Nitrogen compounds removal by membrane filtration in water treatment plant for small communities: full-scale start-up

The aims of the work and research question deals with the removal of two natural nitrogen compounds, ammonium and nitrate and an organic compounds from groundwater in the sensitive aquatic area (Curonian Spit, Lithuania). The effects of both ammonium presence and nitrate compounds were studied using natural groundwater in the water treatment plants. Organic compounds were studied at Total Organic Carbon (TOC), Dissolved Organic Carbon (DOC), Color (Pt scale) and UV methods. The amines were varied in the range of 0.11–0.32 μg L⁻¹. At ammonium concentration of 790 μg L⁻¹, the amines formations were close to 0.66 μg L⁻¹ maximum obtained in the groundwater. The highest ammonium removals were obtained at water treatment plants of approximately 15 mg L⁻¹ TOC. Continuous tests showed a linear relationship between TOC and DOC concentration rates. The conclusions drawn that the most biodegradable compound was the ammonium. The TOC/DOC rates increased with the decreased of ammonium concentrations. Optimal process conditions in this work were obtained at the TOC and DOC of approximately 16 and 14 mg L⁻¹, respectively, with high efficient of ammonium removal, as well as minimum amines formation rate.