Archive for July, 2013


Reethi Beach, a Five-Leaf System member, a jewel dropped in the Indian Ocean, has been producing freshwater from the resort’s desalination plant and rain-harvesting for the last decade.

 

A drop in the ocean

 

Image source: reethibeach.com

Reethi Beach is located on a very small Island in Baa Atoll, and is part of three natural atolls comprising 75 islands, only 13 inhabited. The reefs of this atoll are in pristine condition and this resort has made sure that they will always be kept this way.

Installing a desalination plant was only one of many measures its management saw fit to transform this place into an eco-resort in a location where often the slightest activity may induce catastrophic environmental results and tip the natural balance of the land.

Apart from getting local people in neighbouring islands to tend herb and vegetable gardens and produce more fruit for the resort, the management has also strived to reduce waste by recycling all that is possible and adopting new measures to minimize its impact.

Management changed cocktail plastic straws for straw, all plastic bags were stopped in outlets and rooms, guest toiletries are now re-fillable and drinking water bottled in re-usable glass bottles, thus saving up to 400 disposable plastic ones daily.

Re-cycling of treated water from the sewage treatment plant is used for irrigation purposes and underground tanks of nearly 200 ton capacity provide a welcome for rainwater.

By installing an energy recovery system at the desalination plant almost 10 years ago, it doubled its output with a marginal increase in consumption.

And using the hot water from the heat exchange cycle and a dry-room in the laundry instead of big commercial dryers has also meant energy savings all around.

A good example for us all.

By Silvia Pelham

Our oceans cover ¾ of our planet but the water is too salty to drink. Fresh water dropping from the skies is only 2.5% of all of the earth’s water. And 70% of that water is either buried in deep aquifers or frozen on high mountain tops. A mere 1% is thus free to be tapped by us all. Have we found a way to invert this?

The world’s population is growing and our freshwater needs double every 20 years[1] but with so much salty water around us, transforming it into drinking water[2] should prove to be the solution mankind has been looking for since the Greeks successfully did so centuries ago.

Traditional thermal salt removing techniques require high temperatures. A major impediment has always been the cost of such operations, especially if they are to be thought of on a scale large enough to supply fresh water to entire cities.

Modern desalinization techniques have been in use since the 1950s, either through distillation or by reverse osmosis, more commonly known as RO.

With distillation, the water is left to evaporate and is then condensed, but as it uses a lot of energy in the process, it is mostly used by countries where fossil energy is readily available and at low cost.

With RO the desalination process relies on membranes permeable to water but capable of retaining the dissolved salt. It also relies on the use of high pressure, thus causing damage to the filtering capacity and resistance of the membrane. The result is a short operating life.

Recent approaches have moved towards the use of chemicals[3] and research carried out on alternative components such as the use of nanotubes and aquaporins, water channels which will allow easier water flow at reduced pressure.[4]

http://www.youtube.com/watch?v=ERTkE91ICB8

Source: Sunit Parekh-Gaihede, sunitparekh.com and Hydralab, hydralab.com

As an alternative, electricity is being used in de-ionization processes, applying it to seawater, attracting salt ions towards electrodes where they can be absorbed and later released.[5]

On top of this, most of these processes mean that there is concentrated brine left over, and this is pernicious to local ecosystems – with fossil-fuels linked to this technology bringing on more greenhouse gas emissions.

The 13,000 desalinization plants already in production today are barely enough to provide 0.5% of global daily water needs. Faster, simpler methods had to be found.

And now, at last, a low cost desalination system is being developed, able to produce drinking water in off-grid, remote areas to be used by developing countries and disaster areas.

The next generation technology will hardly use any energy and can be used by all with a simple method which will remove salt from seawater quickly and efficiently by creating a small electrical field.

The process called “electrochemically mediated seawater desalination” will eliminate the need for any membranes by separating the salt from the water on a micro-scale.[6]

The idea is to apply a small voltage of only 3.0 volts to a plastic chip filled with seawater, which has two branches as micro-channels.

At the junction of these channels, the electrode neutralises some of the chloride ions in the seawater, raising the local electric field sufficient enough to divert the salts into one channel and the desalinated water – the freshwater – into another.

The technology is there – these micro-channels are the size of human hair today and produce 40 nanolitres of freshwater per minute. Now we have to make them produce many litres of water per day!

A drop from heaven

Image source: University of Texas, Austin

By Silvia Pelham


[1] Estimated by analysts in Goldman Sachs http : // www.alternet.org / story / 105083 / why_big_banks_may_be_trying_to_buy_up_your_public_water_system and the United Nations expect demand to outstrip supply by more than 30 percent come 2040.

[2] Desalizination.

[3] Oasys, an American firm, is using an ammonia and carbon dioxide mixture which, when heated, decomposes into gases, enabling easy removal of salt. They also use low natural thermal energy such as solar heat and geothermal steam. http://oasyswater.com

[4] By Aquaporin, a Danish firm. http://www.aquaporin.dk/

[5] PROINGESA, a Spanish firm is applying capacitive deionization to sewage and water treatment. http:// www.proingesa.es / en / proyectsidi2 / adecar.html.

[6] This method is being further developed in the United States by Okeanos Technologies. http://www.okeanostech.com/

In the 1960s, drip irrigation was first used by farmers who had little access to water supplies and in the 1980s it was first seen on commercial landscaped areas. Forty years on, shouldn’t everybody be using it?

Drip, micro or trickle irrigation all mean the same – the slow, precise drop of water placed where you need it, when you need it.

Those using this method are keeping roots moist, while saving water from being used where nothing is planted, or ending up running off over hard surfaces, or evaporating in the sun or being displaced by the wind.

Overwatering these days is not considered important where water is readily available, as it is in developed countries but since drinking water is becoming increasingly expensive, it may be that rain harvesting, together with drip feeding, will become the order of the day for purposes other than providing water fit to drink.

Arid countries have taught us how precious rainwater can be and it is relatively easy to obtain any kind of water deposit these days, whether it is made of concrete, PVC or metal lined. It can also be built with traditional materials to suit your purposes.

Once you determine the point source on your irrigation layout[1], you must be certain that your new installation is based on a proper design. This is of paramount importance for successful implementation of the drip system and the certainty that you will reap all benefits it can provide.

This design must be adaptable enough to be used above or below ground level, in any location allowing users to customize its layout to meet their specific needs at all seasons, and thus meet differing irrigation requirements with the minimum of difficulty.

Below there is an example of an installation with adequate components which will guarantee that maintenance will be kept to a minimum. Where large areas make drip feeding less feasible, one can opt for combining it with micro sprinklers which also use low volume water consumption.

Normal sprinklers are rated as having a consumption measured in gallons per MINUTE (GPM) as opposed to the drip system which is measured in gallons per HOUR (GPH). This shows immediately the difference in consumption between conventional watering and dripping.[2]

Another relevant difference between conventional installations and dripping is the water pressure running through the pipe work.

The greater the pressure, the more likely vibration will occur and the wear and tear caused by the weight of the pressurized water against the internal surface of the piping will make it more vulnerable to hairline cracks and consequent leaks.[3]

The ease with which each drip installation can be made is due to the fact that it does not require any special tools. The components are not in any way bound or glued and all fittings can be put together by users with limited plumbing knowledge.

What this also means is that even in oddly-shaped ground areas or those with difficult access, it is still possible to install a drip system which will fit into the existing space without expensive cutting, welding or gluing of components and transporting heavy equipment to perform the job.

But most importantly, investing in the installation of any low volume irrigation technique will certainly bring down your water bill. You will also be contributing to the conservation of drinking water on the planet.

 Dripping can be good 1

Image source: http://www.irrigationtutorials.com

 

By Silvia Pelham


[1] The watering of large areas can be successfully done with a single water supply source, due to the low flow of the drip system.

[2] A lawn sprinkler linked to a conventional tap will consume between 1 to 3 GPM, as opposed to the same sprinkler connected to drip feeding which will consume 1 to 4 GPH.

[3] Conventional water installations will function with pressure ranging from 40 to 80 PSI (pounds per inch) as opposed to 15 to 30 with drip irrigation systems.

It was nearly 20 years ago that many water saving gaskets appeared in significant numbers in the USA[1].

This is especially relevant to hotel management since their buildings have all sleeping accommodation normally coupled with a bathroom and water consumption is left to individual users’ whims.

Most guests forget that water conservation practices which are carried out as a matter of course at home, where the water bill is their responsibility, should be continued at their hotel stay.

Since these rules seem to be promptly discarded by guests the moment they step into a hotel shower, hotel managers should be prepared to take action to keep business costs down and help the environment.

What can be done is to look at all appliances and study all areas where guests are likely to use water and start with these, since staff can easily be trained to save in the rest of the building.

But not all water loss is to be tagged to the guest, since hotel managers have plenty of choice to cut down water consumption if they start to maintain their hotels as if they were their home.

A drop of water leaking 24/7 adds up to nearly a 60 litre per day loss – equivalent to a dozen 5 litre water cans you could be serving guests – and considered to be responsible for 14% of everyone’s water footprint for indoor use.

Leaks are sometimes difficult to detect – especially those outdoors – and managers are increasingly concerned enough to compare monthly water consumption averages so as to detect unusual increase in spending on like-like situations.

And again this can be difficult due to monthly fluctuation with guest type and numbers or the time of the year when readings occur.

Managers can start outdoors by tapping on to the main water reservoir and finish indoors checking their taps or faucets – with valves which provide water intake to pipes and assure control over water flow –and check if they still hold enough power to impede water leaking when taps are closed on kitchen and sinks, showers and bath-tubs.

There are four types of taps with work by:

  • compression – when one turns the tap, the valve stem is compressed against the inlet;

   Dripping can be bad 1

Image source: home.howstuffworks.com

  • cartridge – when the perforated cartridge made of metal or plastic inserts rotates;

Dripping can be bad 2

Image source: visual.merriam-webster.com

  • ball-valve – it also rotates but has the shape of a ball and is placed on top of the tap;

Dripping can be bad 3

Image source: wetheadmedia.com

  • disk – made of two ceramic disks fitting tightly together.

 Dripping can be bad 4

Image source: http://www.hometips.com/how-it-works/ceramic-disc-faucets.html

The sealing of these taps is of paramount importance since water seeps easily along metal and plastic features and the maintenance of rubber washers should be checked regularly at the end of threaded stems and gaskets re-fitted to inlets.

http://www.ehow.com/video_7744689_repair-faucet-leakage.html

Video Source: www.ehow.com presented by Chris Wade.

By Silvia Pelham


[1] USA Federal Energy Management Programme – federally mandated water conservation guidelines were applied from January 1, 1994.