Home > Dairy leader employs DAF system to achieve tough wastewater targets

Dairy leader employs DAF system to achieve tough wastewater targets

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CST Wastewater Solutions  designed and installed a high performance DAF or Dissolved Air Flotation system at the manufacturing site of a major dairy product company to achieve high efficiency discharge targets at its wastewater treatment facility.  

The DAF system is helping the dairy company achieve the desired results from its new $1.5 million wastewater treatment facility for treating effluent at its Southern NSW manufacturing site.  

Capable of treating 300,000 litres of effluent daily, the wastewater treatment plant meets the local council’s demanding discharge standards as well as reduces the discharge fees paid to the council.  

Offering better performance than the more expensive microbial treatment, DAF treatment reduces the high levels of Suspended Solids (SS) and Biological Oxygen Demand (BOD) in the wastewater sufficiently to allow discharge into the local authority’s sewerage system.  

According to Michael Bambridge, Managing Director of CST Wastewater Solutions, the DAF flotation system has been developed in line with advanced solids/liquid separation techniques. He adds that the system features a low volume circular flotation cell, coupled with a high efficiency air-dissolving reactor to achieve 95% air saturation.  

Since the DAF flotation process requires less chemical pre-treatment for flocculation to occur, costs are reduced. DAF clarifiers are also not as expensive to build and install, compared to complex bacterial processes or large settling basins.  

The DAF system at the dairy company comprises of a 94,000 L buffer tank, with the floated sludge collected in a smaller 30,000 L tank. Chemicals are used to remove suspended matter, reducing the pollutant levels in the wastewater. Micro bubbles introduced into the wastewater carry the suspended matter to the surface of the flotation cell, where the matter is removed by a rotating scoop or surface skimmer.  

In addition to the dairy industry, the DAF system finds application in paper manufacturing, oil industry, wineries, tanneries, textile industry, large laundries, chemical industry, refineries, sludge thickening, and primary and secondary clarification in municipal and industrial biological wastewater plants.  

The wastewater load released into the sewerage system at the dairy facility has seen 20% reduction in dissolved solids, 90% removal of suspended solids, 70% removal of BOD and 98% removal of oil and grease.  

Key features of the DAF system:

  • High air saturation efficiency > 90%
  • Automatic control of the injected air
  • Automatic control of the sludge blanket
  • Flexible operation: Recycle, partial flow or full flow
  • Available in sizes from 1.48 - 15.40 metres in diameter and 1.00 - 2.58 metres in height

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