Influent BOD Given Oxygen Demand Of Biomass Calculator

Formula Used:

\[ \text{Influent BOD} = \text{Effluent BOD} + \frac{\text{Ratio of BOD to Ultimate BOD} \times (\text{Theoretical Oxygen Requirement} + (\text{Oxygen Demand of Biomass} \times \text{Volume of Wasted Sludge per day} \times \text{MLSS in Returned or Wasted Sludge}))}{\text{Sewage Discharge}} \]

Effluent BOD (Qb):

kg/m³

Ratio of BOD to Ultimate BOD (f):

Theoretical Oxygen Requirement (O2):

kg/s

Oxygen Demand of Biomass (DO2):

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):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the Influent BOD Calculation?

The Influent BOD calculation determines the total amount of Biochemical Oxygen Demand (BOD) present in incoming sewage, accounting for effluent BOD, oxygen requirements, and biomass dynamics in wastewater treatment systems.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

\( \text{Effluent BOD} \) — BOD present in the treated effluent (kg/m³)
\( \text{Ratio of BOD to Ultimate BOD} \) — Ratio of 5-day BOD to ultimate BOD
\( \text{Theoretical Oxygen Requirement} \) — Calculated oxygen needed for oxidation (kg/s)
\( \text{Oxygen Demand of Biomass} \) — Oxygen required by microorganisms to decompose organic matter
\( \text{Volume of Wasted Sludge per day} \) — Daily sludge removal volume (m³/s)
\( \text{MLSS in Returned or Wasted Sludge} \) — Mixed liquor suspended solids concentration (kg/m³)
\( \text{Sewage Discharge} \) — Flow rate of sewage discharge (m³/s)

Explanation: This equation accounts for the oxygen demand from both the organic matter in the influent and the biomass in the treatment system.

3. Importance of Influent BOD Calculation

Details: Accurate influent BOD calculation is crucial for designing appropriate wastewater treatment systems, determining treatment efficiency, and ensuring regulatory compliance for effluent quality standards.

4. Using the Calculator

Tips: Enter all values in the specified units. Ensure effluent BOD, theoretical oxygen requirement, oxygen demand, sludge volume, MLSS, and sewage discharge are positive values, with ratio of BOD to ultimate BOD and sewage discharge greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is the significance of the ratio of BOD to ultimate BOD?
A: This ratio represents the proportion of the total biodegradable organic matter that is measured in the standard 5-day BOD test compared to the ultimate BOD that would be measured over a much longer period.

Q2: How does oxygen demand of biomass affect the calculation?
A: The oxygen demand of biomass accounts for the oxygen consumed by microorganisms to decompose organic matter present in the biomass itself, which is an important component of the total oxygen requirement.

Q3: Why is MLSS concentration important in this calculation?
A: MLSS (Mixed Liquor Suspended Solids) concentration indicates the amount of active biomass in the system, which directly influences the oxygen demand for organic matter decomposition.

Q4: What are typical values for the ratio of BOD to ultimate BOD?
A: For domestic wastewater, this ratio typically ranges from 0.6 to 0.8, meaning 60-80% of the ultimate BOD is measured in the 5-day test.

Q5: How does sewage discharge rate affect influent BOD calculation?
A: The sewage discharge rate serves as a dilution factor in the calculation, affecting the concentration-based relationship between various components of the oxygen demand.