Focus on physical removal processes through sizing and detention time calculations.

| Parameter | Excel Formula Example | |-----------|------------------------| | Peak factor (Ten States) | =2.5 for small, or =5/Q_avg^0.2 | | Tank diameter (circular) | =SQRT(Area*4/PI()) | | Detention time (hr) | =Vol_m3 / Q_m3hr | | Weir overflow rate | =Q_m3d / weir_length_m | | Air blower power (kW) | =(Air_m3s * Pressure_kPa) / (0.6 * 100) |

A comprehensive WWTP design spreadsheet typically covers these critical stages: How to Calculate Sewage Treatment Plant Capacity - SUSBIO

O₂ = Q × (BOD_in - BOD_out) × 1.0 - 1.42 × P_x + 4.33 × Q × (NH₃-N removed)

Designing a Wastewater Treatment Plant (WWTP) or Sewage Treatment Plant (STP) is a complex engineering task that requires balancing flow rates, pollutant loads, and hydraulic retention times. While specialized simulation software exists, many engineers prefer an Excel-based (.xls/xlsx) calculation approach

Calculate the average daily flow and how long the water needs to remain in a treatment tank. (assumes 85% returns as sewage). HRT: 2. Biological Sizing (Activated Sludge)

| Row | Col A (Parameter) | Col B (Value) | Col C (Unit) | Col D (Source/Formula) | | :-- | :--- | :--- | :--- | :--- | | | INPUTS | | | | | 2 | Average Flow | 5,000 | m³/d | User Input | | 3 | Influent BOD | 250 | mg/L | User Input | | 4 | Influent TKN | 40 | mg/L | User Input | | 5 | Target Effluent NH3 | 1.0 | mg/L | Regulatory Limit | | 6 | Design Temp (Winter) | 10 | °C | User Input | | 7 | COEFFICIENTS | | | | | 8 | $\mu_max$ (20°C) | 0.75 | 1/d | Metcalf & Eddy Table | | 9 | Temp Correction Factor ($\theta$) | 1.07 | - | Metcalf & Eddy Table | | 10 | CALCULATIONS | | | | | 11 | Corrected $\mu_max$ | 0.48 | 1/d | =B8*(B9^(B6-20)) | | 12 | Min SRT Required | 12.5 | days | =1/(B11...) | | 13 | OUTPUTS | | | | | 14 | Design SRT | 15.0 | days | Selected Value (> Min SRT) | | 15 | Reactor Volume | 2,500 | m³ | Calculated via Mass Balance |