What needs to be removed from sewage and agricultural waste water before it is released into the environment?

To ensure that sewage and agricultural wastewater do not negatively impact the environment upon release, several harmful substances must be removed. The correct answer emphasizes the need to eliminate organic matter, harmful microbes, and fertilizers and pesticides from the wastewater.

Organic matter is crucial to remove as it can lead to oxygen depletion in water bodies, adversely affecting aquatic life. When organic waste decomposes, it consumes dissolved oxygen needed by fish and other organisms, resulting in an unhealthy ecosystem.

Harmful microbes, including pathogens that can cause diseases in humans and animals, must also be treated adequately. If these microbes remain in the wastewater, they can contaminate drinking water sources and recreational waters, posing serious public health risks.

Fertilizers and pesticides are another important concern. When released into the environment, they can lead to nutrient pollution, causing issues like eutrophication. This process results in excessive algae growth that can deplete oxygen in the water, further harming aquatic ecosystems.

Therefore, the comprehensive removal of organic matter, harmful microbes, and agricultural chemicals is essential to safeguard both environmental health and public safety before wastewater is discharged into natural water sources.