![]() ![]() The highest N 2 losses, 17.6%, were estimated for P&S. Losses as N 2 were estimated to be 10.4% and 9.7% of total N input concentration for SND and Geo, respectively. The modeled N losses occurred mostly as NO 3 - in water outputs, accounting for more than 82% of N inputs in all drainfields. The model computed N losses from nitrification and denitrification differed little from measured losses in all STAs. increased soil temperature and higher water table. ![]() The calibrated model was used to estimate N fluxes for both conventional and advanced STAs under current and changing climate conditions, i.e. ![]() Average root mean square error (RSME) ranged from 0.18 and 2.88 mg L -1 for NH 4 + and 4.45 mg L -1 to 9.65 mg L -1 for NO 3 - in all drainfield types. The model was calibrated with acceptable goodness-of-fit between the observed and measured values. ![]() Three types of drainfields were simulated: (1) a pipe-and-stone (P&S), (2) advanced soil drainfields, pressurized shallow narrow drainfield (PSND) and (3) Geomat (GEO), a variation of SND. A water content-dependent function was used to compute the nitrification and denitrification rates. Experimental data from a mesocosm-scale study, including soil moisture content, and total N, ammonium (NH 4 +) and nitrate (NO 3 -) concentrations, were used to calibrate the model. We simulated the fate and transport of N in different types of OWTS drainfields, or soil treatment areas (STA) under current and changing climate scenarios, using 2D/3D HYDRUS software. OWTS rely on physical, chemical and biological soil processes to treat wastewater and these processes may be affected by climate change. Nitrogen compounds cause eutrophication, depleting the oxygen in marine ecosystems. Most of the non-point source nitrogen (N) load in rural areas is attributed to onsite wastewater treatment systems (OWTS). ![]()
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