This study investigated the operation of three full-scale Lemna System surface fl ow municipal wastewater treatment plants, built according to the Lemna Corporation design. These plants consist of two ponds, the first aerated and the second for duckweed, with a barrier grid in the latter to ensure uniform plant distribution across its area. According to designers duckweed improves the efficiency of wastewater treatment. The three treatment plants are situated in central Poland and they differ in the occurrence of duckweed, two of them, located in Raków and Bąkowiec, operate without duckweed. and the third in Falęcin Stary, Lemna minor covers ca. 90% of second pond surface. The efficiency of Lemna System wastewater treatment was found not to differ between the plants with and without duckweed. The aerated pond played the main role in reduction of pollutants in the investigated Lemna Systems

The paper presents results of research concerning operating of five small wastewater treatment plants working in two different technologies: hydrobotanical wastewater treatment plant and constructed wetland. Each object was designed for the treatment of domestic sewage after preliminary mechanical treatment in a septic tank. Hydrobotanical wastewater treatment plants and one of constructed wetland beds were built for treating sewage produced in educational institutions and resort. In the article attention is paid to possibility of exceeding the maximum allowable concentration of pollutants for three main indicators of pollution: BOD5, COD, and total suspension. The reduction of these indices is required by the Regulation of the Minister of Environment [14] for wastewater treatment plants with PE < 2000. In addition, the paper presents the effects of wastewater treatment to reduce biogens. The best quality of outflow was reached by outflows from constructed wetland treatment plants. None of the observed objects fulfilled the requirements in terms of allowable concentrations for total suspension. The most effective were objects operating in technology of “constructed wetland”.

In the paper, the research results on the removal of aliphatic hydrocarbons (C7 to C30) on constructed

wetlands have been presented. The research has been realized on the semi-technical scale constructed wetlands.

planted with reed Phragmites australis. The experimental installation is located on the filling station in Balice and treats the fraction of stormwater from this utility. The concentrations of total aliphatic hydrocarbons

in analyzed stormwater were between 96.02 µg/dm3 and 6177.33 µg/dm3

, and from 47.55 µg/dm3 to 5011.14

µg/dm3

in effluent from the installation. The average total aliphatic hydrocarbons removal effectiveness was

48%, the values ranged from 19% to 81%. Hydrocarbons C14 to C18 were removed with the lowest effectiveness (26%–32%), the lighter hydrocarbons – with higher one (39%–68%), however the highest removal

effectiveness were observed for the hydrocarbons with the highest carbon atoms numbers (from 51% for C20

to 92%–93% for C26–C30).

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.