What is membrane fouling and what are common indicators that require cleaning or maintenance?

• A. Accumulation of material on membrane surfaces reducing flux; indicators include rising transmembrane pressure, decreasing permeate quality, and increasing energy use.
• B. Chemical cleaning requirements for membranes due to temperature changes.
• C. Membrane materials swelling due to osmotic pressure; indicators: decreasing flow rate only.
• D. Gas diffusion through membranes; indicators: decreased flow.

Answer: (B)