Tag Archives: water treatment

New nanotechnology to produce sustainable, clean water for developing nations – National Science Foundation

Published on Oct 3, 2016

Tease: This technology would enable communities to produce their own water filters using biomass nanofibers, making clean water more accessible and affordable

Description: The world’s population is projected to increase by 2-3 billion over the next 40 years. Already, more than three quarters of a billion people lack access to clean drinking water and 85 percent live in the driest areas of the planet. Those statistics are inspiring chemist Ben Hsiao and his team at Stony Brook University. With support from the National Science Foundation (NSF), the team is hard at work designing nanometer-scale water filters that could soon make clean drinking water available and affordable for even the poorest of the poor.

Traditional water filters are made of polymer membranes with tiny pores to filter out bacteria and viruses. Hsiao’s filters are made of fibers that are all tangled up, and the pores are the natural gaps between the strands. The team’s first success at making the new nanofilters uses a technique called electrospinning to produce nanofibers under an electrical field.

Hsaio’s team is also looking to cut costs even further by using “biomass” nanofibers extracted from trees, grasses, shrubs — even old paper. Hsiao says it will be a few years yet before the environmentally friendly biomass filters are ready for widespread use in developing countries, but the filters will eliminate the need to build polymer plants in developing areas. Ultimately, those filters could be produced locally with native biomass or biowaste.

The research in this episode was supported by NSF award #1019370, Breakthrough Concepts on Nanofibrous Membranes with Directed Water Channels for Energy-Saving Water Purification.

NSF Grant URL: https://www.nsf.gov/awardsearch/showA…

 

USAID/CDC – Proven Household Water Treatment Options Fact Sheet

Preventing Diarrheal Disease in Developing Countries: Proven Household Water Treatment Options. USAID, CDC, November 2010.

Download Full-text (pdf, 1.19MB)

Five interventions – chlorination, ceramic filtration, slow sand filtration, solar disinfection, and PUR – have been proven to reduce diarrhea in users in developing countries and improve the microbiological quality of stored household water and are discussed below. The most appropriate HWTS option for a location depends on existing water and sanitation conditions, water quality, cultural acceptability, implementation feasibility, availability of HWTS technologies, and other local conditions.

Social, Cultural and Behavioral Correlates of Household Water Treatment and Storage

In the Center for Communication Programs publication, Social, Cultural and Behavioral Correlates of Household Water Treatment and Storage, Drs. Figueroa and Kincaid discuss the many individual, household and community level factors that play a role in water treatment behavior and offer a model that can be used to improve the design and effectiveness of water treatment programs.

The Model of Communication for Water Treatment and Safe Storage Behavior is based on behavior change and communication theories that have been applied and tested worldwide by CCP across several health areas, including water treatment.

Link – http://www.jhuccp.org/node/1558

Stanford University – filter uses nanostructures to purify water at low cost

High-speed filter uses electrified nanostructures to purify water at low cost

By dipping plain cotton cloth in a high-tech broth full of silver nanowires and carbon nanotubes, Stanford researchers have developed a new high-speed, low-cost filter that could easily be implemented to purify water in the developing world.

This scanning electron microscope image shows the silver nanowires in which the cotton is dipped during the process of constructing a filter. The large fibers are cotton.

Instead of physically trapping bacteria as most existing filters do, the new filter lets them flow on through with the water. But by the time the pathogens have passed through, they have also passed on, because the device kills them with an electrical field that runs through the highly conductive “nano-coated” cotton.

In lab tests, over 98 percent of Escherichia coli bacteria that were exposed to 20 volts of electricity in the filter for several seconds were killed. Multiple layers of fabric were used to make the filter 2.5 inches thick.

“This really provides a new water treatment method to kill pathogens,” said Yi Cui, an associate professor of materials science and engineering. “It can easily be used in remote areas where people don’t have access to chemical treatments such as chlorine.”

Cholera, typhoid and hepatitis are among the waterborne diseases that are a continuing problem in the developing world. Cui said the new filter could be used in water purification systems from cities to small villages.

Faster filtering by letting bacteria through

Filters that physically trap bacteria must have pore spaces small enough to keep the pathogens from slipping through, but that restricts the filters’ flow rate.

Since the new filter doesn’t trap bacteria, it can have much larger pores, allowing water to speed through at a more rapid rate.

“Our filter is about 80,000 times faster than filters that trap bacteria,” Cui said. He is the senior author of a paper describing the research that will be published in an upcoming issue of Nano Letters. The paper is available online now.

The larger pore spaces in Cui’s filter also keep it from getting clogged, which is a problem with filters that physically pull bacteria out of the water.

Cui’s research group teamed with that of Sarah Heilshorn, an assistant professor of materials science and engineering, whose group brought its bioengineering expertise to bear on designing the filters.

Silver has long been known to have chemical properties that kill bacteria. “In the days before pasteurization and refrigeration, people would sometimes drop silver dollars into milk bottles to combat bacteria, or even swallow it,” Heilshorn said.

Cui’s group knew from previous projects that carbon nanotubes were good electrical conductors, so the researchers reasoned the two materials in concert would be effective against bacteria. “This approach really takes silver out of the folk remedy realm and into a high-tech setting, where it is much more effective,” Heilshorn said.

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Sudan: People with HIV demand safe drinking water

For years, Lole Laila Lole, chairperson of an association for people living with HIV/AIDS in southern Sudan, had to drink, cook with, and bathe in the dirty, contaminated water he fetched from the River Nile. “There was no other way,” he told IRIN/PlusNews.

Due to their weakened immune systems, people living with HIV are particularly susceptible to infections and diseases that can be present in untreated water. But after testing positive [in Khartoum], Lole was forced to return to the virtually non-existent water system of Juba, the southern capital, which had been at war for close to two decades.

The conflict ended in 2005, but government leaders in the south say they lack adequate resources to redevelop the war-ravaged region and deliver services such as providing safe water.

Since the end of the war, treatment tablets have become available in the shops, and HIV-positive people who can afford them are now able to protect themselves from the outbreaks of cholera and other diarrhoeal diseases.

This year, Population Services International (PSI), with funding from the US Centres for Disease Control, began including water treatment tablets [Water Guard] in the basic care packets they distribute to people with HIV every three months. The decision to include Water Guard in PSI’s care packets was partly in response to pressure from people living with HIV.

Women in Sudan also face very high maternal health risks. The risks are significantly higher for HIV-positive mothers and babies, particularly if they are unable to access safe drinking water.

Read more: IRIN/PlusNews, 12 May 2008

Philippines: Reducing Mercury and Heavy Metals Contamination in Meycauayan River System

Mercury and heavy metals toxicity endanger lives and livelihoods along the Meycauayan river system north of Manila. River clean-up has begun, but contamination may have reached groundwater sources. This Pilot and Demonstration Activity (PDA) approved by the Asian Development Bank (ADB) in January 2008 will help develop technologies to reduce the toxicity of the Meycauayan river system.
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