Wastewater Calculator
Comprehensive activated sludge treatment plant analysis and design calculator
Wastewater Treatment Plant Calculator
Primary Clarifier
Aeration Tank
Secondary Clarifier
SVI Laboratory Test
Wastewater Treatment Results
Key Formulas: F/M = BOD loading ÷ MLVSS weight, HRT = Volume ÷ Flow rate
SVI Formula: SVI = Settled solids (mL/L) ÷ MLSS concentration (g/L)
MCRT: Total MLSS weight ÷ SS leaving system per day
Understanding Wastewater Treatment Parameters
Key Treatment Parameters
F/M Ratio
Food to microorganism ratio. Optimal range: 0.2-0.6
HRT (Hydraulic Retention Time)
Average time wastewater spends in aeration tank
MCRT (Mean Cell Residence Time)
Average time microorganisms stay in the system
SVI (Sludge Volume Index)
Measure of sludge settling characteristics
Treatment Process Stages
Calculation Formulas
BOD Loading:
Metric: BOD (g/L) × Flow (m³/day)
Imperial: BOD (mg/L) × Flow (MGD) × 8.34
F/M Ratio:
BOD Loading ÷ MLVSS Weight
HRT:
Tank Volume ÷ Flow Rate
SVI:
Settled Solids (mL/L) ÷ MLSS (g/L)
Operational Guidelines
Optimal F/M Ratio
0.2-0.6: Good balance of efficiency and cost
SVI Range
100-200 mL/g: Desirable settling characteristics
HRT Considerations
Too low: Incomplete treatment; Too high: Reduced capacity