F:M = (Influent BOD * Q) / (Volume * MLSS) = (0.25 kg/m³ * 10000 m³/day) / (3920 m³ * 3.0 kg/m³) = 0.21 kg BOD/kg MLSS/day (Excellent range: 0.2-0.4). 4. Oxygen Requirements and Aeration Calculating Oxygen Demand (kg O2/day): Fundamentally: Oxygen = Mass of BOD removed - 1.42 * (Waste sludge mass)
| Tab Name | Purpose | | :--- | :--- | | | Raw influent characteristics (BOD, COD, TSS, TKN, Flow) and effluent permit limits. | | Design_Criteria | Key design parameters (SRT, HRT, F/M ratio, temperature, safety factors). | | Primary_Treatment | Screening, grit removal, primary clarifier sizing. | | Secondary_Treatment | Activated sludge basin volume, aeration requirements, return sludge rate. | | Final_Clarifier | Surface overflow rate (SOR), solids loading rate (SLR), weir loading. | | Sludge_Handling | Thickening, digestion, dewatering volume and mass balances. | | Hydraulics | Headloss through each unit, pump sizing. | | Summary_Tables | Equipment schedule, tank dimensions, blower power, chemical dosing. | Part 3: Step-by-Step Design Calculations (with Excel Formulas) Let us walk through the most critical calculations. You can copy these logic structures directly into your "wastewater treatment plant design calculation xls best" template. 1. Preliminary Flow and Loading Calculations Assume an average daily flow (Q_avg) of 10,000 m³/day. Peak factor (PF) often follows the Harmon formula or local standards. wastewater treatment plant design calculation xls best
Cell B1: 10000 (Q) Cell B2: 8 (SRT) Cell B3: 0.6 (Y) Cell B4: (250 - 5)/1000 (Convert mg/L to kg/m³: 0.245) Cell B5: 3.0 (X in kg/m³) Volume (m³) = (B1 B2 B3 B4) / B5 = (10000 8 0.6 0.245) / 3 = 3,920 m³ F:M = (Influent BOD * Q) / (Volume * MLSS) = (0