Massachusetts Wastewater Practice Exam

In a plate and frame filter press, what happens to the filtrate as the cake builds up between the plates?

1. Remains the same.

2. Decreases.

3. Increases.

4. Gets cloudy.

The correct answer is: Decreases.

In a plate and frame filter press, as the cake builds up between the plates, the volume of the filtrate that flows through the filter press decreases. This is primarily due to the progressively thicker layer of solid material (the cake) that forms. As this solid layer accumulates, it creates additional resistance to the flow of liquid, thereby reducing the rate at which filtrate can be extracted. The more cake that builds up, the harder it becomes for the liquid to pass through, leading to a decrease in the volume of filtrate being produced. Additionally, as the pressure increases due to the additional thickness of the cake, it can further restrict the flow of liquid. Therefore, the correct answer reflects the relationship between the buildup of cake and the volume of the filtrate produced, emphasizing how operational dynamics within a filter press affect throughput.