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The work presented the assessment of household wastewater treatment plants with drainage systems on the quality of groundwater in dug wells and deep water wells in the area of 3 selected communes (Drelów, Dębowa Kłoda and Urszulin), located in the Lublin province in south-eastern Poland. The investigations of the physicochemical composition of water from selected 28 dug wells and 2 deep water wells were conducted from June to July 2020, involving 9 measurement series. The microbiological studies consisted in 4 measurement series. The composition of the wastewater from primary settling tanks discharged to soil via drainage systems located in the vicinity of considered wells was also examined on a single occasion. The studies indicate that the water from wells are significantly polluted with ammonia, nitrites, as well as compounds of natural origin: iron and manganese. The presence of microbiological pollution of fecal origin was noted. The studies clearly indicate the possible pollution of the analyzed well waters with domestic sewage discharged to soil via drainage systems. Therefore, it necessary to take the actions aimed at improving the quality of groundwater in the Lublin province, including limitation of drainage systems, especially in the areas with unfavorable subsurface and hydrological conditions as well as low water supply coverage. The need to introduce changes in legal regulations and strategies for the development of technical infrastructure in counties, favoring the most efficient, as well as simple and inexpensive technologies, was indicated.

In this paper, we analysed the pollutant removal efficiency and reliability of a vertical and horizontal flow hybrid constructed wetland (CW) planted with giant miscanthus and Jerusalem artichoke. The wastewater treatment plant, located in south-eastern Poland, treated domestic sewage at an average flow rate of 1.2 m3·d−1. The tests were carried out during. 5-years of operation of the sewage treatment plant (2011–2016). During this period, sewage samples were collected from three stages of wastewater treatment in four seasons (winter – February, spring – May, summer – August, and autumn – November). The following parameters were measured: BOD5, COD, total suspended solids, total nitrogen, and total phosphorus. The average effectiveness of organic pollutant removal expressed by BOD5 and COD was 98.8 and 97.6%, respectively, and the removal efficiency for total suspended solids was 93%. The average values of BOD5, COD, and total suspended solids in wastewater discharged to the receiver were significantly lower than the limit values required in Poland. The efficiency of total nitrogen and total phosphorus removal was 64.1 and 68.1%, respectively, and the average values of these components in the outflow from the treatment plant exceeded the standard levels. A reliability analysis performed using the Weibull probability model showed that the reliability of pollutant removal in the tested CW system was very high for BOD5 and COD (100%). It was also demonstrated that the tested CW did not provide effective elimination of biogenic elements (nitrogen and phosphorus), as evidenced by the low reliability values – 32 and 28%, respectively. The investigated hybrid CW system with giant miscanthus and Jerusalem artichoke removed organic and biogenic pollutants with a similar efficiency as systems using classic plant species such as reed and willow.

This paper is a review of research and experiences related to the application of constructed wetland systems (CWs) in southeastern Poland in 1992–2016. On the basis of literature data, a comparison between pollutant removal efficiencies of one-stage and hybrid CWs was made. Some problems regarding the operation of these treatment plants were also presented. Data from various facilities indicate that one-stage CWs with horizontal or vertical flow were characterised by a quite high (80–89%) efficiency of removal of BOD5, COD and total suspended solids, but were less efficient in removing of biogenic compounds nitrogen and phosphorus – respectively 59 and 66%. Significantly higher removal efficiencies for the basic pollutants (above 92%) were observed in hybrid CWs with a VF–HF bed configuration. Those facilities removed ca. 65% of total nitrogen and 89% of total phosphorus. A statistical analysis revealed that hybrid VF–HF type CWs were characterised by a very high, about 99%, operation reliability. Lower reliabilities were achieved by one-stage CWs, especially those with a VF bed. Twenty five years of research on and experiences in the application of CWs in southeastern Poland indicate that one-stage CWs can be used on a larger scale in Polish conditions in rural areas with a scattered housing structure. Hybrid systems, on the other hand, can be applied successfully in recreational centres or in protected areas, especially in national parks, where a high pollutant removal efficiency is required. It has been shown that the use of hybrid CWs is consistent with the idea of sustainable development.

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&ndash, 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.