Africa wide WASH technology review published

The WASHTech project has published a literature review [1] focusing on 14 technologies used in Africa in the water, sanitation and hygiene (WASH) sector.

Descriptions for each technology include a selection of interesting case studies, and an explanation as to whether the technology meets technical, financial, social and institutional success criteria.
Only two technologies met all four success criteria: hand dug wells and the India Mark II pump, and the latter only with the caveat that there was a functional maintenance system.

The least successful technology was the Playpump. Pending further research, jerry cans and the gulper were only found to meet one success criteria (technical success). Except for bio-additives to pit latrines and Playpumps, all other technologies were technically successful. The other success criteria were met by roughly half of the technologies.

Core issues that WASHTech plans to take up further include the appeal of inappropriate technologies like Playpumps and Lifestraws to naive donors, and ways to get government approval for low-cost, locally managed technologies like rope pumps, biosand filters, constructed rainwater harvesting jars, water jetting and tippy taps.

[1] Parker, A. et al., 2011. Africa wide water, sanitation and hygiene technology review. (WASHTech Deliverable 2.1). The Hague: WASHTech c/o IRC International Water and Sanitation Centre and Cranfield: Cranfield University. 93 p. : 1 box, 9 fig., 1 tab. Includes references.
Available at: http://wp.me/a1szDW-1o
The aim of the WASHTech project (2011-2013) is to introduce a robust Technology Assessment Framework (TAF), with local partners in Burkina Faso, Ghana and Uganda, that will assess the potential of new innovative WASH technologies. WASHTech is co-funded under the 7th Framework Programme of the European Commission’s Africa research programme. To learn more go to washtechafrica.wordpress.com

Manual drilling: engineering students develop “Village Drill” for Tanzania

A team of engineering students from Brigham Young University (BYU) has developed a human-powered drill that can reach a depth of up to 75 metres at 10% to 20% the cost of a traditional motorized well rig. A prototype of the “Village Drill” cost around US$ 4,000 (excluding labour) to make in the USA.

The BYU students created the drill for a project in Tanzania run by WHOLives.org, a nonprofit based in South Jordan, Utah. The project is also co-sponsored by the Ira A. Fulton College of Engineering and Technology.

The drill can be operated by four people. Three spin the wheel that turns the drill bit (cutting tool), and the fourth lifts the bit up and down when necessary to punch through tough spots. A water pump system removes the dirt from the 15 cm-wide hole.

In May 2011, a drilling team was able to construct a 45 m well  with the patented “Village Drill” in 3 days in Magugu, Tanzania.

Related news: WASH technology information packages : for UNICEF WASH programme and supply personnel, E-Source, 24 Aug 2010

Related web sites:

• WHOLives.org
• Akvopedia – water portal
• RWSN – Hand or Manual Drilled Wells
• IRC WASH Library – manual drilling

Source: BYU, 14 Jul 2011

Guatemala: construction guides for rural WASH facilities

Five Cabin Latrine, Aqua Para La Salud (Guatemala). Photo: Global Water

NGO Global Water provides instructions for building rural water, sanitation, and hygiene-related facilities that were developed by its partner in Guatemala, Agua Para La Salud (Water for Health). The facilities include:

• Ferro-Cement Water Storage Tank
• Hand Washing Stations (Lavamanos)
• Complete Spring Catchment System
• Five Cabin Latrine
• Gray Water Seepage Pits

View the designs at www.globalwater.org/how-to-build.html

Extracting water out of thin air now possible

Image via Wikipedia

Thanks to a new technology developed by the Fraunhofer Alliance SysWasser, Germany it is now possible to extract from the humidity in the air water .

The principle behind it is a salt solution that runs down from a tower-shaped system and absorbs water from the air, known as hygroscopic brine. This brine is then pumped into a tank that stands a couple of metres high and contains
a vacuum.

WASH technology information packages

UNICEF has published WASH technology information packages (TIPs) [1], a practical set of guidelines and selection tools for WASH programme and supply staff.

The following WASH technologies are covered:

1. Hand pumps for drinking water
2. Boreholes and drilling equipment for rural water supply
3. Solar powered pumping
4. Motorized and small piped systems
5. Faecal sludge emptying equipment

The TIPs are linked to Excel spreadsheets giving selection tools and bills of quantity.

Originally written for UNICEF WASH Programme Officers (each of whom have received the package on a USB stick), the TIPs have now been made available on the UNICEF web site. They are free to be reproduced as long as UNICEF is credited as the source.

[1] Baumann, E., Montangero, A., Sutton, S. and Erpf. K. (2010). WASH technology information packages : for UNICEF WASH programme and supply personnel. Copenhagen, Denmark, UNICEF. 194 p. : fig., photo. Includes references.

Download package (includes a PDF file and related Excel files).

Eco-home: a model for water and sanitation self-reliance in Kathmandu

A resident of Kathmandu has adopted ecological solutions to cope with the city’s persistent water shortage and power cuts.

Report of a visit to Dr. Shrestha’s Eco-home on 14 March 2010.

Dr. Roshan Raj Shrestha in his Eco-home. Photo: C. Dietvorst

Dr. Roshan Raj Shrestha built his Eco-home in November 2002. The two and a half story building is neither connected to the city water supply nor to the sewerage network. It uses several kinds of water conservation methods including rainwater harvesting, greywater recycling, ecological sanitation, Solar Water Disinfection (SODIS) and organic waste composting. Dr. Shrestha says he was able to recover the extra investment of US$ 1,000 for his water conservations systems within three years.

The Eco-home has helped Dr. Shrestha cope with Kathmandu’s severe water crisis. The public water supply can only meet half of the actual demand and the city’s Bagmati river is turning into an open sewer. The ground water level is decreasing by 2.5 metres a year due to over extraction. The mega Melamchi Water Supply Project, started in 1998 to tackle Kathmandu’s water crisis, has been plagued by delays.

Rainwater catchment terrace and tanks. Photo: C. Dietvorst

With an average annual precipitation of 1,600 mm in the Kathmandu Valley, Dr. Shrestha found that rainwater would provide with enough water for his family of five. Rainwater is collected on two roof terraces and stored in a 9,000 litre underground tank. Excess rainwater is diverted into a dug well, which acts as an intermittent tank that can store nearly 10,000 litres and also supports shallow groundwater recharge. SODIS is used to treat rainwater for drinking water, while water from the dug well is pretreated first in a biosand filter.

Residents constructing new houses in Kathmandu now get a 10% tax rebate on their building permit fee if they include a rainwater harvesting system in their design. The rebate can reach 30% in other municipalities in Nepal, says Prakash Amatya, the Executive Director of NGO Forum.

No water goes wasted in the Eco-home. Dr. Shrestha has installed a urine diversion dry toilet in his master bedroom. Urine and composted feces are used as garden fertilizer. A small reed bed treatment system is used to recycle grey water for garden watering, washing the car and for an extra flush toilet.

Solar panel. Photo: C. Dietvorst

The latest addition to the Eco-home is a 100-Watt Solar House System (SHS), installed in 2009. The solar panels provide enough energy to light the lamps in the house. Costing US$ 1,000, the system is only affordable for middle-class families, Shrestha admits, but it has proved its worth now that power cuts of up to 12 hours a day have become standard in Kathmandu.

Dr. Shrestha is proud of his model Eco-home. He is happy to give visitors and groups of students a tour. He finds that people readily accept the concept of rainwater harvesting and greywater recycling. They are not so keen about ecological sanitation though, because of the socio-cultural barriers associated with feces.

Dr. Roshan Raj Shrestha is Chief Technical Advisor, South-Asia Region for the UN-HABITAT Water for Asian Cities Programme

Sources used:

• Eco-home for sustainable living, Himalayan Times / UrbWatSan Nepal, 19 June 2009
• Eco-home for sustainable water management : a case study in Kathmandu, Nepal. Ministry of Physical Planning and Works / UN-HABITAT. October 2008 (brochure)
• Shrestha, R.R. (2007). Sustainable water management : a case study in Kathmandu. Presentation at Ecosan – Fortaleza 2007

SODIS water bottle. Photo: C. Dietvorst

Reed Bed Treatment System for greywater recycling. Photo: C. Dietvorst

Urine diversion dry toilet. Photo: C. Dietvorst

Biosand filter. Photo: C. Dietvorst

Clean water – it’s right above your head

Rain falls unto roofs and then runs off. And then? You could catch it and drink it. Any suitable roof surface—tiles, metal sheets, plastics, but not grass or palm leaf—can be used to intercept the flow of rainwater and provide a household with high-quality drinking water. Rainwater harvesting systems have been used since antiquity, and examples abound in all the great civilizations throughout history.

The groundwater level may be too deep, groundwater may be contaminated with minerals and chemicals such as arsenic or salt, surface water may be contaminated with faeces or chemicals. Rainwater falls on your own roof, and is almost always of excellent quality. It enables people to manage their own water supply and provides the luxury of “water without walking”, relieving the burden of water carrying, particularly for women and children. This convenience is available at every house on which rain falls, whether on a mountain top or an island in a salt sea. It is a truly great idea.

A women using her water storage tank in Guinnee-Bissau. Photo Paul Akkerman.

Storage tanks
Once you catch the water from the roof (or other hard surfaces), you have to store it somewhere. Ferro-cement tanks, made with a layer of cement with steel-wire reinforcement, are usually the best and cheapest option, and can be made locally. When a tank is below ground, it is called a cistern. No idea why, really.

Roof rainwater is usually of good quality and does not require treatment before consumption. The most important thing to ensure water quality is a good lid, keeping out light and insects, and a filter, keeping out all kinds of dirt.

The cheapest tank of all is to use the ground beneath your feet. This is called groundwater recharge, and is simply accomplished by letting rainwater infiltrate in the ground, instead of letting it escape and flow away. When you need it, you pump it up.

As small or large as you want
A rainwater harvesting system might be a 500 cubic meter underground storage tank, serving a whole community. Or it might be just a bucket, standing underneath a roof without a gutter. Each 20 litre container of clean water might save a kilometers long walk to the nearest source of clean water, and as fetching water on cold, wet and slippery days is particularly unpleasant, even this small yield is highly valued. In Uganda and Sri Lanka, rainwater is traditionally collected from trees, using banana leaves or stems as temporary gutters.

It is a technology which is extremely flexible and adaptable to a wide variety of settings, it is used in the richest and poorest societies on the planet, and in the wettest and driest regions of the world. Let’s build more gutters!

Author: Mark Tiele Westra, Editor Akvopedia.

Links:

• Other blogs in the series “Akvo solution of the week”
• For more low-cost water and sanitation solutions, visit Akvopedia, part of akvo.org
• Indian movie by CSE (www.cseindia.org) promoting use of rainwater harvesting
• Akvopedia article on rainwater harvesting
• Wikipedia article on rainwater harvesting
• Download the book “Roofwater Harvesting: A Handbook for Practitioners” from the IRC website
• Rainwaterharvesting.org, Indian website on rainwater harvesting

Roof-harvested rainwater for potable purposes : application of solar collector disinfection (SOCO-DIS)

Amin, M.T. and Han, M.Y. (2009). Roof-harvested rainwater for potable purposes : application of solar collector disinfection (SOCO-DIS). Water research ; vol. 43, no. 20 ; p. 5225-5235. DOI: doi:10.1016/j.watres.2009.08.041

Abstract

The efficiency of solar disinfection (SODIS), recommended by the World Health Organization, has been determined for rainwater disinfection, and potential benefits and limitations discussed. The limitations of SODIS have now been overcome by the use of solar collector disinfection (SOCO-DIS), for potential use of rainwater as a small-scale potable water supply, especially in developing countries. Rainwater samples collected from the underground storage tanks of a rooftop rainwater harvesting (RWH) system were exposed to different conditions of sunlight radiation in 2-L polyethylene terephthalate bottles in a solar collector with rectangular base and reflective open wings. Total and fecal coliforms were used, together with Escherichia coli and heterotrophic plate counts, as basic microbial and indicator organisms of water quality for disinfection efficiency evaluation. In the SOCO-DIS system, disinfection improved by 20–30% compared with the SODIS system, and rainwater was fully disinfected even under moderate weather conditions, due to the effects of concentrated sunlight radiation and the synergistic effects of thermal and optical inactivation. The SOCO-DIS system was optimized based on the collector configuration and the reflective base: an inclined position led to an increased disinfection efficiency of 10–15%. Microbial inactivation increased by 10–20% simply by reducing the initial pH value of the rainwater to 5. High turbidities also affected the SOCO-DIS system; the disinfection efficiency decreased by 10–15%, which indicated that rainwater needed to be filtered before treatment. The problem of microbial regrowth was significantly reduced in the SOCO-DIS system compared with the SODIS system because of residual sunlight effects. Only total coliform regrowth was detected at higher turbidities. The SOCO-DIS system was ineffective only under poor weather conditions, when longer exposure times or other practical means of reducing the pH were required for the treatment of stored rainwater for potable purposes.

Article Outline

1. Introduction
2. Materials and methods

2.1. SODIS and SOCO-DIS systems
2.2. Microbial analysis

3. Results and discussions

3.1. Sampling site and characteristics
3.2. Characteristics of different weather conditions
3.3. The effects of the collector’s base angle and different backing surfaces in the SOCO-DIS system
3.4. Comparison of the SODIS and SOCO-DIS systems

3.4.1. The effects of radiation and temperature effects on microbial inactivation
3.4.2. The effects of initial pH values on disinfection efficiency
3.4.3. The effects of initial turbidity values on disinfection efficiency
3.4.4. Microbial regrowth in SOCO-DIS system and comparison with SODIS

4. Conclusions
Acknowledgements
References

Contact:

• Assistant Professor, Department of Environmental Sciences, COMSATS Institute of Information Technology, Abbottabad, 22060, Pakistan, e-mail: muhammadamin [at] ciit.net.pk
• bProfessor, Civil and Environmental Engineering Department, Seoul National University, Shinrimdong, Kwanak Gu, Seoul, 151-742, Republic of Korea, e-mail: myhan [at] snu.ac.kr

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.

WaterAid water source options poster

WaterAid has produced a new poster resource that rates different water supply technology options in relation to their relative capital cost, operational cost, water quantity supplied and water quality supplied.

The poster also provides information on the situations in which certain water supply technologies are most applicable.

Levels of appropriateness are colour coded based on different combinations of the above variables.

The resource can be printed as a poster on A4, A3 or A2. You can download it here:

Water source options – a comparison ( PDF 93KB)