Desalination and Water Treatment using the Bubble Column Evaporator

Clean, safe water is vital for everyday life. Water is essential for health, hygiene and the productivity of our community. Recently, demands on limited clean water supplies have resulted in an awareness of the limitations and challenges facing water supply systems. Existing techniques often struggle to achieve acceptable standards for water quality, cost or environmental acceptability. Bubble column evaporator (BCE) technology offers pragmatic solutions to these water treatment problems.The BCE exploits a large air/liquid interface by which heat and mass transfer can be effectively and efficiently carried out. This interface can be enhanced by exploiting the mysterious bubble coalescence inhibition phenomenon observed in some salt solutions. Application of this technique in a simple, efficient desalination process was demonstrated, providing a high water vapour carry over and low energy use. BCE-based sterilisation of coliform bacteria and viruses was also studied and shown to be faster, more efficient and cheaper than conventional heating/boiling methods, as well as being safer due to the lower operating temperatures required. Decomposition of degradable solutes was established, with potential applications for forward osmosis processes, again at a lower temperature, with a lower energy consumption, and quicker than conventional heating. Accurate, precise determination of enthalpy of vaporisation of a range of salt solutions, especially at high air-feed temperatures, was shown and validated by comparison with literature data. These BCE applications have potential uses in many industrial settings, such as for desalination, water/wastewater treatment, forward osmosis (FO) and polymerisation processes, among many others.These studies show that BCE processes have potential applications for inactivating dangerous protozoa, and destroying unwanted solutes, such as hormones and pharmaceutical compounds, say for example, antibiotics present in wastewater. Likewise, the BCE method could lend itself to large-scale applications in novel hybrid technologies, possibly powered by hot industrial waste flue gases, in which multiple treatments such as sterilisation, desalination and decomposition are combined and integrated in a single, simple, economical and efficient process