Which of the following is/are the correct permissible limit(s) for organic compost? (i). Arsenic : 10 mg/kg (ii). Copper : 300 mg/kg (iii). Zinc : 1000 mg/kg
- AOnly (i)
- B(i) and (ii)
- C(ii) and (iii)
- D(i), (ii) and (iii)Correct
Solution
Concept
Compost must meet heavy metal limits set in the Fertilizer Control Order (FCO) and SWM Rules 2016.
Step-by-step solution
1. Recall the heavy metal limits for organic compost (FCO 2009, amended; used in SWM Rules 2016). 2. Arsenic: 10 mg/kg. This is correct. 3. Copper: 300 mg/kg. This is correct. 4. Zinc: 1000 mg/kg. This is correct. 5. All three statements are correct, so the answer is (D).
Explanation
Compost can carry heavy metals from mixed waste. So India sets maximum limits in the FCO and SWM Rules 2016. The limits given for arsenic (10), copper (300) and zinc (1000) mg/kg match these standards.
Why the other options are wrong
A, B and C leave out a statement that is also correct, so they are incomplete.
Shortcut
Remember: As 10, Cu 300, Zn 1000 mg/kg.
Common mistake
Mixing these with limits for other metals such as Pb 100, Cd 5, Cr 50, Ni 50, Hg 0.15 mg/kg.
Correct answer: D) (i), (ii) and (iii)