Which of the following statements is/are CORRECT based on the electron donor $\text{(ED)}$ and electron acceptor $\text{(EA)}$ used in various bacterial mediated reactions in wastewater treatment?
- In anaerobic heterotrophic acid fermentation, organic compounds are used as both $\text{ED}$ and $\text{EA}$.
- In anaerobic heterotrophic methanogenesis, volatile fatty acids and $\mathrm{CO}_{2}$ are used as $\text{ED}$ and $\text{EA}$, respectively.
- In denitrification process by denitrifiers, organic compounds and $\mathrm{CO}_{2}$ are used as $\text{ED}$ and $\text{EA}$, respectively.
- In aerobic autotrophic iron oxidation, $\text{Fe} \text{(II)}$ and $\mathrm{O}_{2}$ are used as $\text{ED}$ and $\text{EA}$, respectively.
