DESALINATION PLANTS: AN AUSTRALIA SURVEY

摘要

A survey of 46 desalination plants in Australia that have capacities greater then 10 kl_/d was carried out during 2008. Operating plants have a total output of 294ML/d, while the outputs for plants under construction amount to 976ML/d, and for proposed plants 925 ML/d. About half of the current plants are located in Western Australia, but by the year 2013 plants will be more evenly distributed across the States.rnThe volumes of feed sources to be utilised are 86% seawater, 1.2% brackish water and 12% industrial effluent. The water recoveries vary from 20-42% for a seawater feed to usually 61-95% for brackish and low salinity feed waters. The total current desalted water usage is dominated by potable supplies (153 ML/d) and 141 ML/d is used for industrial purposes. By the year 2013 the '"desalinated water supply will rise to 1734 ML/d for potable and 461 ML/d for industrial use.rnThe product water cost per kL is mostly in the range of less than $1.25 for potable water and $1.25-$2.00 for industrial water. Of the total water consumption in Australia of 51.5 GL/d in 2004-05, the amount of desalted water in 2008 is 0.294 GL/d, or 0.57% of that total. This will to rise to 4.3% in the year 2013. Waste disposal of the reject salt solution to various environments includes most of it to the sea, although more plants of smaller output use evaporating basins or send the waste to a sewer. Ground infiltration is another option used in some localities.rnIn reverse osmosis process, membrane fouling remains a problem in that it shortens membrane life and increases the cost of the desalination process. Pre-treatment of the feed is required to minimise fouling. Conventional clarification is commonly used, but microfiltration (MF) or ultrafiltration (UF) with membranes is also employed.rnThe average energy consumption is 3-3.7 kWh/kL for sea water RO, 0.7-1 kWh/kL for brackish water and 1.2 kWh/kL for industrial effluent. The total current power used is 30.1 MW, or 722rnMWh/d. By the year 2013 the total power required for the increased desalination capacity in the country will be 277MW.rnThe existing trend towards desalted supplies for municipal and industrial purposes is likely to continue, as climate change effects become more pronounced across the southern part of the Australian continent and the prospect of running out of water becomes more evident. Water reclamation, most notably by industry, will be essential.