Elimination of bacterial contamination from domestic sewage using vertical flow constructed wetland
Paweł Malinowski, Wojciech Dąbrowski, Sylwia Bagińska, Beata Karolinczak
Constructed wetlands (CW) plants are successfully used for treating various types of wastewater. Their most popular use is for the treatment of domestic sewage. The main aim of this research is to assess the change of microbiological parameters (total coliform, faecal coliform, total number of mesophilic and cryophilic bacteria, number of enterococci) during domestic sewage treatment in two CW beds with different fillings. The concentration of organic matter BOD5, COD), total Kjeldahl nitrogen TKN, ammonia nitrogen NH4–N, and total phosphorus were also analyzed. The research installation was based on two vertical subsurface flow constructed wetlands (VS-SF CW) – the first one filled with a Certyd aggregate and the second one with mineral material. Both beds were planted with reeds and worked in parallel with the same hydraulic load 0.1 m3/m2·d (m/d). The research was conducted during vegetative and non-vegetative seasons. Both beds showed a high effectiveness of reduction of most microbiological parameters, amounting to over 95%. The removal efficiency of the total coliform (TC) and faecal coliform (FC) parameters for the Certyd bed during the vegetative season was 99.9%, 98.3% and 97.51%, respectively in the non-vegetative season. In contrast, for the mineral-filled bed, the TC and FC removal efficiency during the vegetative season were, respectively 78.1% and 74.3%, respectively, 65.7% and 58.9% in the non-vegetative season. A difference in efficiency was observed depending on the season. High removal efficiencies of organic matter (measured by BOD5, COD values) and nutrient compounds was observed during the study. The conducted research proved a high efficiency of constructed wetlands in removing microbiological and chemical parameters. Overall, higher efficiency was observed in the bed filled with Certyd.