10 Breakthroughs in Water Purification

Water is just as essential as food and shelter for survival, yet no one can endure for long without it. That’s why ancient civilizations settled near abundant water sources. But having access to water is not enough—it can pose serious risks if polluted or contaminated with harmful substances or microbes. Water used for irrigation, cleaning, and waste management can easily become tainted, putting nearby populations at risk [source: Hassan].

Humanity has long sought ways to purify water. As early as 1500 B.C.E., long before the advent of reverse osmosis, Egyptians used alum to remove suspended particles from drinking water. However, it wasn’t until the late 19th and early 20th centuries that scientists discovered microbes were responsible for illnesses, leading to the use of chlorine and ozone to treat water [source: Environmental Protection Agency].

Though tap water is clean and safe in many countries today, around 11 percent of the global population—783 million people—still lack access to safe drinking water, according to a 2012 United Nations report. To address this, scientists are developing new water extraction and purification technologies using a variety of chemical and physical methods. Below are 10 of the most promising innovations.

10: Direct-Contact Membrane Desalination

If we could harness the immense potential of the oceans for drinking water, there would be an abundance for everyone. However, the challenge lies in extracting the salt, a task that current technologies struggle with due to inefficiency and high costs. This is why a new process created by Kamalesh Sirkar, a professor at the New Jersey Institute of Technology, holds such tremendous promise.

Kamalesh Sirkar's direct-contact membrane distillation (DCMD) system operates by flowing heated seawater across a plastic membrane containing hollow tubes filled with cold distilled water. The tiny pores in the membrane allow water vapor to pass through but block the salt. The vapor then diffuses through the pores and is collected, where it is condensed back into liquid water.

According to Sirkar, his DCMD system is highly efficient—it can produce 80 liters (21 gallons) of drinkable water from 100 liters (26 gallons) of seawater, about double the output of current desalination technologies. A possible drawback is that the system needs a constant, low-cost heat source to maintain the temperature difference across the membrane. However, there is potential for DCMD systems to eventually recycle waste heat from onshore factories and offshore oil drilling, making it a mutually beneficial solution [source: Greenmeier].

9: Ceramic Water Filters

Ceramic filters function similarly to desalination processes. Water passes through the ceramic, which is full of microscopic pores, allowing water molecules to pass but blocking harmful bacteria, dirt, and other contaminants [source: Doulton USA]. British potter Henry Doulton first introduced this technology in the early 1800s to purify the heavily contaminated Thames water, which carried cholera and typhoid due to raw sewage [source: Brodrick].

Since Doulton's invention, the design of ceramic filters has improved. For example, silver coatings have been added to eliminate bacteria, making modern filters even more efficient at removing harmful pathogens. Additionally, humanitarian organizations have established factories to mass-produce and distribute affordable ceramic filters to the developing world.

A 2006 study revealed that Cambodians who used these simple, portable filters saw a 46% reduction in diarrhea and a 95% decrease in E. coli contamination compared to water samples taken in 2003 [source: Resource Development International – Cambodia ]

A downside of ceramic filters is their slow filtration rate, as water passes through the clay at only 2 liters (2.11 quarts) per hour. However, the filtration must occur slowly to allow the silver solution to effectively kill pathogens. Additionally, these filters do not eliminate harmful chemicals such as arsenic.

8: Herbal Defluoridation

In the United States, water suppliers add fluoride to drinking water in small amounts (0.8 to 1.2 milligrams per liter) to help prevent tooth decay. However, in some regions, such as parts of India, the Middle East, and Africa, natural fluoride levels can be dangerously high, leading to health issues. For example, in one Indian village, fluoride concentrations between 5 and 23 milligrams per liter have resulted in severe anemia, joint stiffness, kidney failure, and discolored teeth [source: World Health Organization].

Fortunately, researchers in India found a potential solution, as outlined in a March 2013 article in the International Journal of Environmental Engineering. They developed a filter system that utilizes the medicinal herb Tridax procumbens to remove excess fluoride from drinking water. The plant, known for its ability to absorb toxic heavy metals, attracts fluoride ions when water flows through it at a temperature of approximately 27 degrees Celsius (80.6 degrees Fahrenheit).

This filter could offer an affordable and easy-to-use method for ensuring safe drinking water in areas where fluoride levels are excessively high. It may also be of interest to individuals in the U.S. and other countries who are opposed to the addition of fluoride in their water supply [source: Science Daily].

7: 'Super Sand'

Sand and gravel have been used for water purification for millennia. In 1804, a Scottish inventor named John Gibb created the first sand filter that removed larger particles from water. His invention proved so effective that cities like London soon adopted rapid sand filters to improve the appearance and taste of river water.

By the late 1800s, scientists had discovered that filtering water not only enhanced its clarity but also made it safer by removing the particles that carried harmful microbes. This was clearly illustrated in 1892 when a cholera outbreak in Hamburg, which sourced its water from the River Elbe, resulted in 7,500 deaths. Meanwhile, the nearby city of Altona, which filtered its water from the same river, remained almost unaffected [source: Huisman and Wood].

Researchers have recently discovered a method of coating sand grains with graphite oxide to create 'super sand,' which is said to be five times more effective at filtering harmful contaminants like mercury from water than regular sand. The research continues to explore ways to enhance its absorption capabilities, with hopes to eventually introduce it to developing countries where water pollution is a significant issue [source: Science Daily].

6: How Plastic Bottles Can Remove Arsenic

In the 1940s black comedy 'Arsenic and Old Lace,' two well-meaning aunts attempt to help lonely men by poisoning them with elderberry wine laced with arsenic, a dangerous substance. When arsenic contaminates drinking water, it can lead to cancer of the bladder, lungs, and skin, along with damage to the nervous system, heart, and blood vessels [source: National Resources Defense Council].

Currently, nearly 100 million people in developing countries face dangerous levels of arsenic in their water. Many of them cannot afford the expensive water treatment plants used in the U.S. to remove it. However, a promising solution has been developed by Monmouth University (N.J.) chemistry professor Tsanangurayi Tongesayi. His affordable arsenic-removal system uses pieces of ordinary plastic beverage bottles coated with cysteine, an amino acid.

When plastic pieces are placed in water, the cysteine attaches to the arsenic, effectively removing it and making the water safe to drink. In tests, the system has successfully reduced arsenic levels from a dangerous 20 parts per billion to a safe 0.2 parts per billion, meeting the U.S. Environmental Protection Agency's standard [source: Science Daily].

5: Salt as a Water Purifier

In many impoverished nations where expensive water purification plants are unaffordable, people often turn to sunlight. The combination of heat and ultraviolet radiation from the sun can eliminate most of the microbes that cause diarrhea, which results in 525,000 child deaths annually in Africa [source: WHO]. However, this method requires clear water, which is a challenge in rural areas where people obtain water from rivers, streams, and boreholes containing suspended clay particles.

Joshua Pearce, an associate professor of materials science and engineering at Michigan Technological University, and Brittney Dawney from Queens University in Ontario have devised a solution. In their 2012 article in the Journal of Water, Sanitation and Hygiene for Development, they introduced a solar disinfection method that first treats water through a process called flocculation.

The process involves adding a small amount of table salt to the water, which helps draw out the clay. Although the resulting water contains more salt than what most Americans are accustomed to, it still has less than Gatorade. 'I've drunk this water myself,' Pearce said in an interview. 'If I were somewhere without clean water and had kids with diarrhea, and this could save their lives, I'd use it, no question' [sources: Science Daily, Dawney and Pearce].

4: The SteriPEN Water Purifier

For travelers in developing nations, the risk of exposure to unsafe water is a major concern. Wouldn't it be amazing if you could simply dip a magic wand into the water and make it safe to drink? Well, now you can. A portable device called the SteriPEN, sold by Katadyn Group in Switzerland, uses ultraviolet light to eliminate harmful microorganisms.

The SteriPEN works with the same purification technology used in bottled-water plants but is compact enough to fit into a backpack, weighing only 6.5 ounces (184 grams). Simply immerse it in a liter of stream or pond water for 48 seconds, and it becomes safe to drink [source: Stone]. This portable purifier can eliminate bacteria, viruses, and protozoa like giardia and cryptosporidium, which are common causes of illness [source: New York Times].

SteriPENS are primarily used by backpackers and travelers, but they also serve the U.S. military. Additionally, SteriPEN has donated several devices to game wardens working in remote wilderness regions where access to tap water is unavailable [source: Stone]. One important note about ultraviolet purification: cloudy water needs to be pre-filtered to eliminate particles suspended in the liquid before it can be effectively purified [source: Centers for Disease Control and Prevention].

3: MadiDrop Ceramic Water Purification Disks

Slow sand filters offer an affordable and practical way to purify water in developing nations. However, a non-profit organization based at the University of Virginia, PureMadi, has developed an innovative and user-friendly technology to purify water simply by submerging it in a container [source: Samarrai].

The MadiDrop is a small ceramic disk, about the size of a hamburger patty, which contains silver or copper nanoparticles that destroy microbes. These nanoparticles are extremely tiny particles intentionally designed by scientists to function as a single entity [sources: Samarrai, Mandal].

Compared to the larger ceramic flowerpot filters that PureMadi already produces, the MadiDrop is more affordable, easier to use, and more portable, as stated by James Smith, a civil and environmental engineer who is leading the project. However, the MadiDrop doesn't remove suspended particles that cause cloudy water. To overcome this, users are advised to first pass the water through the flowerpot filter to remove sediment, followed by using the MadiDrop to eliminate microbes [source: Samarrai].

2: Toxin-Eating Bacteria

While many of us associate algae with the unpleasant task of cleaning our fish tanks, they can also pose serious health risks. Cyanobacteria, a type of blue-green algae, thrives in both fresh and saltwater worldwide. These microorganisms produce toxins called microcystins that are easily ingested by those who drink, swim, or bathe in contaminated water.

Once microcystins enter the body, they can damage liver cells, which is obviously a major health concern. Unfortunately, traditional water treatment methods, such as chlorination or sand filtration, are ineffective at removing these toxins. This is why a new water purification technique developed by researchers at Scotland's Robert Gordon University is generating excitement.

Researchers have discovered more than ten distinct strains of bacteria that consume microcystins as their primary food source. These bacteria can metabolize the toxins into harmless, non-toxic substances. By introducing these algae-destroying bacteria into water supplies, they could effectively eliminate microcystins, ensuring the water is safe to drink without the need for harmful chemicals [source: Science Daily].

1: Nanotechnology

We've already discussed the innovative MadiDrop, which uses silver or copper nanoparticles to make water safe for consumption. But nanotechnology—the field focused on designing incredibly small structures, smaller than a human hair—holds even greater promise for improving global drinking water purification efforts.

Researchers from D.J. Sanghvi College of Engineering in India suggest that filters made from carbon nanotubes and alumina fibers might not only remove sediment and bacteria but also eliminate trace amounts of toxic substances like arsenic, offering a powerful solution for contaminated water.

A key benefit of using nanofilters, as they are called, is their superior efficiency compared to traditional water filtration systems. They require lower water pressure and, despite having much smaller pores than conventional filters, they maintain or even exceed the flow rate of regular filters [source: Science Daily]. Additionally, these filters can be enhanced with chlorine dioxide for extra disinfection.

Researchers at the Massachusetts Institute of Technology are exploring the use of nanotechnology for desalination. They are experimenting with graphene sheets—a form of carbon that is only one atom thick—to filter seawater. Nanotechnology allows the creation of these ultra-thin sheets with minuscule holes, just a billionth of a meter wide, capable of blocking salt particles while allowing water molecules to pass through [source: Chandler].