What treatment methods have municipal water treatment plants had to add due to HABs?

• A. Methods to lower finished drinking water toxin content to meet EPA standards.
• B. Methods to increase nutrient levels to promote algae growth.
• C. Methods to raise finished water pH above 9.5.
• D. Methods to remove all phosphorus from the source water.

Answer: (A)

Harmful algal blooms can release toxins that contaminate drinking water, so municipal plants have to adjust treatment to remove or neutralize those toxins before it reaches consumers. These toxins, such as microcystins, can be present even when the water’s appearance or odor isn’t obviously abnormal, so plants must implement steps to bring toxin levels down to what the EPA allows. Treatment options include using activated carbon to adsorb toxins and taste‑and‑odor compounds, applying advanced oxidation processes, and employing filtration methods that can remove or inactivate the toxins. While reducing nutrient levels in the source to prevent blooms is important, that’s a watershed-management approach rather than a routine plant treatment step. Therefore, the goal is to lower finished drinking water toxin content to meet EPA standards.