Research - Category III: Water Quality

The Speciation and Reactivity of Wastewater-Derived Organic Nitrogen
(Funded 2002-2003)

Principal Investigator: David Sedlak
Department of Civil & Environmental Engineering
UC Berkeley
(510) 643-0256
sedlak@ce.berkeley.edu

Executive Summary:
Dissolved organic nitrogen compounds discharged by municipal wastewater treatment plants pose significant threats to aquatic ecosystems and to human health. Nitrogeneous compounds in wastewater effluent can cause algal blooms in receiving waters. Certain nitrogen containing compounds also can form toxic byproducts when they are disinfected with chlorine. These toxic byproducts can have adverse effects on aquatic organisms. Some of the wastewater-derived disinfection byproducts are potent carcinogens. The presence of these compounds in wastewater effluent is especially relevant in California, where planned and unplanned water reuse could result in risks to public health.

Until recently, environmental scientists were unable to distinguish between different forms of organic nitrogen. As a result, little is known about the reactivity of wastewater-derived organic nitrogen. The limited available data collected with new analytical techniques suggest that some organic nitrogen species will be very active (e.g., amino acids and polypeptides) while other species (e.g., humic substances) will be relatively inert. To develop a better understanding of the reactivity of wastewater-derived organic nitrogen species, we propose to use a suite of new analytical techniques to characterize organic nitrogen in samples collected before and after treatment in municipal wastewater treatment plants, engineered treatment wetlands and groundwater recharge facilities. We will also investigate the uptake of the different forms of organic nitrogen by algae as well as the tendency of different organic nitrogen species to form byproducts during chlorine disinfection.

Results of this research will be very useful to the protection of water quality in California. For example, an improved understanding of the uptake of organic nitrogen species by algae is needed for the implementation of total maximum daily loads (TMDL) programs in nitrogen-limited watersheds. Information on the tendency of different organic nitrogen species to form toxic disinfection byproducts will be useful in the design and management of indirect potable water reuse programs.