California Wastewater Treatment Operator Practice Exam

How is mechanical dewatering performed?

1. Through chemical processes in tanks

2. Using mechanical equipment, such as centrifuges or belt presses

3. By natural evaporation methods

4. Through gravity thickening systems

The correct answer is: Using mechanical equipment, such as centrifuges or belt presses

Mechanical dewatering is performed using specialized mechanical equipment designed to separate water from solids in wastewater treatment. Equipment such as centrifuges or belt presses applies physical forces to achieve this separation. Centrifuges employ high rotational speeds to generate centrifugal force, which effectively separates the solid and liquid phases of sludge. Belt presses use two or more porous belts to apply pressure to the sludge, squeezing out water while allowing the solids to remain on the belts for collection. This method is essential for reducing the volume of sludge and making it easier to transport and further process. The efficiency of mechanical dewatering not only helps in reducing disposal costs but also enhances the overall performance of wastewater treatment facilities. The other choices represent different processes that are not classified as mechanical dewatering. Chemical processes involve the use of chemicals to enhance separation but do not utilize mechanical equipment. Natural evaporation methods rely on environmental conditions for water removal, and gravity thickening systems depend on settling without mechanical intervention, neither of which defines mechanical dewatering.