1. What is Theoretical Oxygen Demand?

Theoretical Oxygen Demand (ThOD) represents the calculated amount of oxygen required to completely oxidize a chemical compound. It's used in environmental engineering to assess the oxygen requirements for wastewater treatment and pollution control.

2. How Does the Calculator Work?

The calculator uses the ThOD equation:

Where:

• \( C \) — Number of carbon atoms in the compound
• \( H \) — Number of hydrogen atoms in the compound
• \( O \) — Number of oxygen atoms in the compound
• \( N \) — Number of nitrogen atoms in the compound (if present)

Explanation: The equation calculates the oxygen needed to convert all carbon to CO₂, hydrogen to H₂O, and nitrogen to NO₃⁻.

3. Importance of ThOD Calculation

Details: ThOD helps in designing wastewater treatment systems, evaluating organic pollution potential, and comparing different pollutants' oxygen demand.

4. Using the Calculator

Tips: Enter the number of atoms for each element in the compound's molecular formula (CₐHₓOᵧNᵩ). Nitrogen is optional if not present in the compound.

5. Frequently Asked Questions (FAQ)

Q1: How does ThOD differ from BOD and COD?
A: ThOD is theoretical, BOD (Biochemical Oxygen Demand) measures oxygen used by microorganisms, and COD (Chemical Oxygen Demand) measures oxygen equivalent of organic matter oxidized by a strong chemical oxidant.

Q2: What are typical ThOD values?
A: Values vary by compound. For example, glucose (C₆H₁₂O₆) has ThOD of 1.07 g O₂/g, while methane (CH₄) has 4 g O₂/g.

Q3: When is ThOD most useful?
A: For pure compounds where the exact molecular formula is known. For complex mixtures, BOD or COD are more practical.

Q4: Does ThOD account for phosphorus and sulfur?
A: The standard equation doesn't, but extended versions can include these elements if needed.

Q5: What are the limitations of ThOD?
A: It assumes complete oxidation, which may not occur biologically. Some compounds may be resistant to biodegradation despite high ThOD.