Lessons on drought from down under
Singapore and Australia are each battling their own water resource problems. A British Water global mission visited both countries to see how they are dealing with the issue. Dr Ian Pallett reports.
The two countries are contending with water resource problems but for very different reasons.
Singapore and Australia both have water resource problems but with different causes, however, they are dealing with them in similar ways. Singapore receives a considerable quantity of water from Malaysia and the contracts are due for renewal in 2011 and 2061, but the governments of both states cannot agree on terms (primarily costs) of the new agreements.
As is well known Australia is in the grips of a drought - now in its tenth year - and forecasters are pessimistic about any significant extended periods of rain in the near future.
Singapore has embarked on a programme to review all possible new sources of water coupled with better, more efficient use of water and demand management.
The Public Utilities Board (PUB), a government-owned utility, manages the entire water cycle of Singapore and is implementing a holistic policy. PUB is promoting water conservation measures which feature along with "The Four National Taps" (sources of water) in publicity campaigns to consumers as part of the sustainable water resource management in Singapore.
The programme includes a very active Research & Development (R&D) programme as well as infrastructure developments that will increase the island's water catchment area.
Following successful piloting of state-of-the-art technology, including 16in RO vessels, four large wastewater treatment plants designed to provide high quality treated effluent for reuse have either been completed or are nearing completion. The four plants are to be supplied with wastewater from residential areas via large deep sewers. The secondary effluent is treated by MF, UF and RO membranes and UV disinfection.
A small proportion (3% by 2011) of the reclaimed water will be diverted to public supply reservoirs as the largest planned indirect potable reuse (IPR) scheme in the world. The reclaimed water has been branded as "NEWater" and PUB has managed an extensive, costly and successful education and marketing drive giving it a very high degree of public confidence.
The severe ten-year drought and a rising demand for water fuelled by an increasing population in many of its urban centres are all major drivers for resource and supply management by the water industry.
Water supply is a State responsibility which may be devolved to municipalities, but increasingly the State and Federal governments are proposing policies designed
to develop a coordinated response to the water shortage.
Phase 1 of the National Guidelines for Water Recycling, published November 2006, covers non-potable uses of treated wastewater and greywater. Phase 2 (summer 2007) will give guidance for IPR, managed aquifer recharge and stormwater use.
The National Water Commission (NWC) is responsible for helping to drive national water reform and advising the Prime Minister and State and Territory governments. It is responsible for managing the implementation of the National Water Initiative and implementing two programmes of the Australia Government Water Fund - the Water Smart Initiative and Raising National Water Standards.
The National Water Initiative, a comprehensive intergovernmental agreement, aims to increase the efficiency of Australia's water use leading to greater certainty for investment and productivity as well as benefits for the environment. The Australian Government Water fund is a package to invest in water infrastructure, improved water management and better practices in the stewardship of Australia's scarce water resource.
The potential intensity of the drought became apparent when resource estimations were based on the most recent ten-year average rather than 100-year average rainfall.
Some large scale recycling of treated wastewater to industry has been put in place but State authorities are developing plans for using recycled treated wastewater to smaller applications and residential areas. Some water suppliers have discounted indirect potable reuse, others are considering it, but in one referendum the public have rejected it. However, the Queensland premier has recently said there is no alternative in some regions and so has scrapped another plebiscite.
As well as supplying large industries (steel, petrochemicals) recycled water is being used for park and leisure facility irrigation and in some extensive developments.
Sewer mining is practiced where a convenient main sewer can be tapped and the sewage treated using a package plant or reed beds. Greywater recycling combined with rainwater harvesting is being trialled and many large new developments incorporate dual networks for the supply of potable and recycled treated wastewater.
The pipework comes in two distinct colours and cross connections are monitored for either by comparing meter readings or, as in South Australia, by five-yearly audits - one region even has "water police" to help guide the correct use of water! There are examples of in-building recycling of blackwater and rainwater.
Planning regulations now require the installation of rainwater tanks and plumbing to allow it to be used for external domestic use, toilet flushing and laundry, its use for domestic hot water is being considered but there are some health concerns.
Stormwater collection is being trialled using reed beds or wetlands to treat the water before it is used for aquifer recharge, irrigation or by industry (wool washing).
A major problem is the amount of water used for irrigation. Typically 50% of the domestic water supply has been used to water gardens and the use for irrigation by agriculture has been extensive. Demand management practices are being introduced leading to restrictions on garden watering but legal historical agreements with the irrigators are making for problems with reducing agricultural demands.The findings of the mission will be fully reported in the free dissemination seminar in London on March. 26.
For information and to register go to the Global Watch Service website http://www.globalwatchservice.com/pages/ThreeColumns.aspx?PageID=107
Dr Ian Pallett is technical director at British Water.
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