Question

2. Nitrifying bacterial communities are essential in the removal of ammonia (NH3) from municipal wastewater. The bacteria obtain energy for their metabolism by catalyzing the following overall reaction: NH3+202NO3 +H20+H+ The bacteria are able to use NH3 but not NH for this process. a. (5 points) Based on the p Ka for NH, if the pH of the wastewater is initially around 7, will the pH of the wastewater need to be raised or lowered in order to maintain the correct nitrogen speciation to optimize this process? Tell me raised or lowered and explain your answer.

Answer 1

The reaction given here is

• NH₃ + 2O₂ ==> NO₃^- + H₂O + H⁺

Given that the pH of the wastewater initially is around 7(that means it is neutral).

also it is given that the above reaction doesn't take place when the NH₄⁺ is present in the process.

We know that the NH₄⁺ is generated in the following manner

• NH₃ + H⁺ ===> NH₄⁺

So for the required reaction to happen and also do not produce NH₄⁺ at the same time the pH of the wastewater need to be raised above 7. Because raising pH above 7 provides excess OH^- ions which will be ready to consume any H⁺ generated or present in the mixture. Therefore the above reaction takes place and also there won't be any possibility of NH₄⁺ to be produced.