Basic Wastewater Operator Practice Exam

Which type of filtration is commonly used for the removal of fine solids in wastewater?

1. Coarse filtration

2. Microfiltration

3. Ultrafiltration

4. Both B and C

The correct answer is: Both B and C

The correct choice encompasses both microfiltration and ultrafiltration, both of which are effective techniques for removing fine solids from wastewater. Microfiltration utilizes pore sizes typically between 0.1 to 10 microns, allowing it to efficiently separate suspended solids, bacteria, and large viruses from the water. This makes it particularly suitable for treating wastewater where the objective is to remove larger fine solids that could interfere with subsequent processes or harm equipment. Ultrafiltration, with even smaller pore sizes, generally ranging from 1 to 100 nanometers, takes the filtration process a step further. It is capable of removing smaller solids, such as colloids and some macromolecules, while also effectively retaining larger organic materials and microorganisms. Both filtration methods are essential in modern wastewater treatment facilities for achieving high levels of clarity and purity. They are often implemented sequentially or in conjunction, depending on the specific treatment goals and the characteristics of the wastewater being treated. Coarse filtration, while useful for larger particles, does not address the removal of fine solids effectively, making it less suitable in scenarios where fine solids represent a significant concern. Thus, for comprehensive solids removal, microfiltration and ultrafiltration are the preferred choices.