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The Human Kidney: Inspiration of and Solution to the Water Crisis

<p>Startup company AguaVia thinks it's found a solution to the world's looming water crisis that offers much more than a drop in the bucket.</p>

Water is a critical resource used by all businesses. Even if your business is not directly water intensive, many products use a great deal of water. Electricity, computers, paper and packaging all have a large water footprint.

Whether flowing into or out of your operations, water can be a cost center and a source of risk, and water stress is looming as one of the big challenges facing the business world in the coming years.

Given the potential size of the business opportunity, it's no surprise that companies are focused on building a better water filter.

Gayle Pergamit, founder of AguaVia, "used the human body as the basis for solving the water crisis," and in doing so is building off a technology that was first engineered by nature 3.5 billion years ago: the human kidney, which filters between 40 to 50 gallons (150 -- 200 liters) of water each day with only a small percentage lost when filtering.

AguaVia created a filter that mimics nature's filtration systems to eliminate 100 percent of the contaminants with no gunky build-up. It is built using nanotechnology to produce a membrane that is one atomic layer thick.

The innovative filter technology is significantly smaller, cheaper and easier to operate. It can be used to purify water, clean up toxic wastewater and desalinate water from the ocean. The energy required for desalination using AguaVia filtering technology is estimated to be cut by two-thirds and overall costs by half.

Pergamit presented her company's disruptive technology at a recent Sustainable Silicon Valley event, and then met with me to provide more details. Before we dive into how Pergamit and her team developed this new technology, let's review the scope of the problem and the state of current filtering technology.

The Water Problem: Invisible to Many

In the developed world most of us are sheltered from water issues. We may be asked to reduce irrigation of our gardens during a particularly dry summer. We may read a news report about contamination of ground water. Or hear about pharmaceutical and recreational drugs entering the water supply from millions flushing drugs down the toilet.

But on the frontlines of water management, the water engineers are having a difficult time satisfying demand for clean water.

As we know, water is inextricably linked to agriculture and consumes nearly 40 percent of the fresh water used in the U.S. But less well known is that energy production requires huge amounts of water. According to the most recent U.S. Geological Survey, almost 40 percent of the fresh water used in the U.S. is used in the production of energy.

Transporting water to where it is needed is also an energy hog. In California, nearly 20 percent of the total state's electricity is consumed to transport water. Given the need to transport water, California also has a large number of desalination plants to provide water closer to where it is needed.

But making fresh water is an expensive option given the huge amount of energy required. The journal Nature reports that desalination costs 3.5 times more than getting water from traditional sources such as pumping from an aquifer.

Supply of clean water is declining as underground aquifers are being tapped for water and seasonal rainfall is unable to replenish. A United Nations assessment found that more than a third of the world's population is living in water-stressed regions, with projections that this will grow to over 50 percent by 2025.

Willen Buiter of Citigroup stated in an article for the Financial Times that "Water ... will eventually become the single most important physical commodity… dwarfing oil, copper, agricultural commodities and precious metals."

Some businesses are already experiencing significant challenges. PepsiCo and Coca-Cola encountered hostility from local communities in the parched region of Kerala in India when their bottling facilities were accused of using too much local water.

Clean-up of waste water is becoming increasingly important in more lax regions. As reported by Reuters, China's Ministry of Environment Protection found that nearly 50 percent of China's surface water is so polluted that it is unfit for drinking. Almost 25 percent is unfit for industrial use.

These sorts of issues are likely to grow; causing disruptions and escalating costs for business.

Conventional Water-Filtering Technology vs. Nature's Approach

The standard filtering approach is to determine what must be removed and then apply the most cost-effective methods. This sounds straightforward, but there are many challenges, ranging from widely differing size of contaminants, the energy needed to push water through nano-scale filters, cost to maintain, and difficulty in implementing.

To overcome the many challenges, an ideal water filter would offer the following performance improvements:

figure 1

Pergamit looked at the water problem differently, and found inspiration in how the kidney functions. The kidney is considered the "gold standard" of biological filters. As Pergamit explained, "The kidney keeps the good stuff -- water and electrolytes -- and gets rid of everything else."

A kidney-like filter handles the ever-changing components in the water supply without additional remediation methods. This is a paradigm shift from current water management strategy that focuses on removing contaminants. Pergamit instead asks, "What do you want to keep?"

Pergamit also noticed that the kidney is not backwashed to remove waste. The kidney uses "cross-flow" filtration. As the feed enters the kidney, the "bad stuff" goes forward to be washed away, while the "good stuff" travels tangentially across the surface of the kidney and is maintained.

Pergamit realized that it would be too complex to directly copy the kidney. Instead the team would use the kidney's overall approach. Pergamit explained, "The system would be designed for 99.5 percent water recovery. Just like the human kidney."

Keeping most of the water reduces filtration costs but also makes disposal of filtration waste simpler. The waste will be so concentrated that the small amount of water remaining may be evaporated. Any contaminants may then be safely incinerated.

The Smart Membrane

Pergamit and team looked again to nature to find a simpler structure to filter water. They were able to use the scientific work of Dr. Peter Agre, who won a Nobel Prize for his efforts. As a graduate student, Agre was funded by a National Institute of Health grant that led to his serendipitous discovery of the body's aquaporin, or "water pore."

The aquaporin that Agre identified is much more than a single example. It turns out to be a basic component of both animals and plants that has been in existence for billions of years. It is used to efficiently move water through cells.

Rather than try to replicate the full aquaporin, Pergamit's team focused on the neck that performs the selection and water channeling functions.

The next step was to transform nature's design to a working membrane. The AguaVia team created a membrane that was one atomic layer thick and the diameter in the range of a water molecule. This is thousands of times smaller than conventional filter pores. Pergamit compared the sizes as follows: "If the new smart membrane was the size of an ant, then existing microscopic technology is the size of a whale."

Pegamit described that "AguaVia's approach is to build at the atomic level which allows precision filtration. Each of the millions of pores that will go into a membrane [filter] is constructed individually with complete precision. Then individual pores -- think of them like 'lego blocks' -- align and snap into place to form the membrane."

Pergamit and team did nature one better when developing their aquaporin inspired membrane. They made it "smart." It is programmable to handle different purification scenarios. The "smart membrane" may be modified at the atomic level to change its characteristics such that it creates an on/off switch to allow or prevent components through the filter as needed.

The "smart membrane" has already been programmed to produce high purity drinking water even from toxic waste.

In the future it could be programmed for water softening. Hard water over time will deposit minerals. This build-up in pipes causes pipes to narrow and increases the amount of energy required to pump water. In some cases the extra energy is 25 percent more compared to clean pipes. The "smart membrane" would be programmed to maintain the right balance and quantity of minerals for health requirements. Everything else, including the excessive minerals that cause "hard water" issues, would be removed.

Finally, the biofilm issues that foul conventional filters are resolved. The "smart membrane" surface is so smooth that any imperfections on the membrane are smaller than the hooks of the bacteria trying to establish a biofilm colony. With no fouling and no back-washing, the "smart membrane," in Pergamit's words, is "filter and forget."

What's Next

AguaVia's "smart membrane" is able to filter for contaminants at very low energy and operating costs. It meets the design criteria of an ideal filter.

Pergamit is now actively pursuing funding to develop equipment to manufacture a commercial "smart membrane" filter. Other entrants in the field are also actively working on new water technologies.

When these come on-line, they will be game changing for business and life changing for billions without access to clean water and sanitation.

Replacing expensive and harsh industrial processes, nature's gentle yet highly efficient filtering methods may achieve some potentially game-changing successes: Treat wastewater so it can be used endlessly, make brackish and salt water readily usable, eliminate the conflict between industrial and human needs, and, finally, allow all of us to enjoy a drink of clean water in good health.

Water photo via Shutterstock.

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