Solar powered reverse osmosis desalination: Technology for remote communities

Don Harrison

The need for desalination to provide drinking water of acceptable standards has been established. A review of desalination techniques suggests that solar powered reverse osmosis with energy recovery is likely to satisfy the widest range of applications in inland Australia and elsewhere. Of the energy recovery techniques, the 'flow-regulated' approach appears well suited to remote applications, because it maintains its set recovery ratio regardless of insolation levels, and starts and stops automatically at sunrise and sunset. Operating and capital costs of units needs to be minimised and operational flexibility maximised for wide application in remote areas. This project aimed to develop, produce and test a low cost solar powered desalinator that was portable, reliable and flexible. The thesis describes the theoretical and practical development of a production model through the four prototypes. The prototypes were tested to determine the performance of a variety of membranes, the efficiency of the pumps and energy recovery system, and the water slippage of valves and seals. The available energy from the two-panel tracking array was also assessed. A model which describes the hydraulics of 'flow-regulated' energy recovery systems was developed and incorporated in a spreadsheet program and used to assess the performance of the prototypes. The relevance of all the variable components affecting fresh water production can be assessed through graphically presented results from the spreadsheet. A production model solar powered desalinator capable of 400 L/day from a 120 W peak array has been developed as a result of the project. The flow-regulated approach to energy recovery appears to work well in the field and may be contributing to the maintenance of high water production rates at all sites without resorting to chemical pretreatment or frequent cleaning. High pulsation rates and low feed flow rates through large diameter spiral wound membranes do not appear to adversely affect membrane life at the low pressures used in these machines. Further research is required to monitor the long term reliability and running costs of these machines, their degree of acceptance in remote communities, and their ability to maintain the quality of product water to acceptable standards.

Solar powered reverse osmosis desalination: Technology for remote communities

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