrial and municipal wastewater treatment.
• self sealing in off periods.
• quick and easy fitting.
• economical conversion of existing systems.

Mechanical Aerators The two objectives of a mechanical aeration system are oxygenation and mixing. These are achieved through movement of the liquid using different types of stirring and or pumping devices.

The principal use of mechanical aeration is in activated sludge plants. Aerators may be fixed or mounted on a floating platform and used in practically any size or shape of tank. Oxygenation rate is controlled by aerator speed adjustment or varying aerator immersion. The one minor disadvantage of this type of system is the lack of processing flexibility.

Floating Medium Speed Surface Aerators

High speed floating aerators are reliable, energy efficient, have a long service life and can operate in basins with static or variable water levels.

The high speed floating aerator is a low weight device thus it is easy to launch and needs only mooring cables and a power supply to make it operable. They are well suited to aeration basins, sludge tanks, treated effluent ponds and leachate lagoons.

To provide these economical aerators, EPCO Australia represents the Environmental Equipment Engineer, Inc. range. The EEE aerators have an enviable reputation for economy, ease of installation and long term reliability.

 

 

Oxidation Ditch Rotors

Oxidation ditches are high efficiency robust units usually used in carousel type reactors. Otherwise known as brush aerators, they are slow speed horizontal spindle units. These devices are primarily used in the aeration and mixing of activated sludge. Sewage retention in the oxidation channel of one to two days enables extensive degradation of pollutants. Top