engineering recuitment NHPC JE & THDC JE 2023 Mock Test Environmental Engineering Water Treatment Filtration
The effective size of the sand particles used in the top layer of slow sand filter is in the range of:
1
0.45 to 0.70 mm
2
0.40 to 0.60 mm
3
0.20 to 0.30 mm
4
0.35 to 0.55 mm