Analysis of Organic Nitrogen Removal in Municipal Wastewater by Reverse Osmosis

Abstract

Organic nitrogen (N org ) removal by the reverse osmosis (RO) process is not well documented in the literature. Unlike inorganic nitrogen (e.g. ammonia, nitrate, nitrite), which is consistently removed across a RO membrane as a function of process operation (e.g. flux and recovery), pH and membrane type; N org removal may vary depending on its characteristics (e.g. size, charge and hydrophobicity). The results of a pilot study that was conducted to determine the total nitrogen (TN) removal by the RO process are presented. The N org removal rates are compared with removals observed from three full-scale RO facilities and four pilot studies. The results of this analysis suggest that N org removal is variable and that RO may not consistently produce TN levels <1.0 mg/L without additional treatment. Three hypotheses to explain the variability in N org removal in the different data sets are presented.

Effect of Short‐term Exposure of Selected Aromatic Nitrogen Compounds on Wastewater Treatment

“…Organic nitrogen can be a significant fraction of total nitrogen in the effluent because many organic nitrogen compounds in industry effluent discharges are difficult to remove in WRRFs (Stockinger et al, 1995). Dissolve organic nitrogen (DON) may therefore account for more than 20% of total nitrogen in secondary effluent (Pagilla et al, 2008;Merlo et al, 2012). As management of organic nitrogen in the effluent is needed for wastewater reuse and drinking water supply (Chen et al, 2011;Chon et al, 2013), it is important to determine the impact of aromatic nitrogen compounds such as melamine (C 3 H 6 N 6 ) and p-nitrophenol (PNP or 4-nitrophenol, C 6 H 5 NO 3 ) on activated sludge treatment performance.…”