Efficiency of Wastewater Treatment Constructed Wetlands during Non-Vegetation Season in the Czech Republic

Abstract

In the Czech Republic, water management authorities are required to maintain continuous treatment, throughout the year, of organic pollution and suspended solids at wastewater treatment plants (WWTP) with under 500 population equivalents (PE) and at WWTP 500–2000 PE also for the presence of ammonia nitrogen. Constructed wetlands built for wastewater treatment are not excepted. But their treatment efficiency during the winter period, when the macrophytic vegetation (mostly Phragmites australis and Phalaris arundinacea) is senescent, is often questioned. Under the climatic conditions of the Czech Republic (Central Europe, temperate climate), there is a non-vegetation period between half of October and the end of March. This non-vegetation period coincides with the winter period. In this chapter we assess the results of this treatment efficiency monitoring during the mentioned period of a year. The data were collected monthly at six constructed wetlands built for the load between 150−800 PE during the period 2000−2008. The main result is that the monitored constructed wetlands, which are representative samples of the Czech constructed wetlands, do not have statistically lower treatment efficiency during the non-vegetation period for the organic pollution and suspended solids. Only for the ammonia nitrogen, a significantly lower treatment efficiency during the non-vegetation period in comparison with the rest of year (vegetation period) was confirmed. The results have validated that constructed wetlands are applicable to wastewater treatment in villages under 500 PE and they can be used for the same purpose in the villages between 500 and 1000 PE, but the stable ammonia nitrogen treatment efficiency must be ensured by another wastewater treatment technology.