Which among the following are typical causes of turbidity in raw water supplied to treatment plants?

Introduction / Context:
Turbidity is an optical property that describes the clarity of water. It interferes with disinfection, affects aesthetics, and indicates the presence of particulate matter. Understanding its causes is essential for selecting adequate treatment steps (coagulation, flocculation, sedimentation, filtration).

Given Data / Assumptions:

• Turbidity measured in NTU or JTU depending on method.
• Particles include inorganic and organic fractions.
• Typical surface-water sources.

Concept / Approach:
Common sources include inorganic mineral fines (clay, silt) eroded from catchments and organic debris (plankton, detritus). All scatter light and elevate turbidity. Effective treatment targets particle destabilization and removal to protect downstream disinfection.

Step-by-Step Solution:

Verification / Alternative check:
Laboratory jar tests and particle-size analysis in raw water corroborate these typical particle sources.

Why Other Options Are Wrong:
Each individual option represents a valid single cause; none alone is exhaustive, so “all the above” is the best answer.

Common Pitfalls:
Assuming turbidity is solely mineral; ignoring organic colloids and bio-particulates that can dominate during algal blooms.

Final Answer:
all the above.