Why are excessive chlorides in wastewater problematic?

Excessive chlorides in wastewater can significantly disrupt treatment processes, making option B the correct choice. When chlorides are present in high concentrations, they can affect the biological processes crucial for the effective treatment of wastewater. Many treatment systems, particularly biological treatment methods such as activated sludge processes, rely on specific conditions for microorganisms to thrive. Elevated chloride levels can be toxic to these microorganisms, inhibiting their growth and activity, which ultimately leads to reduced treatment efficiency.

Furthermore, high chloride concentrations can also influence the chemistry within treatment facilities, leading to issues such as increased corrosion of equipment and infrastructure, which can result in costly maintenance and operational challenges. This toxicity and operational disruption underscore the importance of managing chloride levels within permissible limits to ensure the overall effectiveness and stability of wastewater treatment systems.

Other options are not suitable, as chlorides do not promote algae growth, enhance odor control measures, or increase the efficiency of water treatment. In fact, excessive chlorides could have the opposite effect on water quality and treatment efficiency.