During the primary treatment of sewage, solid paricles that settle down are called

Options

A. flocs
B. primary sludge
C. activated sludge
D. anaerobic sludge

Answer

B

Explanation

Primary or physical treatment in the process of removal of small and large, floating and suspended solids from sewage through two processes of filtration and sedimentation. First floating and suspended matter is removed through sequential filtration with progressively smaller pore filters. The sediment is called primary sludge while the supernatant is called primary sludge while the supernatant is called effluent. The primary sludge traps a lot of microbes and debris. it is subjected to composting, land fill or anerobicdigestion to produce biogas adn manure.