Answer to problem 4
4.The town you live in is concerned that the local
lake is eutrifying. As a result,
The town council is considering upgrading the local sewage
plant from secondary some form of tertiary treatment. Which
piece of information would be most helpful to you right now
(assume that the existing plant works fine):
- Phosphorus, not nitrogen is the limiting nutrient in the lake ecosystem.
- The kind of aquatic life that naturally inhabit the lake
- The strength of the influent to the sewage plant.
- The pH of the lake.
A is the correct answer. Although
B through D are interesting parameters that may need to be
addressed at some point, the limiting nutrient will determine
what kind of tertiary treatment is appropriate. Recall that
phosphorus removal is also a kind of tertiary treatment. If
phosphorus were the limiting nutrient for the lake,
denitrification might not solve the problem.
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