Effluent BOD given Mass of Wasted Activated Sludge Calculator

Effluent BOD Formula:

\[ Qo = Qi - \frac{Mws + (Ke \times V \times X')}{Y \times Qs} \]

Influent BOD (Qi):

kg/m³

Mass of Wasted Activated Sludge (Mws):

Endogenous Respiration Rate Constant (Ke):

1/s

Volume of Tank (V):

m³

Mixed Liquor Suspended Solids (X'):

kg/m³

Maximum Yield Coefficient (Y):

Sewage Discharge (Qs):

m³/s

Effluent BOD (Qo): kg/m³

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1. What is Effluent BOD given Mass of Wasted Activated Sludge?

Definition: This calculator determines the effluent Biochemical Oxygen Demand (BOD) based on the mass of wasted activated sludge and other wastewater treatment parameters.

Purpose: It helps wastewater treatment professionals estimate the BOD remaining in treated effluent after the activated sludge process.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ Qo = Qi - \frac{Mws + (Ke \times V \times X')}{Y \times Qs} \]

Where:

\( Qo \) — Effluent BOD (kg/m³)
\( Qi \) — Influent BOD (kg/m³)
\( Mws \) — Mass of wasted activated sludge (kg)
\( Ke \) — Endogenous respiration rate constant (1/s)
\( V \) — Volume of tank (m³)
\( X' \) — Mixed liquor suspended solids (kg/m³)
\( Y \) — Maximum yield coefficient
\( Qs \) — Sewage discharge (m³/s)

Explanation: The formula accounts for BOD removal through sludge wasting and endogenous respiration in the activated sludge process.

3. Importance of Effluent BOD Calculation

Details: Accurate effluent BOD estimation is crucial for assessing treatment plant performance and ensuring compliance with environmental discharge regulations.

4. Using the Calculator

Tips: Enter all required parameters with appropriate units. Typical values are provided for some fields, but actual plant data should be used for accurate results.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical value for Ke?
A: The endogenous respiration rate constant typically ranges from 0.02 to 0.05 per day (about 2.31e-7 to 5.79e-7 per second).

Q2: How do I determine the maximum yield coefficient (Y)?
A: Y is typically 0.4-0.8 mg biomass/mg substrate for domestic wastewater, but should be determined experimentally for specific wastewaters.

Q3: What if my effluent BOD calculation is negative?
A: Negative values suggest an error in input parameters, as BOD cannot be negative. Verify all inputs, especially units.

Q4: How does sludge wasting affect effluent BOD?
A: Increased sludge wasting typically improves BOD removal by increasing the mass of microorganisms treating the wastewater.

Q5: What's the relationship between MLSS and effluent quality?
A: Higher mixed liquor suspended solids (X') generally improve treatment efficiency up to a point, beyond which settling problems may occur.