Water treatment process terminology:\r The process of passing water through beds of granular media (such as sand and anthracite) to remove suspended and colloidal impurities is called

Introduction / Context:
Surface water treatment trains typically include screening, coagulation-flocculation, sedimentation, filtration, and disinfection. Understanding the distinct purpose of each step helps in proper design and troubleshooting of plants.

Given Data / Assumptions:

• Granular media beds (slow sand, rapid gravity, or dual-media) are employed.
• Targeted removal: fine suspended solids, floc carryover, and some microorganisms.
• Pretreatment (coagulation/flocculation) may or may not be present depending on raw water quality.

Concept / Approach:
Filtration is the passage of water through porous media to retain particles by straining, interception, sedimentation within pores, and to some extent adsorption and biofilm action (particularly in slow sand filters). It complements sedimentation by removing particles that escaped settling.

Step-by-Step Solution:
Identify the defining feature: flow through granular media bed.Relate to process name: filtration.Eliminate other processes: screening is coarse-bar removal; sedimentation is gravity settling without media.

Verification / Alternative check:
Pilot studies and plant data show turbidity removal polishing across filters, taking settled water from a few NTU to <0.3 NTU, confirming the function of filtration in the treatment chain.

Why Other Options Are Wrong:

• Screening removes large debris only.
• Sedimentation removes heavier floc by gravity without media.
• “Adsorption only” is incomplete; several mechanisms act in filtration.

Common Pitfalls:

• Operating at excessive filtration rates that compromise effluent turbidity and pathogen barrier performance.
• Skipping coagulation where needed, overloading filters with fine colloids.

Final Answer:
Filtration