Hybrid constructed wetland systems have recently been used to treat wastewaters where high demand for removal of ammonia is required. However, these systems have not been used too often for small ...on-site treatment systems. This is because in many countries ammonia is not limited in the discharge from small systems. Hybrid systems have a great potential to reduce both ammonia and nitrate concentrations at the same time. In our study we employed a three-stage constructed wetland system consisting of saturated vertical-flow (VF) bed (2.5
m
2, planted with
Phragmites australis), free-drained VF bed (1.5
m
2, planted with
P. australis) and horizontal-flow (HF) bed (6
m
2, planted with
Phalaris arundinacea) in series. All wetlands were originally filled with crushed rock (4–8
mm). However, nitrification was achieved only after the crushed rock was replaced with sand (0–4
mm) in the free-drain wetland. Also, original size of crushed rock proved to be too vulnerable to clogging and therefore, in the first wetlands the upper 40
cm was replaced by coarser fraction of crushed rock (16–32
mm) before the second year of operation started. The system was fed with mechanically pretreated municipal wastewater and the total daily flow was divided into two batches 12
h apart. The evaluation of the results from the period 2007 to 2008 indicated that such a system has a great potential for oxidation of ammonia and reduction of nitrate. The ammonia was substantially reduced in the free-drained VF bed and nitrate was effectively reduced in the final HF bed. The inflow mean NH
4-N concentration of 29.9
mg/l was reduced to 6.5
mg/l with the average removal efficiency of 78.3%. At the same time the average nitrate-N concentration rose from 0.5 to only 2.7
mg/l at the outflow. Removal of BOD
5 and COD amounted to 94.5% and 84.4%, respectively, with respective average outflow concentrations of 10 and 50
mg/l. Phosphorus was removed efficiently despite the fact that the system was not aimed at P removal and therefore no special media were used. Phosphorus removal amounted in 2008 to 65.4%, but the average outflow concentration of 1.8
mg/l is still high. The results of the present study indicate very efficient performance of the hybrid constructed wetlands, but optimal loading parameters still need to be adjusted. The capital cost of the experimental system is comparable to the conventional on-site treatment plant but the operations and maintenance costs are about one third of the conventional plant.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Between March 2006 and June 2008 removal of 34 trace elements was measured on a monthly basis at three horizontal-flow constructed wetlands in the Czech Republic designed to treat municipal ...wastewater. In general, the results indicated a very wide range of removal efficiencies among studied elements. The highest degree of removal (average of 90%) was found for aluminum. High average removal was also recorded for zinc (78%). Elements removed in the range of 50–75% were uranium, antimony, copper, lead, molybdenum, chromium, barium, iron and gallium. Removal of cadmium, tin, mercury, silver, selenium and nickel varied between 25 and 50%. Low retention (0–25%) was observed for vanadium, lithium, boron, cobalt and strontium. There were two elements (manganese and arsenic) for which average outflow concentrations were higher compared to inflow concentrations. Reduced manganese compounds are very soluble and therefore they are washed out under anaerobic conditions.
The paper describes the removal of trace elements in constructed wetlands treating municipal sewage.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•Wetland C sequestration and nutrient retention depends on their landscape position.•In agricultural landscapes, land use intensity drives C and nutrient retention.•Mineral soil wetland sequester as ...much C as peatlands, though burial by sediment.
We measured soil organic carbon (C) sequestration and nutrient (nitrogen-N, phosphorus- P) burial in Czech and Midwest U.S. freshwater floodplain and depressional wetlands to evaluate how landscape position and agricultural land use intensity affects C, N, and P retention. Land use in the South Bohemia of the Czech Republic is dominated by forest and pasture, whereas in the Midwest U.S., land use is dominated by row crop agriculture. Cs-137 and 210Pb dating of soil cores revealed comparable rates of soil accretion among wetland types, ranging from 0.5mm/yr in a Czech floodplain wetland to 2.3mm/yr in a U.S. depressional wetland. Carbon sequestration and N & P burial did not differ among floodplain (47+14gC/m2/yr, 3.7+1gN/m2/yr, 0.47+0.16g P/m2/yr) and depressional wetlands (50+19g/m2/yr, 3.6+1.3gN/m2/yr, 0.51+0.14g P/m2/yr). However, sediment deposition in Czech floodplain and depressional wetlands was only 10–50% (150–340g/m2/yr) of rates measured in U.S. wetlands (650–1460g/m2/yr). Our results suggest that, in agricultural landscapes, land use intensity rather than landscape position – floodplain versus depression – drives wetland C sequestration and nutrient retention through increased sediment deposition.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Three-stage hybrid constructed wetland removed efficiently organics, TSS and nitrogen.•Outflow NH4-N concentrations were below 5mgl−1 also during winter.•Saturated VF CWs as a first stage exhibited ...a positive role in total nitrogen removal.•Substantial amounts of both nitrogen and phosphorus were sequestered in plant biomass.
Hybrid constructed wetlands (HCWs) are very efficient in removal of total nitrogen. So far hybrid-constructed wetlands have been composed of various combinations of wetland units but most common combination is vertical flow–horizontal flow system. Also, multistage HCWs have recently been used. The present study describes the use of three-stage HCWs for treatment of municipal sewage. The system consists of saturated vertical flow, free-drain vertical and horizontal flow units in series. The experimental system with a total surface area of 10.1m2 has been operated for 19 months between March 2009 and October 2010. The results proved that multistage hybrid constructed wetland was able to remove efficiently organics, suspended solids and nitrogen. The overall removal efficiency amounted to 92.5%, 83.8%, 96.0%, 88.8% and 79.9% for BOD5, COD, TSS, NH4-N and TN, respectively. The aerobic vertical flow stage provided high degree of nitrification (removal rate of 4.17g NH4-Nm−2d−1) while remaining anaerobic stages (first and third) provided suitable conditions for denitrification (removal rates of 0.83g N-NO3m−2d−1 and 0.47g N-NO3m−2d−1, respectively). The outflow NH4-N concentrations were below 5mgl−1 throughout the monitored period including winter period when the air temperature dropped below −20°C. Plant biomass sequestered 28% and 26% of phosphorus and nitrogen inflow load, respectively.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•Fishponds, man-made lakes, form an important part of Central European landscape.•In the Czech Republic (CZ) there is c. 24,000 fishponds of total area 518 km2.•There is c. 200 mil. m3 of sediments ...in CZ fishponds for removal and recycling.•Content of toxic metals, organic pollutants and nutrients in sediment is given.•Data from 200 localities in CZ collected in the period 2011–2017 are given.
The results of long-term screening of sediments from the Czech Republic from 2011 to 2017 are presented, more than 80% of the samples of which were taken from fishponds. The total sediment volume of Czech Republic fishponds is estimated to be 197 mil. m3. Quality of the sediment is impacted by numerous factors. Sediment may be used for land application, etc., as long as it abides with legislation limits. All results from our database, containing some 200 sites, have been compared with the Decree regulating the conditions for the application of sediments on agricultural land.
We have evaluated toxic metals (As, Pb, Zn, Cu, Hg, Cd), organic pollutants (C10–C40, BTEX, PAH, PCB, DDT) and nutrient volume. The assessment of results reveal the average concentrations of evaluated metals to have the following ranking: Zn > Cu > Pb > As > Cd > Hg. The most frequent excesses of the limit listed in Decree No. 257/2009 Sb. were reported for cadmium (21 sites, i.e. 13.2%). In the case of organic pollutants, the worst pollutant exceeded the limits for 7.2% of sites. DDT volume values were all below the threshold. The ratio between available nutrients and overall nutrient volume was: 0.5% P; 1.3% N; 48.1% Na; 20.4% Mg; 5.8% K; and 65.7% Ca.
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Common reed (
Phragmites australis) and reed canarygrass (
Phalaris arundinacea) are two most commonly used plant species in constructed wetlands for wastewater treatment in the Czech Republic. ...Growth characteristics of both plants (biomass, stem count, and length) have been measured in 13 horizontal sub-surface flow constructed wetlands since 1992. The results revealed that while
Phalaris usually reaches its maximum biomass as early as during the second growing season,
Phragmites usually reaches its maximum only after three to four growing seasons. The maximum biomass of both species varies widely among systems and the highest measured values (5070
g
m
−2 for
Phragmites and 1900
g
m
−2 for
Phalaris) are similar to those found in eutrophic natural stands. The shoot count of
Phragmites decreases after the second growing season while length and weight of individual shoots increases over time due to self-thinning process. Number of
Phalaris shoots is the highest during the second season and then the shoot count remains about the same. Also the shoot length remains steady over years of constructed wetland operation.
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Constructed wetlands with horizontal subsurface flow (HF CWs) designed for treatment of municipal sewage have been monitored extensively with respect to removal of organics, suspended solids, ...nitrogen, phosphorus and bacteria. However, the information on the removal of various metals and metalloids in these systems is very limited. During the period 2002–2004 aboveground and belowground biomass of
Phragmites australis (common reed) and
Phalaris arundinacea (reed canarygrass) were sampled in three HF CWs in the Czech Republic. Concentrations of monitored elements in both aboveground and belowground plant tissues were similar to those found in plants growing in natural stands. The concentrations were much lower as compared to those found in plants growing in wetlands receiving acid mine drainage waters, waters from smelters or highway runoff. Concentrations decrease in the order of roots
>
rhizomes
>
leaves
>
stems. The leaf:stem concentration ratios were quite similar for all monitored elements ranging between 1.0 and 1.9. The root:leaf concentration ratio varied widely between 1.5 (Cu) and 54 (Cr) with a mean value of 20.0. Belowground/aboveground plant tissue concentration ratios varied from 2.2 (Cu) to 32 (Cr) with the average value of 9.9.
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Constructed wetlands for wastewater treatment in the Czech Republic are commonly planted with reed canarygrass (
Phalaris arundinacea).
Phalaris is a fast-growing grass which may be cut several times ...during the growing season. During 2005, the experiments were carried out at horizontal sub-surface flow constructed wetland Břehov to evaluate whether multiple harvest may increase the amount of 23 trace elements removable via mowing. The plants were cut in mid-June and re-harvested in mid-August. The single harvest was carried out at the end of July during the peak standing crop of this species. The biomass of
Phalaris cut once and twice during the year was nearly identical but analyses of the biomass indicated that the amount (standing stock) of trace elements varied. For 13 elements (As, Ba, Co, Cr, Cu, Fe, Ga, Hg, Mn, Ni, Pb, Sb and U) the standing stock was higher for single harvest, indicating that these trace elements are transported to the aboveground biomass later in the growing season. Standing stock found in the biomass harvested at the peak standing crop as percentage of the cumulative standing stock from two harvests was highest for Hg (385%), Pb (249%) and U (244%). On the other hand, for 10 elements (Al, Cd, Li, Mo, Rb, Se, Sn, Sr, Tl and Zn) cumulative standing stock was higher than the standing stock for one harvest, indicating high accumulation during the early growth stages. For those elements, multiple harvest could be beneficial for element removal from wastewater.
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The paper describes the removal of nitrogen in horizontal sub-surface flow constructed wetlands (HF CWs) for various types of wastewater. The survey includes more than 900 annual means from more than ...300 systems in 36 countries that were categorized into municipal, industrial, agricultural, and landfill leachate. The results revealed that the highest average concentration of total nitrogen (TN) was found in landfill leachate (211 mg l−1), while the highest average loading (3,080 g N m−2 yr−1) was recorded for systems treating wastewater from industrial operations. The average inflow TN concentration and loading for all systems were 63 mg l−1 and 1,158 g N m−2 yr−1, respectively. For ammonia-N the results were similar — the highest average inflow concentration (162 mg l−1) was recorded for landfill leachate and the highest average loading was recorded for agricultural wastewaters (2,722 g N m−2 yr−1). The results also indicated that there is a good relationship between inflow and outflow concentrations and loadings for both TN and NH4-N. Harvesting aboveground biomass of emergent macrophytes in HF CWs removes only limited amount of nitrogen as compared to inflow load (commonly < 10%).
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Biomass of
Phragmites australis growing in four constructed wetlands with horizontal sub-surface flow (HF CWs) designed for treatment of municipal sewage in the Czech Republic have been analyzed for ...19 trace elements. The biomass was harvested during the peak standing crop in early September and divided into stems, leaves, flowers, roots and rhizomes. Concentrations of monitored elements in both aboveground and belowground plant tissues were similar to those found in plants growing in natural stands. The highest concentrations were recorded for Al, Fe, Mn, Ba and Zn while the lowest concentrations were those of Hg, U and Cd. Concentrations decreased in the order of roots
>
rhizomes
>
leaves
>
stems. The root/leaf ratio averaged 70 and varied between 1.4 for molybdenum and 392 for cobalt. The belowground/aboveground concentration ratio ranged between 0.9 and 69.5 with an average value of 19. Due to average aboveground/belowground biomass ratio
>
1, the belowground/aboveground standing stock ratios were lower with six elements (Ba, Zn, Se, Hg, Mo, and Mn) having this ratio
<
1.
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