California Wastewater Treatment Operator Practice Exam 2025 – All-in-One Guide to Master Your Certification

Heavy metals are known to be toxic to microorganisms that play a critical role in wastewater treatment processes. These microorganisms, including bacteria and protozoa, are essential for the breakdown of organic matter and the reduction of pollutants in wastewater. When heavy metals such as lead, mercury, cadmium, and chromium enter the treatment system, they can disrupt the metabolic functions of these organisms, leading to decreased treatment efficiency.

Furthermore, heavy metals can accumulate in biosolids, which are the solid byproducts of wastewater treatment. This accumulation poses a significant environmental risk, as the use of contaminated biosolids in agriculture or landscaping can lead to heavy metal introduction into the soil and, subsequently, into the food chain. This makes it crucial for wastewater treatment facilities to monitor and manage heavy metal concentrations to protect both the treatment processes and the environment.

In contrast, the other choices suggest a positive impact or lack of influence by heavy metals, which does not align with established science regarding their detrimental effects on biological treatment systems.