Influent BOD given Mass of Wasted Activated Sludge Calculator

Influent BOD Formula:

\[ Q_i = \frac{M_{ws} + (K_e \times V \times X')}{Y \times Q_s} + Q_o \]

Mass of Wasted Activated Sludge (M_ws):

Endogenous Respiration Rate Constant (K_e):

1/s

Volume of Tank (V):

m³

Mixed Liquor Suspended Solids (X'):

kg/m³

Maximum Yield Coefficient (Y):

Sewage Discharge (Q_s):

m³/s

Effluent BOD (Q_o):

kg/m³

Influent BOD (Q_i): kg/m³

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

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

Purpose: It helps environmental engineers and wastewater treatment professionals design and monitor activated sludge systems.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ Q_i = \frac{M_{ws} + (K_e \times V \times X')}{Y \times Q_s} + Q_o \]

Where:

\( Q_i \) — Influent BOD (kg/m³)
\( M_{ws} \) — Mass of wasted activated sludge (kg)
\( K_e \) — Endogenous respiration rate constant (1/s)
\( V \) — Volume of tank (m³)
\( X' \) — Mixed liquor suspended solids (kg/m³)
\( Y \) — Maximum yield coefficient
\( Q_s \) — Sewage discharge (m³/s)
\( Q_o \) — Effluent BOD (kg/m³)

Explanation: The formula accounts for biomass production, endogenous respiration, and system flow rates to estimate the incoming BOD load.

3. Importance of Influent BOD Calculation

Details: Accurate influent BOD estimation is crucial for proper system design, aeration requirements, and ensuring regulatory compliance for effluent quality.

4. Using the Calculator

Tips: Enter all required parameters. 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 K_e?
A: The endogenous respiration rate constant typically ranges from 0.04 to 0.06 per day (≈ 4.63×10^-7 to 6.94×10^-7 per second).

Q2: How do I determine the mass of wasted activated sludge?
A: Measure the dry weight of sludge removed from the system over a specific time period.

Q3: What affects the yield coefficient (Y)?
A: Y depends on wastewater characteristics, temperature, and microbial community, typically ranging from 0.4 to 0.8.

Q4: Why include effluent BOD in the calculation?
A: Effluent BOD represents the portion of organic matter that passes through the system untreated.

Q5: How accurate is this calculation?
A: It provides a good estimate but actual values may vary due to system dynamics and varying wastewater characteristics.