AJ Bush improves sustainability and efficiency with new aerator

AJ Bush & Sons (Manufacturers) is one of Australia’s largest protein recovery providers, operating rendering and manufacturing plants in NSW and QLD. The plants specialise in processing animal by-products for the meat/butchery industry. The NSW (Riverstone) plant’s collection area, in addition to Sydney Metro, ranges from Nowra in the south to Canberra, Dubbo and Bathurst inland and up to Newcastle and Tamworth in the north. The material collected is recycled into products used for livestock, pet food, aquaculture, fertiliser and biofuels.

How are AJ Bush & Sons operations sustainable?

AJ Bush’s Riverstone plant has undergone numerous upgrades over the years, aligning with company goals of minimising waste, reducing the risk of pollution (odour), and continuous improvement in providing a safe work environment for employees. As part of this sustainability program, Plant Engineer Nick Lawrance contacted Hydro Innovations for advice and assistance in replacing aging surface (floating) aerators on their wastewater treatment system. Nick wanted an aeration system that could be monitored and maintained from the lagoon banks and provide a safe environment that operators could attend to maintain and keep the aeration system at peak operational efficiency.

Sustainable aeration solution

Hydro Innovations proposed an ‘Echo-Storm’ aeration system from Gorman-Rupp as an alternative to traditional surface-floating aerators which have always been considered difficult and potentially hazardous to service or maintain. These surface aerators can only be accessed by crane or row boat, or need to be tethered to lagoon banks by a system of cables. Because of these impediments to access, maintenance is often neglected or postponed for prolonged periods.

What is an Echo-Storm aerator?

The Echo-Storm is a ‘bank-mounted’ venturi aerator used to mix and aerate tanks, ponds and lagoons; it uses Bernoulli’s principal, whereby a low-pressure area is created by an accelerated fluid. It is used in conjunction with a Gorman-Rupp self-priming pump. The pump draws water from the source and pumps it into the aerator under pressure.

How do Echo-Storm aerators work?

Within the Echo-Storm aerator, there is an ‘acceleration zone’ where the pumped fluid is accelerated, creating a low-pressure area within the ‘aspirating zone’. Here it draws in atmospheric air at the rate of 2.2 times the rate of the fluid being pumped. The air and water then pass into the ‘mixing and oxidation zone’ where the waste water and air are mixed under pressure. The turbulent mixing facilitates the removal of substances with weak Henry’s constants such as CO₂ and VOCs.

Why are Echo-Storm aerators sustainable?

WHS risks are minimised because operators don’t need cranes or row boats to access equipment.
Maintenance and operating costs are reduced (when compared with surface aerators).
Bank-mounted aerator and equipment is easy to access.
Longer lifespan because equipment is more likely to be monitored and maintained.

Installation at AJ Bush & Sons’ plant

Echo-Storm aerators can produce the desired level of mixing and dissolved oxygen transfer because they are easily scalable and can inject discharged oxygenated water at multiple points around the lagoon (basin, tank or lake). Importantly, thanks to the use of self-priming pumps, water can be drawn from any spot or spots within the water body to ensure complete mixing.

The rendering plant had been operating five floating surface aerators and when one of these failed it was decided to install an Echo-Storm aeration system to trial the effectiveness and operation of the system.

The result

After just a month of operation, significant results had been achieved, especially in the reduction of surface scum, maintaining required dissolved oxygen levels, improved operating efficiencies and contributing to lower odour levels.

The other obvious benefit of the newly installed bank-mounted Echo-Storm aeration system is the ability to quickly, safely and easily inspect the system or make any adjustments to the operation of the equipment if required, ensuring a completely safe working environment for operators.

Nick is pleased with the results and is considering replacing the balance of the old system to bank-mounted aerators.

What sizes are Echo-Storm aerators available in?

The Echo-Storm is available in four sizes, from 2″ (50 mm) through to 6″ (150 mm), providing dissolved oxygen transfer rates up to 30 kg per hour with a single unit, but capable of meeting any demand by using multiple units. Efficiencies can also be gained by using larger (more efficient) pumps to drive multiple Echo-Storm units.

The Echo-Storm not only transfers dissolved oxygen at efficient rates, it also conditions the wastewater by breaking down organic matter as it is accelerated through the unit, making more surface area available for biological treatment. It also oxidises sulphur-containing molecules such as hydrogen sulphide and mercaptans for effective odour and corrosion control.