Design of CSTR with Biomass Recycle - Wastewater Treatment | CVEN 5534, Study notes of Civil Engineering

Download Design of CSTR with Biomass Recycle - Wastewater Treatment | CVEN 5534 and more Study notes Civil Engineering in PDF only on Docsity! EXAMPLE: DESIGN OF CSTR WITH BIOMASS RECYCLE Oxygen supply is an important constraint for process design. Oxygen transfer through conventional aeration devices is limited, with 1,000 g-O2/m 3 -d to be assumed to be a maximum rate of oxygen supply Aeration via compressed air supplied by mechanical blowers (bubble) or turbines is costly – especially in terms of energy consumption Purpose of this example: develop a CSTR-biomass recycle process to minimize plant size while maintaining oxygen requirement < 1,000 g-O2/m 3 -d. Given SSO = 250 g/m 3 COD SS ≤ 10 g/m 3 COD (discharge permit) SNHO = 40 g/m 3 NH4-N SNH ≤ 0.5 g/m 3 NH4-N Kinetic and stoichiometric data, 1 A 1 H d1ˆ d4ˆ KS = 25 g/m 3 COD KNH = 3 g/m 3 NH4-N b = 0.05 d -1 for both heterotrophs and nitrifiers YH = 0.64 g-heterotrophic cell COD/g-substrate COD YA = 0.12 g- autotrophic cell COD/g- NH4-N fD = 0.2 g-debris COD/g-biomass COD decayed iNXB = iNXD = 0.09 g- NH4-N/g-cell COD )SK( S ˆ )SK( S ˆ NHNH NH AA SS S HH assume XBA << XBH and nitrogen synthesis requirement to autotrophs can be neglected