1. What is Ultimate Biochemical Oxygen Demand?

Ultimate Biochemical Oxygen Demand (BOD_u) represents the total amount of oxygen required to completely decompose all organic material in a water sample over an infinite time period. It provides a comprehensive measure of the organic pollution load in water.

2. How Does the Calculator Work?

The calculator uses the Ultimate BOD formula:

Where:

• \( BOD_u \) — Ultimate Biochemical Oxygen Demand (kg/m³)
• \( BOD_5 \) — 5-day Biochemical Oxygen Demand (kg/m³)
• 0.68 — Conversion factor representing the fraction of ultimate BOD consumed in 5 days

Explanation: The formula assumes that approximately 68% of the ultimate BOD is consumed within the first 5 days of the decomposition process, allowing for estimation of the total oxygen demand from the 5-day measurement.

3. Importance of BOD Calculation

Details: BOD measurement is crucial for assessing water quality, determining the effectiveness of wastewater treatment processes, and evaluating the impact of organic pollution on aquatic ecosystems. Ultimate BOD provides the complete picture of organic loading.

4. Using the Calculator

Tips: Enter the 5-day BOD value in kg/m³. The value must be greater than zero. The calculator will compute the ultimate BOD using the standard conversion factor of 0.68.

5. Frequently Asked Questions (FAQ)

Q1: Why is the 0.68 factor used?
A: The 0.68 factor represents the typical fraction of ultimate BOD that is consumed within the standard 5-day incubation period, based on empirical studies of organic matter decomposition rates.

Q2: What are typical BOD values for different water types?
A: Clean rivers: 1-2 mg/L, Moderately polluted: 3-5 mg/L, Polluted: 6-9 mg/L, Raw sewage: 100-400 mg/L. Values are typically expressed in mg/L (equivalent to g/m³).

Q3: When should BOD testing be conducted?
A: BOD testing is essential for wastewater treatment monitoring, regulatory compliance testing, environmental impact assessments, and research on water quality and pollution control.

Q4: Are there limitations to this calculation?
A: The 0.68 factor is an average value and may vary depending on temperature, type of organic matter, and microbial population. For precise applications, laboratory determination of ultimate BOD may be necessary.

Q5: How does temperature affect BOD?
A: BOD reaction rates approximately double for every 10°C temperature increase. Standard BOD tests are conducted at 20°C to ensure consistent and comparable results.