Chemical and Biomolecular Engineering - Research Publications

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Author: Chen, George × Author: Gras, Sally × Author: Kentish, Sandra × End date: 2018 × Start date: 2014 ×

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    A review of salty waste stream management in the Australian dairy industry
    Chen, GQ ; Talebi, S ; Gras, SL ; Weeks, M ; Kentish, SE (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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    The effect of restriction membranes on mass transfer in an electrodialysis with filtration membrane process
    Deng, H ; Chen, GQ ; Gras, SL ; Kentish, SE (ELSEVIER SCIENCE BV, 2017-03-15)
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    Removal of lactic acid from acid whey using electrodialysis
    Chen, GQ ; Eschbach, FII ; Weeks, M ; Gras, SL ; Kentish, SE (ELSEVIER SCIENCE BV, 2016-01-28)
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    Crystallisation of minerals from concentrated saline dairy effluent
    Kezia, K ; Lee, J ; Zisu, B ; Weeks, M ; Chen, G ; Gras, S ; Kentish, S (PERGAMON-ELSEVIER SCIENCE LTD, 2016-09-15)
    An understanding of crystallisation within saline effluents is important for the design of both brine crystallisers and brine disposal ponds. In this work, crystallisation of a saline effluent concentrate from the Australian dairy industry has been examined at 22 wt% and 30 wt% total solids and at temperatures between 10 and 70 °C. The precipitation occurs more rapidly at higher temperatures. This trend is dictated by precipitation of calcium phosphate salts, albeit the major constituents of the mixture are NaCl and lactose. The crystallisation induction time can be shortened by introducing cavitation induced by ultrasound. In particular, the use of two short acoustic pulses between 3.7 J/g and 16 J/g at 20 kHz spaced ten minutes apart has maximum impact upon both induction time and crystal size. It is believed that the first ultrasound pulse either generates new nuclei or enhances the mass transfer of solute toward the surface of sub-micron growing crystals. Conversely, the second pulse disrupts the growing crystals and forms secondary nuclei. The ultrasound cannot shift the solution equilibrium and so is not able to improve the low crystal yield. To increase this total yield, further evaporation is necessary. The work provides direction to personnel in the dairy industry of the feasibility of brine crystallisation with respect to energy demand and solid recovery.