PWN Technologies launched, has water treatment solutions for developing countries

PWN, the water supply utility for North Holland, The Netherlands, launched PWN Technologies, a new international company for the commercial exploitation of their expertise and advanced water treatment solution designs. PWN has provided technology and services across Europe, as well as in Asia, Africa and the Americas, also providing emergency water services following catastrophes like the 2004 Indian Ocean Tsunami.

Specifically for developing countries, PWN Technologies has developed the Perfector series of water treatment solutions to produce drinking from surface water through coagulation, flocculation, separation, filtration and disinfection. Perfector units have been installed in Indonesia and Viet Nam.

The Perfector-R is a water treatment plant for the production of drinking water for communities of 50,000
to 250,000 people, and overall net production capacities of 60, 120 or 240 l/s. The modular design consists of:

• raw water intake on floating pontoons, process units, chemicals preparation and dosing systems, clear water reservoirs, distribution pumping station, electrical infrastructure and various other facilities such as emergency generator, laboratory, offices, work shop, etc.
• optional waste water storage and pumping

The Perfector-P is a purification installation with a production capacity of 10 l/sec.

Source: PWN Technologies, 21 Jun 2009

Pefector-R. PWN Technologies

Slow sand filtration: creating clean, safe water

The Japan International Cooperation Agency (JICA) has produced a multimedia-based learning package “Slow sand filtration: creating clean, safe water” in English and Japanese, consisting of a video and reference materials. There are examples of the use of slow sand filtration technology in Japan and in a project in Sierra Leone.

Read more

Floating toilets for floating villages on Cambodia’s Tonle Sap lake

The Singapore-based nongovernment organization, Lien Aid, has introduced  floating toilets as part of its “River of life” project for the floating communities of Tonle Sap lake in Cambodia (see also an earlier blog post on this project). In February 2009, Lien Aid was introducing “different toilet designs that they can build on their houseboats”, CEO Sahari Ani told the Asian Development Bank . “Simultaneously, we’re providing them with a safer choice for drinking water by building a floating water treatment plant” Mr. Ani said. “We are exploring several options including the use of especially adapted septic tanks plus ecological sanitation using the urine diversion-dissecting (UDD) toilet”.

Based on the villagers’ preferences, Lien Aid “determined the size of the toilets, buckets to be used for storage of excreta, ecosan pans (2-hole or 3-hole), and other design considerations [resulting in] 3 workable designs to date” (see sample designs of the three options here). “Our next challenges are to modify existing toilets to incorporate the UDD options, ensure availability of suitable drying material for covering feces, and keep the costs manageable”, Mr. Ani explained.

Lien Aid, which works together with the Ministry of Rural Development (MRD) and local authorities, “is developing simple [...] publications on methods of construction, use, and maintenance of the floating toilets”.

Floating toilets cost “between US$50-200, depending on whether the family will just upgrade their existing drop-hole toilet to accommodate the UDD technology or whether the entire toilet, including superstructure, will be constructed from scratch. The size of the toilet will also dictate the cost – toilets that can accommodate 2 tanks will obviously cost more [The 2 tanks will be for families who wish to avoid handling semi-decomposed excreta every few months. Once the first vault is full, it can be sealed for a few months until the feces dries up, and the alternate second vault will be used. Toilets with only 1 vault means the family will have to dispose of semi-composted feces at monthly intervals.]. We’re still trying to lower the cost by using indigenous materials and encouraging local entrepreneurs to manufacture the UDD pans”.

Together with the floating toilets, “a land-based composting unit and collection system will be established to manage the semi-composted feces. We hope to promote the use of fully decomposed feces as compost”.

Lien Aid had “already set up a community center for water-sanitation related training and advocacy activities” and “will also form a water-sanitation group from among the residents and community leaders”.

Source: ADB, Feb 2009

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

Filtration: producing activated carbon from coconut and oil palm shells

A pilot and demonstration activity (PDA) funded with US$ 49,500 from the Asian Development Bank (ADB) examined the feasibility of setting up a factory in Thailand’s Tap Sakae district to produce activated carbon from coconut and palm oil shells that can be used for industrial water pollution control and low-cost water filters.

Based on an assessment of the legal, institutional, technical, economic, and environmental issues related to the establishment of the plant, the team led by Prof. Thierry Lefevre, Director of the Centre for Energy Environment Resources Development (CEERD), produced the following recommendations:

• Replicating the project elsewhere in the ASEAN region, which is richly endowed with coconut shell and oil palm shell (feedstock resources)
• Establishing large activated carbon plants, with a minimum production threshold of 6-7 metric tons of Activated Carbon (AC) per day, to ensure acceptable level of economic feasibility, as the technology requires high capital investments
• Establishing a Training Center within the AC plant to train coconut growers and coconut charcoal producers in improving quality of coconuts and coconut charcoal
• Involving the local community and related associations as direct stakeholders and shareholders to reinforce the project’s long-term sustainability
• Assessing the development of a water and/or gas filter production line associated with the activated carbon production facility, as local and international markets of water and gas filters are already well established
• Working in cooperation with manufacturers of water and gas filter systems, rather than competing with them on the water and gas filter systems manufacturing field
• Securing the financial resources to implement the project’s next phase which will allow the project to move forward

Read more about the project here

Read the Final Report (May 2008) [PDF]

Arsenic mitigation: Bangladesh and Vietnam – different groundwater compositions require different approaches

Hug, S.J., Leupin, O.X. and Berg, M. (2008). Bangladesh and Vietnam : different groundwater compositions require different approaches to arsenic mitigation. Environmental science and technology ; vol. 42, no. 17 ; p. 6318-6323. DOI: 10.1021/es7028284

To be successful, the mitigation strategy must take into account the geological differences in groundwater, the economic resources of the population, and the availability of infrastructure for water treatment.

Conclusions:

Vietnam and Bangladesh are both confronted with high arsenic concentrations, but distinct water compositions require different solutions. Arsenic mitigation depends for the most part on natural factors, such as the availability of alternative water sources and the feasibility of water treatment.  If several options are available, socioeconomic factors determine which mitigation option is implemented most successfully.

The socially accepted and already widespread sand filters in the Red River delta have advantages for their simplicity and low cost of operation. The removal of iron from the pumped water is immediately apparent even to people who are not aware of the arsenic problem. Thus, sand filters are a good option in Vietnam and in other affected regions with high concentrations of dissolved iron.

Arsenic removal in the worst-affected districts of Bangladesh is considerably more difficult. Since there are currently no selective sorbents, both arsenic and phosphate have to be removed and fixed-bed columns will require frequent regeneration or replacement. Activated alumina columns that can be regenerated have shown very good results. Filter columns with zerovalent iron are very promising, as metallic iron is inexpensive, widely available, and capable of forming precipitates with very high sorption site densities. An
improved understanding of the reactions over long periods of operation can lead to further optimization and wider applicability. An issue that is often discussed is the sludge produced in water treatment units. Sludge with elevated arsenic concentrations needs to be collected and handled properly. Containment under oxic conditions or in closed disposal sites are good solutions. However, the quantities of arsenic in water used for drinking are small compared to the amounts of arsenic pumped into rice fields by irrigation and probably partly remobilized during monsoon flooding. In the long term, controlled transport and release of treatment
sludge into large rivers during high water levels, ensuring rapid dilution and transport into the ocean, could be studied as an alternative to containment. Several mitigation options are now available and should be implemented to avoid further exposure to arsenic-tainted drinking water.

Joe Brown and Mark Sobsey win IWA project innovation award for ceramic filters

Joe Brown and Mark Sobsey of the University of North Carolina School of Public Health, USA, are the Grand Winners of the 2008 Project Innovation Awards for small projects. They received the prize for “Ceramic Water Filters in Cambodia: A Sustainable Solution for Rural Drinking Water Treatment”.

The Ceramic Water Purifier (CWP) was introduced in Cambodia in 2001. Further investment in the technology is planned by NGOs and the Cambodian government. An independent study was commissioned by UNICEF and WSP-Cambodia to examine implementation efforts undertaken by the two main producers, IDE and RDI. The study suggested that the filters can significantly improve household water quality (up to 99.99% less E. coli in treated versus untreated water), although the filters were susceptible to breakage in household use (about 2% per month, post-implementation) and contamination through improper handling practices. Households using the filter reported nearly half the cases of diarrhea as matched control households without a filter. Results suggest that filters may be used longer and more effectively by households when other water, sanitation, and hygiene (WSH) interventions are bundled with the CWP; that access to replacement filters and spare parts is key to ensuring long-term success of CWP programs; and that cost recovery is positively associated with continued use.

Read more here and here.

The International Water Association (IWA) established the Project Innovation Award Programme (PIA) in 2006 to recognize excellence and innovation in water engineering projects throughout the world. The awards will be presented on September 10th, 2008 at the IWA World Water Congress and Exhibition in Vienna.

See the full list of winners here.

Meteorology: Taming the sky

Is it really possible to stop rain, invoke lightning from the heavens or otherwise manipulate the weather? Jane Qiu and Daniel Cressey report on the once-scorned notion of weather modification.

[...]

China has one of the largest programmes for weather modification in the world. It spends between 400 million yuan (US$60 million) and 700 million yuan a year on it, and employs 32,000 people to operate 35 specially equipped planes, 7,000 anti-aircraft cannons and 5,000 rocket launchers. Official figures from the China Meteorological Administration say that the country created 250 billion tonnes of rain between 1999 and 2006, an annual production of more than 30 billion tonnes. This is enough to meet the needs of more than 500 million of its 1.3 billion people, but the country aims to generate 50 billion tonnes a year by 2010.

Many researchers, both in and outside China, doubt that sufficient evidence has been accumulated to support this claimed success. “In fact, China is very much behind in this area,” says Zhang Hong-fa, an atmospheric scientist at the Cold and Arid Regions Environmental and Engineering Research Institute in Lanzhou. “A false sense of achievement would impede genuine progress.”

Read more: Nature, 453, 970-974 (2008) – doi:10.1038/453970a – Published online 18 June 2008

Adaptation and Verification of Arsenic Mitigation Technology in Cambodia

Arsenic contamination in Cambodia has reached alarming levels and is threatening the health of rural communities. One technology, the Kapchan Arsenic Filter (KAF), promises to be a suitable and affordable solution in neighbors Nepal and Bangladesh. This Pilot and Demonstration Activity (PDA) funded by the Asian Development Bank (ADB), will test the suitability of the KAF as a viable arsenic mitigation solution in Cambodia’s rural areas.

The Kanchan Arsenic Filter (KAF) was developed at Massachusetts Institute of Technology (MIT) and is the product of 7 years of extensive interdisciplinary laboratory and field studies in rural villages of Nepal. The KAF is a low-cost household-level technology that can be constructed using simple materials such as gravel and iron nails, and requires neither external energy nor material input for its operation and maintenance. The KAF is also currently being tested in Bangladesh.

Consultations with key stakeholders including the Cambodian Ministry of Rural Development (MRD) resulted in an agreement to begin a KAF performance verification process that consists of 3 phases — laboratory study, field technical research, and pilot demonstration. The laboratory study phase was successfully completed in 2006 by the Institute of Technology of Cambodia (ITC) with support from the Centre for Affordable Water and Sanitation Technology (CAWST) and MIT. The 8-week laboratory study showed that the KAF consistently removes over 90% arsenic, total coliforms, and E.coli from arsenic-contaminated groundwater near Phnom Penh. Another laboratory study found that the formation of red rust using small nails is crucial to the filter performance.

The PDA will support phases 2 and 3 of the KAF performance verification process.

Read more: ADB, Feb 2008

Ceramic silver-impregnated pot filters for household drinking water treatment in developing countries

Ceramic silver-impregnated pot filters for household drinking water treatment in developing countries: material characterization and performance study
D. van Halem, S.G.J. Heijman, A.I.A. Soppe, J.C. van Dijk and G.L. Amy
Water Science & Technology: Water Supply ; Vol 7, No 5-6, p. 9–17 ; 2007
doi:10.2166/ws.2007.142

ABSTRACT
The ceramic silver-impregnated pot filter (CSF) is a low-cost drinking water treatment system currently produced in many factories worldwide. The objective of this study is to gather performance data to provide a scientific basis for organisations to safely scale-up and implement the CSF technology. Filters from three production locations are included in this study: Cambodia, Ghana and Nicaragua. The microstructure of the filter material was studied using mercury intrusion porosimetry and bubble-point tests. Effective pores were measured with a mean of 40 mm, which is larger than many pathogenic microorganisms. The removal efficiency of these microorganisms was measured by using indicator organisms; total coliforms naturally present in canal water, sulphite reducing Clostridium spores, E.coli K12 and MS2 bacteriophages. The removal of these organisms was monitored during a long-term study of several months in the laboratory. Ceramic silver impregnated pot filters successfully removed total coliforms and sulphite reducing Clostridium Escherichia coli K12 were also removed, with log(10) reduction values consistently higher than 2. MS2 bacteriophages were only partially removed from the water, with significantly better results for filters without an impregnation of colloidal silver. During this study the main deficiency of the filter system proved to be the low water production; after 12 weeks of use all filter discharges were below 0.5 Lh-1, which is insufficient to provide drinking water for a family.