2000 m3/d flow from a dairy industry is treated in an activated sludge plant. The BOD5 is 300 mg/L, and most of it is in soluble form. Calculate (a) the volume of aeration basin, (b) aeration period, (c) return sludge, (d) volume of waste activated sludge at sp. gr. of 1.025, food-to-MO ratio, and oxygen requirement. Use the following data:

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.