Define loading?

Hint: Loading is related to the sedimentation process. The sedimentation process is when the solid particles present or suspended in a liquid get settled at the bottom due to gravity. This is mainly used to separate impurity from the liquid.

Complete answer: Loading is the process by which the mixture of liquids and liquids containing tiny impurities is separated by adding a chemical that sticks to the impurities and makes them heavier. This is used in sedimentation to speed up that process. The chemical that is used here is known as ‘Alum’.
Loading is used mainly for those mixtures where impurity does not settle properly at the bottom or sometimes they do not settle at all. In loading, the impurities are lighter so alum is added which makes them heavier and then they settle at the bottom, and after they get settled the liquid is removed. E.g. suppose we have a sample in which there is a beaker containing muddy water in it. We need to separate the mud from the water present inside. Now we cannot wait for the entire mud to settle at the bottom quickly as it will not happen completely some particles will still be present. Hence alum will be added to it. Now when alum is added it gets adhered to the small mud particles and makes them heavier thus causing the entire mud to settle at the bottom and therefore we get clear water on top which now can be taken out.

Note:
Sedimentation is not a very accurate process as it does not give ideal results. It is a very time-consuming process and hence processes like loading and decantation are used. Decantation is used when the impurity and the liquid or the mixture of liquids are immiscible. Loading is used during the filtration of water in water filtration tanks.