Alum is used for cleaning water in water tanks. This is called loading.
How does the chemical help? What happens if we do not use it?
Answers
Answer:
One of the first of the several steps that municipal water suppliers use to prepare water for distribution is getting it as clear and as particulate-free as possible. To accomplish this, the water is treated with aluminum sulfate, commonly called alum, which serves as a flocculant. Raw water often holds tiny suspended particles that are very difficult for a filter to catch. Alum causes them to clump together so that they can settle out of the water or be easily trapped by a filter.
Usually a mixture of water with 48 percent filter alum is injected into the raw incoming water at a rate of 18 to 24 parts per million. The alum promotes coagulation of fine particles which helps resolve problems of color as well as turbidity. If the process is given enough time to work and is applied properly, it not only corrects problems in the water but actually results in removing most of the aluminum used in the process.