1. What is Organic Matter at Start of BOD?

Definition: This calculator determines the initial organic matter present in sewage at the start of the Biochemical Oxygen Demand (BOD) reaction.

Purpose: It helps environmental engineers and wastewater treatment professionals analyze sewage characteristics and plan treatment processes.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( L \) — Organic matter at start (kg/m³)
• \( Y_t \) — Organic matter oxidised (kg/m³)
• \( K_D \) — Deoxygenation constant (1/sec)
• \( t \) — Time in days (converted to seconds)

Explanation: The formula calculates the initial organic load based on the amount oxidized during the BOD test period and the deoxygenation rate.

3. Importance of Organic Matter Calculation

Details: Knowing the initial organic matter helps in designing wastewater treatment systems and predicting oxygen demand in receiving waters.

4. Using the Calculator

Tips: Enter the organic matter oxidized, deoxygenation constant (default 0.00000266 1/sec), and time in days. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is the deoxygenation constant?
A: It's a rate constant that describes how quickly organic matter is oxidized in water, typically ranging from 0.05 to 0.4 per day (converted to 1/sec for this calculator).

Q2: How is time converted in the calculation?
A: The calculator automatically converts days to seconds (1 day = 86400 seconds) for consistency with the deoxygenation constant units.

Q3: What's a typical range for organic matter in sewage?
A: Raw sewage typically contains 100-400 mg/L (0.1-0.4 kg/m³) of organic matter, but this can vary widely.

Q4: Why is the organic matter at start important?
A: It helps determine the treatment capacity needed and predicts oxygen depletion in receiving waters.

Q5: Can this be used for industrial wastewater?
A: Yes, but industrial wastewater may have different deoxygenation constants depending on the organic compounds present.