UC Berkeley professor invents rapid way to purify drinking water

UC Berkeley scientist Ashok Gadgil has created a cheap, quick and scalable method to cleanse arsenic from drinking water.

The technology, which leverages the natural binding properties of arsenic, would be able to deliver water to about 50,000 people from a plant that fits in a small garage, according to Gadgil, a campus civil and environmental engineering professor.

“I was looking for the next thing to do in my research, addressing the next big water challenge,” Gadgil said. “That’s why I started working on removing arsenic. I kind of cast around to try to figure out something that is robust, effective and still affordable.”

Gadgil and his research group invented the underlying process more than a decade ago — iron is dissolved in the contaminated water to form rust, and arsenic then binds to the rust to form denser, easily removable sediment, according to a 2009 report from Gadgil’s team. The team’s demonstration plant in India, constructed in 2016, still provides safe drinking water to about 8,000 people daily, Gadgil said.

Gadgil and his team have now improved this methodology by developing air cathode assisted iron electrocoagulation, or ACAIE, and Fe(iron)-electro-coagulation with external oxidizer, or FOX, which use other rapid ways to oxidize iron rather than relying on atmospheric oxygen dissolved in water.

This made the oxidation step “ten thousand times faster,” according to Gadgil, and a purification process that would previously have taken three hours now spans 30 seconds.

According to Gadgil, his team recently secured funding to demonstrate a tabletop ACAIE device in California’s Central Valley.

“The next step would be to go through all the required licensing from the state of California’s regulatory bodies, so that local communities in California could use it,” Gadgil said. “The university can license (the technology) to private sector entities that can build these plants.”

After a successful round of groundwater testing last summer in Allensworth, California, researchers are estimating the cost of building a larger-scale demonstration plant in the area. Sara Glade, a campus graduate student who led the trial, noted the economic impact of the prospective plant, as many Californians currently “rely on expensive bottled water.”

Worldwide, more than 200 million people are forced to drink water containing toxic levels of arsenic, according to Gadgil, resulting in “horrific health effects,” including cancer.

Exposure to arsenic in childhood or in utero also causes stunted brain development and increased susceptibility to chronic disease, according to Andres Cardenas, UC Berkeley School of Public Health assistant professor in residence. These impacts are often disproportionately borne by low-income or minority communities, said Sadie Costello, campus School of Public Health assistant researcher and lecturer.

Gadgil said he and his team plan to develop similar techniques for chromium and uranium, contaminants that are likewise prevalent in groundwater. According to Gadgil, the researchers believe they already have a grasp on the chemistry necessary to modify the technology.

“The problem should be solved, that’s the key thing,” Gadgil said. “Currently we have what is best available, anywhere. But if some competition does emerge, I’ll be the first to applaud them, and say ‘all success to you, go solve the problem.’”

Contact Annika Rao at arao@dailycal.org and follow her on Twitter at @annikyr.

SOURCE

Taxonomy

• Arsenic
• Arsenic Mitigation

2 Comments

1. A domestic (costs less than USD.10/ unit) Biosand filter when added in the top layer with metallic chips is upto 95% effective in Arsenic removal for drinking water portability. The same technique can be applied for community level Biosand filters.....thanks 

   1 Comment reply

   1. A domestic (costs less than USD.10/ unit) Biosand filter when added in the top layer with metallic chips is upto 95% effective in Arsenic removal for drinking water portability. The same technique can be applied for community level Biosand filters.....thanks 

      Let me explain the technology in my simple language, Sirs and maams:
      

      Extremely simple to remove heavy metals from water for drinking!

      In similar manner, fluoride removal by use of bio-sand filters with a layer of metallic nails/ chips helps in removal of Arsenic from water (see my TF report to NJJM, India). 

      Magnetic Mufflers

      It is true that like poles repel and unlike poles attract. But it is also true that the north pole of a magnetic compass points towards the geographical north direction of the Earth. This sure does create a confusion but the answer is quite simple.
      Earth behaves like it has a giant magnet within it. This magnet, however, works rather differently. Earth's geographical north pole is actually its magnetic south pole and the geographical south pole is actually its magnetic north pole.
      So, when you ask why the north pole of the compass and the north pole of Earth attract (points in the north direction), it is because the geographical north pole is actually the magnetic south pole. It is already known that unlike charges attract.

      This is why the north pole of a magnetic compass points towards the geographical north (magnetic south).

      So how does the magnetic force work? How does it travel over a distance? Does this magnet somehow know that there is another magnet out over there? How does it know? Is it aware of it's surrounding? What's going on? Well, here's how we like to think about it today. 

      We don't think that the magnets directly push and pull on each other. Instead, we like to say that this magnet, for example, creates some kind of an influence around itself making it's presence felt far away. And it's because of this influence the second magnet gets affected. Just for example, when I entered the house, I immediately got a strong smell of jasmine, So because of that fragrance, I immediately could feel the presence of Jasmine used by someone in the house, from a far away distance. So, what the flowers have done, created some kind of fragrance all around the house, making it's presence felt. And the moment I walked in, my nose came in contact with that fragrance and I automatically experienced a smell. 

      In a similar manner, we could think that this magnet, for example, is creating some kind of magnetic fragrance all around it. And when the second magnet comes in contact with that fragrance, it automatically doesn't experience a smell, but it automatically experiences a force. 

      So this magnetic fragrance, we give a technical name for it. We call it the magnetic field. So this magnet is generating a magnetic field around itself and when the second magnet comes in contact with the field, it's getting pushed by that field. And similarly, even this magnet is generating its own magnetic field, and that field is the one that's pushing and pulling on this magnet. So it's the fields that push and pull on other magnets. 

      However, there is a big difference between magnetic fields and the fragrance created by flowers. You see, what we call as fragrance is basically some molecules which are spread out by the flower which mix into the air and enters into my nostrils and creates a smell, a reason why some people like my wife is allergic to perfumes, deodorants, spices/ masalas (In India) and any such smelly articles presence in the house. 

      But over here the magnets are not spreading out any particles into the air. There are no particles moving anywhere. But still their magnetic field exists. So that makes it a little bit more interesting, a little bit deep. But another question we could ask over here is if there are no real particles that we can detect, then how do we know that this magnetic field is real?  

      Now, Suppose I keep this magnet close to this magnet. And we know that right now this magnet is pushing this magnet away from it. But what do you think would happen if I were to instantly make this magnet disappear? You might expect the force on the magnet to also disappear, right? But careful studies, careful experiments show us that the force does not immediately disappear. It shows us that for a very, very small fraction of a second that force still exists. The force does not instantly disappear, but it lasts for a very small amount of time, same as the smell of Jasmine will disappear from my house, even if i throw these out of my house.

      Similarly over here, this magnet is producing its own magnetic field around it. Now, when we make this magnet disappear, it's field doesn't instantly disappear. It fields last for a very, very small amount of time. Now that time is extremely small, maybe fractions of a nanosecond, something that we may not be able to detect in our experiments, but it doesn't matter. It does exist for a very small time. And it's during that time, this magnet can still feel the presence of the other magnet. So the very fact that the force is still present for a very short time, but it doesn't matter. 

      And the field concept is so incredible that we have now applied them even for other forces over a distance. For example, how do these charges pull and push each other over a distance? Well, we can say that the charges produce an influence around themselves making their presence felt. This influence is called the electric field. It's called the electric field because it only affects electric charges. And similarly, even the force of gravity, say between Earth and the Moon, acts over a distance. How does it work? Well we say both the Earth and the Moon create a gravitational field. And it's the gravitational field that pushes other objects which have masses. Gravitational fields affect masses, electric fields affect electric charges, and magnetic fields affect magnetic materials or magnets. So to summarize, how do magnets push and pull each other over a distance? Well, they don't directly. A magnet will create a magnetic field around it making its presence felt far away. And when any other magnet (the heavy metals in water) comes in contact with that field, it automatically experiences a force. 

      Avinash

2. Interesting, I have seen the use of this technology in the rural areas of Uttar Pradesh India.  Iron nails are used to remove arsenic presence in water. Locally produced filters are very economical.

   Are there any published research ?  

   1 Comment reply

   1. Yes, you can get some info. @ CAWST website and Sehgal foundation website, resp.