Wastewater Treatment Operator Certification Practice Test

What is a biomass?

1. Bacteria that change ammonia into oxidized nitrogen

2. Organisms that grow in a thread or filamentous form

3. A mass of organic material consisting of living organisms that feed on the wastes in sewage

4. Wastes such as sand, salt, and calcium that are present in the plant influent

The correct answer is: A mass of organic material consisting of living organisms that feed on the wastes in sewage

Biomass refers to a mass of organic material that predominantly consists of living organisms, particularly microorganisms such as bacteria and protozoa, that play a critical role in the treatment of wastewater. In the context of wastewater treatment, these organisms thrive on the organic matter found in sewage, consuming the nutrients and pollutants, which helps in breaking down and stabilizing the waste. This process is vital for the biological treatment stages in wastewater treatment plants, where the biomass effectively reduces the load of harmful substances and facilitates the conversion of these wastes into less harmful byproducts. The presence of a healthy biomass is essential for the efficacy of biological treatment methods like activated sludge systems or bioreactors. The other options do not accurately define biomass. The option discussing bacteria converting ammonia into oxidized nitrogen highlights a specific type of biological activity, but it does not encompass the broader definition of biomass itself. The reference to organisms growing in a filamentous form speaks to a characteristic of some microorganisms but misses the larger concept of biomass as a collection of living matter engaged in waste processing. Lastly, the mention of wastes such as sand and salt relates to inorganic materials rather than organic biomass, further distinguishing the importance of living organisms in biological treatment processes.