g 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: