Chemical and Biomolecular Engineering - Research Publications
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ItemUtilisation of salty whey ultrafiltration permeate with electrodialysis(Elsevier, 2019-12-01)Salty whey is a waste by-product that incurs increasingly high disposal costs for the dairy industry. This study investigated electrodialysis of the ultrafiltration permeate of salty whey as either a concentrate for the treatment of sweet whey or as a source of lactose and salt. The type of concentrate (0.1 m NaCl or salty whey permeate) did not affect the rate of sweet whey demineralisation or the energy consumed per tonne of whey, but less sodium and more divalent cations were removed when salty whey permeate was used as the concentrate. Salty whey permeate could be effectively demineralised using either 0.1 m NaCl or a second stream of salty whey permeate as the concentrate. The concentrate purity could be enhanced using monovalent selective membranes without increasing the energy consumption of the process (3.2 ± 0.3 kWh per kg of NaCl removed from the diluate at 15 V).
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ItemFouling and in-situ cleaning of ion-exchange membranes during the electrodialysis of fresh acid and sweet whey(ELSEVIER SCI LTD, 2019-04-01)This work investigated the fouling of ion-exchange membranes during the electrodialysis of sweet and acid dairy whey. Fresh whey was used, rather than solutions made up in the laboratory, giving a unique perspective. While membrane fouling occurred in all experiments, the effects on system performance were limited. Reductions in the current during pure NaCl circulation fell to a minimum of 80% of the original value after 5 h of whey processing. The use of an alkaline concentrate resulted in the strongest increase in system resistance, but the mineral deposits formed appeared to detach readily, thereby reducing these effects. The use of an acidic concentrate gave significantly greater rates of lactic acid removal, which is important in industrial applications. A solution of HCl with a pH of 1.0 ± 0.15 was effective for in-situ cleaning of the mineral deposits. However, protein deposits were not readily removed using the recommended base cleaning formula of 3% NaCl at a pH of 9.2 ± 0.2.
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ItemA review of salty waste stream management in the Australian dairy industry(ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2018-10-15)Saline wastewater is a by-product of cheese manufacturing and whey processing that can have serious environmental and economic consequences. Salty streams originating from dairy processing operations include chromatography wastes, clean-in-place wastewater, acid whey, salty whey and waste generated from whey demineralization processes such as nanofiltration, electrodialysis and ion exchange. With the participation of the major dairy companies in Australia, an industry wide survey was conducted to acquire a comprehensive understanding of the management strategies for these salty waste streams. High salinity waste streams are commonly directed to evaporation ponds. However, environmental impacts from land degradation, odour and dust have prevented the construction of further evaporation ponds in some areas of Australia. The survey results also show that disposal to municipal trade waste is not always effective, as the current levels of some salinity-related parameters are significantly higher than the levels allowed by the local water/environmental authorities. For high salinity streams, salt removal can lead to more substantial savings in trade waste charges compared to wastewater volume reduction. Thus, salt removal and recovery from salty waste streams has become a major focus of the sustainability agenda of the Australian dairy industry.
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ItemThe Role of Ion Exchange Membranes in Membrane Capacitive Deionisation(MDPI, 2017-09)Ion-exchange membranes (IEMs) are unique in combining the electrochemical properties of ion exchange resins and the permeability of a membrane. They are being used widely to treat industrial effluents, and in seawater and brackish water desalination. Membrane Capacitive Deionisation (MCDI) is an emerging, energy efficient technology for brackish water desalination in which these ion-exchange membranes act as selective gates allowing the transport of counter-ions toward carbon electrodes. This article provides a summary of recent developments in the preparation, characterization, and performance of ion exchange membranes in the MCDI field. In some parts of this review, the most relevant literature in the area of electrodialysis (ED) is also discussed to better elucidate the role of the ion exchange membranes. We conclude that more work is required to better define the desalination performance of the proposed novel materials and cell designs for MCDI in treating a wide range of feed waters. The extent of fouling, the development of cleaning strategies, and further techno-economic studies, will add value to this emerging technique.