Waste Water Aerators

Vertec Aerators are efficient and economical for treating effluent discharged into oxidation ponds.


Vertec Aerator Advantages

  • Almost silent operation
  • Provide speedy assistance to a naturally occurring biological process
  • Proven superior oxygen transfer rate and greater mixing ability
  • Cage Rotor Aerators are more efficient per kilowatt hour
  • 30 years of proven experience & reliability operating in a wide range of locations throughout NZ.
  • Full parts and service available.

Over 300 VERTEC cage rotor aerators sold throughout NZ for use in oxidation ponds, 18 local authorities use our aerator as well as a number of processing companies.

Talk to us about your requirements.

Power Options

The current range comprises:

  • 0.55kW, 
  • 1.1kW, 
  • 2.2kW, 
  • 4kW, 
  • 5.5kW, 
  • 7.5kW and 
  • 15kW

Vertec Aerators are available in stainless steel & galvanised mild steel - all made in New Zealand.

The smaller .55kW, 1.1kW and 2.2kW aerators have been specifically designed for private and dairy farm oxidation ponds to comply with the New Zealand Resource Management Act and have the option between P.T.O and electric motor drive.

The 1.1kW & 2.2kW are transported fully assembled.

The modular design of the larger machines ensures that they can quickly and easily be dismantled for ease of transportation.

Re-assembly on site can be accomplished easily and quickly.

Ammoniacal Nitrogen & Biochemical Oxygen Demand

Recent studies by the NIWA have shown that injection of oxygen into a pond system has the potential to greatly reduce the impact of dairy wastewater. Mechanical aeration is widely used to treat sewage and industrial effluent.

Research in New Zealand has demonstrated that aeration processes can significantly reduce Ammoniacal Nitrogen and BOD levels in stored effluent. Recent research showed that after both continuous and night-only aeration, the BOD was halved.

There was also an Ammoniacal Nitrogen reduction of 99% when an aerator was run continuously, or 90% with night-only aeration. With the addition of geotextile sheets to the night-only aeration, the reduction was 93%. Geotextile sheets act as an attachment surface upon which the slow growing bacteria which reduce the Ammoniacal Nitrogen can grow as thin bacterial film. 

Any durable, non-toxic material with a high surface area can be suspended in the water for this purpose. These attachment surfaces are helpful in shallow ponds particularly when placed just below the pond surface (top 300mm of the pond).


Ammoniacal Nitrogen (NH3-N), is a measure for the amount of ammonia, a toxic pollutant often found in landfill leachate and in waste products, such as sewage, liquid manure and other liquid organic waste products.

Biochemical Oxygen Demand (BOD, also called biological oxygen demand) is the amount of dissolved oxygen needed (i.e., demanded) by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period.

Aerator Operation

The Vertec Cage Rotor has unique helical designed blades which operate at the optimum depth, supplementing the natural process by bringing the bacteria into contact with the sewage & oxygen. Therefore keeping this top layer, aerobic and mixed while disturbance of the sludge at the bottom of the pond to a minimum.

As a result any possible imbalance in bacteria production is also minimised. This process prevents dead spots in the pond and in turn prevents odours, midges and eliminates public nuisance. Sludge built up on the bottom of the pond should be dredged and disposed of as a separate operation.
We recommend mooring the Cage Rotor at the inlet end of the pond, to prevent sediment building up in that area. This area is also where the highest oxygen demand occurs.

In cases where multiple aerators are required in one pond, placement can be arranged to suit the most effective mixing patterns depending on the size and shape of the pond. In most cases Aerators are conveniently moored in a stationary position approximately 2.5m from an adjacent bank.

Design Features


  • The rotor comprises of eight helical designed paddle arms mounted on the tips of four star shaped end plates.
  • The rotor is driven by a shaft mounted, geared motor.
  • The rotor is mounted to the pontoons via self aligning flange mounted bearings.
  • The bearing mounts are of a robust construction and fully welded to the pontoons.

Floating Pontoons

  • The machine floats on pontoons which are fabricated from 3mm mild steel plate.
  • Levelling and height adjustment can be accomplished by filling the pontoons with water or by adjusting the rotor up and down via an adjusting screw mechanism on the bearing mounted plates.
  • A walkway between the pontoons allows for easy access from one side of the machine to the other and the design of the pontoons allows for safe walking over the length of the pontoons.
  • All steel components are hot dip galvanised to protect against corrosion.
  • All major components of the machine are quickly and easily unbolted allowing for ease of transport, assembly and dismantling for site transfer.

Client Testimonial

"Coromandel District Council have used a 1.1kW Vertec aerator at Matarangi beach on the Coromandel Peninsula during peak summer periods for the past three years and I have no hesitation in recommending the machine. It is very reliable, working for two months at a time, 24 hours a day without stopping, maintaining required dissolved oxygen levels in the primary pond at the most difficult time of the year. The aerator has very low running cost and is easily maintained and serviced. We run the 4kW machines elsewhere for 35,000 hours without stoppages – that reliability."
Cliff Olsen, Utility Services Manager Coromandel Project Consultants