The constructed wetland (CW) for 326 PE with horizontal subsurface flow at Kotenčice, Central Bohemia, Czech Republic, was built in 1994. Despite the relatively high efficiency of the CW, the filtration beds suffered from clogging, and therefore it was decided in 2011 to rebuild the whole system. The new treatment system was built as an experimental system consisting of four different combinations of horizontal and vertical beds. The major aim of the design was to determine the best hybrid combination which then could be used in the future for refurbishment of older horizontal flow CWs or for the new systems. The mechanical pretreatment consists of mechanical bar screens, a new Imhoff tank, and the original settling tank which has been converted into the accumulation tank from where the wastewater is pumped into the wetlands. The filters are planted with Phragmites australis, Phalaris arundinacea, Iris pseudacorus, Iris sibirica, Glyceria maxima and Lythrum salicaria in order to evaluate and compare various plant species' effect on the treatment process. The new technology includes a tertiary treatment which consists of a greenhouse with a photo-reactor for the cultivation of algae and hydroponic systems (residual nutrients removal), sludge reed-beds and a composting field.

In the Czech Republic, a significant amount of agricultural landscape nutrients is swept away by surface washes and leakages to subsoil. Subsequently there is a negative influence on surface water quality, where of course also point sources of pollution participate in. Flowing surface water often becomes stagnant while the certain self-purifying processes proceed both in the flowing and stagnant waters. It can be simultaneously stated that the self-purifying process is practically uncontrollable, primarily due to the impact of many entering factors. One of the environmental and technical elements providing quality improvement of water running off a water reservoir is deployment of constructed floating wetlands (CFW). The theoretical background, as well as the laboratory measurements carried out on the test land of the Brno University of Technology in experimental tanks, evidence the significant treatment efficiency of the CFW. Within the research activities, we focused on the general pollution parameters set for surface waters. The first results show that the total phosphorus concentration removal efficiency is 38.8 % after 22 days with employment of the CFW which is a considerably higher value compared to the lysimeter with no CFW where the removal efficiency was only 4.37 %. The results can be large-scale applied to most of the small water reservoirs situated in the agricultural landscape.

In recent years, natural wastewater treatment wetland plants have been gaining more attention from researchers and the public due to their low operating costs and efficient way of treating wastewater. Treatment wetland plants with pulse-fed vertical flow filters are one of the most efficient treatment technologies. For optimum operation, intermittent loading of wastewater onto the filter surface is necessary, for which various types of automatic siphons can be used in addition to pumps. This kind of automatic siphons do not require electricity for their operation. The aim of the actual measurements was to specify the hydraulic characteristics of four different types of automatic siphons used in France, Germany, and the Czech Republic. In the course of the laboratory measurements, it was possible to define the basic hydraulic characteristics of the different technical solutions - e.g. maximum water flow, starting and shut-off water level, emptying rate and discharge flow. The measured values then lead to the determination of the total hydraulic losses of the device, while the limits and nature of the individual solutions are shown in comparison with each other. The results can be used for the design of the downstream hydraulic system of the distribution piping that is spread over the filter surface.

As the planet-s population increases, pollution entering waterways increases, and the availability of non-renewable raw resource materials reduces. It is possible to reduce this pollution by constructing treatment wetlands, but these wetlands use significant amounts of natural aggregates. The question arises: is it not possible to replace non-renewable resources with recycled materials made from construction and demolition waste? This article examines the applicability of recycled building materials as filter media for vertical subsurface flow filters. The recycled aggregates of the 0-4 mm fraction are evaluated in terms of grain size and hydraulic conductivity. For the Czech Republic-s available raw recycled aggregates, washing methods are proposed to produce materials that meet the required grain size limits. Untreated aggregates contain a significant proportion of particles smaller than 0.063 mm (up to 21.8%), significantly reducing their hydraulic conductivity and preventing their use in water filtration. However, concrete and masonry aggregates with dust particle contents of 0.3% and 1.5% can be obtained through washing. The washed materials subsequently show an increase in hydraulic conductivity up to the required range of values, that is 10?4-10?3 m s?1. According to the evaluation carried out, it is possible to apply treated recycled materials to wastewater filtration. At the same time, the application of construction waste in constructed treatment wetlands creates opportunities to use fine recycled aggregates (0-4 mm) in these areas, which are currently limited, in the future.