Nitrogen Species Measurement in Low Total Nitrogen Effluents

The purpose of this study was to measure dissolved organic nitrogen (DON) in low total nitrogen (TN) wastewater effluents. Digestion efficiency, measurement technique, and sample pretreatment by ion exchange were investigated for low level DON and TN measurement. Persulfate digestion procedure selected gave a nitrogen yield of 100 percent in the concentration range of 0-3 mgN/L. Second derivative ultraviolet spectroscopy (SDUS) method was found to be simple, reliable, and accurate measurement technique in DON quantification as nitrate following persulfate digestion. The detection limit by SDUS method was as low as 0.05 mgN/L with a standard deviation of 0.0015 mgN/L. Sample pretreatment to remove nitrate is required to minimize variance of measurement in DON. Ion exchange using strongly basic anion exchange resin (Dowex 1-X8) was able to completely remove nitrate from low TN wastewater effluent samples, allowing direct measurement of DON in the eluents.