Rivers

The restoration of Gârla Mare and Vrata sites, two adjacent marshlands in a former side branch of the Danube River, has enhanced biodiversity and ecosystem service function. In the past, the area was prepared for fish farming (fish breeding nursery and ponds) using dyke systems, isolating the river from the natural marshlands. This caused the mix of species and habitat in the area to change over time, transforming the marsh into a reed bed.

The main objective of the project was to improve water inundation in the Gârla Mare and Vrata marshlands in the Danube floodplain to preserve and restore the wetlands and associated habitat. The water supply channel was modified through the introduction of sluices and dredging (See Figure 5‑1 for site map). Furthermore, the flood storage capacity was increased and the dykes were reinforced in order to protect active fish ponds against flooding. Project specifications are given in Table 5‑1 (WWF, 2021).

Bulgarian wetlands along the Danube provide essential spawning grounds for numerous species of fish and provide critical winter and feeding habitats for water birds (WWF, 2021). The Persina and Kalimok wetlands are found in the floodplain of the Lower Danube in northern Bulgaria. Persina is the largest of the Belene islands in the Danube River. The island landscape consists of freshwater marshes, riverine forests (which are inundated by the Danube on a seasonal basis), and agricultural land.

In the Orhei Municipality of Moldova, a French Vertical-Flow Treatment Wetland (French VFTW) was constructed in 2013 for primary and secondary treatment of wastewater. Before the construction of this French VFTW, the city of Orhei made use of a wastewater treatment plant located at the top of a hill. The city wastewater had to be pumped up the hill and treated using a high-rate percolating filter. This had become a very expensive operation. The plant’s limited capacity, coupled with increasing wastewater volumes, rendered it ineffective for city-wide treatment. The Moldovan government, under a World Bank funded programme, decided to replace this WWTP with a French vertical-flow treatment wetland (French VFTW). The French VFTW was selected for its ability to minimize operational costs based on the maximum affordable water tariff within the local economic context.

Constructed Wetlands are widely used in Ukrainian peri-urban and rural areas, where conventional centralized WWTPs are not economically feasible or do not exist (Vergeles et al., 2015). Among them, there is also a full scale constructed wetland located in East Ukraine that treats pharmaceuticals (e.g., carbamazepine, diclofenac, ibuprofen, etc.) in hospital wastewater, with removal rates of up to 90 % (depending on the pollutant) (Vystavna et al., 2017). Pharmaceuticals in surface water are considered a threat to drinking water supplies. Similar treatment yields are also achieved for the removal of BOD, COD, TSS and NH₄-N.

The removal of pharmaceuticals was surveyed on a full scale constructed wetland near the settlement of Khorosheve in the Kharkiv Oblast. The treatment site is in the upper part of the Udy River’s floodplain (total treatment area: 2750 m², Qavg: 100 m³/d, residence time: 10-13 days, planted with Phragmites australis). It includes a wastewater piping and distribution system, pre-treatment unit with aeration, four treatment wetland units, two vertical/two horizontal subsurface flow systems, a well, and two sludge drying beds (Figure 5‑5). Treated wastewater is discharged into a ditch, 800 m upstream its inflow into the Udy River, a tributary of the Seversky Donets River. Table 5‑4 (below) summarizes the Khorosheve project specifications.