Five Water Purification Designs

20 May.,2024

 

Five Water Purification Designs

According to the World Health Organization (WHO), 748 million people lack access to uncontaminated drinking water sources. Moreover, WHO estimates that 1.8 billion people use a fecally contaminated drinking water source, 2.5 billion lack access to improved sanitation facilities and more than 840,000 people die from water related diseases annually. Contaminated water is the number one cause of death in developing countries, causing diseases such as cholera, hepatitis, typhoid fever, malaria, ascariasis, dengue fever and many other deadly illnesses. In fact, contaminated water is the number one public health concern globally based on its impact to society, according to the WHO. Fortunately, the WHO estimates that 10% of the global disease burden could be prevented with improved water supply and sanitation. In light of this, a number of innovations and technologies are providing growing solutions to this problem.

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Ultra Violet Filtration

Ultraviolet water filtration systems such as the Camelbak 25 Ounce All Clear Bottle and the UV Waterworks systems use ultraviolet (UV) rays to destroy harmful pathogens in drinking water. UV light filtration is highly effective, eliminating up to 99.9% of harmful microorganisms in water. The Camelbak Bottle has several advantages including quick filtration, (it takes just one minute to produce clean water), easy portability, and simplicity of use. Further, the UV bulb inside the Camelbak lasts for 10,000 cycles and produces enough energy to clean three liters of water for seven years. Some of the disadvantages of the Camelbak bottle include its high cost; at $99, it may be beyond the reach of many users, especially in developing countries. Further, the Camelbak only purifies drinking water and is not suitable for cleaning other water such as water for cooking. It also has limited sanitation applications. The UV waterworks has the advantage of being able to purify up to four gallons of water in a minute, which is enough drinking water for almost 2000 people. Its main disadvantage lies in the fact that that it requires electricity or another power source such as a car battery or solar cell to function.

Solar Purification

Solar water purifiers typically use sunlight to disinfect contaminated water and make it safe for drinking. Purification systems such as the SODIS (Solar Disinfection) uses clear water bottles filled with drinking water and set out in sunlight for up to six hours. The UV lights from sunlight destroy germs such as viruses and bacteria as well as parasites such as giardia and cryptosporidia. The SODIS has several advantages: It is cheap and easy especially since it uses PET bottles, which cost little and can be recycled easily. Disadvantages include: limited volume of water purified, a large number of bottles required in order to purify sufficient quantities of water, and long purification time.

Another system is (Solar Power) from MIT. The system is consists of photovoltaic panels, a large tank to store water, and a small shed to store the pumps, filter water, and auto-compute tasks.

The main advantage of this system is the fact that a large volume of water can be produced at a cheap cost. The disadvantages arise from the fact that the solar system must be built and community members trained to maintain the system, change out filters and replace additives in the water.

Ceramic Filtration

Ceramic filters work by extracting dirt, bacteria, protozoa and debris from water as it passes through small pores of the ceramic material. It is usually used in conjunction with other filtration methods such as carbon and colloidal silver. Filtration systems are available as buckets from organizations such as Waterislife and local manufacturers. There are several advantages to using the ceramic filtration system: One, it has been proven effective in the removal of bacteria and protozoa from water. Second, the system is easy to use and is widely acceptable as a purification system. Finally, it involves a onetime-only cost to make. Disadvantages include: Slow filtration time, producing only 1-3 liters per hour for turbid water, no residual chlorine protection which can lead to recontamination and filters which break down easily and must be cleaned regularly.

The Water Purifying Bicycle

The water purifying bicycle system filters water through the pedaling of a bicycle. Bicycle systems such as the Nikkon Cycloclean consist of a purifying case attached to the rear of the bicycle. The pedaling action forces water through a filtration system before being stored in a vessel of your choice. The main advantages of this system include quick purification (up to five liters in one minute), portable and easily accessible in areas where other vehicles cannot reach, and water which can be used for multiple purposes such as cooking, cleaning and drinking. One of the main disadvantages of this system is its relatively high cost.

Personal Filter Straws

These are small flute-shaped portable water filter with internal filtration components such as membranes, iodized crystals and carbon. Filter straws such as the LifeStraw and WaterisLifeStraw filter pathogens from water to make it safe for cleaning. Its advantages include ease of use, ideal for emergencies since it does not require electrical power and it is highly portable. Its disadvantages are low durability (lasting only a year) and the fact that it only purifies drinking water and not water for cooking or cleaning.

Conclusion

The water purification solutions discussed in this article have been highly effective in combating the water crisis in developing countries and in ensuring the delivery of clean, safe and affordable drinking water to communities in affected areas.

Ten Low-Cost Ways to Treat Water

Clean water solutions for low- and middle-income countries don’t have to be expensive, but they have to be available. The statistics are sad: 1.7 billion people use a drinking water source contaminated with feces, and more than 500,000 people die of waterborne disease each year, most of them younger than 5 years old.

Clean water straight from the tap is as good as it gets. But until everyone has gold-standard infrastructure, there are lower cost solutions available. Boiling water over a wood fire is one of the most widely used methods in low- and middle-income countries, but it is also a health hazard for those working in poorly ventilated kitchens. Cooking fires also exacerbate deforestation. Instead, we’ve rounded up ten low-cost technologies to treat water, and not one requires boiling. Most of these are for household use, but a few are for community-wide treatment.

Do you know of other methods? Please let us know in a comment below.

Ceramic Filters

Clay, sawdust and a plastic bucket can make a water filter that catches dirt and disease-causing microbes. In the classic design, mix clay with a combustible material like sawdust or rice husks, give it a flower pot shape and fire it in a kiln. The sawdust or rice husks burn away, leaving tiny pores in the ceramic through which water filters.

Potters for Peace promotes an open source system called CT Filtron, distributed in Ghana, that treats water with silver-enhanced ceramic filtration. CT Filtron is one of 25 ceramic filters archived for comparison in our Solutions Library.

Bamboo Charcoal

In this spin on the charcoal filter, a team of E4C members in Bangalore propose a filter made of locally available materials including charred bamboo, gravel and natural adsorbents. “The process we propose is indigenous, eco-friendly, low cost and entails minimum maintenance,” the team wrote in a message to E4C. They estimate that their filter can handle 30 liters of water per hour, and it would be affordable for average households in the region.

 

Solar Disinfection (SODIS)

If cost is a bigger concern than time or convenience, the cheapest way to treat water is to leave it in a plastic bottle in the sunlight. Leave clear bottles in the sun for a few hours and UV radiation and heat kills the microbes that cause diarrhea and other waterborne illness. The Sodis (for solar disinfection) method was deployed in some parts of Haiti after the earthquake in 2010, and it is used in emergencies and impoverished regions worldwide.

“It is the combined effect of UV irradiation and high temperature that leads to antimicrobial action,” according to a paper published in 2020 in the journal ACS Catalysis.

Link to UVDF

WADI Solar Disinfection Indicator

Solar disinfection is one of the cheapest ways to kill microbes in water, but it is possible to make mistakes. Clouds, shade and the placement of the bottles and the murkiness of the water can change the amount of time needed to disinfect. To take solar disinfection to the next level and remove the guesswork, try WADI. WADI, by Helioz, is a device that measures solar radiation levels to indicate when the water is sterilized. Just look for the happy smiley face on WADI’s display.

Yet there may be room for competing designs in this category: we came across this prototype of a solar indicator at IEEE’s Global Humanitarian Technology Conference in Seattle, Washington (USA).

Portable Solar Distiller

Not to be confused with solar sterilization or disinfection, solar distillation purifies even muddy, salty or otherwise undrinkable water through evaporation and condensation. The power of distillation to purify saltwater makes it unique among the treatment methods featured on this page.

A solar still can actually be a cheap and simple piece of shaped plastic or glass, or they can be more highly designed devices such as Henry Glogau’s award-winning portable solar distiller featured in the video above. “The portable design merges local resource production with community architecture, providing freshwater and a shaded gathering place,” according to the video’s description.

To work, the still places water contaminated with salt or other impurities in direct sunlight where it heats and evaporates. The water vapor is trapped and condenses into droplets that run off into a container. This simple process takes huge amounts of energy, which is why solar stills can make more sense than stills powered by other fuels.

For another take on the solar still, see the Eliodomestico terracota household still in our Solutions Library.

Bicycle-Powered Water Filter

Bicycles in all their glorious versatility and simplicity are a favorite at E4C, and we were pleased to find a small but thriving supply of bicycle water filter videos, including this one by mechanical engineering students at the University of Maine. The Clean Water Team developed the bike-powered filter, and their project page describes the build, including a bill of materials.

For more bicycle action, see our list of ten things you can do with a bicycle.

Emergency Homemade Filter

The plastic bottle makes yet another appearance as a water treatment device, this time as a simple filter that can remove sediment and even disease-causing microbes. Simply cut the bottom from the bottle, fill it with layers of gravel, sand cloth and charcoal, filter the water through it and hope for the best.

Slow Sand Filtration

Slow sand filtration has the advantage of working on an entire community’s water source, not just individual households. West Virginia University offers a technical brief on slow sand filtration systems, including a design summary.

A slow sand filtration system is a combination of several parts: water storage tanks, an aerator, pre-filters, sand filters, disinfection stages, and filtered water storage tanks. The number of filters and filter types that are used in a given slow sand filtration system will depend on the quality of the source water and will be different for each community.

WATA Sodium Hypochlorite System

Chlorine is one of the most versatile and effective clean water solutions in LMICs and everywhere else. Chlorine can work in a community water supply to kill microbes before it enters people’s jerry cans or home water supplies. And it keeps the water safe from new contaminations long after it is added.

Community-wide water treatment with chlorine is now possible using only water, salt, electricity and a portable device called WATA. The system converts a measure of salt and water into sodium hypochlorite (bleach) by the process of electrolysis, passing an electric current through the saline soluiton. Designed by the Antenna Foundation in Geneva, Switzerland, WATA produces enough chlorine in two hours to treat 2,500 liters of water. The product has been tested for more than 10 years, it is commercially available and comes in five sizes depending upon the quantity of active chlorine desired (from 0.5 liters to 60 liters).

Aguaclara Reach Water Treatment Plant

The AguaClara Reach Full Scale Plant is a compact gravity-fed water treatment system that uses a five-step process to treat and filter water. The system adds a coagulant to the water to settle out sediment and other particles, then runs the water through a sand filter and adds chlorine before storing it.

This community treatment plant can serve 1,000 to 50,000 people.

E4C’s Solutions Library

Please see E4C’s Solutions Library for more clean water solutions suitable for communities in low- and middle-income countries. In our database you can view standardized information about hundreds of products and compare similar technologies side by side.

Want more information on water purifier equipment for sale? Feel free to contact us.