Fate of Organic Nitrogen in Four Biological Nutrient Removal Wastewater Treatment Plants

Abstract

This study investigated the fate of nitrogen species, especially organic nitrogen, along the mainstream wastewater treatment processes in four biological nutrient removal (BNR) wastewater treatment plants (WWTPs). It was found that the dissolved organic nitrogen (DON) fraction was as high as 47% of soluble nitrogen (SN) in the low‐SN effluent plant, which limited the plant's capability to remove nitrogen to very low levels. A lower DON fraction was observed in high‐SN effluent plants. Effluent DON concentrations from the four plants ranged from 0.5 to 2 mg N/L and did not vary significantly, even though there was a large variation in the influent organic nitrogen concentrations. Size fractionation of organic nitrogen by serial filtration through 1.2‐, 0.45‐, and 0.22‐µm pore‐sized membrane filters and the flocculation‐and‐filtration with zinc sulfate (ZnSO4) method was investigated. The maximum colloidal organic nitrogen (CON) fractions found were 68 and 45% in the primary effluent and final effluent, respectively. The experimental results showed that effluents after filtration through the 0.45‐µm pore‐sized filter contain significant colloidal fractions; hence, the constituents, including organic nitrogen, are not truly dissolved. A high CON fraction was observed in wastewater influents and was less significant in effluents. The flocculation and filtration method removed the colloidal fraction; therefore, the true DON fraction can be determined.

Abiotic Effects on Effluent Dissolved Organic Nitrogen Along an Estuarine Transect

“…It is likely that UV disinfection results in the breakdown of DON in a similar fashion to the breakdown that occurs during natural UV exposure (Simsek et al, 2013). This study's results differ from that of Sattayatewa et al (2010), which showed no changes in DON concentration after UV disinfection, which could be attributed to low UV dosage and contact time (Simsek et al, 2013). If a fraction of DON is converted to inorganic LMW-N as a result of UV disinfection, there will be less DON released into the environment.…”

“…UV disinfection alone has not shown to cause any concentration changes in DON (Sattayatewa et al, 2010). This could be attributed to the low UV intensity and duration of the system, which is too weak to oxidize organic matter (Sattayatewa et al, 2010). It is likely that different disinfection processes affect EDON's chemical properties, which could results in different interactions in the environment.…”

“…Examples of N-DBPs are nitrosamines, halonitroalkanes, and haloamides, which happen to be toxic compounds (i.e., Plumlee et al, 2008;Shah and Mitch 2012;Zhao et al, 2008). UV disinfection alone has not shown to cause any concentration changes in DON (Sattayatewa et al, 2010). This could be attributed to the low UV intensity and duration of the system, which is too weak to oxidize organic matter (Sattayatewa et al, 2010).…”

Meteorological Influences on Nitrogen Dynamics of a Coastal Onsite Wastewater Treatment System

“…His study showed median Total Kjeldahl N values for effluent of approximately 80 mg/l. In a recent study DON effluent was evaluated at 4 biological nutrient removal wastewater treatment plants, including one on the Neuse River, North Carolina (Sattayatewa et al 2010). They found that treatment plants could remove 60–80% of DON, but effluent contained between 0.5–2 mg/l DON.…”

Activated Sludge – 100 Years and Counting

“…rDON has emerged as a topic of interest for facilities that are required to meet strict effluent TN limits (<3 mg/L), since rDON can represent between 0.5 and 1 mg N/L of the effluent N (Sattayatewa et al, 2010). rDON has emerged as a topic of interest for facilities that are required to meet strict effluent TN limits (<3 mg/L), since rDON can represent between 0.5 and 1 mg N/L of the effluent N (Sattayatewa et al, 2010).…”