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Reverse Osmosis Systems Flashcards

7 cards from real CWS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Reverse Osmosis Systems flashcards as text

  1. Calcium carbonate scaling on an RO membrane is most effectively prevented by:

    Answer: Lowering feedwater pH with acid injection

    Acidifying the feedwater converts carbonate to bicarbonate, dramatically reducing calcium carbonate precipitation on the membrane.

  2. Which fouling type is characterized by a gelatinous, difficult-to-remove layer on the RO membrane?

    Answer: Biofouling

    Biofouling involves microbial growth forming an extracellular polymeric substance (EPS) matrix that is notoriously resistant to chemical cleaning.

  3. In a multi-stage RO system, what happens to the TDS concentration in the reject stream as water progresses through stages?

    Answer: Increases in each subsequent stage

    As permeate is extracted at each stage, dissolved solids become increasingly concentrated in the remaining reject stream.

  4. What is 'Langelier Saturation Index' (LSI) used for in RO system design?

    Answer: Predicting calcium carbonate scaling or corrosion tendency

    LSI predicts whether water will tend to form calcium carbonate scale (positive LSI) or be corrosive (negative LSI) in the concentrate stream.

  5. A RO membrane is cleaned using a low-pH cleaner followed by a high-pH cleaner. What foulants does each target?

    Answer: Low-pH removes inorganic scale; high-pH removes organics and biofilm

    Acidic cleaners dissolve inorganic scale (carbonate, sulfate), while alkaline cleaners saponify and disperse organic foulants and biofilm.

  6. What is the purpose of a permeate pump in a residential RO system?

    Answer: Use reject stream energy to boost feed pressure, improving efficiency and recovery

    A permeate pump (energy recovery device) uses hydraulic energy from the reject stream to pressurize the storage tank, reducing waste water ratio by up to 80%.

  7. Which parameter should a CWS technician test FIRST when troubleshooting declining permeate flow in an RO system?

    Answer: Feed water pressure

    Inadequate feed pressure is the most common cause of low permeate flow, and it can be quickly measured with a pressure gauge.