Hey Folks,
This week we talked about different sponge-y innovations, ancient Mayan filtration methods, and some methods to mitigate rain induced flooding.
Disclaimer - the views expressed herein are ours and ours alone.
To kick things off, we talk about something called the Marangoni effect. Enough has been written about filtration membranes being made nanoporous and more durable all to avoid (to the extent possible) fouling and scaling. Researchers say that the Marangoni effect may hold the key to easy desalination. Why? - Well, this study by a joint team between MIT, USA and Politecnico di Torino, Italy have devised a solar desalination setup that will spontaneously remove accumulated salt!, and no salt accumulation = no fouling of membranes. Their designed prototype can supply more than 15 liters of water per day, and the salt removal process is up to 100 times faster than predictions based on spontaneous diffusion.
To arrive at this remarkable crossroads, the team thoroughly studied the mechanisms underpinning the transport of salt particles in desalination devices and identified the Marangoni effect as the principle to exploit to avoid any salt accumulation. What is it? - Named after Italian physicist Carlo Marangoni, it uses the fact that a liquid with high concentration pulls more strongly on the surrounding liquid than one with low concentration, hence the presence of a gradient in concentration will naturally cause the liquid to flow away from regions of low concentration generating a re-mixing of solutions with different concentrations. Thus, using solutions of seawater at different concentrations, the Marangoni effect enables them to avoid the accumulation of salt and all the subsequent benefits that brings.
Sponge based on cat litter for PFAS
A research team at KU Leuven in Belgium have developed a mineral based sponge to extract PFAS from water. For the new readers, per- and poly-fluoroalkyl substances (PFAS) are dumped into the environment and water bodies because they are used in everyday goods, such as non-stick pans, fire extinguisher foams, food packaging, and waterproof clothing. They are extremely hard to detect and harder still to remove.
Drawing on how zeolite works in cat litter, the team developed a sponge using zeolite, a porous substance with tiny cavities. This material in powder form attracts PFAS molecules and traps them in its pores. Due to the selective nature of zeolite, harmful PFAS substances are filtered, but other innocuous components in the water are not. Above is a visual representation of the zeolite filter, where we can see that the material's pores have an ideal shape and size to catch PFAS particles.
Fabric sponge pulling water from air
Staying with sponges being developed in Europe, Sponsh a start-up out of TU Eindhoven in the Netherlands has developed a temperature-sensitive smart textile. At night, when temperatures are low, the material is super-hydrophilic. This means the material attracts water and absorbs water from the air. The fibres swell up to 4 times their size. During the day, when temperatures are high, the material turns super-hydrophobic. This means the material repels the water. The fibres contract and squeeze-out the water like a sponge. Watch the below video from 0:46 to see how it works.
They are now working on converting the tested prototypes into a marketable product that can be sold ‘on the roll’, and will begin validating the product in real-life conditions in Southern Europe early next year.
Biochar to sponge-up water and hold on to it longer
Rather than extracting water, this find from the good people at Rice University in Texas is that biochar (charcoal produced through pyrolysis, the high-temperature decomposition of biomass, including straw, wood, shells, grass and other materials), while very good for carbon sequestration use cases can be used to hold water as well. Their research shows that there are significant irrigation cost savings from increased water-holding capacity (WHC) of biochar amended into the agricultural soil. In one comprehensively studied plot of sandy soil, they calculated a specific water savings of 37.9% for soil amended with biochar.
They go on to say that regions of the country with sandy soils would see the most benefit, and thus the most potential irrigation savings with biochar amendment would be areas primarily in the southeast, far north, northeast and western United States (which sounds an awful lot like everything but the Midwest!). In the best-case scenario for some regions, extensive use of biochar could save farmers a little more than 50% of the water they now use to grow crops. Not bad at all.
Magnets + IoT = 40% savings in irrigation water
Students of the Sona College of Technology in Salem, India have developed a magnetisation-based and IoT-powered water treatment technology that can reduce the quantity of water used for growing crops and naturally decrease farmers' woes. How? - Most agri land is irrigated by borewells, which unfortunately are hard water sources. Hard water has a high mineral composition and is not as useful for crop growth. By introducing Permag Neodymium (N406), a rare-earth permanent magnet, these students altered the mineral composition in the water.
In a field test conducted on farmland, the students divided the field into two equal parts, one part for untreated water while the other one was irrigated with magnetised water. The water requirement calculated was 2,500 litres in the former to 1,500 litres in the latter, with the savings of 40% showing the benefits of water magnetisation. Where does the IoT come in? - Automation. With IoT sensors, farmers will be able to monitor soil quality, the amount of water and NKP (Nitrogen, Potassium, Phosphorous) quotient of the soil needed to irrigate the field, which in turn will inform the number of times the water should be magnetised, the intensity of the magnet used and so on. Kudos to these final year undergrad students!
In other news
Less Disinfectant is More - A new study at the University of Sheffield has shown that overusing chemicals to disinfect water is actually bad for us. The researchers found that using a lower chlorine residual in water is beneficial in supporting the growth of biofilms that have less of an impact on water quality compared to those grown under a higher chlorine residual. Residual being the disinfectant used to protect drinking water from the regrowth of microorganisms in the water column.
Ancients Mayans knew their modern water filtration! - The University of Cincinnati has discovered evidence of a filter system at the Corriental reservoir, an important source of drinking water for the ancient Maya in what is now northern Guatemala. This filter used crystalline quartz and zeolite which ironically are used in modern water filtration. They had it all figured out 2,000 years ago!
Flood Mitigation methods - With the rain coming down across the world we came upon this interesting article from interestingengineering.com, about a bunch of innovative ways to mitigate flooding. They talk about everything from rapid response gates (like those being deployed in Venice) to LIDAR and personal property protectors. The 36 year old system on the Thames in London caught our eye for its steampunk-esque shape. Enjoy the article!
That’s all folks! Stay warm, hydrated and keep that mask on! Also if you like what you read, share it with your friends!
Ta!