Effluent Flow Rate given Wasting Rate from Return Line Calculator

Effluent Flow Rate Formula:

\[ Q_e = \frac{V \times X}{\theta_c \times X_e} - \frac{Q_w' \times X_r}{X_e} \]

Reactor Volume (V):

m³

MLSS (X):

kg/m³

Mean Cell Residence Time (θc):

seconds

Solid Concentration in Effluent (Xe):

kg/m³

WAS Pumping Rate from Return Line (Qw'):

m³/s

Sludge Concentration in Return Line (Xr):

kg/m³

Effluent Flow Rate (Qe):

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1. What is Effluent Flow Rate?

Definition: Effluent Flow Rate is the total quantity of the flow of sewage from the secondary clarifier in a wastewater treatment system.

Purpose: This calculation helps wastewater treatment plant operators determine the proper flow rates for system balance and regulatory compliance.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ Q_e = \frac{V \times X}{\theta_c \times X_e} - \frac{Q_w' \times X_r}{X_e} \]

Where:

\( Q_e \) — Effluent Flow Rate (m³/s)
\( V \) — Reactor Volume (m³)
\( X \) — MLSS concentration (kg/m³)
\( \theta_c \) — Mean Cell Residence Time (seconds)
\( X_e \) — Solid Concentration in Effluent (kg/m³)
\( Q_w' \) — WAS Pumping Rate from Return Line (m³/s)
\( X_r \) — Sludge Concentration in Return Line (kg/m³)

Explanation: The formula calculates the effluent flow by considering the mass balance of solids in the activated sludge system.

3. Importance of Effluent Flow Rate Calculation

Details: Accurate calculation ensures proper treatment process control, meets discharge permit requirements, and maintains system equilibrium.

4. Using the Calculator

Tips: Enter all required parameters in their respective units. Ensure Mean Cell Residence Time is in seconds for accurate calculations.

5. Frequently Asked Questions (FAQ)

Q1: What is MLSS?
A: Mixed Liquor Suspended Solids (MLSS) is the concentration of suspended solids in the aeration tank of an activated sludge system.

Q2: Why is Mean Cell Residence Time important?
A: It determines how long microorganisms stay in the system, affecting treatment efficiency and sludge characteristics.

Q3: What if my WAS pumping rate is zero?
A: The second term becomes zero, and the calculation simplifies to just the first term of the equation.

Q4: How do I convert days to seconds for MCRT?
A: Multiply days by 86400 (24 hours × 60 minutes × 60 seconds).

Q5: What's a typical MLSS range?
A: Typically 1500-4000 mg/L (1.5-4.0 kg/m³) for conventional activated sludge systems.