A certain wastewater treatment plant uses aerobic bacteria, anaerobic bacteria, and archaebacteria during secondary treatment of sewage. Unfortunately, during a bad blizzard the aerated tanks froze, killing the microbes inside. What is likely to result?

Question

A.  Floc levels will diminish.
B.  Methane production will go down.
C.  Solid material will not be effectively filtered out.
D.  Floc will not be effectively filtered out.

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?

  Gather Content
· What do you already know about wastewater treatment with bacteria?

  Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?

  Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

A.  Floc levels will diminish.

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses wastewater treatment with bacteria.
· What type of thinking is required?
        o This question is asking you to analyze the information given, using logic, to dissect the problem and determine the answer.

  Gather Content
· What do you already know about wastewater treatment with bacteria?
        o Wastewater is treated in two, or three, stages called primary, secondary, and advanced treatment. Microorganisms play critical roles in the secondary and sometimes advanced treatment stages.
        o In aerobic treatment of wastewater, material is fed into large aerated tanks that are continuously agitated where oxidative breakdown of any remaining organic material occurs. The bacteria and other organisms in the aerobic tanks form aggregates called floc. Degradation of the remaining carbon containing compounds in the wastewater occurs on this floc, which is later removed in settling tanks.
        o Anaerobic digestion of wastewater occurs in sealed reactors called sludge digesters. In the sludge digester, anaerobic bacteria catabolize polysaccharides, lipids, and proteins remaining after primary treatment into their constituent monomers. The resulting fatty acids, amino acids, and sugars, are metabolized into products such as acetate, hydrogen gas, and carbon dioxide. Archaebacteria in the sludge digester can convert these molecules to methane, carbon dioxide, and water. The methane can be burned to heat or power the wastewater treatment plant.

  Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o If the aerated tank loses its microbes, the production of floc will diminish.

  Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o The question required you to analyze the information given, using logic, to dissect the problem and determine the answer.
        o Did you recognize that the aerobic bacteria in the aerated tanks are responsible for creating floc ?