The objective of the study was to determine the possibility of using organic soil under willow for wastewater purification of excess nitrate and phosphates, and to estimate the applicability of redox potential for the assessment oftransformation ofnitrogen compounds in the soil under study. The study showed the suitability of organic soil and willow for wastewater purification under the conditions of the ,,Hajdów" experimental object. Also, significant relationships were shown between redox potential and nitrogen transformation occurring in soil irrigated with wastewater after 2nd stage of treatment.

The paper presents results obtained during experiments with constructed wetlands that were built and monitored on the site of a municipal landfill in Southern Poland. The wetland was filled with gravel and rock in which reeds, cattails and willow were planted. A control plot without vegetation was also constructed. Each wetland was loaded with a portion of the leachate generated by the landfill. Measurements of the leachate quality showed very high concentrations of several pollutants. Particularly high concentrations of BOD, COD, nitrogen, and heavy metals were measured. High pollutant levels were probably responsible for the demise of the willows, which were dead within several months of planting. The efficiency of pollution removal with detention time up to 24 h ranged from O to 87% based on decreasing concentration of selected parameters. However, the removal efficiency of the control plot was typically only several percent lower than the removal efficiencies of the plots with vegetation.