Oxygen Required In Aeration Tank Given Oxygen Demand And Ultimate BOD Calculator

Formula Used:

\[ Oxygen Required = \frac{(Sewage Discharge \times (Influent BOD - Effluent BOD))}{\left(\frac{5 Days BOD}{Ultimate BOD}\right)} - (Oxygen Demand of Biomass \times Volume of Wasted Sludge per day \times MLSS in Returned or Wasted Sludge) \]

Sewage Discharge (Qs):

m³/s

Influent BOD (Qi):

kg/m³

Effluent BOD (Q):

kg/m³

5 Days BOD (BOD5):

kg/m³

Ultimate BOD (BODu):

kg/m³

Oxygen Demand of Biomass (DO2):

Volume of Wasted Sludge per day (Qw):

m³/s

MLSS in Returned or Wasted Sludge (XR):

kg/m³

Oxygen Required (Or):

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1. What is Oxygen Required in Aeration Tank?

Oxygen Required is the amount of oxygen needed to sustain biological processes in an aeration tank, which is a critical component of wastewater treatment systems. It ensures proper decomposition of organic matter by microorganisms.

2. How Does the Calculator Work?

The calculator uses the following formula:

\[ Oxygen Required = \frac{(Qs \times (Qi - Q))}{\left(\frac{BOD5}{BODu}\right)} - (DO2 \times Qw \times XR) \]

Where:

\( Qs \) — Sewage Discharge (m³/s)
\( Qi \) — Influent BOD (kg/m³)
\( Q \) — Effluent BOD (kg/m³)
\( BOD5 \) — 5 Days BOD (kg/m³)
\( BODu \) — Ultimate BOD (kg/m³)
\( DO2 \) — Oxygen Demand of Biomass
\( Qw \) — Volume of Wasted Sludge per day (m³/s)
\( XR \) — MLSS in Returned or Wasted Sludge (kg/m³)

Explanation: The equation calculates the net oxygen requirement by considering the oxygen needed for BOD removal minus the oxygen demand from biomass in the wasted sludge.

3. Importance of Oxygen Calculation

Details: Accurate oxygen calculation is crucial for designing efficient aeration systems, ensuring proper treatment efficiency, and optimizing energy consumption in wastewater treatment plants.

4. Using the Calculator

Tips: Enter all values in appropriate units. Sewage discharge and sludge volume should be in m³/s, BOD values in kg/m³, and MLSS in kg/m³. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why is oxygen required in aeration tanks?
A: Oxygen is required to support aerobic microorganisms that break down organic matter in wastewater, converting it into stable end products.

Q2: What is the difference between BOD5 and Ultimate BOD?
A: BOD5 measures oxygen demand over 5 days, while Ultimate BOD represents the total oxygen required for complete decomposition of all organic matter.

Q3: How does MLSS affect oxygen requirements?
A: Higher MLSS concentrations typically require more oxygen to maintain aerobic conditions and support the larger biomass population.

Q4: What factors can affect oxygen transfer efficiency?
A: Temperature, salinity, atmospheric pressure, and aeration system design all impact how efficiently oxygen is transferred to the wastewater.

Q5: How often should oxygen requirements be calculated?
A: Oxygen requirements should be calculated during system design and periodically reassessed as wastewater characteristics or treatment loads change.