Question

Why might denitrification in wastewater treatment plants face issues with organic carbon availability, despite nitrification being carried out by autotroph bacteria?

a. Autotrophs use organic carbon for vital functions
b. Nitrification-oxidation consumes organic carbon
c. Autotrophs don't need organic carbon
d. Denitrification doesn't follow nitrification

Answer 1

Denitrification in wastewater treatment plants faces issues with organic carbon availability because denitrifying bacteria require organic carbon to convert nitrates to nitrogen gas, whereas autotrophic nitrifying bacteria do not consume organic carbon.

Step-by-step explanation:

The issue with organic carbon availability for denitrification in wastewater treatment plants, despite nitrification being performed by autotrophic bacteria, is that these bacteria do not consume organic carbon. Autotrophic bacteria involved in nitrification, such as Nitrosomonas, oxidize ammonia to nitrites and then to nitrates using inorganic sources of electrons and do not depend on organic carbon. However, denitrification bacteria require a source of organic carbon to use as an energy source to convert nitrates (NO3) into nitrogen gas (N2). The nitrification process does not consume organic carbon, thus creating a disparity in the availability of organic carbon for denitrifying bacteria. This can be limiting, as these bacteria rely on this carbon to carry out the energy-demanding process of converting nitrates back to atmospheric nitrogen in anoxic environments.

Answer 2

Denitrification in wastewater treatment plants might face issues with organic carbon availability because c. Autotrophs don't need organic carbon.

Step-by-step explanation:

In wastewater treatment, nitrification is carried out by autotrophic bacteria that don't require organic carbon for their metabolic processes. These bacteria derive their energy from inorganic compounds. However, during denitrification, heterotrophic bacteria are involved, and they rely on organic carbon for their vital functions.

The lack of organic carbon can hinder the denitrification process, as these heterotrophic bacteria need a carbon source to support their activities. While autotrophs involved in nitrification can thrive without organic carbon, the transition to denitrification, carried out by different bacteria, creates a need for an external carbon source. Therefore, if there is a deficiency in organic carbon availability, it can impede the denitrification stage in wastewater treatment plants. This highlights the interconnected nature of different microbial processes in wastewater treatment and emphasizes the importance of maintaining a balanced environment to ensure effective nitrogen removal.

So, the correct option is c. autotrophs don't need organic carbon.