Grant Thompson’s Youtube channel has over 11 million subscribers (as of June 2019) and his top video covering ‘Lego Gummy Candy’ has over 33 million views. As ‘The King of Random‘ the channel publishes daily DIY and how-to lessons, and their July 6, 2017 episode titled, “DIY: Make Swamp Water Drinkable” with 5,000,000 views is the number one most viewed video for ‘Filtration’.
The Youtube transcript is below, and by watching the video or reading, we can see that many of the major challenges in filtration are addressed:
1. Physical strength
Water carries a lot of force – the filter media requires sufficient physical and tensile strength. Our narrator, Nate, begins his gradient sand bed filter with gravel to ‘absorb the force of the water’. For anyone working with any kind of liquid filtration, strength of the filter media is important – if there is a single hole, then the fluid will flow through it and not be properly filtered.
2. Gradient – Gradient Design
Nate starts with a fine sand filter at the bottom – supported in place by the woven / nonwoven mesh (he uses a paper towel). He creates a gradient structure backwards, and the water flow encounters in order – gravel, smaller gravel, large sand, carbon, fine carbon and then finally fine sand. Gradient filtration – using different size media (fibrous or particulate) to create a gradient pore structure, allows a filter to have good flow and optimum capacity.
3. Torturous Path
As Nate is producing his gradient he mentions that the, “water will have to travel further, catching more material.” Bingo! The longer and more difficult the path, the more likely small materials will be caught and the filter will also increase in capacity.
4. Settling, Flocculation, Gravity
Nathan starts his experiment by letting the water settle. He scoops big particulate off the top. Several times he admires the material that is left sitting together on top of the sand bed in clumps. The narrator never adds a flocculant to promote clumping and aid filtration, but he does let the material settle and lets gravity do some of the work for the filter.
Three elements are designed with different media layers. As he comes back from his 90 second commercial break, Nate comments on the different rates of completion from each of the elements. Here we’re seeing that the flux – or flow rate – through each of the elements is not consistent.
6. Clarity – NTUs as Measurement
Nate scoops up pond water from his fish tank – and it is pretty dirty. It looks to be over 30 NTUs. While Nephelometric Turbidity Units (“NTUs”) are never mentioned – he frequently discusses the visual clarity (aka turbidity) of the water – the filtrate – which he ultimately drinks.
7. Fibrous Media – Paper Towel
As noted above, Nate’s finest filter layer – or at least the mechanical structure that supports the whole composite – is a paper towel. Everything rests on that material. It is common in filtration to have a fibrous layer as the efficiency layer – or to have some kind of synthetic / man-made material as the finest layer, such as a microporous or cast membrane.
8. Fine Pore Size, Big Surface Area
Nate hypothesizes that the cleanest water comes not from the element with the most carbon, but rather from the one with the most fine powdered carbon. Those fine particulate materials create a big boost in pore size and a big boost in surface area – just like the fine diatomaceous earth (“DE”) used in the final clarification steps when brewing beer and championed by some of the pharma production equipment makers.
9. Element Design is Hard
Nate proceeds with three design concepts – the flux is different, the layers are different, and based on the varying amounts of yellow water – the filtration efficiency is different. Even in a limited setting with a few designs, there is great variability in performance.
10. Dwell Time / Surface Area of the Media
“The finest carbon particles performed the best” – based on Nate’s performance. The longer tortuous path exposes the material to the most surface area. The finer particles give the longest path and have the most surface area.
11. Re-use, Cleaning
Nate describes how the elements can be re-sealed with bottle tops – given that they are made from plastic water bottles that contain the sand bed materials. Cleaning matters – especially for liquid filtration. Figuring out how to clean-in-place and work with other materials is part of getting new media qualified.
Thank goodness he boils the water! There are a lot of ways to treat water – filtration is just one of many.
13. PPE for Fines
This is a general safety issue – the narrator, Nate, is not wearing sufficient personal protective equipment (PPE) for working with small particles, and he intentionally grinds up fine powder carbon! He also doesn’t wear any eye protection – again, this isn’t filtration specific, but it will make anyone in manufacturing cringe.
14. Not LRV
For anyone coming with a bio-pharmaceutical or protein production background with a familiarity with log-retentive values (“LRVs”) for measurement of a filter’s efficiency at a given particle size. For example – a 99.99% efficient element is 4 LRV, add another 9 to get to 99.999% efficient and 5 LRV.
Having used many online advertising platforms it is interesting that the in line advertising roll is for a survival focused video game. It is interesting to see what businesses look to sponsor / advertise against filtration themed videos.
This video is sponsored by Next Games, creator of AMC’s official game The Walking Dead:No Man’s Land. I put a link in the description so you can go download the game for free and it comes with a special offer! I’ll tell you about in a few minutes.
July you’ll unlock the character, Negan go get em Boys!