Drinking water from air humidity

Research scientists at the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB in Stuttgart working in conjunction with their colleagues from the company Logos Innovationen have found a way of converting air humidity autonomously and decentrally into drinkable water. “The process we have developed is based exclusively on renewable energy sources such as thermal solar collectors and photovoltaic cells, which makes this method completely energy-autonomous. It will therefore function in regions where there is no electrical infrastructure,” says Siegfried Egner, head of department at the IGB.

Drinking water from air humidity. Image: Fraunhofer-Gesellschaft

The principle of the process is as follows: hygroscopic brine – saline solution which absorbs moisture – runs down a tower-shaped unit and absorbs water from the air. It is then sucked into a tank a few meters off the ground in which a vacuum prevails. Energy from solar collectors heats up the brine, which is diluted by the water it has absorbed.

Because of the vacuum, the boiling point of the liquid is lower than it would be under normal atmospheric pressure. This effect is known from the mountains: as the atmospheric pressure there is lower than in the valley, water boils at temperatures distinctly below 100 degrees Celsius.

The evaporated, non-saline water is condensed and runs down through a completely filled tube in a controlled manner. The gravity of this water column continuously produces the vacuum and so a vacuum pump is not needed. The reconcentrated brine runs down the tower surface again to absorb moisture from the air.

“The concept is suitable for various sizes of installation. Single-person units and plants supplying water to entire hotels are conceivable,” says Egner. Prototypes have been built for both system components – air moisture absorption and vacuum evaporation – and the research scientists have already tested their interplay on a laboratory scale. In a further step the researchers intend to develop a demonstration facility.

Source: Fraunhofer, June 2009

For an overview of Atmospheric Water Generators (AWG) see the Wikipedia entry on this technology.

Most AWGs seem to be commercial systems sold in developed countries, although WaterMaker (India) Pvt. has installed an AWG system in the Indian village of Jalimudi.

A different technology to collect water from the air is fog collection, which has been widely used in developing countries in coastal areas in Latin America (Chile, Ecuador, Peru) and Southern Africa, and in mountainous areas such as Nepal. See the entry and links in the Akvopedia item on fog collection.

Onsite chlorine production: seminar promotes WATA technology in Nepal

[A]seminar on ‘Safe Drinking Water, was jointly organized by Environmental Camps for Conservation Awareness (ECCA Nepal), Vertical Shaft Brick Kiln (VSBK) and Antenna Technologies, Switzerland on April 21, 2009 at Hotel Himalaya, Lalitpur. About 30 participants representing different social organizations, I/NGOs participated in the one-day seminar.

[Antenna Technologies has developed a WATA line of devices, part of the Watasol approach, for the local production of active chlorine through the electrolysis of salted water. The devices can produce chlorine for both drinking water chlorination and for disinfection or cleaning].Three different models [are available], the Mini-WATA, the Standard WATA and the Maxi-WATA. The Mini-WATA kit produces 1.5 litres of concentrated Chlorine Solution (6000 ppm) in 12-hours, [the] Standard WATA kit produces 1 litre per hour and Maxi-WATA kit produces 180 litres per day in 12-hours.

WATA kit for schools in Nepal. Photo: Antenna Technologies

Jai Rajbhandari from ECCA Nepal [...] told that [his organisation] has already installed WATA devices at twelve different locations and has provided training to the device handler. Among the 12 locations, eleven are producing chlorine solution using Mini WATA and one is using Standard WATA. The chlorine solution production stations are mostly schools, a brick factory and a community water distribution system. He added that ECCA – Nepal produced Chlorine solution in its office premises for the relief of flood victims during the time of flood disaster in the month of August, 2008 at Eastern Nepal. The supplied chlorine solution was sufficient enough to treat 80,000 litres of water.

[...] Mirza Md. Rafiqul Islam from Bangladesh representing Center for Mass Education of Science (CMES) presented [a] study [on the use of] WATA devices and their plan to implement [them] in the Basic School systems and alternative empowerment opportunities to disadvantaged groups. Mr. M. Manoj Kumar, a representative of Development Alternatives, Delhi, India presented a [...]  case study carried out by the organization in Gol-Kuan Slum that could be [seen as a model for the] WATASOL approach in South Asia.

Source: ECCA Nepal / NGO Forum, 30 Apr 2009

Nanotechnology for clean water

Can nanotechnology provide solutions to water treatment in the developing world and improve access to safe drinking water? SciDev.Net has launched a spotlight on 07 May 2009 to address this question, with a series of articles and commentaries written by international experts that:

• explore the potential of nanotechnology for clean water;
• outline the opportunities and hurdles facing policymakers on the ground;
• examine key issues including risk, regulation and technology transfer;
• and highlight progress made to date.

Go to the SciDev.Net Nanotech for Clean Water page

Micro Mapper: participatory tool for mapping poverty, (water) resources

Micro Mapper is a software tool, which provides an interface for village information and planning in India. Primary and secondary information can be entered.Village level activities and facilities can be viewed and monitored. Water budgeting can also be calculated. An Indian local language interface is available. A village resource / participatory rapid appraisal (PRA) application can be drawn with a GIS interface.

It uses a scanned image for digitizing maps and adding data, labels etc. The user can design the map page. However there is no facility to port the map file, but users send it as an attachment.

Dr. Megha Phansalkar has used a Marathi local language version of Micro Mapper to collect water related information of two villages in Ratnagiri district in Maharashtra state, India. She reports that the community found the tool user friendly and simple to use. However it has to be seen whether the community will continue to update and use the system after the project has ended.

The English version of Micro Mapper costs INR 100 to download. Other language versions are available on CD-ROM.

Hospital water treatment: fact sheet on system for Shechen Clinic in Kathmandu, Nepal

A system for treating groundwater for the Shechen Cliinc in Kathmandu, Nepal, was constructed with a € 28,000 microgrant from the Fondation Ensemble. The system delivers water in three different qualities for different uses, as shown in the scheme below.  Read the 2-page technical sheet “Water autonomy and quality in the Katmandu Shechen Clinic” by Roger Rousse here (Fondation Ensemble, 2009).

Fondation Ensemble

Upflow biofilters: treating septic tank effluent in squatter settlement in Nepal

Thirty-one households in Narayan Tole squatter settlement near Maharajgunj of KMC-3 , Kathamdu, have recently constructed ‘up-flow bio-filters’ to treat septic tank effluent. They have constructed two such filters spread in over 342 sq ft area with the financial and technical support of UN-HABITAT Water for Asian Cities Programme Nepal, WaterAid Nepal and Lumanti Support Group for Shelter.

Only 16 households in the area had toilets until a year ago. They used to let their toilet waste mix directly into nearby rivers. [...] All the households in the area now have toilets. They have constructed a 180-metre-long sewer to channel the toilet waste to the filters.

The filter first separates solid and liquid wastes and treats the liquid waste. After the treatment, the waste water [flows] into the rivers while the solid waste remains in the tank. The bio-filters were constructed with Rs. 0.2 million collected from the donors and locals. The locals have formed Narayan Tole Sudhar Samiti (NTSS) to take care of the filters.

Kalpana Karki, treasurer of the Samiti, told that it collects Rs. 35 per month from each household for the maintenance of the filters. [...] “We will use the digested solid waste as fertilizer in our fields,” Karki said.

Related news: Nepal, Kathmandu: squatters seek NGO help to defeat river pollution, Source Weekly, 15 Dec 2008

Source: NGO Forum,10 Feb 2009

Drinking water treatment: becoming more affordable with U.S. help

An affordable, sustainable drinking water treatment system designed by a U.S. laboratory is being used successfully in Ghana, India, Sri Lanka, Mexico, South America and the Philippines.

The technology, which uses ultraviolet light to disinfect water safely and cheaply, was designed by Ashok Gadgil at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory.

[...] The lab licensed the purification system to the U.S. firm WaterHealth International (WHI), which is working to expand access to affordable drinking water in developing countries.

WaterHealth Centre, India. Photo: WHI

[...] 1 million people have access to clean water from more than 200 WHI water centers in India, where the technology was introduced in 2006 and established through a partnership with the Naandi Foundation.

Other NGOs such as the Lions Club also have provided funding, as have several foreign-born physicians residing in the United States who want to support their home towns.

[...] In the past, donated or purchased water treatment technology sometimes failed [...] because communities had to struggle to maintain the facilities.

To overcome this, WHI developed “WaterHealth Centres” where water is treated centrally for a small community using a variety of approaches, including:

• ultraviolet water disinfection technology, which is highly effective against harmful germs, and does not require high energy, high water pressure or sophisticated maintenance procedures;
• new buildings, which also can be used for community meetings and social events, to house the systems;
• local personnel hired and trained to operate and maintain the systems;
• hygiene and health education programs that emphasize the economic benefits of avoiding waterborne illnesses;
• narrow-neck water-storage containers to avoid water recontamination;
• marketing to inform residents of the water treatment and its benefits;
• financing for a portion of initial installation costs ($20 per person for a small village in India, for example).

WHI asks communities to make a down payment – sometimes provided by a local government, philanthropist or NGO – and then helps finance the remaining balance. Once the loan is repaid, the community owns the center.

To cover loan payments and operation and maintenance costs, consumers are charged a small fee for purified water. [O]ne village in Ghana charges 5 cents for 20 liters of treated water.

Local entrepreneurs often start businesses delivering treated water by bicycle or truck.

Customers at the WaterHealth Centre in Afuaman, Ghana, wait for their water.

[In Ghana] WHI partners with U.S. nonprofit World Vision Ghana for the health-education component of the program. In December 2007, WHI opened a pilot water center in Afuaman, serving about 3,700 people. [...] Construction of five additional WHI centers in Ghana will be completed by March [2009] in partnership with the U.S. nonprofit Safe Water Network, which funds the project.

“The government of Ghana has been extremely supportive at both the district level, by assisting the communities in raising the down payments, and at the federal level, by waiving import taxes and duties on imported equipment,” said Bismark Nerquaye-Tetteh, who has worked with the U.S. Agency for International Development’s West Africa Water Initiative.

Source: Nancy Pontius, America.gov, 12 Jan 2009

Solar disinfection: inventor unveils solar-powered water purifier

Photo: Solvatten

Swedish inventor, Petra Wadström, has unveiled Solvatten, a solar-powered water purifier, that she hopes will be used to provide household drinking water in developing countries.

Developed over a period of eleven years, the device resembles a standard jerrycan. It can be filled with up to 10 litres of water, opened out and left in the sun. A simple indicator uses a red or green face to show users when the temperature has reached 55°C and the water is safe to drink. It uses both thermal energy (heat) and UV radiation from sunlight, a created turbulence and a filter to treat water of up to 200 NTU. Water samples with more than 200.000 E. coli/100 ml have successfully been treated, the Solvatten web site claims.

Serving a family of five, a Solvatten device costs US$ 35 and lasts 5 years or more. The estimated cost per litre of water is 0.002 USD ( based upon 10 litres of water treated, 300 days per year).

The Solvatten company has already tested its device in Kenya and Nepal. In 2009 the first units of Solvatten will reach Nepal for a user study involving a number of families, schools and health centres. The programme is being implemented in collaboration with UN-HABITAT and ENPHO, the Environment and Public Health Organisation.

The Solvatten can also be used a solar water heater to produce hot water.

See videos below on Solvatten trials in Nepal and a product presentation by Petra Wadström.

Source: edie, 12 Jan 2009 : Solvatten web site

Terafil water filters: clay filters promise clean drinking water in villages in Jharkand, India

Terafil technology will not only ensure clean drinking water in villages but also turn the rural people into entrepreneurs.

Chakdoha and Chapri, two villages of Ghatshila in East Singhbhum district [of Jharkand state, India], will play host to the pilot project.

The initiative has been taken by the Rural Development Trust under the Art of Living Foundation, Bengaluru. Terafil water filters have been designed by S.K. Kuntia, the head of design and rural technology department at the Institute of Mineral and Material Technology (IMMT), Bhubaneswar, a wing of the Council of Scientific and Industrial Research (CSIR), New Delhi.

[...] The terafil would cost around Rs 350 to Rs 500. The foundation has planned to rope in the corporate sector to help donate the filters as a part of their corporate social responsibility.

The filters would encourage self-employment, too. The foundation would also arrange for resources to train the villagers and help them turn into entrepreneurs.

[...] The filters are being manufactured and would be distributed across the two villages from March 31 [2009].

Source: The Telegraph, 23 Dec 2008

The Terafil water filter is especially suited for water that is rich in sediments, suspended particles, iron and certain microorganisms, i.e. for areas where water from both surface & ground water sources like dug wells, ponds, tube wells and rivers is used for drinking water.

Terafil (red clay) filtration disc. Photo: IMMT

Terafil is a burnt red clay porous media [...] produced from mixture of red clay (silt clay), river sand and wood saw dust, without using chemicals. The dough of the mixture of these materials is sintered at high temperature in a low cost coal / wood fired furnace to make the terracotta disc porous.

About 99% of turbidity, 90-95% of micro-organisms, 80-95% of soluble iron,

Domestic Terafil filter. Photo: IMMT

colours etc. are effectively removed from the raw water during filtration process through the Terafil. 100% bacteria can be removed when a pinch (0.01 gm) of bleaching powder is added to a liter of filtered water. Rate of filtration is dependent upon turbidity and pressure of raw water over the Terafil.

Terafil filters are available for both domestic use and community-level use (gravity flow and on-line pressure flow models).

Read more technical specifications here (IMMT brochure, May 2008).

In 2007, IMMT had already licensed the technology for making and marketing Terafil discs to four parties in Orissa and had demonstrated the technology in several other states including Uttar Pradesh and Meghalaya. Over 50,000 water filters had been distributed. The domestic Terafil filter was used extensively in Orissa in 1999 when the state was severely hit by a cyclone.

Contact: S. Khuntia, Head, Design & Rural Technology, Institute of Minerals and Materials Technology, P.O. RRL, Bhubaneswar – 751013, India.  Tel (off) : 0674 2581635-39, Fax: 0674 2581637, 2581160. Email: khuntias [at] gmail.com, skhuntia [at] immt.res.in

Source: CSIR news, Oct 2007

Kanchan Arsenic Filter: verification update

Field testing of the Kanchan Arsenic Filter (KAF), a biosand filter modified to remove arsenic from contaminated raw water, is generating encouraging results in Cambodia and Bangladesh.

The KAF was found to be highly effective in Phase 1 testing, with average arsenic removals in the 95 to 97 per cent range. All of the 10 test filters consistently reduced levels from an average of 637ppb to less than 50ppb, which is the Cambodian standard for arsenic in drinking water.

Performance of the filters was consistent over the 30-week testing span, which produced 8,400 litres of filtered water.

Phase 2 testing, now underway, involves installing the filters in more challenging locations to determine if their arsenic removal capacity can be exhausted.

The tests will also examine hardness and pH levels, water usage patterns and include a social assessment.

Related news: Arsenic removal: field testing the Kanchan Arsenic Filter in Cambodia, Source Weekly, 22 Mar 2008

See also:

• MIT TechTV video “Arsenic Poisoning and the Kanchan Arsenic Filter”  here
• Centre for Affordable Water and Sanitation Technology (CAWST): Adapting the Biosand Filter for Arsenic Removal (10 Apr 2008)

Source: CAWST Newsletter [not yet online, but should become available here], Winter 2008