Which of the following pollutants is generally compatible with the operation of a POTW?

Ammonia is generally compatible with the operation of a Publicly Owned Treatment Works (POTW) for several reasons. First and foremost, many POTWs are equipped to biologically treat ammonia through the process of nitrification, where ammonia is converted into nitrite and then into nitrate by specialized bacteria. This biological process is a fundamental part of wastewater management, as it helps in reducing nitrogenous pollution, which can be harmful to aquatic environments if released untreated.

Furthermore, ammonia can be naturally present in wastewater, primarily from sources such as human waste, food processing, and agricultural runoff. As such, treatment plants are designed to handle and efficiently remove ammonia to meet regulatory standards before discharge.

In contrast, the other pollutants mentioned in the options pose greater challenges for treatment facilities. Heavy metals are toxic at even low concentrations and can accumulate in the environment, leading to strict limitations on their presence in wastewater. Surfactants can interfere with biological processes in treatment plants, potentially disrupting the microbial populations essential for breaking down organic matter. Chlorinated compounds can be resistant to biodegradation and can create harmful byproducts during treatment, complicating the overall treatment process and possibly leading to environmental concerns.

Thus, the compatibility of ammonia with POTW operations lies in the treatment processes that