Enter your wastewater parameters — Influent Flow Rate, BOD Concentration, MLVSS, and Aeration Tank Volume — then select the Parameter to Calculate to get your result alongside BOD Loading, MLVSS Mass, and a plain-language Interpretation.
Calculated Value
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BOD Loading
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MLVSS Mass
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Result Interpretation
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The three stages are: Primary treatment (physical removal of solids), Secondary treatment (biological treatment using activated sludge), and Tertiary treatment (advanced treatment for nutrient removal and disinfection).
BOD can be reduced through biological treatment processes like activated sludge, where microorganisms consume organic matter. Optimizing F/M ratio, maintaining proper aeration, and ensuring adequate retention time are key factors.
SVI (Sludge Volume Index) is calculated as: SVI = (Settled Sludge Volume after 30 min in mL/L) ÷ (MLSS concentration in mg/L) × 1000. Values between 50-150 mL/g indicate good settling characteristics.
MCRT (Mean Cell Residence Time) is the average time microorganisms remain in the activated sludge system. It's calculated as the total biomass in the system divided by the biomass wasted daily, typically ranging from 3-30 days.
The Food to Microorganism (F/M) ratio typically ranges from 0.1-0.5 kg BOD/kg MLVSS/day. Lower ratios (0.1-0.2) favor nitrification and produce better effluent quality, while higher ratios increase treatment capacity.
Hydraulic Retention Time (HRT) is the average time wastewater spends in the aeration tank, calculated as tank volume divided by flow rate. Typical HRT for activated sludge ranges from 4-8 hours.
Poor settling can be caused by filamentous bacteria growth, low F/M ratios, nutrient deficiency, temperature variations, or toxic substances. Monitoring SVI helps identify settling problems early.