Answer
a. Algae and protozoa.
Step-by-step explanation:
Objectionable tastes and odors in public water supplies are commonly caused by the presence of algae and protozoa. Algae and protozoa are microorganisms that can grow and reproduce in water sources such as lakes, rivers, and reservoirs. Some species of algae and protozoa produce compounds that can cause unpleasant tastes and odors in the water.
For example, blue-green algae (cyanobacteria) can produce compounds such as geosmin and 2-methylisoborneol that can cause a musty or earthy taste and odor in water. Other types of algae can produce compounds that cause a fishy or grassy taste and odor.
To reduce the presence of algae and protozoa in public water supplies, water treatment facilities may use techniques such as filtration, chlorination, or ultraviolet radiation to kill or remove these microorganisms.