Identify the incorrect statement about water treatment and boiler feedwater quality for high-pressure steam systems.

Introduction / Context:
High-pressure boilers are sensitive to corrosion, deposition, and carryover. Proper feedwater conditioning and accurate understanding of microbiological control are essential to protect tubes, drums, and steam turbines.

Given Data / Assumptions:

• High-pressure steam generation (e.g., power plant service).
• Attention to oxygen, alkalinity, and silica limits.
• Knowledge of microbial survivability under cold conditions.

Concept / Approach:
Caustic embrittlement is associated with excessive localized alkalinity (high NaOH) causing intergranular cracking. Silica tolerances drop sharply with pressure because silica volatilizes and deposits in turbines. Dissolved oxygen must be minimized (deaeration plus scavengers). Freezing/cooling does not guarantee pathogen kill; many microbes survive low temperatures and revive when warmed.

Step-by-Step Solution:
Evaluate each statement with boiler chemistry principles and microbiology.(a) True: high NaOH promotes embrittlement in stressed zones.(c) True: higher pressures demand lower silica to prevent carryover and turbine fouling.(d) True: dissolved oxygen must be near zero to avoid pitting corrosion.(b) False: low temperature preserves many bacteria; it is not a reliable disinfection method.

Verification / Alternative check:
Industry standards (e.g., power-plant chemistry guidelines) prescribe stringent oxygen and silica limits and recognize that disinfection requires heat or chemical methods, not cold storage.

Why Other Options Are Wrong:
They are technically correct best practices; only the claim that cooling/freezing “kills bacteria” is incorrect.

Common Pitfalls:
Assuming low temperature equals sterilization; ignoring oxygen ingress in condensate returns; neglecting silica monitoring at high pressure.

Final Answer:
Cooling and freezing of water reliably kill the bacteria present.