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Question: Flocs' is a) The primary sludge produced in sewage treatment b) A type of biofortified food c...

Flocs' is
a) The primary sludge produced in sewage treatment
b) A type of biofortified food
c) A mesh-like structure formed by the association of bacteria and fungal filaments in sewage treatment
d) The effluent in primary treatment tank obtained during sewage treatment

Explanation

Solution

A floc is a type of microbial aggregate that can be contrasted with biofilms and granules or is considered to be a specialized type of biofilm. Flocs appear as cloudy suspensions of cells floating in water, rather than being attached to and growing on the surface like most biofilms.

Complete answer:
The floc is typically held together by an extracellular polymeric substance (EPS) matrix, which may contain variable amounts of polysaccharide, protein, and other biopolymers. The formation and properties of flocs may have an impact on the performance of industrial water treatment bioreactors such as activated sludge systems where flocs form a sludge blanket.
The formation of floc may benefit constituent microorganisms in a number of ways, including protection from pH stress, resistance to predation, manipulation of microenvironments, and facilitating mutual relations in mixed microbial communities.
Microbes are used in activated sludge treatment to reduce organic matter in sewage water. Flocks are used in this method. Flocks are bacterial and fungal mass. Bacterial cells and filaments of fungal species are combined to form a mesh or network-like structure. These organisms reduce organic matter and help in reduction of the BOD (Biological oxygen demand) of sewage water.

Thus, the answer is option C: A mesh-like structure formed by the association of bacteria and fungal filaments in sewage treatment.

Note:
In general, the mechanisms by which flocculating microbial aggregates hold together are not well understood. Work on the activated sludge bacteria Zoogloea resiniphila has shown, however, that PEP-CTERM proteins must be expressed for the formation of flocs; in their absence, growth is planktonic, even if exopolysaccharide is produced.