What Role Does Soil Play in Wastewater Treatment?
Soil is the most important treatment mechanism for many onsite wastewater treatment systems, including traditional or gravelless drainfields and mound systems. There are two important ways that soil treats wastewater — through the soil’s physical characteristics and as a site for biological activity. It treats wastewater by filtering out particles, removing some chemicals and nutrients, and acting as a site for destroying pathogens. Soil — physical treatment Soil particles provide surface area for wastewater to pass over to be treated. Large particles in the wastewater, including bacteria, are filtered out. Some particles are adsorbed or stick to the soil. Soil particles are negatively charged and will attract and hold positively charged chemicals and viruses. Soils also contain minerals that bind with some pollutants, immobilizing them. Soil helps treat wastewater by removing some of the nutrients. The two principle nutrients of concern are nitrogen and phosphorus. Nitrogen from the s
