California Tackles Nitrogen from Onsite Wastewater Systems

Approximately 25 percent of U.S. households use onsite wastewater systems to treat and disperse wastewater into the soil, representing ten percent of the wastewater flow generated in the United States. Onsite wastewater treatment systems include septic systems and a variety of small biomechanical treatment and disposal systems that discharge wastewater underground into soil. Thirty percent of new buildings are using onsite wastewater systems for their sanitary needs, suggesting a rise in their use. The pollutants from domestic wastewater that cause the greatest concern for human health and the environment include biochemical oxygen demand (BOD), total suspended solids (TSS), nitrate (NO super(-) sub(3)) or total nitrogen (TN), and bacteria. Due to a lack of significant degradation in groundwater, nitrate limits are increasingly being imposed on onsite wastewater systems.