The waste sludge production from a trickling-filter plant is 12.5 m^3/d containing 620 kg of solids (70% volatile). The proposed anaerobic digester design to stabilize this waste consists of two floating-cover heated tanks, each with a volume of 480 m^3 when the convers are fully raised and a volume of 310 m^3 with the covers rsting on the landing brackets.
(a) Caluclate the digester volume per equivalent population with the covers fully raised. Assume 100g of solids production per capita.
(b) Calculate the digester loading in terms of kg volatile solids fed/m^3 of tank volume below the landing brackets/day.
(c) Calculate the digested sludge storage time available between lowered and rasied cover positions. Assume a volatile solids reduction of 60% during digestion and a digested-sludge moisture content of 93%.