Drinking water quality: The presence of manganese in supply water most directly promotes the growth of which organisms or nuisances?

Introduction:
Trace metals such as iron and manganese in water create aesthetic and operational problems. Beyond staining and taste, these metals can support biofilm development and encourage the growth of specific nuisance micro-organisms. Identifying the correct biological response informs treatment choices like oxidation and filtration.

Given Data / Assumptions:

• Distribution system carrying finished water with manganese present.
• Normal temperature conditions.
• Focus on biological growth influenced by manganese.

Concept / Approach:
Manganese can act as an energy source for certain bacteria, often referred to as manganese oxidizing or reducing bacteria. In distribution systems, these organisms produce deposits and slimy films, degrade aesthetics, and can shield pathogens. While nutrients such as nitrates and phosphates drive algal blooms in surface waters, manganese specifically correlates with biofilm and microbial nuisance issues inside pipes and fixtures.

Step-by-Step Solution:
Differentiate open water algae problems from closed pipe biofilm issues.Recognize that manganese favors specific micro-organisms that metabolize manganese compounds.Note that mosquitoes require stagnant surface water, not trace metals in treated water.Therefore, the presence of manganese promotes growth of micro-organisms.

Verification / Alternative check:
Utilities experiencing manganese problems report black deposits and microbiological growth, and remedy them through pre oxidation, greensand filtration, or biological filtration that targets iron and manganese removal.

Why Other Options Are Wrong:
Algae and higher plants are primarily nutrient limited by nitrogen and phosphorus. Mosquitoes depend on breeding habitats rather than dissolved manganese. Files is a typographical error for flies and is unrelated to dissolved metals.

Common Pitfalls:
Confusing nutrient driven algal blooms with metal associated biofilms. Control strategies differ substantially.

Final Answer:
Micro-organisms including nuisance bacteria