7.1.2. Gravimetric Measurement

We will do total suspended solids in water. So what we are measuring really is Rho 32. We are measuring solids in water, we are not measuring chemical concentration, we are measuring solids concentration in water. So it is like this. You take a water sample. The water sample looks muddy, okay. It looks muddy, then you know that something is there in the water sample, yeah. So, in order to measure the amount of this thing, so what we are actually measuring is m3 by volume of2, this is our measurement.

In this chunk, we start with the concept of Total Suspended Solids (TSS) which refers to the amount of solid materials found in a water sample. TSS does not consider chemical concentrations; it is solely focused on the mass of solid particles. When we analyze a water sample that appears murky, it indicates the presence of suspended solids. The key measurement we aim for is the ratio of mass of these solids (m3) to the volume of water sampled.

Imagine you have a glass of muddy water. The cloudiness you see is due to particles suspended in the water. If you want to know how 'dirty' the water is, you would need to measure how much solid material is in a specific volume of water. This is similar to how a doctor might measure the amount of sugar in your blood to assess your health; you're measuring the 'dirtiness' of the water.

So what is the simplest way to do this? You simply want to measure mass over volume. So what are 2 measurements we need? One is the volume of this water. So, I can take a water sample, I can measure. If this says 1 liter, let us say 1 liter, I can fill up this water to 1 liter and I know that this is 1 liter, right. Let us assume that we know it is 1 liter okay, and then how do I measure the mass that is contained in this 1 liter?

To measure the total suspended solids, we need to perform two key measurements: the volume of the water sample and the mass of the suspended solids. If we take exactly 1 liter of water, we have a definitive volume for our measurement. The next step is to determine the mass of the solids present in that liter of water, which will indicate the concentration of suspended solids in the water sample.

Think about measuring ingredients when baking a cake. If a recipe calls for 1 cup of flour, you fill a measuring cup until it shows exactly 1 cup, just like measuring the 1 liter of water. After that, if you need to measure the sugar, you would weigh it on a kitchen scale. Here, the volume is like the measuring cup, and the measurement of mass for the solids is similar to weighing the sugar accurately to ensure the cake turns out just right.

I need to filter. What am I doing when I am filtering? Separating the solids from the liquids. So I am separating, this is the separation of the solids from the water. I can do it in different ways, okay. The simplest way in which is done is by filtration.

To determine the quantity of suspended solids, we need to separate the solids from the water. The standard method for doing this is filtration, where the water is passed through a filter that traps the solid particles so they can be weighed. The clean water that passes through is called the filtrate, and the particles captured on the filter are referred to as the residue.

Consider making a cup of tea. Once you steep tea leaves in hot water, you use a strainer to remove the leaves. The liquid that passes through the strainer is your tea, which is free of solids. Similarly, in the lab, we’re using filters to remove the suspended solids from the water.

Now, how do I measure the amount of solids here. I have separated it and the solids that are collected on the filter paper, I can I have to measure it. Now, I measure it using weighing balance. I do what is called as a gravimetric measurement. When we say gravimetric measurement, it is mass measurement. We use a physical we use a balance, weighing balance to do it.

Once the solids are separated from the water, the next step is to measure their mass. This is done using a weighing balance, which allows us to perform a gravimetric measurement. Gravimetric measurement refers specifically to measuring mass, and it is crucial in determining the concentration of suspended solids by providing a precise weight for the collected residue on the filter paper.

Think of a farmer weighing harvested fruits on a scale. The farmer puts the fruits on the scale to find out how much they weigh. Just like that, in our lab work, we place the residue collected from filtration on a balance to find out the mass of solids present in the water sample.

If I take a water sample that does not look brown, that not look even like yellow, can I say that there are no suspended solids in it by this method, I mean I cannot say it unless I do this method, okay.

It's important to understand that even if a water sample appears clear, we cannot automatically conclude that it has no suspended solids. The clarity of the water does not guarantee the absence of particles, highlighting the limitations of visual assessment. Only through the gravimetric method can we accurately determine the concentration of solids in the sample.

Imagine looking at a clear glass of water. While it may look pure, there could still be tiny dirt particles that are invisible to the naked eye. This is similar to how some pollutants can exist in clear water but require tests to detect their presence, much like how it’s crucial for doctors to run blood tests even when a patient appears healthy.

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