The study presents the results of the treatment of domestic and industrial wastewater with respect to the reduction of nitrogen and phosphorus compounds. The analysis encompasses the results of physical and chemical tests of effluents from two facilities based on hydroponic technology: wastewater treatment plants with hydroponic lagoons using the BIOPAX technology – Paczków, Poland and the Organica technology – Szarvas, Hungary. Monthly treatment effectiveness was determined basing on these analyses. The composition of wastewater flowing into the lagoon (after mechanical treatment) and wastewater discharged to the collector in 2009–2011 was subject to physical and chemical analysis in both facilities. The effluent quality was determined basing on the concentration of total phosphorus, total nitrogen and ammonium nitrogen. Mean annual results of the operation of both objects were high. For the wastewater treatment plant in Paczkow, operating in the BIOPAX technology, the effectiveness of treatment with respect to total nitrogen throughout the analysed period ranged from 76.9–84.4%. Total phosphorus was eliminated from wastewater with an effectiveness of 96.4–98.0%. Such high reduction level was caused by the application of additional precipitation process in the chambers of activated sludge reactor. The hydroponic plant in Szarvas (Organica technology) was characterised by a high effectiveness of reduction with respect to ammonium nitrogen: 92.0–93.0%, while the reduction of total phosphorus fell into the range 49.3–55.3%.