Recycling Water Crucial To NT Water Supplies

In the face of global water supply shortages, recycled water has the potential to help us be more climate-independent. And even though it seems novel, reused water is already cycled back into the supply. If you live in a community downstream of another one, chances are, you are reusing its water.

Australians and Americans have embraced “sustainability” in so many aspects of modern life, but not when it comes to water resources.

Recycled or reclaimed water is water that is used more than one time before it passes back into the natural water cycle. Treated wastewater, including sewage and water used for industrial processing, can be cleanly recycled for agricultural and landscape irrigation, industrial processes, toilet flushing, replenishing a groundwater basin and even for drinking water.

Scientifically proven advances in water technology — including reverse osmosis, ultraviolet disinfection, and oxidation — applied to wastewater allow communities to reuse water for many different purposes, treating the water differently depending on the intended use.

And the best part is: there is huge potential for growth in using recycled water. Thirty-two billion gallons of municipal wastewater are produced everyday in the United States but less than 10 percent of that is intentionally reused and the equation is quite similar in the Northern Territory, particularly in the northern areas, as Alice Springs now does have an aquifer recharge program using treated wastewater from the effluent ponds.  

Also, it is known that the NT uses up to four times water per person more than temperate Australia, and much of that extra water is used outside, where non potable water would do.  It is certainly wasteful to treat all water to drinking standards and then use 70% outside as is common in Darwin.

One key reason that water reuse is not a bigger part of the nation’s water supply is that it is still characterized as a waste product in most places. 

In a progressive move, California in the US recently enacted legislation that reclassifies recycled water as a water resource. The state government also recently streamlined the permitting process for using recycled water for irrigation and allocated $200 million in grants to encourage related projects.  While California uses different legislative systems to Australia, the truth is, Australia could do a lot ore with use of appropriately treated wastewater.  AND......such programs would be sensible infrastructure development in a continent as dry as ours.

In other parts of the USA,communities in dry west Texas have used state-of-the-art technology to augment their drinking water supply with reused water; Phoenix in Arizona has had an aquifer recharge program using treated effluent which is subsequently redrawn for use, for about 50 years; the governor of Oklahoma just signed a law to encourage water reuse; and Florida’s most recent water reuse report indicated that 719 million gallons of water is beneficially reused each day in 2013 — the largest amount in the country.  Yet here in north Australia as we discuss developing the north, there is little discussion about reuse of water, in an environment which is totally dry for 6-8 months each year, while in the other few months water flows away freely [ admittedly it is used by the environment!].

The amount of water intentionally reused in both Australia and the USA still quite low and it will stay that way as long as the public regards reuse as an emergency measure. Citizens have embraced “sustainability” in so many aspects of modern life, but not when it comes to water resources.

Conservation cannot meet future water demands alone and other measures that create new sources of water, like desalination, are still more expensive, with some people believing that it is too expensive although newer technologies are encouraging in possibly lower costs.  Desalination has its advocates though, with WA a champion of the technology, with development being driven by the woman who is the Chair of the WA Water Corporation.

In the Top End of the NT the only avenue seemingly being explored for more water is to develop more dams or other above ground storage systems, such as the pumped off river system discussed for an area in hills north of Adelaide River, and the dam above Adelaide River.  Desalination of seawater is also a possible option around Darwin. 

Water reuse is the easiest and most economical fix. It should be included in the water supply portfolio of the Darwin region, and in fact for all  communities.  It at least should be given equal weight in assessing future water resources for the region.

[ partially adapted from an article by Melissa Melker of the US Water Reuse Association in the NY Times 30 June 2014]

UPDATE - http://ecowatch.com/2014/03/20/solar-technology-californias-water/
This is a solar technology to distill irrigation tailwater from agriculture fields using solar technology to heat a oil filled tube and then use the heat to distill the tailwater.  It works and can be scaled up, with a projected cost of about one quarter the cost of desalination of sea water [ many places say a cost for this of $2 per kilolitre].  Search for Water FX online for more details.

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Water Demand To Soon Exceed Supply in Many Areas

Analysts with Bank of America Merrill Lynch Global Research have released a report that predicts global demand for fresh water will soon outstrip supply, according to an article on CBS MoneyWatch.

Stylised water supply system

"Water scarcity is a pressing people and planet issue," the report stated.  This is hardly new to many working in the sector, or those in aid / development areas.

According to the article, 768 million people around the world have no access to clean drinking water and 2.5 billion are without proper sanitation, noted the article, while about 2.5 percent of all water on earth is fresh water.

Addressing these issues is a priority for the Water and Sanitation Program [ see more at www.wsp.org] and many simple measures can be effective, especially on the sanitation side.  But fresh water supply is more difficult, with wasteful water use a big issue itself, especially in developed countries.

The report states that humans have already reached "peak water," at or approaching the limit of renewable freshwater supply, the article reported, and half of the world's population will face "water stress" conditions by 2030.

According to the article, as many as 50 nations can be expected to be involved in conflicts over water by 2050.

You can read the full article here.

Urban Stormwater Management – Smarter Solutions and Better Stormwater Use

While almost no urban sewerage system in Australia is designed to also handle stormwater, as is the case in some older cities, particularly in the USA, the management of stormwater productively is quite a challenge.  With our increasingly hard surfaced cities, the stormwater system has grown, usually channelling away water that previously would have often dissipated within the landscape where it was generated, often even into the ground, or at least nearby.

While there are places around Australia where the stormwater is planned to move and actually recharge local aquifers, with Mawson Lakes near Adelaide a good example, as is some stormwater even around Palmerston, recharging the aquifer under the city in the wet season.  Normally, most stormwater runs off, and is lost to local use.

With about 80% of contaminants on hard surfaces, being moved with the first flush of rain [even more in the tropics with the first break storms of the wet season], colleting that and filtering through land and used by plants is a major and distinct improvement to the quality of stormwater discharged into nearby rivers, creeks and ultimately the harbours and oceans.  Most of the pollutants are remediated by soil borne organisms.

But driving that change is difficult as engineering has dominated how urban stormwater has been managed and the usual method has been pipe, or surface hard channel it, away.

More localities are reconsidering this however, through design modification to use plant based drains and detention areas before excess water flows elsewhere.  Volumes handled by expensive engineered solutions are often decreased as is cost, and water is used productively near where it is produced.

Better design can actually increase volumes handled by bioengineering approaches, so often even reducing overall costs.  This type of approach may even be retro fitted at modest cost or with little disruption to existing facilities.

It is more difficult in monsoonal areas with major differences in urban water between the wet and dry seasons, but it is possible to modify designs to at least allow a reduction in irrigation in the early and late wet seasons by better using locally generated surface waters locally with better design of roads and local parklands.

Some projects have been finished in Sydney as well as overseas. There are some smart designs on the web site of www.atlantiscorp.com.au  used in Sydney, an Australian company in this design space.  See more here -  http://www.atlantiscorp.com.au/solutions/civil-engineering/road-solution-drainage .

More are being planned, with some further details here –

http://e360.yale.edu/feature/to_tackle_runoff_cities_turn_to_green_initiatives/2613/

And then there are green roofs, aimed at collecting and using water that falls on buildings and preventing much of that getting to street level – it helps cool buildings too, reducing heat load on concrete roofs.  More of these options are developing.

 

We just do not do enough of these more appropriate solutions here in the NT. 

Climate Change May Boost Agriculture in SE Asia

 

Climate change 'may boost South-East Asian agriculture'

Prime Sarmiento

Increased rainfall and temperature due to climate change could bring benefits to South-East Asian agriculture, a study suggests, contradicting more common expectations that a warmer planet will reduce agricultural productivity in the region.

Scientists from the International Water Management Institute (IWMI) have predicted that precipitation levels in vast areas of South-East Asia will remain stable, and most of the anticipated changes will occur over the sea, rather than over land.

In southern Vietnam and Cambodia, for instance, precipitation changes will be so minimal that farm production will barely be affected. In central and northern Myanmar, the increase will in fact help to raise crop output, as these are the driest areas in the region.
A
n increase in temperature may also increase crop yield in northern parts of Thailand, Laos and Myanmar, since crops such as rice and vegetables rely on regular rainfall and are most vulnerable to variability in weather. "At the regional scale, precipitation and temperature changes should benefit agricultural production, as significant precipitation increases will occur in the drier areas, whereas the steepest temperature rises will affect the coldest parts," says the study.

The study was carried out by IWMI scientists Guillaume Lacombe, Chu Thai Hoanh and Vladimir Smakhtin.  Lacombe, the study’s lead author, told SciDev.Net that the findings will help the region's policymakers plan for food security — which is being threatened by climate change.
"This study helps characterise and quantify climate change," said Lacombe. "It could help [in sustaining] food security by showing where most drastic changes in rainfall patterns over the long term will occur. This should help the prioritisation of areas of intervention for climate change adaptation."

Lacombe said he and fellow hydrologists drew this conclusion through using PRECIS (Providing Regional Climates for Impacts Studies), a regional climate modelling system designed to run on a Linux-based (an open source operating system) computer and to give detailed climate change projections in any region.

Despite optimistic results, Lacombe pointed out that climate change will have other impacts, such as rises in sea level, which could make the Mekong Delta in southwestern Vietnam more saline, leading to the destruction of rice farms. Climate change could also increase pest numbers and disease prevalence.

Lacombe said that policymakers in the region needed to consider climate projections obtained using several other climate models — in addition to the PRECIS model — before making any decisions about an appropriate response. He also stressed that PRECIS is a regional model and not a global model.

The study concludes with a call for further studies to focus on how climate trends might interact with other environmental changes caused by the region's demographic and economic developments.
Link to article

Climatic Change doi: 10.1007/s10584-011-0359-3 (2012)

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Everyone seems to believe that climate change will result in less rainfall.  This recent article seems to allay those fears for much of SE Asia. Work related to north Australia also seems to point in this same trend.

Sea level rise is still a serious issue in Asia as well as north Australia, so outcomes are not just that simple.

But it is relevant to at least see some outcomes more focused on our region.
 

Rainwater Harvesting in the Tropics

Rainwater Harvesting in the Tropical north

In north Australia where rainfall is mostly very seasonal, with relatively well defined wet and then drier periods of the year it is possible to collect significant amounts of rainfall – rainfall harvesting. The hardest issue to contend with is the need to store relatively larger percentages due to the seasonally dry conditions.
This is particularly so in the north west of Australia – Darwin and areas west around the Kimberley coast where 4 – 8 months may have zero rain, and rainfall declines as you move away from the coastal areas.
However..............look at the data. Columns 2 and 3 show the amount potentially falling on the roof, in Kilolitres [KL] under a range of roof areas , for two different annual rainfall amounts

Roof area [sq metres] Rainfall – 1000mm/yr Rainfall - 1500mm /yr
200 200KL 300KL
250 250KL 375KL
400 400KL 600KL

If you assume a capture rate of 80%, the amounts potentially available are shown in the tables below. A capture rate of 80% could be considered in the low range area, as in the tropics much of the rain falls in significant storms, and in this situation a smaller proportion is wasted in first flush diversion or similar systems that divert the first smaller volumes of rain to ensure clean water is captured and goes into storage.

Roof area – sq m 80% capture of 1000mm/yr -KL 80% capture of 1500mm/yr-KL
200 160 240
250 200 300
400 320 480

The roof areas selected have been used as examples of small, medium and medium/large areas under roof with gutters and collection systems, and include the additive potential from a house roof, garage and sheds. They apply equally to urban and semi-rural locations.

For straight “in house” domestic use, with sensible management, a family of four could use less than 100KL. And there are a lot of options and management ideas to be considered.

For use outside the household areas, a modest lawn and garden could be developed with usage in the 100 – 200KL/year, especially if sensible grey water and effluent use was practised, using systems that allow subsurface disposal of these products.

One option is the use of KISSS subsurface irrigation systems [see www.iwtech.com.au] along with a range of approved alternative wastewater treatment systems – that is, a system somewhat superior to the older style septic tank, which treats effluent at least to secondary standard or better.

There are a wide range of these, and in Australia each State or local government region has approval systems for various brands and types, so you need to check what is legally available and approved.

The really tricky part is to work out how much you need stored around the end of the rainy season.

Some sort of monthly water balance is required, to calculate input and usage, but as a very broad guide, somewhere between 100 and 150KL would be needed at around the end of the rainy season.

More storage allows more extensive outside greenery development, naturally. Also remember that this stored water is a valuable resource for any fire fighting, and bushfires can be a threat in the drier months.

Tank Management

A few short comments.......
· Many users of tank water do not worry about water treatment, but there are some simple treatments if needed. Use in line or in tank UV treatment – this seems to be now seen as the most efficient way to kill any nasties in the water
· Clean water in – means clean water in the tank, so keep gutters clean and use pre treatments such as first flush diversion, leaf guards and similar systems.
· Keep mosquito larvae out of the tank.......screening has usually been seen as a simple solution, and of course this also keeps some particles out of the tank. The screen must be cleaned regularly to allow easy flow of the water into the tank, and two stage mesh systems do work well. In parts of Asia some areas use copepods [small animals that eat mosquito larvae] in tanks to prevent development of larvae.

Mosquito and mosquito larvae management is vital in those areas known to have the dengue mosquito present.

This is not a complete guide to using rainwater and tanks, but to show it is very definitely possible in this region, based on rainfall, and usage patterns and known areas of roof cover.

Even if there is no need to provide all of a households water needs, there are opportunities to collect and store rainwater for outside use – filling swimming pools, washing cars, garden watering to reduce using expensive treated potable water.

If planning a new house..........a suitable place for a tank may be under the driveway or under the lawn areas, rather than an above ground object in the yard! Many designs allow for traffic across the top of the tank.

It is not always difficult and can be an option where groundwater supplies are poor, or there are other issues around groundwater usage.