PACKAGED WATER PLANTS

Conventional Activated Sludge Wastewater Plant Sizing Calculator

Influent Wastewater Characteristics

Wastewater Flow ($Q$):

Units: Million Gallons per Day (MGD)

Wastewater Temperature ($T$):

Units: Celsius ($^\circ C$) (Affects biological rates)

Influent BOD ($S_o$):

Units: $mg/L$

Influent TSS ($TSS_o$):

Units: $mg/L$ (For reference)

Influent COD ($COD_o$):

Units: $mg/L$ (For reference)

Treated Effluent Requirements

Effluent BOD ($S_e$):

Units: $mg/L$

Effluent TSS ($TSS_e$):

Units: $mg/L$ (For reference)

Effluent COD ($COD_e$):

Units: $mg/L$ (For reference)

Design Parameters

Hydraulic Retention Time ($\theta_{HRT}$):

Units: hours (Typical for conventional activated sludge: $6-24$ hours)

Mean Cell Residence Time (MCRT or $\theta_c$):

Units: days (Typical for conventional activated sludge: $5-20$ days)

Mixed Liquor Suspended Solids (MLSS or $X$):

Units: $mg/L$ (Typical: $2000-4000 \text{ mg/L}$)

Yield Coefficient ($Y$):

Units: $lbs\text{ biomass}/lbs\text{ BOD_removed}$ (Typical: $0.4-0.8$)

Endogenous Decay Rate ($k_d$ at $20^\circ C$):

Units: $day^{-1}$ (Typical: $0.05-0.15$)

RAS Concentration ($X_r$):

Units: $mg/L$ (Typical: $8000-12000 \text{ mg/L}$)

WAS Concentration ($X_u$):

Units: $mg/L$ (Typical: $8000-12000 \text{ mg/L}$)

Tank Depth:

Units: feet (ft) - Used for Aeration, Primary, and Secondary Tanks

Actual Oxygen Transfer Efficiency (AOTE):

Units: % (Percentage, e.g., 6 for 6%)

Aeration Tank Length:Width Ratio:

Units: dimensionless (e.g., 2 for $L=2W$, 1 for square tank)

Primary Clarifier Avg. SOR:

Units: $gpd/ft^2$ (Typical: $800-1200 \text{ gpd/ft}^2$)

Sludge Storage Tank HRT:

Units: hours (Typical: $12-48$ hours)

Secondary Treatment Type:

Secondary Clarifier Membrane Bioreactor (MBR)

Secondary Clarifier Avg. SOR:

Units: $gpd/ft^2$ (Typical: $600-800 \text{ gpd/ft}^2$)

Secondary Clarifier Avg. SLR:

Units: $lbs/day/ft^2$ (Typical: $20-30 \text{ lbs/day/ft}^2$)

MBR Average Design Flux:

Units: $L/m^2/hr$ (LMH) (Typical: $15-25$ LMH)

Calculation Results

Aeration Tank Volume: --

Aeration Tank Volume: --

Aeration Tank Length: --

Aeration Tank Width: --

Primary Clarifier Volume: --

Primary Clarifier Volume: --

Primary Clarifier Diameter: --

Primary Clarifier HRT: --

Secondary Clarifier Volume: --

Secondary Clarifier Volume: --

Secondary Clarifier Diameter: --

Secondary Clarifier HRT: --

MBR Required Membrane Area: --

Sludge Storage Tank Volume: --

Sludge Storage Tank Volume: --

RAS Recirculation Ratio ($Q_r/Q$): --

RAS Recirculation Flow: --

Total Oxygen Required: --

Blower SCFM: --

Sludge Wasting Rate (Solids): --

Sludge Wasting Rate (Volume): --

Food to Microorganism (F/M) Ratio: --

Process Flow Diagram

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