Which of the following describes a major environmental concern related to sewage treatment?

The major environmental concern related to sewage treatment revolves around the release of untreated sewage. When sewage is not properly treated before being discharged into water bodies, it can introduce harmful pathogens and pollutants into the environment. This can lead to severe contamination of water sources, posing health risks to humans and wildlife. Moreover, untreated sewage can disrupt local ecosystems, leading to problems such as eutrophication, which depletes oxygen levels in the water and can cause large-scale fish kills and biodiversity loss.

While the production of methane gas, disruption of wildlife habitats, and the release of treated sewage can be concerns in certain contexts, they do not represent the immediate and critical risk associated with sewage treatment processes. The key issue is ensuring that sewage is treated adequately to prevent untreated wastewater from entering the environment and causing significant harm.