Tennessee Wastewater Operator Practice Exam

Which type of digester tank is favored when there is extra land area and a limited construction budget?

1. Cylindrical

2. Pancake

3. Rectangular

4. Cubic

The correct answer is: Pancake

The pancake digester tank is favored in scenarios where there is extra land area available but a limited construction budget because of its shape and design. This type of tank is typically wider and shorter, which allows for a larger volume of digestate without requiring extensive vertical construction. As a result, building a pancake digester can be more cost-effective, as it minimizes material and labor costs associated with constructing taller structures. Additionally, pancake digesters can offer operational advantages such as more efficient heat distribution and easier maintenance access, which are beneficial in the long-term management of the wastewater treatment process. The design allows for a greater surface area exposed for gas collection, improving overall efficiency in digesting organic material. Given that cylindrical, rectangular, and cubic tanks may require more complex construction techniques or involve greater depth, they may not be as economically viable when a budget is constrained. The pancake digester's ability to capitalize on horizontal space while managing costs effectively makes it a suitable choice under these circumstances.