Septic systems are designed to pre-treat the sewage before it is applied to the soil. Pre-treatment removes solids suspended in sewage and separates oil and greases form sewage. After pre-treatment, the septic effluent flows to the drainfield where it is disposed into the soil. At this point the main pollutants found in the effluent are nitrogen, phosphorus and pathogens. The soil matrix provides biological, chemical and physical treatment for these pollutants. However, this treatment may or may not be complete depending on the factors such as soils, hydrology and weather conditions of the site.

Learn more about:

• nitrogen NPS pollution,
• phosphorus NPS pollution,
• pathogenic NPS pollution,
• ongoing and emerging issues , and
• contaminants in the environment.