Influent BOD Given Ultimate BOD Calculator

Formula Used:

\[ Qi = Qub + \frac{\left(\frac{BOD5}{BODu}\right) \times \left(O2 + (1.42 \times Qw \times XR)\right)}{Qs} \]

Effluent BOD Given Ultimate BOD (Qub):

kg/m³

5 Days BOD (BOD5):

kg/m³

Ultimate BOD (BODu):

kg/m³

Theoretical Oxygen Requirement (O2):

kg/s

Volume of Wasted Sludge per Day (Qw):

m³/s

MLSS in Returned or Wasted Sludge (XR):

kg/m³

Sewage Discharge (Qs):

m³/s

Influent BOD (Qi):

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1. What is Influent BOD Given Ultimate BOD?

Influent BOD given Ultimate BOD represents the total biochemical oxygen demand present in incoming sewage, calculated using the relationship between 5-day BOD, ultimate BOD, and other wastewater treatment parameters.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ Qi = Qub + \frac{\left(\frac{BOD5}{BODu}\right) \times \left(O2 + (1.42 \times Qw \times XR)\right)}{Qs} \]

Where:

\( Qi \) — Influent BOD (kg/m³)
\( Qub \) — Effluent BOD given Ultimate BOD (kg/m³)
\( BOD5 \) — 5 Days BOD (kg/m³)
\( BODu \) — Ultimate BOD (kg/m³)
\( O2 \) — Theoretical Oxygen Requirement (kg/s)
\( Qw \) — Volume of Wasted Sludge per Day (m³/s)
\( XR \) — MLSS in Returned or Wasted Sludge (kg/m³)
\( Qs \) — Sewage Discharge (m³/s)

Explanation: This formula calculates the influent BOD by considering the ratio of 5-day BOD to ultimate BOD, oxygen requirements, sludge characteristics, and sewage flow rates.

3. Importance of Influent BOD Calculation

Details: Accurate influent BOD calculation is crucial for designing and optimizing wastewater treatment systems, determining treatment efficiency, and ensuring compliance with environmental regulations.

4. Using the Calculator

Tips: Enter all required parameters in their respective units. Ensure all values are positive and valid (BOD5, BODu, and Qs must be greater than zero).

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between BOD5 and Ultimate BOD?
A: BOD5 measures oxygen consumption over 5 days, while Ultimate BOD represents total oxygen consumption over an infinite period for complete organic matter decomposition.

Q2: Why is the 1.42 factor used in the calculation?
A: The 1.42 factor represents the oxygen equivalent of bacterial cell mass, accounting for the oxygen demand of biomass in the system.

Q3: How does MLSS affect the influent BOD calculation?
A: MLSS (Mixed Liquor Suspended Solids) represents the concentration of microorganisms in the system, which directly impacts the oxygen demand for organic matter decomposition.

Q4: What are typical values for these parameters?
A: Values vary significantly based on wastewater characteristics, but typical ranges are: BOD5 (100-400 mg/L), Ultimate BOD (1.5-2.0 times BOD5), and MLSS (2000-4000 mg/L).

Q5: When is this calculation most useful?
A: This calculation is particularly useful for wastewater treatment plant design, process optimization, and performance evaluation of biological treatment systems.