16.11 A water treatment plant has a flow of 6 MGD (22.7MLD). The plant has 12 identical rapid granular filters operating at a filtration rate of 2 gpm/ft2 (81.4 L/min/m2) and a backwash rate of 30 in./min (762 mm/min). Compute the required capacity of an elevated water tank needed to backwash two filter units at a time. Assume a backwash time of 5 min per filter

Awall of 0.5m thickness is to be constructed from a material which has average thermal conductivity of 1.4 w/mk. the wall is to be insulated with a material having an average thermal conductivity of 0.35 w/mk so that heat loss per square meter shall not exceed 1450 w. assume inner wall surface temperature of 1200°c and outer surface temperature of the insulation to be 15°c. calculate the thickness of insulation required.