Usually, when sludge is removed from drains, it is left in heaps next to the drain for 3–4 days. Afterward, it is transported to a garden or a field where it can be used as manure. This approach reduces transportation cost of the sludge and enhances the safety of individuals handling it. Reflect upon it and explain how.
When sludge is left in heaps for 3-4 days, the water present in the sludge evaporates into the air. This evaporation significantly reduces the weight and volume of the sludge.
Since the sludge becomes lighter and less bulky after water evaporation, the transportation cost is reduced because less fuel and fewer trips are needed to transport it.
Additionally, the evaporation process helps dry out the sludge, which reduces the growth of harmful microorganisms that thrive in wet conditions. This makes the sludge safer for individuals who handle it during transportation and application in fields or gardens.
The dried sludge is also easier to spread as manure and decomposes more effectively in the soil.
Explanation
The chapter discusses evaporation throughout, explaining that water evaporates continuously even at room temperature. On page 3, it mentions that 'drying of wet clothes, mopped floor, and sweat on our body are some examples' of evaporation. The same principle applies to sludge—the water content evaporates when left in heaps, reducing weight and volume. This practical application of evaporation helps reduce costs and improve safety.
Solution Steps
Water present in the sludge evaporates into the air when left in heaps for 3-4 days.
This evaporation significantly reduces the weight and volume of the sludge.
Reduced weight and volume lower transportation costs by requiring less fuel and fewer trips.
Drying out the sludge reduces the growth of harmful microorganisms that thrive in wet conditions.
The process makes the sludge safer for individuals handling it during transportation and application.
Dried sludge is easier to spread as manure and decomposes more effectively in the soil.