What environmental issue is addressed by improving effluent treatments in municipal sewage facilities?

Improving effluent treatments in municipal sewage facilities directly addresses the issue of cultural eutrophication. Eutrophication is a process where water bodies become enriched with nutrients, primarily nitrogen and phosphorus, often as a result of runoff from agricultural lands and wastewater. When sewage is inadequately treated, it can release excess nutrients into nearby water systems, leading to rapid algal blooms. These blooms can create dead zones, deplete oxygen levels, and adversely affect aquatic life due to the excess growth of algae.

By enhancing the treatment processes at sewage facilities, the release of these nutrients can be significantly reduced, thus mitigating the onset of cultural eutrophication. This leads to healthier aquatic ecosystems, improved water quality, and better overall environmental health.

The other options—global warming, ocean acidification, and deforestation—are not directly linked to municipal sewage treatment improvements. Global warming is primarily associated with greenhouse gas emissions, ocean acidification results from increased CO2 levels in the atmosphere, and deforestation is related to land use changes rather than wastewater management.