A review of the fate and transport of nitrogen, phosphorus, pathogens, and trace organic chemicals in septic systems

ABSTRACT

A large population living in suburban and rural areas in the world uses septic systems, also called onsite wastewater treatment systems, to dispose of household wastewater. In a conventional septic system, the wastewater flows from a household to a septic tank, where solids settle and a clarified effluent is produced. This effluent is dispersed into the soil for further treatment and can be a potential source of various contaminants such as nutrients, pathogens, and a new class of compounds known as trace organic chemicals (TOrCs) in shallow groundwater and surface waters. We review the current state of the science on the fate and transport of three groups of contaminants—nutrients (nitrogen, phosphorus), pathogens, and TOrCs—and water quality impacts associated with these contaminants in conventional septic systems. We also discuss alternative technologies that may be employed when site conditions or environmental needs preclude the use of conventional septic systems.

Keywords:

• Groundwater
• nitrogen
• pathogens
• phosphorus
• septic systems
• trace organic chemicals

Funding

We thank several funding sources that provided support for this work: Mary Lusk received University of Florida Alumni Fellowship for her PhD degree, Mriganka De (for PhD degree) and Yun-Ya Yang (for Post-doctoral work) were supported by National Integrated Water Quality Grant Program no. 2011-51130-31173 from the USDA National Institute of Food and Agriculture.

Notes

¹ For brevity, we will use STU in remainder of the document.