If filter effluent quality declines, what action should be taken?

• A. Increase filtration rate
• B. Replace media
• C. Take filter out of service
• D. Ignore issue

Answer: (C)

When filter effluent quality declines, the immediate step is to take the filter out of service. This prevents poor-quality water from continuing through the system and protects downstream processes and disinfection from being undermined. Isolating the unit gives you a controlled situation to diagnose and fix the problem without compromising plant safety or regulatory compliance.

With the filter offline, you can perform necessary maintenance and inspection—backwashing or air scouring to remove accumulated grime, checking headloss and flow distribution, inspecting the media for fouling, channeling, or media degradation, and replacing or recharging media if needed. This approach stops further deterioration, preserves water quality, and makes corrective actions effective.

Increasing the filtration rate would typically worsen effluent quality by reducing contact time and increasing breakthrough. Replacing media might be required, but it’s part of the corrective maintenance after isolating the unit and diagnosing the cause. Ignoring the issue is unsafe and noncompliant.