Method development for measuring biodegradable dissolved organic nitrogen in treated wastewater.

A method for determining biodegradable dissolved organic nitrogen (BDON) in treated wastewater was developed. The method adopts the approaches used in the biochemical oxygen demand and biodegradable dissolved organic carbon tests to make it usable as a routine procedure at wastewater treatment plants (WWTPs). The development focused on various aspects of the procedure, including inoculum type and concentration, incubation period, and the need for sample filtration after incubation. The method was tested with filtered effluent samples from two nutrient removal WWTPs and standard organic nitrogen solutions. Accurate and precise BDON results were obtained with 2 mL of acclimated mixed-liquor suspended solids diluted to a concentration of 240 mg/L as an inoculum and an incubation period of 20 days. Sample filtration after incubation was not required.