In this paper, the pollutant removal efficiency and the reliability of a vertical and horizontal flow hybrid constructed wetland (CW) planted with common reed, manna grass, and Virginia mallow were analyzed. The wastewater treatment plant, located in south-eastern Poland, treated domestic sewage at an average flow rate of 2.5 m3/d. The tests were carried out during five years of its operation (2014–2018). The following parameters were measured: biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids, total nitrogen, and total phosphorus. The results showed that more than 95% of BOD5, COD, and total phosphorus was removed in the tested CW system. The average effectiveness of removal of total suspended solids and total nitrogen exceeded 86%. A reliability analysis performed using the Weibull probability model showed that the removal reliability in the tested CW was very high for BOD5, COD, total suspended solids, and total phosphorus (100%). The probability that the total nitrogen concentration in the treated effluents would reach the limit value (30 mg/L) established for effluents discharged from a treatment plant of less than 2000 PE (population equivalent) to standing waters was 94%. The values of all the pollution indicators in wastewater discharged to the receiver were significantly lower than the limit values required in Poland. The investigated hybrid CW system with common reed, manna grass, and Virginia mallow guaranteed stable low values of BOD5, COD, total suspended solids, and total phosphorus in the treated wastewater, which meant it was highly likely to be positively evaluated in case of an inspection.

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The goal of the present study was to evaluate the efficiency of filters filled with Rockfos for removal of phosphorus (Total-P) from domestic wastewater. Rockfos is a material obtained by calcination of carbonate-silica rock (opoka) at a temperature of 900 °C. A field study was conducted in two filters with volumes of 2.0 and 0.8 m 3 which were components of hybrid constructed wetlands with an average capacity of 2.0 m 3 /L, located in two national parks in south eastern Poland. Samples of the influent to and the effluent from the filters were analyzed for Total-P concentrations and pH. Eighty sewage samples were tested over a five year study period. It was shown that the test filters removed Total-P with an average efficiency of 31.5% and 30.2% and that they could be successfully used to remove phosphorus from domestic wastewater in small wastewater treatment plants.

One of the prerequisites for maintaining good quality of environment in a given area is the creation of an appropriate water and sewage infrastructure. Despite a significant progress which occurred in the previous 20 years, the population of Poland, especially the people inhabiting rural areas, have a limited access to the water supply and sewage infrastructure. According to the data collected in 2018 by the Polish Central Statistical Office, 85% of people in rural areas had access to water supply network, whereas only 41% had access to a sewage system [GUS 2019a]. In turn, in the Lublin province, 80.6% of rural population was connected to a water supply network, but only 21.8% used a sewage system [Statistical Office in Lublin, 2019]. One of the main reasons for a slow development of the sewage infrastructure in rural areas of Poland, especially in the Lublin province, is the significant dispersal of settlements, which adds to the cost intensity of the investment process. In accordance with the Water Act [2017] as well as the Announcement of the Marshal of the