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6/30/2025
WT Staff
 Got water questions? Give us a call at 877-52-WATER (877-529-2837), or email us at info@wtny.us
June 30, 2025 638 pm EDT
Interview with the Grandfilter
Inventor of inventors, Dr. Evan Koslow mastered nuclear, biological, chemical defense filtration before delivering third generation countertop drinking water filtration
(edited for length and clarity)
WT: Welcome Dr. Koslow, thank you for being here. Before we get into your latest drinking water filter technology, tell us a bit about yourself.
Dr. Evan Koslow: I've been in the filtration industry for about 45 years, in consumer potable water industry for 35 of those. I'm a general purpose inventor, I can invent pretty much anything anywhere, it's kind of a weird capability. I have about a hundred patents, maybe a little bit under.
WT: What is your formal education path?
Koslow: I have an engineering degree from Yale. I was not really enjoying graduate studies in engineering, so when I got a call from Yale Forestry, the oldest forestry school in America looking for a scientist, I responded. A professor there who knew me quite well asked me to come in and lead certain programs in Forestry. They had funding, so I went for my Master's degree. After Yale, I went to Cornell and got a PhD in Agricultural Engineering.
WT: At what point did you start inventing?
Koslow: When I was at Yale, myself and another student spent a couple years inventing a method of inventing. He went on to Caltech, eventually became a very famous inventor, one of the people whose work led to the invention of 3-D printing. If you look at my patents, they are all over the place. I did chemicals for a period of time, chemical engineeering, materials technology. Making a water filter is actually quite complicated, there is a lot of chemistry and chemical engineering materials technology, a lot of physics, so on and so forth.
WT: You don't strike me as the employee type. Did you always invent, work for yourself?
Koslow: I was an employee once in my life. I was hired pretty much out of graduate school by a famous filtration company called Pall Corporation. I was there for some years, initially supporting the Land and Marine division with filters for armored fighting vehicles and trucks. From there, I moved into Aerospace, developed filters for fighter jets and cruise missiles, things like that. I have a really weird background, a lot of physics education. Pall asked who could go over to the Nuclear, Biological and Chemical (NBC) division, if anybody had experience in that area.
I have a nuclear background, if you go way back to the 1970s, you'll see I have a whole pile of papers written on nuclear research. So I raised my hand and spoke up for it. I built filters for the US Army to protect soldiers, armored vehicles, underground shelters. Eventually I was promoted to Chief Technical Officer of the NBC division. I became quite fond of that field.
I moved on from Pall to start a defense company with permission from the United States government to work with the People's Liberation Army of China (PLA), building their business in NBC defense. I obtained the export rights, and for about a decade I ran exports of NBC defense equipment for China. I helped the PLA modernize their industry and get out from Soviet support, which they didn't want anymore. That venture was sold to a British defense company, after which I moved on to a joint venture KX, with Exxon's multi-billion dollar Chemical division.
My first challenge was to develop a very sophisticated chemical separation system, the IMF - Isomobility Focus Machine. When we completed that work, Exxon offered to back me on any venture I wanted to pursue next. They were the largest company in the world in those days, and I was a private inventor. So I said, "Okay, I'll be back in 30 days."
I returned thirty days later, snapped down some bottles of small pellets on the table and said, "We're gonna make THAT." Effectively what I ended up doing that day was dragging them into the business of making consumer water filters.
We developed a media called Bonded Activated Carbon in the form of a porous carbon block. Something close to 90% of all water filters used in consumer products today are this carbon-block. It serves as both a chemical absorber as well as a particulate interception device, a filter that gives exceedingly high performance. We invented that in 1988-89, basically commodotized that industry. We made it a big business at retail, a multi-billion dollar business.
WT: How did your latest water filter technology come about?
Koslow: Over the years I went into a number of other fields before developing this new water filter. I made a really slick technology which involved the production of a very inexpensive nanofiber and a complex composite. It's a mouthful: electrokinetic nanofiber composite. We use long nanofibers to mechanically entrap, wrap around the particulate absorbent material which can be very small, just four or five microns.
The performance is huge, much better even than carbon-block. The result, you can miniaturize the filters. These are much smaller filters that are still performing magnificently. They flow like crazy and they are not expensive, attractive in every way for the consumer.
WT: Your new technology is certified by National Sanitation Foundation (NSF) to reduce PFAS (per-and polyfluoroalkinated substances) in drinking water?
Koslow: Yes. The latest NSF protocol, standard 53 has seven PFAS, some of which your readers are probably well familiar with, PFOA, and PFOS, but they also go to the low molecular weight PFAS, to those with and without a charge, to really check performance of the filter against the full spectrum of PFAS. In addition, the influent for this testing protocol is high volume, as most PFAS contamination is found in groundwater. The high volume influent stream has to be reduced for all seven chemicals down to below 20 parts per trillion, total. We meet that. Most testing in the past used the old protocol, a low influent volume with a higher contaminant level allowed, 70 parts per trillion, not 20; it was much easier to pass.
Our new filter technology is about 600% better than carbon-block. The carbon block 10" standard filter has about a 300 gallon capability against PFAS. The new nanotechnology filter would be 2200 gallons, so it's really a very substantial improvement. The nanofiber is made at my company from natural cellulose, and the fibers get down to around 30 to 40 nm all the way up to half a micron, 500 nm. The point is they can be very small. The nanofibers trap the particulate absorbent, the activated carbon, the metals absorbent. The nanofiber wraps around each of these particles and holds it, like the binder system in a carbon block. The binder system in a carbon block destroys some of the binding ability, about 20 to 30% loss. In a nanofiber composite, you don't have that loss. Everything is up on deck. The absorbent has not been flooded with a liquid resin to hold the whole thing together. So the result is, you get superior performance and the particles that can be put into a nanofiber material are about ten times smaller than what can be put into a carbon-block.
With the new technology, the kinetics of absorption are intense. I'll give you an example. In the municipal water treatment plant, the contact time between the activated carbon and the water can be somewhere in the range of ten to twenty minutes. In the new generation filter, the residency time for water in the filter is very, very short. Contact time is as low as three seconds. The reason for that is what are called absorption intensified structures , giving enormously fast kinetics of absorption. Every three to seven seconds, which is the range that we usually work in, you get quantitative reduction of the contaminants and a long life of the filter. So not only do you capture the contaminants within a structure like a piece of paper, just one to two mm thick, the bed depth is tiny but it also has a long life. This filter runs effectively with every imaginable claim on reduction, removing VOCs, TTHM's, all the 401's pharmaceutical products, the herbicides, pesticides and industrial chemicals. It removes all your PFAS chemicals, it removes microplastics and pretty much everything else, lead and mercury. So you get about 80 certified NSF claims on the technology.
WT: Is this technology at scale for municipal use?
Koslow: It's in a municipal plant, yes. We do have a program with a large water utility. They are using our filters in a test to remove PFAS as there has so far not been an efficient system to remove PFAS in municipal wells. The testing is underway now, but I'm not allowed to discuss it.
Introducing this additional filtration unit in a drinking water facility with a million gallon per day volume works because the machine is quite small. The contact time required to capture the PFAS is just seconds, rather than the destruction machines which take minutes, or longer. We can capture the PFAS, all the chemicals, the result is a very efficient pre-concentration. Periodically, usually once a day, the filter unloads the trapped PFAS, concentrates it by a factor of about 5000. So you go from a million gallons per day down to something like 1000 gallons. You could take all day to run that 1000 gallons through a destruction device at a low, low flow. It's really easy to destroy PFAS, anybody can do it.
WT: Is the PFAS molecule truly destroyed or has it just been changed into a shorter chain PFAS?
Koslow: If you have Teflon or compounds which are perfluorinated but inert, once you get it down to a really very simple molecule, it's no longer soluble in water, and therefore it's really destroyed. I am not doing the destruction part, I'm only doing the pre-concentration. The destruction is either electrochemical or it could be UV. Once the volume is reduced 5000-fold, you can sit on that with a UV reactor for half an hour and just destroy it. There are a number of technologies that can handle a very small volume waste stream.
Right now, our Fusion Filtration division works on filters that are used by households mostly, either point of use or point of entry. What it does is polish the potable water of pretty much everything. The only thing it doesn't do is the reverse osmosis, it doesn't remove minerals or salt. It removes VOCs, pretty much all organics and you know all the higher organics under the NSF 401's, which are larger molecules. So you get everything out, the particulate, the organic molecules, inorganic molecules, lead and mercury, all gone. The beauty about our device is unlike the old carbon block, which we invented, this is much more effective per unit volume and for unit cost.
WT: This was a question we put to the NSF, now that there are household filters certified for PFAS reduction, how are householders advised to handle the used filter, is it a hazardous material?
Koslow: So they basically throw it in the municipal waste and hopefully it is incinerated there. Most people will not do any special handling for a household filter. I'm being very practical and telling you, they won't. We are protecting the human with this filter. The PFAS will not degrade in a reasonable amount of time, but it is going to stay trapped in the filter.
WT: Can you speak of the scope of your distribution?
Koslow: When I owned KX we had a broad range of distributors, we were selling millions and millions of filters. Now we are a very well established organization. Large brands are switching to our material, replacing one technology with a better technology. Weirdly, it's the same customers I sold carbon-block years ago, now I'm selling them something new. The advantage is, everybody wants to be able to remove PFAS, and carbon-block is lousy at that. So the result is, our material will be chosen to meet the latest standards, including microplastics. Basically NSF wants you to have a half-micron filter to intercept microplastic, and half-micron is really tough to get in carbon-block. The pressure drop across such a filter would be exceedingly high, whereas in our new filters, it is not. So we can take out microplastic in a filter as thin as a piece of paper.
WT: Would you refer to this as a second generation filter?
Koslow: This is third generation. The first generation was dominated by what we call Granular Activated Carbon, all through the 1960's, 70's and 80's. Carbon-block took over in the nineties, that would be the second generation. The 3rd generation is the nanofiber composite.
See Fusion Filtration, here.
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