Abattoir improves energy efficiency of wastewater management

Cedar Meats is a progressive and contemporary meat exporter in Victoria, with a continual improvement philosophy. The company needed to upgrade its DAF (dissolved air floatation) system due to aged and decommissioned components at the site. The research was conducted on the best available technologies — Cedar Meats’ driving force of continual improvement meant looking beyond what had worked previously and investigating how its existing system could be not only repurposed but significantly improved.

Cedar Meats wanted a fully functional, more energy-efficient system that could deliver low running costs for the life of the DAF unit.

The ‘conventional’ DAF system consists of a number of components:

1. A centrifugal pump that pulls clean effluent from the DAF tank and feeds it into a pressurised air saturation vessel.
2. A compressor that also feeds compressed air into the same vessel and the air saturates into the effluent water under pressure. The water is then fed back into the bottom of the DAF tank where the air comes out of solution (because of the lower pressure) to form tiny microbubbles, which attach to fats and grease in the system and float it to the top of the tank where it is scraped away. The pressure vessel requires regular certification for safety purposes.
3. A control system to combine air and water requirements.

Assessing the sustainable options

The Chief Engineer at Cedar Meats, Yogesh Mistry, started investigating the options available for an innovative and sustainable solution. The elimination of intricate and delicate control systems was on his wish list for the ideal solution. Additionally, a system that did not need ongoing Worksafe certification for pressure vessels was another requirement he was trying to incorporate into the new system. Mistry contacted Hydro Innovations to find out more information about the EDUR DAF pump.

Consideration was given not only to the purchase price of the new system but also the lifetime maintenance and running costs were examined.

The combined maintenance of the DAF pump, compressor and pressure vessel were costly, and finding a way to reduce the energy consumption of both pump and compressor was researched. Capital costs and running costs are not cheap for the standard or traditionally used DAF systems.

The solution

EDUR, a German Pump manufacturer since 1927, has developed a multi-stage multiphase pump capable of handling a gas/water mixture, making it suitable as a DAF pump.

The efficient and smart pump solution draws clean effluent from the DAF tank, and at the same time, draws in atmospheric air on the suction side of the pump. The pump sheers and mixes the air with the water, and under pressure from the multi-stage pump, air saturates into the effluent water. The water is then pumped into the bottom of the tank, where the air comes out of solution, as in conventional systems. No compressor or air saturation pressure vessel is required.

Mistry was impressed with the simplicity of the system and promptly arranged the purchase of an EDUR DAF pump. He has been pleased with the positive results, which include:

• a higher rate of solids removed;
• less power used (reducing power costs);
• less complicated controls.
   

Mistry has a low-maintenance future ahead for this system.

The EDUR multiphase range of pumps is available with flow rates from 0.5 L/s through to 15 L/s to enable them to handle a wide range of DAF plant in-flows. Pumps are constructed of either C.I./Bz/SS, Nodular Cast Iron, all-bronze, all stainless steel or all Super-Duplex stainless steel construction, so may be used to handle a variety of liquids. Air, oxygen, carbon dioxide and ozone gases can be introduced into the suction line and transported and used to mix or disperse the gases.

The advantages of the EDUR DAF pump over conventional DAF systems can be summarised as follows:

• Reduction in system components.
• Smaller footprint.
• Reduced energy consumption.
• Reduced maintenance costs.
• Reduced noise levels.
• Improved WHS.
• Simplified system operation.
• Optimum microbubble size for perfect rising speed.
   

Cedar Meats had an old air saturation vessel onsite, so rather than becoming landfill, the air saturation vessel was upcycled to become part of the solution line for the new system. Because it was no longer being used as a pressure vessel, it no longer requires certification.