10 Simple life-saving methods for water purification (Part 2)

In our previous post, we shared about 5 water purification methods that you can use to obtain clean drinking water.
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We know that you are thirsty for more, so here are 5 more low-cost water treatment methods that will prove useful in rural areas.

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Summary

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Ceramic Filter

Slowly but surely, I’m filtering your water
​Source: https://www.pinterest.com/pin/518125132109352567/?lp=true​

Ceramic filters are commonly used in remote parts of the world to treat water in households. A ceramic filter has fine micro-pores that can mechanically remove suspended particles when water flows through it via gravity.
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The filter may be coated with colloidal silver, which acts as a disinfectant to kill pathogens. However, the filter can be clogged easily, especially if the inlet water is turbid. While the inner surface of the ceramic filter can be scrubbed to remove the impurities trapped, this maintenance method is limited in its effectiveness.

Advantage	Drawback
- Low cost - No electricity required - Materials could be sourced locally	- Low flow rate and long wait time (over-night) - Disinfection is not complete - Inconsistent quality of output water - Heavy and not portable - Brittle material and heavy weight make it vulnerable to breakages

Bio-sand Filter

I have a highly layered personality…I mean structure
Source: https://www.cawst.org/services/expertise/biosand-filter/more-information

Bio-sand filter has the advantage of material simplicity and is typically made up of sand and gravel. It utilizes a mechanical and biological process to treat the water.

The microorganisms establish a community on the top layer of sand (biofilm) and cleans the water by “eating” the organic and inorganic particles as it flows through the system. Due to insufficient oxygen in the middle of the filter, most microbes will only grow on the top layer of sand, keeping it safely separated from the effluent (out-put) water.

A well-built bio-sand filter is typically able to remove about 98 to 99% of bacteria and protozoa, but is less effective for viruses and is unable to remove dissolved contaminants such as salts, arsenic and fluoride.

The removal of organic and inorganic particles through biofilm may be limited as biochemical reduction is highly dependent on the contact time and density of the biofilm; increasing both factors will also reduce the flow rate of the filter.
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Maintenance can be tricky as the filter may stop working when the biofilm becomes too thick and dense. To recover the system, scrape away the top few centimeters of sand to reduce the thickness of the biofilm. 

Advantage	Drawback
- Easy to operate - Can be built from locally available materials - Relatively low capital cost - Able to reduce some level of organic and inorganic particles	- Installation is manpower intensive - Not portable and difficult to transport - Disinfection is not complete - Inconsistent reduction of organic and inorganic particles, which is highly dependent on contact time and thickness of biofilm - Requires that the filter be used on a regular basis to maintain the biofilm

Boiling

Hot.
Source: https://www.wonderopolis.org/wonder/why-does-water-bubble-when-it-boils

Boiling is an effective method to destroy most biological pathogens and most of us still boil our water even if we have other water treatment solutions.

​The water should be brought to a rolling boil for at least 5 minutes and preferably up to a period of twenty minutes. Longer boiling time is needed at higher elevations to ensure all the pathogens are destroyed.

Prior filtration is usually needed because any particles in the water can provide a hiding place for bacteria, protecting them from the heat. Basically, brown water remains brown, even after intense boiling.

Boiling can affect the taste of water due to the loss of oxygen in it. The taste can be improved by re-oxygenizing it through vigorously stirring or shaking the water. 

Advantage	Drawback
- Simple - Effective in removing biological pathogen for clear water	- Energy intensive (need fuel or electricity) - Time-consuming - Boiling affects the taste of water - Does not remove colloidal or suspended particles

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Chlorination

Staying behind for residual disinfection
​Source: https://www.gettyimages.com/detail/photo/effervescent-tablets-in-water-high-res-stock-photography/594844889

Chlorination is the most common disinfection method used in water treatment plants and in our swimming pools. Chlorine is widely used because it is relatively low-cost and effective in destroying biological pathogens.

It is most commonly available in the form of liquid bleach (sodium hypochlorite) and chlorine tablets. The active component in chlorine disinfectant is the hypochlorite ion (OCL-), which oxidizes the cellular structure of germs and kills them in the process.

For untreated water with low turbidity, dosing the water with appropriate amounts of chlorine and giving the hypochlorite ions a minimum contact time of 30 minutes can improve the quality of water tremendously.

Chlorination works for most pathogens with the exception of some protozoa due to their protective cysts (thick outer shell). To ensure potability (drinkability), the protozoa needs to be removed by other means such as filtration.

​The dosage of chlorine also needs to be adjusted appropriately to ensure proper disinfection. Too little chlorine may result in incomplete disinfection while too much chlorine may affect the water's taste.

Advantage	Drawback
- Low cost - Chlorine ions stays in water for prolonged periods, ensuring residual disinfection	- Ineffective for water with high turbidity - Requires constant resupply - May create bad “chemical” taste - Challenging to determine dosage - Long wait time (at least 30min contact time with appropriate dosage)

Solar Disinfection

Sun day fun day
Source: https://www.scidev.net/global/water/news/mistrust-slows-spread-solar-disinfection-tech.html

Solar disinfection (SODIS) is a simple and effective way to kill microorganisms in water. The only materials needed are transparent bottles and sunshine, which can be obtained easily,

SODIS uses heat and ultraviolet (UV) radiation to destroy pathogens. However, the water has to be clear because suspended solid particles can block the UV rays and reduce its effectiveness.
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The water should be exposed to strong sunlight for about five hours to destroy all pathogens. But if the water temperature rises to 50°C, the exposure period can be shortened to one hour.

Source: https://bluesolarcity.com/guide-solar-disinfection-sodis/

Advantage	Drawback
- Easy to use - Low cost - Effective and reliable	- Ineffective for water with high turbidity - Long wait time up to 5 hours - Low volume treated at one time - Harmful chemicals may leach when the plastic bottles are heated up - Not suitable for regions with intermittent sun exposure, high cloud cover or low temperatures

Ultrafiltration (by ROAMfilter™ Plus)

1L of water in seconds!

Ultrafiltration (UF) is a process that physically separates microscopic particles from the water based on the principle of size-exclusion. UF removes essentially all colloidal particles (0.01 to 1.0 microns) from water and some of the largest dissolved contaminants. 

The ROAMfilter™ Plus is a water filtration system that is specifically made for disaster and rural development areas. The filter is designed to be safe, simple and swift.

Safe because our technology utilizes 0.02-micron pore membranes, capable of removing bacteria and viruses.

Simple because it works exactly like a bicycle pump, making it easy to operate and maintain  without electricity. 

And Swift because at a light weight of 3 kg, it can be easily carried over any terrain and deployed to produce more than 200 litres of clean water per hour.

Advantage	Drawback
- Safe: Ultrafiltration membrane removes 99.9999% of bacteria and 99.99% of viruses - Simple: Intuitive design operated by a hand pump mechanism; no electricity is required. Easy maintenance - Swift: Only 3 kg in weight, you can carry it over any terrain - Durable: Replaceable filter cartridge lasts 2 years - Efficient: With a flow rate of 200L/Hr, it can serve up to 100 people	- Requires complementary solutions to remove chemicals and heavy metals

Missed Part 1 of this article? ​

​Check out 10 simple life-saving methods for water purification (Part 1) to catch up on what you missed!

 

10 Simple life-saving methods for water purification (Part 1)

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​​Did you know, 525,000 children under 5 die from diarrhoeal diseases every year? Millions more fall ill  due to water-borne diseases caused by the lack of access to clean drinking water.

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​Blog Author: Ze Yong Yeoh