Basking Filter Reimagines Wastewater Treatment With the Mouth of a Shark
Updated: Sep 15, 2020
The kingfisher inspired Japanese bullet trains. Humpback whales inspired the shape of the blades on a wind turbine. The skin of a shark inspired swimsuits responsible for 98% of the medals won at the 2008 Olympic Games.
Nature is often the most intelligent designer, and this time, the gaping mouth of a basking shark is inspiring the design of our water filters.
The big idea: This shark-like filter won’t clog.
Basking Filter, a new filter designed by University of Oregon architecture graduate student Alex Balog and Ben Cooper, a recent MBA graduate, is an anti-clogging skeleton that could make wastewater treatment cheaper, less wasteful and easier to maintain. The team will compete in this year’s Invent Oregon Collegiate Challenge.
“In our type of filtration, the water flows parallel to the filtration device, to the slots. And so this creates additional vortices,” said Alex Balog. “Imagine giant gills in a shark's mouth. The water enters from one side, but it exits from all directions.”
The Basking Filter uses passive fluid dynamics to help filters remove unwanted particulates from water, and it was inspired by basking sharks and other filter feeders that swim with their mouths agape to survive. When they open their mouths, basking sharks reveal what Balog describes as “little fingers” between their gills, which catch plankton as the basking shark swims.
If their mouths weren’t shaped by a very specific geometry, the plankton would get stuck there and the basking shark would suffocate. This special geometry creates special vortices that frees plankton without releasing them, capturing the food they need while expelling water from their gills.
Balog and Cooper have reproduced that special geometry to use the same vortices to trap waste while water escapes all the cleaner. This is different from the traditional method of filtration, which is entrenched in the working model of water passing through a membrane.
Basking Filter doesn’t work that way.
"Think of filtration as your at-home Brita filter,” Balog said. "It's a pretty popular filtration where water enters the filter from one side and flows through in a very direct method.” This kind of filtration requires that water pass through a medium specifically designed to filter unwanted particulates—waste. Water flows through a bag filter or, in the case of Brita, a cartridge, but because particles of waste accumulate in the filter, it requires regular replacement.
“Basically, we have a special skeleton,” Cooper said. "Water flows into it through the helical pattern on the outside. The water spins within the helix. That keeps a lot of whatever you're trying to filter out suspended in the water.”
Basking Filter is different for the main reason that particles remain in water that is continually moving. They are far less likely to accumulate on a filter or membrane. That means the Basking Filter won’t clog as often, it won’t slow as particles build up and it won’t require as much energy to operate.
In the past, these waters and their contents were either discharged into the environment, where nature would just handle the toxicity, or waters were treated with expensive technology that required more regular maintenance.
"These cartridge filters, bag filters have to be replaced regularly,” Cooper said. "Our idea, our main value proposition is that you don't have to replace your membranes often. This thing runs continuously without clogging."
The team envisions their innovation being most readily applicable to wastewater treatment. In rural communities, wastewater treatment can be costly for homeowners who don’t have access to centralized wastewater treatment facilities. “They need new cost-effective solutions for what they already use, which would be more in the realm of septic tanks and anaerobic digesters,” Balog said. “We could get them a cheaper solution."
On an industrial scale, Basking Filter could be a vast improvement in facilities that reuse wastewater in their operations elsewhere. The team at Basking Filter will target the food and beverage industry, where stormwater runoff or water used in operations like washing dishes or clothes, collectively called gray water, could be filtered for reuse in plumbing or irrigation.
Consider that a liter of coffee or a bottle of wine takes almost 1,000 liters of water to produce. With such numbers, anything that can be should be reused.
But there are many other applications, as well. Construction companies are fined heavily for emitting turbid water that runs off construction sites. Basking Filter could remove nitrogen phosphate fertilizers from water that runs off agricultural fields, preventing dangerous algal blooms that decimate aquatic ecosystems.
That’s a big win for the environment, of course, where algal blooms are becoming more frequent, in part thanks to the effects of industrialized agriculture. But it’s a win for industry, too, which will spend less to meet environmental safety standards.
Cooper is a wine industry veteran. "California had issued a stormwater pollution prevention plan law that small, medium sized wineries had to start complying with,” Cooper said. "The winery I worked for also had a horse ranch. So we were kind of a prime target for upcoming stormwater pollution prevention plans.”
As an architect, Balog said Basking Filter solves an industrial design challenge. "They either have to use a lot of land or a lot of energy to clean water,” Balog said. “This might be that happy middle where it doesn't take up a lot of space, but it also can use existing pumps to reduce some of the energy impact."
"It's all about improving water quality without making the water potable again, safe for discharge, without harming existing surface or groundwater,” Cooper said. Making water safe to drink is more tightly regulated by the government.
Biomimetic designs like the Basking Filter imply more than just the improvements they bring to traditional designs. They show us that a better world can be achieved with, not in spite of, the diversity of life found around us.
"There are so many needs for conservation in the world, but often there aren't real ways to quantify what conservation can do for us,” Balog said. "So having these biomimetic examples—how they directly help people and reveal that to people and have them be able to understand those impacts that these systems can have on us—is really important."