Blue-green algae issue solved for protein rendering unit

Craig Mostyn Group is one of Australia’s leading diversified food and agribusiness companies. Established in 1923, the company is now claimed as Western Australia’s largest vertically integrated pork, lamb and beef business. It also has seafood operations, which include three abalone farms and multiple sites across Tasmania. Its protein rendering unit, Talloman, is a core division of the Craig Mostyn Group, and when it started to have issues with a wastewater treatment pond, plant manager Carlos Mendes went looking for a solution.

The EchoStorm venturi aerator from Gorman-Rupp was recommended to him and he contacted Hydro Innovations (Australian Gorman-Rupp distributor) for a solution. Mendes wanted a reduction in BOD, COD, NH₃ and also a solution to a troublesome blue-green algae issue.

Adding dissolved oxygen to aerobic bacteria allows organic compounds in wastewater to be broken down quickly, preventing it from becoming septic and odorous. The addition of dissolved oxygen allows these organic compounds to be converted into non-polluting compounds.

The solution

Based on the size of the pond, the inflow rate and water analysis provided, Hydro Innovations recommended a 4″ (100 mm) EchoStorm system. This system comprises a Gorman-Rupp U4B60S-B self-priming centrifugal pump with 15 kW motor, ‘powering’ a Gorman-Rupp V4A EchoStorm venturi aerator.

The EchoStorm is a static venturi aeration device that is installed on the discharge side of a Gorman-Rupp self-priming centrifugal pump to introduce dissolved oxygen into the liquid being pumped. With no moving parts, the EchoStorm will only require routine maintenance of the Gorman-Rupp pump. The simplicity of the system makes it easy to install, operate and maintain.

The U4A60S-B 4″ self-priming effluent pump is highly efficient because of its multi-vane impeller and ‘straight-in’ suction design, making it a good choice for keeping power consumption of the system low. It is also capable of passing a 20.6 mm solid and operating on suction lifts up to 6.1 m.

The pump draws in water from the lagoon, then pumps it at pressure through the EchoStorm unit, which draws in atmospheric air, mixes it with the water and delivers it back to the lagoon. The unit not only ‘saturates’ the water with dissolved oxygen, but it also ‘conditions’ the flow, breaking down organic matter into smaller particles, allowing for enhanced organics reduction. This conditioning effect also ruptures the buoyancy vacuoles within the blue-green algae, causing it to sink, depriving it of the sunlight required for growth and stripping CO₂ from the water, depriving it of carbon dioxide.

Mendes and the Talloman evaluation team liked the idea of the equipment being mounted on the bank of the pond, rather than floating in the middle of it, and could see the ongoing benefits of easier access and the maintenance advantages of the system. As a safety-first company, the team also saw the system as being much safer for operators than other systems they had seen.

But as the technology is relatively new to wastewater treatment in Australia, Mendes was cautious in his evaluation about the results the system could achieve moving forward. Hydro Innovations, however, was very confident of the success of the system (unit) and not only offered a five-year warranty on the pump (which is standard), but also a money back guarantee if the unit failed to deliver the promised results. Mendes was happy with this arrangement and proceeded with the purchase.

The results

The Talloman crew did an excellent job setting the unit up exactly to specifications, and wanted to be sure their investment in the future was a good one. To this end, Mendes had his crew track the progress of the EchoStorm by measuring the total of all taxa from ‘Day 1’. When the unit was installed in March, total taxa measured 217,000. Mendes called off the measuring when the last reading was taken in May, where the measure was down to 6630 (a reduction of 97%). Needless to say, Mendes and the Talloman team are happy with the results.

They have also been pleased at how easy the unit is to access for monitoring and maintaining.

The EchoStorm aerator units are available in sizes from 2″ (50 mm) through to 6″ (150 mm), but multiple units can be used to cater for larger requirements.

When the application calls for even higher levels of oxygen, much larger (and even more efficient) pumps can be utilised, each providing flow to two, three, four or even five EchoStorm venturi aerators. The efficiency of these pumps drives up the standard oxygen transfer efficiency (SOTE) even further. The use of multiple EchoStorm units also enhances mixing and virtually eliminates dead spots that are often left by competing technologies.

EchoStorm units are versatile because they can draw water from any level in the water source and from any part, and can discharge it at any level and any part. This gives the asset owner numerous options for mixing or creating different treatment zones.

Venturi aerators are not used just for treating food process wastewater, but also for treating municipal wastewater and mine water, and also for lake destratification.