Separation technologies

Overview

The Separation technologies theme focuses on commercial and emerging separation technologies to improve the recovery of dairy products, reduce waste disposal costs and reduce environmental impact (Figure 1). The focus is on a sustainable and cost effective approach. The work includes scoping studies of separation technologies not previously applied to dairy streams, such as membrane distillation and capacitive deionisation for recovery of salt and charged proteins from dairy solutions. Advanced nanofiltration technology and electrodialysis are also being studied as potential methods for salt reduction and for the removal of lactic acid from acid whey.  

Figure 1. Overview of separation technologies used to analyse acid, sweet and salty whey streams.

Capabilities and technologies

Ultrafiltration

A process used for the recovery of protein from whey.

Nanofiltration

A process used for the concentration of lactose and partial demineralisation of sweet and acid whey.

Figure 2. Ultrafiltration/nanofiltration unit.

Electrodialysis

A process used for the demineralisation of sweet and acid whey and clean salt production from salty whey (Figure 3).

Figure 3. Diagram of an electrodialysis cell.

When used in conjunction with nanofiltration for the recovery of protein and milk sugar from acid whey (Figure 4), this technique has the potential to become a multi-million dollar commercial opportunity.

Figure 4. The energy consumption for demineralisation of acid whey is comparable to that of sweet whey using electrodialysis.

Membrane distillation

A process used for the concentration of high salinity effluent. This methodology can concentrate effluent beyond the limits of reverse osmosis. It can be used in conjunction with a crystallisation unit to remove the salt from salty whey (brine) leading to a reduction in both waste volume (up to three times) and solid content (Figure 5b). Membrane distillation uses minimal energy and also has the potential to use waste heat (Figure 5a). This technique has the ability to reduce the disposal costs and environmental impact of dairy byproducts.

Figure 5. (a)  Process for membrane distillation and (b) cryo scanning electron microscopy (cryo SEM) images of salt crystals.

Forward osmosis

A process used for the pre-concentration of dairy whey. This technology has the ability to reduce the energy consumption of evaporators and generate a potential saving of 0.5–1.0 MJ/tonne of dairy powder produced.

Capacitive deionisation

A process used for the removal and/or recovery of specific salts from dairy solutions.

Ultrasound

A process used to increase shear in intensive dairy processing.

Outcomes

  • We have conducted an industry survey on salty waste stream management in the Australian dairy industry.
  • We have conducted an extensive technology review into technologies for wastewater recovery and reuse in the dairy industry.
  • The team has been working closely with industry partners to ensure industry needs are addressed.
  • The team has evaluated the feasibility and commercial applicability of various separation technologies.

Publications

Chen, G. Q., Eschbach, F. I. I., Weeks, M., Gras, S. L. & Kentish, S. E. (2016). Removal of lactic acid from acid whey using electrodialysis. Separation and Purification Technology, 158, 230–237.

Kezia, K., Lee, J., Zisu, B., Weeks, M., Chen, G. Q., Gras, S. L. & Kentish, S. E. (2016). Crystallization of minerals from concentrated saline dairy effluent. Water Research, 101, 300–308.

Chandrapala, J., Chen, G. Q., Kezia, K., Bowman, E. G., Vasiljevic, T. & Kentish, S. E. (2016). Removal of lactate from acid whey using nanofiltration. Journal of Food Engineering, 177, 59–64.

Chandrapala, J., Ong, L., Zisu, B., Gras, S. L., Ashokkumar, M. & Kentish, S. E. (2016). The effect of sonication and high pressure homogenization on the properties of pure cream. Innovative Food Science & Emerging Technologies, 33, 298–307.

Kezia, K., Lee, J., Weeks, M. & Kentish, S. E. (2015). Direct contact membrane distillation for the concentration of saline dairy effluent. Water Research, 81, 167–177.

Kentish, S. E. & Rice, G. (2015). Demineralisation of Dairy Streams and Dairy Mineral Recovery Using Nanofiltration, in Hu, K., Dickson, J. M. (Eds.), Membrane Processes for Dairy Ingredient Separation. Wiley, pp. 112–138.

Hu, K., Dickson, J. M. & Kentish, S. E. (2015). Microfiltration for Casein and Serum Protein Separation, in Hu, K., Dickson, J. M. (Eds.), Membrane Processes for Dairy Ingredient Separation. Wiley, pp. 1–34.

Kentish, S. E. & Feng, H. (2014). Applications of power ultrasound in food processing. Annual review of Food Science and Technology, 5, 263–84

Researchers

  • Prof Sandra Kentish

    Chief Investigator

  • Dr George Chen

    Postdoctoral Researcher

  • Sahar Talebi

    PhD Student