1.6. Filtration and Total Suspended Solids (TSS)

So, I want to sidestep a little bit here and talk about filtration a little bit. So, we have discussed something called total suspended solids. I think we have not discussed it in detail. So, is it a good base to do this now, when you say total suspended solids it is we are taking a water sample and filtering it through a filter paper and all the solids are trapped on here and you get water and the mass of filter that is collected here divided by the volume of water will give you TSS.

Total Suspended Solids (TSS) refers to the solids that are suspended in water. When we take a water sample and pass it through filter paper, the solids are retained on the paper, while the clean water flows through. The amount of solids collected on the filter paper is then measured, and we calculate TSS by dividing the mass of these solids by the volume of water filtered. This gives a quantitative measure of the concentration of suspended particles in the water.

Imagine you are brewing a cup of coffee. The coffee grounds represent the TSS. When you pour hot water over the coffee grounds, the liquid that comes out is similar to filtered water, while the coffee grounds left behind are like the suspended solids that TSS measures.

There is one piece of information that is needed here is, what is the filter paper that we use? ... So, ideally what would I want to use if I have filter papers available for 0.1 pore size. Can I use 0.1 pore size?

The choice of filter paper is crucial in measuring TSS. Filter paper comes in different pore sizes, each capable of filtering particles of different sizes. While a smaller pore size might seem ideal because it could catch more particles, it can also slow down the filtration process and require more pressure to push the water through. For practical purposes, a filter paper with a pore size of around 1 micron is commonly used for TSS analysis, as it balances effective filtration and efficient water flow.

Think of using a kitchen sieve. If you use a very fine sieve (like a 0.1 micron filter), it takes longer to separate the liquid from food particles compared to a bigger-holed sieve. If you're just straining pasta, a larger sieve works better and faster, catching enough particles without taking too long. Similarly, for TSS analysis, a 1 micron filter is often preferred.

So you have to put some negative pressure here, so you have to apply a vacuum to do this. ... So, between 1 and 0.7 micron if there is this much difference, I would rather use a 1 micron filter.

During the filtration process, especially with smaller pore sizes, the clogging of the filter becomes a significant issue. Applying a vacuum helps to pull the water through the filter more efficiently, but using very fine filters can lead to overly long filtration times and potential clogging. This is why 1 micron filters are often the standard—they provide efficiency in filtration while still capturing most of the suspended particles without excessive clogging.

Imagine using a straw in a smoothie. If the straw is too thin, it might get clogged with chunks of fruit, making it hard to drink. Whereas a thicker straw allows for a smooth flow, letting you enjoy your drink without obstruction. Similarly, a 1 micron filter strikes the right balance between capturing solids and allowing water to pass through efficiently.

Now, it does not mean that the water that is filtered through 1 micron does may contain collides which have organic and for that you have to measure the TOC and then correct that value.

Measuring TSS is important because it provides insight into the water quality. However, even after filtering, there might still be some dissolved organic carbon (TOC) in the water. To get a complete understanding of the water's quality, one needs to measure TOC as well and correct the TSS value based on that measurement. This ensures a more accurate representation of the pollutants present in water.

Consider checking the cleanliness of a swimming pool. Just because the surface looks clear does not mean there aren’t dissolved impurities. To truly assess the pool's cleanliness, one needs to test for both visible debris (like leaves or dirt) and dissolved contaminants (like chlorine levels). This is akin to measuring both TSS and TOC to properly evaluate water quality.

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