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Antibiotics contamination and related antibiotics resistance genes (ARGs) in wastewater sludge have been a concern for environmental pollution and human health risk for years. This study investigated the fate of antibiotics and related ARGs in sludge from sludge treatment wetlands (STWs). We examined three sludge treatment beds i.e. unit No.1 was sludge drying bed with aeration tubes; unit No.2 was a ventilated sludge drying reed bed; and the unit No.3 was a sludge drying reed bed without aeration tubes. The targeted antibiotics included oxytetracycline, roxithromycin and azithromycin. The targeted ARGs included tetA, tetC, msrSA and ermB. The results indicated that in all three units antibiotics were removed significantly and related ARGs declined over one year period. The antibiotics concentrations in the surface layer were lower than those in the bottom layer. The highest removal efficiency of the targeted antibiotics was observed in the unit No.2. The removal efficiency of the targeted ARGs influenced by different parameters, especially reeds, aeration tubes and temperature. Correlation analysis between the concentrations of antibiotics and corresponding ARGs showed that in both the bottom and surface layer of all three units, a significant correlation (p 0.05) was found between the concentrations of roxithromycin and azithromycin and the absolute abundances of msrSA. A significant correlation (p 0.05) was also observed between the concentrations of oxytetracycline and the absolute abundances of tetA and tetC. The results demonstrated that STWs can effectively reduce the target antibiotics contents and related ARGs; and the STW with reed and aeration tubes performed better.

Background The dynamics and structure of many bird communities are changing due to the global warming and changes in the land use and management. The Ebro Valley constitutes one of the chief wintering areas for several passerine species in Iberia, and the reed beds spread across this Valley concentrate huge numbers of birds that use them to roost, while the surrounding agricultural areas serve as main foraging habitats. The aims of this work are (1) to quantify how variable a non-breeding passerine bird community associated to a reed bed area in the Ebro Valley is, and, (2) to test for the effect of weather on possible annual fluctuations in species’ proportions at a regional/local scale. Methods We used for that ringing data collected at Badina de Escudera lagoon (Navarra) over a 12-year period. Results Though, overall, the assemblage did not vary strongly among years (most similarity values were > 0.8), we still found a significant linear effect of year on the proportion of captures of Reed Buntings (Emberiza schoeniclus), i.e., the dominant species detected in our passerine community. The increasing loss of weight of Reed Buntings in the community was due to a progressive decrease in its abundance. Conclusions The structure and diversity of passerine community in Badina Escudera was not influenced by meteorological conditions at a local scale, suggesting that local weather would not have an impact on numbers of Reed Buntings in winter.

Nowadays swine slurry management is a very important environmental issue. Sludge treatment reed bed systems are sludge treatment systems based on constructed wetlands. The present study characterizes via 16S rRNA gene high-throughput the bacterial communities contained in untreated swine slurry and treated swine slurry by means of mesocosm-scale sludge treatment reed beds receiving different slurry loadings. The bacterial community composition varied between the treated and untreated slurry, with a notable slurry loading influence also observed. Richness, diversity and ordination measurements of the studied communities evidenced profound differences between the untreated and treated swine slurry bacterial communities; and only slight differences among the treated swine slurry communities. Interestingly, the slurry loading allowed to define two groups: mesocosm communities residing in the highest hydraulic slurry loadings and other mesocosm communities. The pH value emerged as an important community composition, diversity and ordination predictor. The functional bacterial community composition was predicted through the in silico approach. Results confirmed that the main nitrogen cycle metabolic pathways were present in the mesocosm communities with ammonification and assimilatory nitrate reduction as the most commonly detected nitrogen pathways in treated swine slurry.

The succession-driven reed bed habitat hosts a unique flora and fauna including several endangered invertebrate species. Reed beds can be managed through commercial winter harvest, with implications for reed bed conservation. However, the effects of winter harvest on the invertebrate community are not well understood and vary across studies and taxonomic levels. The aim of this study was to investigate the effects of reed harvest on invertebrate communities. Ground-dwelling and aerial invertebrates were continuously sampled for 10 weeks in the largest coherent reed bed of Scandinavia in order to assess how time since last reed harvest (0, 3, and 25years) influences invertebrate biomass, biodiversity and community structure across taxonomic levels. Biomass was measured and all specimens were sorted to order level, and Coleoptera was even sorted to species level. The invertebrate community showed distinct compositional differences across the three reed bed ages. Furthermore, biomass of both aerial and ground-dwelling invertebrates was highest in the age-0 reed bed and lowest in the age-25 reed bed. Generally, biodiversity showed an opposite trend with the highest richness and diversity in the age-25 reed bed. We conclude that it is possible to ensure high insect biomass and diversity by creating a mosaic of reed bed of different ages through small-scale harvest in the largest coherent reed bed in Scandinavia. The youngest red beds support a high invertebrate biomass whereas the oldest reed beds support a high biodiversity. Collectively, this elevate our understanding of reed harvest and the effects it has on the invertebrate communities, and might aid in future reed bed management and restoration.

We investigated the accumulation of litter along a transition gradient from the dunal beaches (B), to the backdunes (BD), to the channels of a coastal wetland (W), considering both the total litter and a sub-category represented by expanded polystyrene (EPS). Using a removal sampling technique carried out in spring (April and May), we hypothesized that: (i) the total accumulation of litter decreases progressively from the dunes to the backdunes to wet environments while (ii) the lighter polystyrene concentrates in the BD-W fringe where the Phragmites australis reedbeds can have a sink role for this polymer. The total litter density showed a significant decrease along the gradient B-BD-W in both months, with an evident collapse between BD and W. Analogously, EPS showed a significant difference in density along the B-BD-W gradient in both months, although with a different pattern: a maximum in the BD and a significant collapse between BD and W. The presence of backdune hygrophilous vegetation (Phragmites australis’ reedbeds) may act as a sink trapping all types of litter in both cases (total litter and EPS). The different accumulation pattern between total litter and the EPS is due to the lower specific weight of the latter polymer: while the generic litter tends to decrease quantitatively moving away from the sea, the lighter EPS is removed by the winds and pushed towards the land, beyond the dune, where it is trapped by the vegetation, thus showing a peak in density in the backdunes. No significant differences were observed between the litter density in the two months (before and after the removal) either considering the total litter and only EPS. This may suggest a continuous supply of litter from the sea, highlighting how clean-ups actions should be carried out with a higher frequency rather than monthly. This may be even more valid in the period of greater frequency of intense weather-marine events (autumn-winter) when a greater quantity of litter is deposited. These are the first data for the Mediterranean regarding a specific role of wetland hygrophilous vegetation as a sink for anthropogenic litter, mainly expanded polystyrene.

Greenhouse gas emission data from the mineralisation process in Sludge Treatment Reed Bed systems (STRB) are scarce. The aim of this study was to quantify the emission rates of carbon dioxide (CO 2 ), methane (CH 4 ) and nitrous oxide (N 2 O) and to investigate seasonal variations in order to estimate the annual greenhouse gas emission rate of the mineralisation process. The full-scale STRB at Helsinge wastewater treatment plant (WWTP) in Denmark was chosen as the study site. Gas emission rates were measured using static surface flux chambers. The measurements were carried out in October/November 2014, March/April 2015, June/July 2015 and January/February 2016. We found that the emission rates of all included gas species were significantly affected by season. For CO 2 and CH 4 , the highest emission rates were recorded in summer, being138 and 5.2 g m −2 d −1 , respectively, while the lowest rates were recorded in winter, being 442 and 0.7 g m −2 d −1 , respectively. For N 2 O, the highest and lowest rates were recorded in autumn and spring, being 0.47 and 0.31 g m −2 d −1 , respectively. Emissions of CO 2 and CH 4 appeared to be affected by changes in temperature, while N 2 O appeared to be affected not only by temperature, but also by the amount of precipitation. An annual greenhouse gas emission rate (given in CO 2 equivalents) of the mineralisation process was calculated for two scenarios based on the assumptions; 1) gas emission rates are not affected by the amount of sludge accumulated in the STRB and 2) gas emission rates are affected by the amount of sludge accumulated in the STRB. The results revealed that the annual global warming potential is to be found in a range between 7 and 13.4 kg CO 2 -eq·PE −1 y −1 .

Industrial coffee processing effluents are acidic and have high contents of organic matter and dissolved solids. These effluents can subsequently cause several adverse effects to human health and aquatic life if discharged directly. Unfortunately, very limited research attention has been focused on the treatment of coffee wastewater. This study highlights the application of phytoremediation as a sustainable approach to treat coffee processing wastewater using local plants in Malaysia, namely, Phragmites karka. A continuous reed bed system with a hydraulic retention time of 3 d is operated for 34 d to observe the efficiency of phytoremediation treatment in removing the total suspended solids (TSS) and colour concentration of industrial coffee effluents. This system effectively reduces the concentration of TSS and colour by 95 % and 76 %, respectively. It is proved that the rooting system of the plants helps in terms of removal performance for both parameters when compared to the unplanted system.

Domestic wastewater is one of the sources of pollutant for water bodies if not disposed properly. Reed bed system is very potential to be used to treat domestic wastewater as it is good in terms of overall performance, low in operation and maintenance costs, and environmentally friendly. This study examined the overall performance of pilot reed bed system planted with two native Malaysian plants of Scirpus grossus and Lepironia articulata in treating real domestic wastewater under short term batch reactor. Four systems were used in this experiment, in which first system planted with S. grossus, second system planted with L. articulata, third system planted with 50% S. grossus + 50% L. articulata, and the fourth system was left unplanted as control reactor. A total of 5 days of parameters observation and two sampling points (on the top of medium and at the bottom of medium) were chosen to analyse the effect of the treatment period and the contribution of rhizosphere area to the overall reed bed performance. The planted system performed very well in removing pollutant reaching up to 99% for TSS, 99.7% for BOD, 96.6% for COD, 100% for ammonium, and 99.6% for phosphate. The addition of plants significantly increased the DO concentration inside reed bed. Both plants showed no significant difference performance in terms of the removal efficiencies. There was a significant difference in terms of removal between both sampling points (up and down) at day 0 and day 1, indicating that rhizosphere area played a very important role in the treatment of wastewater which provide lower pollutant concentration in shorter period of time. There are no significant differences obtained for measured parameter at day 3 and day 5 in all reactor, indicating that the systems already achieved the steady state at day 3 of the observation.

A hybrid reed bed constructed wetland (HRBCW) with aeration system was employed in three-stages; a Surface-Flow (SF) system, a Vertical-Flow (VF) system, and lastly a Horizontal-Flow (HF) system in series. The system was planted with Malaysian native aquatic plant (Scirpus grossus) and it was made up of media arranged in three layers of medium gravel ( ϕ 10–15 mm) at the top, river sand ( ϕ 3–5 mm) in the middle, and larger gravel ( ϕ 30–35 mm) in the bottom of the CW. S. grossus could survive and reproduce with a continuous feed of 86.5 L raw wastewater per day. The results indicate that the system with a 3-day HRT achieved an average removal of 84.7 and 71.0% for NH4-N and PO4-P respectively. Based on this study, the use of HRBCW system for treating household sewage in small communities is a technically and economically feasible using S. grossus that has high effectiveness for treating domestic wastewater.

Due to water scarcity in many arid countries, there is considerable interest in recycling various wastewater streams such as treated urban wastewater for irrigation in the agricultural sector. The aim was therefore to assess if domestic wastewater treated by different wetlands can be successfully recycled to water commercially grown crops. The objectives were to assess variables and boundary conditions impacting on the growth of two different types of peppers fed by domestic wastewater pre-treated by diverse mature constructed treatment wetlands. The growth of both Sweet Pepper (California Wonder; cultivar of Capsicum annuum Linnaeus Grossum Group) and Chilli (De Cayenne; C. annuum (Linnaeus) Longum Group ‘De Cayenne’) fed with different treated and untreated wastewater types were assessed. A few plants suffered from either a shortage and/or excess of some nutrients and trace minerals. The overall growth development of Sweet Peppers was poor due to the high concentrations of nutrients and trace minerals. In contrast, Chilies did reasonably well, but the growth of foliage was excessive and the harvest was delayed. High yields were associated with tap water and an organic growth medium, and a wetland with a high aggregate size, leaving sufficient space for biomass. Low fruit numbers correlated well with inorganic growth media and irrigation water contaminated by hydrocarbons. Findings indicate that nutrient concentrations supplied to the Chillies by a combination of compost and treated waste water are usually too high to produce a good harvest. However, as the compost is depleted of nutrients after about eight months, the harvest increased for pots that received pre-treated wastewater. The project contributes to ecological sanitation understanding by closing the loop in the food and water chain. Findings will lead to a better understanding of the effects of different wetland treatment processes on the recycling potential of their outflow waters.

Wastewater treatment and subsequent effluent recycling for non-drinking purposes such as irrigation contributes to the mitigation of the pressure on freshwater resources. In this study, two vertical sub-surface flow constructed wetland (VSSF-CW) pilot plants were operated to treat municipal wastewater and their effluents were reused for irrigation purposes. One of the wetlands was vegetated with Phragmites australis (Cav.) Trin. ex Steud. (common reed) to compare its efficiency of pollutant removals with the non-vegetated system, which had the same design. COMSOL Multiphysics 3.5a was operated for the Activated Sludge Model 2 (ASM2) to predict the chemical oxygen demand (COD) and ammonia-nitrogen (NH4-N) concentrations. The effluent quality of both treatment systems was assessed for several parameters. Computer simulations show a good compliance between the measured and predicted values of COD and NH4-N for the vegetated system. The calibrated model could be effectively used to predict the behaviours of those parameters as a function of time. Moreover, the effluents of both vegetated (VFp) and non-vegetated (VF) VSSF-CW were significantly (p

The aim of our research was to estimate the amount of energy, C, N and P that potentially could be extracted from the plant biomass harvested annually in the Narew National Park (NE Poland). We found that the conversion of biomass through anaerobic digestion (AD) delivers not only power and heat but also ensures the recovery of nutrients and organic matter for their reuse in agriculture. The most productive community with the highest biomass yield was reed bed of Phragmites australis (9.78 ± 1.66 t d.w. ha−1). It was followed by Phalaridetum and tall sedge communities with Carex elata and C. gracilis (6–7 t d.w. ha−1), rushes of Glyceria maxima (3.61 ± 0.63 t d.w. ha−1), and sedge moss communities with C. lasiocarpa (~1 t d.w. ha−1). Annual vegetation management would result in ~33·103 t d.w. of biomass. The primary net energy output was related to the productivity of the vegetation and ranged from ~17 GJ ha−1 for the sedge moss communities to 160 GJ ha−1 for Phragmitetum australis. The methane potential of the studied species was low and varied between 89 Nm3 t−1 d.w. for Phragmites and 188 NL kg−1 d.w. for Glyceria maxima. Consequently, the unit related net gain of energy in CH4 ranged between 23 and 30 GJ ha−1 for the perennial grasses and tall-sedge communities, and 3.5 GJ ha−1 for the low-productivity sedge-moss communities. As a result of low energy inputs for harvesting, the wetland biomass exhibited a favorable energy balance. The annual potential of CH4 for the whole studied valley section was 3286 ± 439·103 m3 resulting in net electricity potential of ~9.1 GWh and waste heat –32.3 TJ. An “average” hectare of wetland could power 1.2 household and provide 1010.4 ± 169.4 kg of C, 117.8 ± 19.6 kg of N, and 11.9 ± 2.0 of P applied do crop soils along with a digestate.

Eutrophication is a major threat for several species-rich habitat types e.g. fens and meadows in riparian discharge areas throughout Europe, but few data are available to support the supposition that nutrient-contaminated groundwater from agricultural land is the direct cause for the continued decline of these formerly widespread habitat types. In the present study we investigated the role of nitrogen for the distribution of groundwater-dependent vegetation types in discharge areas in Denmark. Specifically we hypothesised (1) that the nitrogen availability in riparian discharge areas is linked to agricultural intensity in the topographic catchment and (2) that the spatial distribution of vegetation in riparian areas is influenced by nitrogen in the groundwater e.g. high productive reed beds dominate in areas with high levels of groundwater nitrogen, whereas species rich fens occur in areas with lower levels of groundwater nitrogen reflecting that incoming nutrients influence the productivity within the areas. We find evidence that the percentage of agriculture in the topographic catchment directly influenced the amount of nitrate in the discharging groundwater in the study areas and that groundwater nitrogen is closely coupled to the distribution of groundwater-dependent vegetation. Meadow and reed bed vegetation being highly productive were associated with higher levels of nitrate in the groundwater compared to low productive rich fen vegetation. From these findings we recommend that protected groundwater-dependent vegetation is mapped in groundwater discharge areas and that only those without presence of protected habitats are considered in rewetting plans to mitigate nutrient loss from agricultural production.

Common reed (Phragmites australis) beds are frequently considered as aggressive and invasive, being subject to numerous conservation management efforts aimed at their eradication by repeated mowing or more aggressive measures. However, the reed beds are associated with a specific community of reed bed specialists, represented typically by various bird flagship species or by Lipara flies. We show here that the reed beds and particularly the reed galls induced by Lipara flies provide unique habitat serving at least 183 bee and wasp species (amounting to 13.6% of the total bee and wasp species known to occur in the Czech Republic, throughout which the sampling sites were located). The reed galls themselves were found to host 13 species of bees and wasps, five of them red-listed, and some of them considered as reed bed specialists. Pemphredon fabricii and Hylaeus pectoralis were the dominant reed gall aculeate hymenopteran inquilines. Hylaeus moricei, Passaloecus clypealis, Rhopalum gracile and Trypoxylon deceptorium were identified as species tightly bound to the presence of reed galls. Among the other species detected was also one previously considered as regionally extinct (Nysson quadriguttatus), nine were critically endangered, 11 were endangered, and 19 were considered as vulnerable. The species found displayed specific habitat requirements, often requiring not only the presence of reed, but also the presence of loose sandy bedrock below the reed bed. These species, which have nearly disappeared from the surrounding cultural landscape, found their surprising refuge in reed beds occurring newly on the loose bedrock of (post)industrial sites, including gravel-sandpits, ash ponds and tailing ponds. The data obtained challenge the common view of the expanding reed beds as a threat to biodiversity, and highlight the importance of reed beds, particularly those of the oligotrophic nature, for effective conservation of the aculeate hymenopteran reed gall inquilines.

The capacity of a hybrid constructed wetland (CW) system consisting of two vertical flow (VF) CWs working alternatively (3 m(2)), one horizontal flow (HF) CW (2 m(2)) and one surface flow (FWS) CW (2 m(2)) in series to eliminate 13 emerging organic contaminants (EOCs) under three different hydraulic loading rates (HLRs) (0.06, 0.13 and 0.18 m d(-1) considering the area of the two VF beds) was studied through a continuous injection experiment General toxicity, dioxin-like activity, antimicrobial activity and estrogenicity were also measured under the highest hydraulic loading rate. The hybrid system was highly efficient on the removal of total injected EOCs (except for antibiotics, 43 +/- 32%) at all three HLRs (87 +/- 10%). The removal efficiency in the hybrid CW system showed to decrease as the HLR increased for most compounds. The VF wetlands removed most of the injected EOCs more efficiently than the other two CWs, which was attributable to the predominant aerobic degradation pathways of the VF beds (70 +/- 21%). General toxicity was reduced up to 90% by the VF beds. Estrogenicity and dioxin-like activity were similarly reduced by the VF and the HF wetlands, whereas antimicrobial activity was mainly removed by the FWS wetland. Bearing this in mind, this injection study has demonstrated that the use of hybrid CW systems is a suitable wastewater technology for removing EOCs and toxicity even at high HLRs. (C) 2013 Elsevier B.V. All rights reserved.

Common reed (Phragmites australis (Cav.) Trin. ex Steud.) is a key wetland species with cosmopolitan distribution. In this study, we examined nitrogen (N) and phosphorus (P) stoichiometry in reed organs, using data of 28 samples from Wuliangsuhai Lake and 17 samples from the wetlands of the city of Zhangye, both located in northern China. Our results showed that the average N and P contents and N:P ratio of the whole plant (geometric mean of mass ± standard deviation) were 14.1 ± 5.3 mg g−1, 0.95 ± 0.54 mg g−1, and 16 ± 5, respectively. These values exhibited significant differences among the organs of reed, including the flowers, leaves, stems, roots, and rhizomes, ranging on average from 6.4 ± 4.2 (stem) to 31.4 ± 5.2 mg N g−1 (leaf), from 0.652 ± 0.647 (stem) to 2.05 ± 0.33 mg P g−1 (flower), and from 10 ± 6 (stem) to 24 ± 4 (leaf) on N:P ratio. The N content closely co-varied with P content within and across organs, and interestingly, P content was more variable than N content. The N and P contents of the whole reed plant, stems, and rhizomes were positively correlated with the availability of these nutrients in water and sediment, but were relatively stable in leaves and flowers. Structural organs probably perform a buffering function of storing N and P in plants. All such stoichiometric patterns can influence the reed bed stand structures such as stem density, stem height, and basal diameter, and may contribute to the wide distributions of reed species in various environments. Our findings are applicable to the management of reed-dominated wetlands.

Landscape changes are driven by several factors, such as habitat loss, fragmentation and degradation. Untangling the independent contribution of each process is crucial, since effective conservation actions depend on the clear identification of the threatening process. Nevertheless in most landscape scale studies configuration metrics are often grouped together without further distinguishing between different habitat properties (e.g. subdivision vs scatteredness of habitat patches) furthermore few landscape scale studies have included measurements of habitat quality thus possibly overlooking important interactions with landscape structure. In order to tackle these issues we carried out a large scale field study following an experimental design that allowed us to disentangle the independent role of landscape processes. We chose the European reed warbler (Acrocephalus scirpaceus) as model species due to its ecological characteristics. Probability of the reed warbler presence increased in landscapes with increasing amounts of habitat and increased with the proportion of flooded reed bed patches in the landscape; variables related to the configuration of habitat, instead, did not play a relevant role in shaping distribution patterns. Results of the modelling inference revealed a crucial complementarity between habitat quality and landscape structure: regulation of the amount of water in the canals increased the habitat suitability of patches only for landscapes with intermediate amounts of habitat.

Three discontinuous batch shallow constructed wetland systems with recirculating subsurface horizontal flow with reed, willow, and without plants were used to assess the removal of nitrogen from landfill leachate in relation to hydraulic retention time and climatic conditions. In all systems redox potential in the beds increased asymptotically from negative anoxic conditions to +67 (reed bed), −2 (willow bed), and +17 mV (control bed), reaching a plateau in two wk. During the first 24 h after feeding the beds all forms of nitrogen decreased significantly. It has been shown that plants release O2 and Norg which was then hydrolyzed to ammonia. Plant-available radiation significantly (p < 0.05) increased the release of Norg and removal of ammonia after the 9th day of the experiment. Low, and relatively constant concentrations of nitrite and nitrate indicated that denitrification had taken place in the beds.

Sludge-drying reed beds can be a cost-effective and sustainable solution to surplus activated sludge dewatering and mineralization, especially for small wastewater treatment plants. However, the simplicity as well as low energy and monitoring requirements of this technology are often counterbalanced by frequent operational problems consisting of slow and insufficient dewatering, poor vegetation growth, odor, and overall poor mineralization of the sludge residues. The main reason is that the general rules for facility design and operation are based on empirical experience rather than on the actual and current sludge parameters. In this study a new method for the assessment of activated sludge drainage properties has been applied to determine the reasons behind operational problems faced by the operators of reed bed facility accepting surplus activated sludge from two wastewater treatment plants in Esbjerg, Denmark. The importance of sludge quality monitoring as well as the damaging effect of shear forces, oxygen depletion, and long-distance sludge transportation were demonstrated. Finally, more general guidelines for reed bed facility design and operation are given, based on experimental data from seven full-scale plants.

The influence of light weight aggregates made of fly ash from sewage sludge thermal treatment (FASSTT LWA) on the nitrogen removal efficiency from artificial wastewater in constructed wetlands (CW) with vertical flow reed bed was investigated. Thirty lysimeters with six different double-layer bed constructions (upper layer of FASSTT LWA with thicknesses of: 0 cm, 12 cm, 25 cm, 50 cm, and 100 cm of the total depth of the lysimeter, above a lower gravel layer), either with or without reed plants were operated with wastewater hydraulic loading rate of 4.67 mm/d. During a six-month experiment, high efficiency of ammonia removal was observed. The influence of FASSTT LWA as a bed material and the presence of reed on CW treatment efficiency was determined. The highest total nitrogen removal efficiency, 59.5%, was obtained in the CW with double-layer lysimeters consisting of 25% FASSTT LWA (upper layer), and 75% gravel (lower layer), and planted with reed.

Constructed wetlands (CWs) for wastewater treatment have evolved substantially over the last decades and have been recognized as an effective means of “green technology” for wastewater treatment. This paper reviews the numerous modeling approaches ranging from simple first-order models to more complex dynamic models of treatment behaviour in CWs. The main objective of the modeling work is to better understand the process in CWs and optimize design criteria. A brief study in this review discusses the efforts taken to describe the process based model for the efficient removal of pollutants in CWs. Obtaining better insights is essential to understand the hydraulic and biochemical processes in CWs. Currently, employed modeling approaches can be seen in two categories, i.e. “black-box models” and “process-based models”. It is evident that future development in wetland technology will depend on improved scientific knowledge of internal treatment mechanisms. Not applicable

In order to investigate the nutrient (namely nitrogen and phosphorus) removal efficiency and the governing internal dynamics of the most widely used wetland type, the horizontal subsurface flow reed bed, in receiving domestic septic tank and secondary effluent in a temperate climate such as Ireland, two systems were designed, constructed and rigorously monitored for a period of over 2 years. Nitrogen removal, as expected, was found to be poor across both reed beds, with only 29% removal of TN across the secondary treatment bed and 41% removal across the tertiary treatment bed, with little distinctive seasonal change. A 15N stable isotope tracer study revealed, in line with the results from the chemical analysis, that nitrogen kinetics in the secondary treatment bed were dominated by continuous plant litter decomposition and mineralisation processes converting stored org-N to NH4-N indefinitely. Similar analysis on the tertiary treatment bed indicated that only limited denitrification of the oxidized forms of N was occurring in the anoxic environment of the bed, while NH4-N and org-N were merely changing form on a cyclic basis. Removal of PO4-P from the secondary and tertiary treatment beds was equally poor at rates of 45% and 22%, respectively. While at their maximum growth in the third year of operation, the total phosphorus in the stems and roots of the Phragmites australis in the secondary treatment bed equated to only 10% of the total P removed over the duration of the bed's operation. In the tertiary treatment bed, more seasonal variability was recorded with intermittent negative removal found during winter periods. This was somewhat more reflected in the P-uptake study for this bed with the roots and stems of the Typha and Iris containing phosphorus, which accounted for 31% of the overall mass removed.

This research investigated the feasibility of using constructed wetland system with a second-stage processing, included duckweed lagoon as a polishing stage, as an appropriate technology for treating the domestic wastewater generated by small communities in the economical underdeveloped cold regions. The reed bed pilot included four basins, of which two were used to plant reed and the two others as witness. The duckweed pilot was set up near the reed beds. The pilot plant was tested with six different BOD, COD, TN, TP, TSS and TDS loadings. The test results showed the artificial reed bed with subsurface flow capable of removing TSS by 92%, BOD by 89% and COD by 78%. Moreover it is possible to remove phosphorus and nitrogen containing compounds by 29% and 35%, respectively. The reed bed effluents were discharged into duckweed lagoon and the removal ratios of the above parameters were once again studied. The results showed reductions of 20% in BOD, 10% in COD, 24% in TSS, 8% in TN and 29% in TP. Based on these studies, the use of artificial reed beds for treating household wastewater in small communities is a sound technical and economical solution, while duckweed can be used as a complementary post-treatment process during the warm seasons.

Sludge reed beds have been used for dewatering (draining and evapotranspiration) and mineralisation of sludge in Europe since 1988. Although reed beds are considered as a low cost and low contamination method in reducing volume, breaking down organic matter and increasing the density of sludge, it is not yet clear whether this enhanced biological treatment is suitable for degradation of organic micro-pollutants such as personal care products. Within this project the effect of biological sludge treatment in a reed bed on reducing the concentrations of the fragrances HHCB, AHTN, OTNE was studied as on the bactericide Triclosan. Additionally, the capacity of different macrophytes species to affect the treatment process was examined. Three different macrophyte species were compared: bulrush (Typha latifolia), reed (Phragmites australis) and reed canary grass (Phalaris arundinacea). They were planted into containers (lysimeters) with a size of 1 m × 1 m × 1 m which were filled with 20 cm gravel at the bottom and 50 cm sludge on top, into which the macrophytes were planted. During the twelve months experiment reduction of 20-30% for HHCB and AHTN, 70% for Triclosan and 70% for OTNE were determined under environmental conditions. The reduction is most likely due to degradation, since volatilization, uptake into plants and leaching are insignificant. No difference between the containers with different macrophyte species or the unplanted containers was observed. Considering the usual operation time of 10 years for reed beds, an assessment was made for the whole life time.

Soil microbial activities in a reed-bed used for effluent purification of a small cheese-dairy farm under a Mediterranean climate were described and studied. This work aims to demonstrate (i) whether certain enzyme activities used as bioindicators of dairy waste degradation (beta-galactosidase and protease) vary over time, which might influence organic matter degradation and (ii) whether specific microbial communities are selected through contact with the discarded effluent using community level catabolic profiles (CLCPs). beta-galactosidase and protease activities were followed in a 14-month monitoring experiment. These enzyme activities were strongly expressed during the whey-discarding period from February to May. CLCPs using Biolog Ecoplate showed great microbial diversity, as described by Shannon-Weaver index, and no difference was observed in microbial diversity between areas at the receiving end of the reed-bed (where effluent was discarded) and those at the opposite end. This may be explained by successive environmental factors which made enzyme activities vary: whey discarded from February to May and Mediterranean climate conditions (drying-rewetting effects on summer). Microbial enumeration using epifluorescence microscopy also showed a pattern linked to Mediterranean conditions with a drastic decrease in biomass during summer drought. These results on functional biodiversity were correlated with high purification yields: the minimum decrease in Biological Demand in Oxygen was 84% and that in suspended solids was 75%.

The reuse of grey water for non-potable water applications is a potential solution for water-deprived regions worldwide. Adequate treatment of grey water prior to reuse is important to reduce the risks of pathogen transmission and to improve the efficacy of subsequent disinfection. This study investigated the presence of common pathogens in grey water and compared the pathogen removal performance of leading contender treatment technologies. The opportunistic pathogens Pseudomonas aeruginosa and Staphylococcus aureus were detected in the grey water tested. Three configurations of constructed wetland, a membrane bioreactor (MBR), and a membrane chemical reactor (MCR) were evaluated for indicator bacteria (total coliforms, Escherichia coli, Enterococci, Clostridia, and heterotrophs) removal over a period of 2 years under conditions of low and high strength grey water influent. Total coliforms were found to be good indicators for P. aeruginosa, showing strong and significant Spearman's rank correlations in the influent grey water (rs = 0.77, P = 0.005) and treated effluents (rs = 0.81, P ≤ 0.001). The MBR provided the highest quality treated effluent and was the most robust treatment technology, remaining unaffected by an increase in influent grey water strength. Of the three constructed wetlands, the VFRB was the most reliable performer under low and high strength influent conditions, indicating aerobic unsaturated wetland to be the most suitable form of the technology for pathogen removal.

At dairy farms in the UK, dirty water is produced from dairy wash water, runoff from soiled yard areas and in some cases silage effluent. It typically contains organic matter, solid matter, nitrogen and phosphorus compounds and pathogens. The purpose of this paper is to test the hypothesis that reed beds can be used to treat high-strength agricultural effluent of 5-d biochemical oxygen demand (BOD5) up to 6000 mg l−1, following either dilution with treated water or pre-treatment such as intensive aeration. The experimental process was designed to treat up to 1/50th of the average volume of 25 m3 d−1 of wastewater produced on the farm. When 500 l d−1 wastewater had been pre-treated in an intensive aeration unit BOD5 removals of the order 98.6% occurred in the aeration plant, 75.1% in the reed bed and 99.6% in the whole system incorporating the reed bed. However, the supply of a smaller volume of 50 l d−1 of raw dirty water diluted with a recycle of 1100 l d−1 of treated water to the reed bed only, led to removal rates of BOD5 as low as 58%. A mathematical model based on the tidal flow of water and first-order BOD5 removal was applied to predict the outlet concentration of BOD5 from the reed beds. During the summer months the correlation between predicted and actual BOD5 was high, as indicated by a correlation coefficient (R2) of 0.882, but in the winter months the correlation was poorer, with a correlation coefficient of 0.763.

Research was conducted at Middle East Technical University (METU), Ankara, Turkey in 2000 to determine whether a reed bed filled with an economical Turkish fill media that has high phosphorus (P) sorption capacity, could be implemented and operated successfully under field conditions. In batch-scale P-sorption experiments, the P-sorption capacity of the blast furnace granulated slag (BFGS) of KARDEMIR Iron and Steel Ltd., Co., Turkey, was found to be higher compared to other candidate filter materials due to its higher Ca content and porous structure. In this regard, a vertical subsurface flow constructed wetland (CW) (30 m(2)), planted with Phragmites australis was implemented at METU to treat primarily treated domestic wastewater, at a hydraulic rate of 100 mm d(-1), intermittently. The layers of the filtration media constituted of sand, BFGS, and gravel. According to the first year monitoring study, average influent and effluent total phosphorus (TP) concentrations were 6.61+/-1.78 mg L(-1) and 3.18+/-1.82 mg L(-1); respectively. After 12 months, slag samples were taken from the reed bed and P-extraction experiments were performed to elucidate the dominant P-retention mechanisms. Main pools for P-retention were the loosely-bounded and Ca-bounded P due to the material's basic conditions (average pH>7.7) and higher Ca content. This study indicated the potential use of the slag reed bed with higher P-removal capacity for secondary and tertiary treatment under the field conditions. However, the P-sorption isotherms obtained under the laboratory conditions could not be used favorably to determine the longevity of the reed bed in terms of P-retention.

This study assessed the accumulation of metals in a horizontal subsurface flow constructed wetland treating domestic wastewater of 350 PE after three years of operation. Metal concentrations in the influent wastewater, effluent, sediment, leaves, stems, and belowground biomass of Phragmites australis were analysed. Spatial variations were assessed by sampling at increasing distance from the inlet and at different positions across the width of the reed bed. All metals except Fe and Mn were efficiently removed in the CW, total metal concentrations in the effluent complied with basic environmental quality standards for surface water, and dissolved metal concentrations were often lower than analytical detection limits. Removal efficiencies varied between 49% for Ni and 93% for Al. Export of dissolved Mn and particulate Fe occurred, probably related to redox conditions in the sediment. After 3 years of operation, the sediment in the inlet area was significantly contaminated with Zn, Cu, and Cd, whereas Pb could form a contamination problem within the near future. The Cr and Ni levels in the sediment were low throughout the entire reed bed. At this stage of operation, the contamination problem was still situated within the inlet area and metal concentrations in the sediment decreased towards background values further along the treatment path. An exponential decrease of the metal mass in the sediment and belowground biomass was seen for all metals except Mn. Contrary to the other metals, Mn concentrations in the sediment increased with distance. For all metals, less than 2% of the mass removed from the wastewater after passage through the reed bed is accumulated in the aboveground reed biomass. The sediment acts as the primary sink for metals.

Sludge Reed beds have been used for dewatering (draining and evapotranspiration) and mineralisation of sludge in Denmark since 1988 when the first sludge processing system was introduced. Sludge from wastewater treatment plants (2500–125 000 PE) is treated in sludge reed bed systems with 1–18 basins with loading rates of 25–2200 tonnes dry solids/year for 10 years. In 2002, approximately 95 systems were in operation. Dimensioning and design of reed bed systems depends on the sludge production rate, sludge type, quality and regional climate. The maximum sludge loading rate is approximately 50–60 kg DS m −2 year −1 . Loading cycles are related to the sludge type and the age of the sludge reed systems. The sludge residue will, after approximately 10 years of operation, reach an approximate height of 1.2–1.5 metres with dry solids content of 30%. The concentration of LAS and NPE (total) in the sludge residue was reduced by a total of approximately 98% and 93%, respectively. Experience has shown that the quality of the final product with respect to heavy metals, hazardous organic compounds and pathogen removal after 10 years of treatment make it possible to recycle the biosolids to agriculture as an Enhanced treated product.

A sand bed and a pond; both vegetated by reed (Phragmites australis), were monitored since their construction in summer 1997 till winter 1999/2000.The mean capacity during the study period equaled 79 ± 21 m3d−1. The flow behind the secondary clarifier was divided equally between the reed bed and the reed pond, both of the same surface area about 300 m2, giving the same hydraulic loads of 132 ± 35 mm d−1. The pH, TC, TOC, IC, N-NO3−, N-NH4+, NTotal, P-PO43− and PTotal have been analysed at the inlet and outlet of both systems The performance of the secondary stage was sufficient except for nitrification (11.2–45.4 mg N-NH4+ dm−3 in the effluent from the secondary clarifier). No significant improvement in ammonia removal in the constructed wetlands has been observed. However, the nitrates quantities has been reduced by half. The investigations revealed better removal of suspended solids, total nitrogen and phosphorus by the reed bed than by the pond. The differences were greater during cold seasons.

This paper describes seven case studies in which ecotechnological approaches are being used to reduce the discharge of nitrogen to the environment in three local government jurisdictions in the moist subtropical zone of eastern Australia. Both technical performance and factors relating to acceptance of the technologies are examined. Three of the technologies have survived early setbacks to achieve increasing acceptance. Composting toilets and reed beds (sub-surface flow wetlands) have achieved takeoff in the on-site wastewater context in the Lismore City Council area where the level of adoption (based on 2004–2005 figures) for both technologies was approximately 30% of newly approved systems. In both cases, the level of adoption has been favoured by local scientific studies which have confirmed claims regarding technical performance and by regulations which encourage the reduction of nitrogen discharge to the environment. Free water surface (FWS) wetlands are installed as polishing devices at three of the 10 sewage treatment plants (STPs) in Lismore and the adjoining Byron and Richmond River Shires. Early problems arising from inexperience at design, construction and management of these wetlands have been overcome as local familiarity has increased. This confidence has been a factor in the decision to support a major upgrade to the West Byron constructed wetland system and to install a further three wetlands locally. A further two technologies each have one full-scale system in operation. A 24 ha multipurpose wetland regeneration project for effluent polishing and transpiration, acid sulfate soil management, wetland regeneration, and carbon sequestration, recently installed at the end of the West Byron STP treatment train, is reducing total nitrogen concentrations from approximately 4–1 mg/L. A landfill leachate treatment system incorporating pond, macrophyte zones, horizontal flow gravel filter and single pass sand filter is reducing NH 4 -N and TKN concentrations by 95% and 84%, respectively. The final two technologies described are associated with the reuse and/or treatment of municipal wastewaters. The annual crops hemp and kenaf have both exhibited high N uptake rates in irrigated crop trials. However, their short growing season has resulted in rejection as production crops at one STP in the Byron Shire. The recent realization that the perennial pasture grass Setaria sphacelata can perform the role of wetland macrophyte has given rise to the concept of the “wet-and-dry-land” cell. Still at the pilot stage, this ecotechnology may have application in areas with distinct wet and dry seasons.

Aspecific leachate that contained 1.036 mgl–1 of 2-chlorobiphenyl was used in the study (255 mgl–1 COD and 133 mgl–1 BOD5). When operated on a 10 day hydraulic retention time (RT), reed beds planted with Juncus effusus removed 60% of the leachates COD, compared to 25% in unplanted beds. The constructed wetlands proved effective at reducing the level of acute toxicity to A. aquaticus and G. pulex. In untreated leachate, the LC50 for A. aquaticus was 57% v/v leachate in deionized water and 5% for G. pulex. When reed beds were operated on a 1–10 day RT, the LC50 for Asellus increased from 69% to below the LC50 threshold. The Gammarus LC50 also rose from 10% to 50%. The maximum toxicity reduction achieved by unplanted beds was 10% towards A. aquaticus and 5% for G. pulex, when operated on a 10 day RT. However, in sub-lethal concentrations of reed bed effluent (100%, 80% and 60% dilutions, obtained from planted beds on a 10 day RT), the final length of Asellus was significantly reduced, in comparison to a deionized water control. It is also speculated that chronic leachate stress may have affected the fecundity of Gammarus, however, insufficient data was collected to statistically validate this hypothesis.

A tidal flow constructed wetland system was investigated for the removal of organic matter and ammoniacal-nitrogen from diluted piggery wastewater. The results demonstrated that the operation of tidal flow enhanced the transfer of oxygen into wetland matrices. The supply of oxygen by the operation (473 gO2/m2d) matched the demand for wastewater treatment. The overall oxygen consumption rate in the system was considerably higher than the typical rate obtainable in conventional wetlands; most oxygen being used for the decomposition of organic matter. Compared with conventional systems, the tidal flow system demonstrated greater efficiency in the removal of organic matter. Significant nitrification did not take place, although 27-48% ammonia was removed from the wastewater. Immobilization by microbial cells and adsorption were the likely routes to remove ammonia under the specific experiment conditions. Percentage removals of BOD5, NH4-N and SS increased after effluent recirculation at a ratio of 1:1 was employed.

Winter cutting of Common Reed Phragmites australis (Poaceae) is increasing in Camargue, southern France, potentially affecting wetlands of high conservation value. We studied its impact on arthropods by comparing four cut and uncut sites with special respect to avian prey availability in the breeding season. The two most important prey groups for breeding passerines, spiders (Araneida) and beetles (Coleoptera), were identified to species in trap catches and diet samples. The arthropod assemblages differed significantly between cut and uncut sites. Phytophagous and saprophagous species showed contrasting responses. Numbers of homopterans increased in cut reed beds, where green Phragmites stem density was higher. Saprophagous woodlice decreased, presumably due to the reduced amount of litter. Densities of some vegetation-dwelling spider and beetle species were lower at cut sites, including two of the most preferred prey species for passerine birds. Consequently, large-scale mechanically harvested reed beds host altered arthropod communities, missing major food components used by vulnerable passerines. However, reed cutting on a small scale may increase habitat heterogeneity and species richness on a landscape level. To contribute to reed bed conservation, EU schemes should reward management that leaves uncut reed patches in the proximity of cut areas to permit their recolonization by arthropods.

The A34 Newbury bypass was opened in England in November 1998. This 15 km of roadway has nine constructed vegetative treatment systems incorporating oil separators, silt traps, grass filters for primary filtration and chemical absorption, reed wetlands for secondary biofiltration, a deep water pool and outflow device to control the rate of water discharge into existing watercourses. Two of these facilities discharge stormwater into the Lambourn sites of special scientific interest (SSSI) river. An evaluation of the heavy metal levels in these two ponds (Ponds J and K) has been undertaken in the 39-month period after the opening of the bypass. Motorway-derived contaminants including Pb, Cd, Cu and Zn were evaluated within pond sediment throughout these treatment facilities. Results reveal that heavy metal levels within the treatment system that possesses a well-established reed bed system decrease rapidly though the facility. It is postulated that the high reed biomass within this facility may be primarily responsible for reducing hydraulic flow thus allowing a greater residence time for sedimentation, filtration and bioaccumulation processes.

During the last decade, the number of constructed wetlands in Flanders (Belgium) increased exponentially. Extensive data collection resulted in a database of 107 constructed wetlands that was used to evaluate certain trends and treatment performances. Design sizes vary between 1 and 2000 population equivalents (PE), with the majority of reed beds having a size smaller than 500 PE. Most reed beds are used as single treatment units, although they are sometimes also combined with other reed beds or even conventional systems. The main purpose is to treat domestic and dairy wastewater. Average removal efficiencies were lowest with free-water-surface (FWS) reed beds (chemical oxygen demand (COD), 61%; suspended solids (SS), 75%; total nitrogen (TN), 31% and total phosphorus (TP), 26%). The best overall performance was obtained with vertical flow (VF) wetlands (COD, 94%; SS, 98%; TN, 52%; TP, 70%), except for total nitrogen removal where combined reed bed systems even did better (COD, 91%; SS, 94%; TN, 65%; TP, 52%). Despite this considerable achievement in removal, the effluent nutrient concentrations of many systems remain too high and entail a tangible danger of eutrophication.

Water-level fluctuations may be used to promote the expansion of emergent vegetation along lakeshores. The authors present the case of the lake Volkerak-Zoommeer in the Netherlands, a freshwater lake created in 1987 after the enclosure of an estuary. Using an experimental area in which the water level could be manipulated, it was shown that partial summer drawdown of the shoreline created suitable conditions for germination and growth of tall emergent species (in particular Phragmites australis). Plant survival and growth depended on subsequent water-level fluctuations and grazing by waterbirds. Based on the experiment and empincai data, a model was developed to predict the effects of the water-level regime on potential reed bed development. The model was applied for four hydrological scenarios that have been considered for the water-level management of the lakeWater-level fluctuations may be used to promote the expansion of emergent vegetation along lakeshores. We present the case of the lake Volkerak-Zoommeer in the Netherlands, a freshwater lake created in 1987 after the enclosure of an estuary. Using an experimental area in which the water level could be manipulated, it was shown that partial summer drawdown of the shoreline created suitable conditions for germination and growth of tall emergent species (in particular Phragmites australis). Plant survival and growth depended on subsequent water-level fluctuations and grazing by waterbirds. Based on the experiment and empirical data, a model was developed to predict the effects of the water-level regime on potential reed bed development. The model was applied for four hydrological scenarios that have been considered for the water-level management of the lake.

On the basis of different sets of aerial photos the dynamics of the reed bed areas of Lake Constance were investigated in relation to the dynamics of the water levels. The objectives of the study were to quantify the changes of reed areas due to different flood events in the last decades and their recovery in the time periods between these events. The results should given information of the relevance of water level variations on reed bed dynamics and the regeneration times of reed beds after extreme disturbance events. Following the extreme flood at Lake Constance in 1999 the reed belts of Lake Constance lost approximately 30 ha (24%) of the lakeside reed beds. The loss is comparable to the situation in the late 1960s, when approximately 40 ha died back due to the extreme flood in 1965 and the high spring water levels in the subsequent years. In the time period between the extreme floods of 1965 and 1999, the reed areas expanded to nearly 85% of the area before 1965. The expansion rates increased with increasing distance to the flood event of 1965. Especially in periods with series of years of low spring water level the expansion rates were high. The damage degrees of the reed areas in the years 2000 and 2002 showed a clear relation to the elevation (i.e. average water level) of the stands. The damage degree increased with decreasing elevation. Furthermore the regeneration process of severely damaged stands was related to the elevation level of the stands. Whereas stands at high elevation regenerate fast, those at low elevation died off completely in the years after the extreme flood. This supports the hypothesis that the water level flutuations play a major role in the reed dynamics of Lake Constance. As a consequence of the climate change an increase in the frequency of high spring water levels is expected. Thus, it seems unlikely that reed stands will ever expand again to the same area as before 1965.

This study investigated the simultaneous variations of temperature, redox potential ( E H ), and contaminants over the width, length, and depth of horizontal flow reed bed (HFRB) systems treating wastewater. The hydrodynamic behavior of HFRBs was also assessed. Experiments were carried out on two HFRB systems. One of the systems treats wastewater from a housing scheme in four pairs of lined, parallel beds with almost equal surface areas (54–56 m 2 each bed) and different length-to-width ( L : W ) ratios, granular medium sizes, and water depths. The other system treats the domestic wastewater from a hotel in two parallel beds, each with a surface area of 187.5 m 2 . The results indicate that temperature does not vary across the width, while changes with length and depth can be significant, especially those associated with depth. Vertical temperature gradients are very important in unplanted beds in summer (12 °C/m) but are greatly reduced in planted beds due to shading (3.4 °C/m). Daily variations in temperature gradients do not have a clear effect on the quality of the effluents from the HFRBs. E H , organic matter, and ammonia do not vary significantly across the width, but they do change with length and depth. These changes are attributed to the fact that the mechanisms involved in water oxygenation mainly occur at the top of the gravel beds. Tracer studies demonstrated that the HFRB systems evaluated had preferential bottom water flow near the outlet.

Effluent recirculation was investigated in a vertical flow reed bed system treating an agricultural wastewater. A comparison was made for the efficacy of this system before and after recirculation was adopted. Recirculation considerably improved the removal of BOD5, COD, suspended solids (SS) and NH4-N. The most significant improvement was made for NH4-N, and nitrification of NH4-N into NO2-N and NO3-N only took place when recirculation was employed. The removal of PO4-P, however, was only slightly improved by recirculation. Generally, the removal rate of NH4-N increased proportionally with its loading onto the system. With recirculation the pH value of the wastewater gradually decreased as a result of alkalinity being consumed during the nitrification process, whereas without recirculation the pH remained virtually unchanged. When recirculation was employed, the ambient temperature did not have a significant influence on the removal of BOD5 but appeared to affect NH4-N removal.

A pilot subsurface flow constructed wetland (CW) has been constructed in the Liaohe Delta, China to treat heavy oil-produced water with large amounts of dissolved recalcitrant organic compounds. Pollutant concentrations and change of wetland plants were periodically monitored. Treatment effectiveness was evaluated and indicated high mean removal efficiencies, 81% for chemical oxygen demand (COD), 89% for biochemical oxygen demand (BOD 5 ), 89% for mineral oil, and 81% for total Kjeldahl nitrogen (TKN) achieved in reed bed#2, to produce wetland effluent average concentrations with COD 77 mg l −1 , BOD 5 3.5 mg l −1 , TKN 2.2 mg l −1 , and mineral oil 2.9 mg l −1 . We observed that during the vegetation growth period there was no influence of heavy oil-produced water on the numbers of leaves of reeds in CW, whereas, the biomasses and heights of reeds showed significant loss with increasing hydraulic loading. The heavy oil-produced water had no obvious effect on the reed indices of cellulous, lignin, pentose and the length/width ratio of cellulose.

Phragmites australis is the most frequently used species in constructed wetlands (CW) for dewatering and mineralization of sludge. Such CW create a very hostile environment for plants because their roots are exposed to permanently anaerobic conditions. Our working hypothesis assumed a simple relationship between the success of reed in colonising sludge flood stands and maximalisation of shoot oxygen production and transport to rhizomes and roots. Morphometric parameters and density of common reed shoots growing in reed bed systems inundated with sewage sludge were investigated. It was proved that flooding with sewage sludge significantly influenced characteristics of common reed populations. In comparison with natural stands, on stands treated with sewage sludge, maximal density of shoots was higher, biomass was twice as high, shoot diameter was significantly greater, and leaf weight ratio of an individual shoot was also significantly higher. Tendency to shorten shoots was noted. Growing period was longer for reed shoots treated with sewage sludge than on natural stands.

The Surrey section of the London Orbital M25 motorway uses mainly detention pond facilities for the treatment of stormwater runoff. A majority of these implement the use of dry detention basins. However, in a few locations biofiltration facilities operate through the use of reed bed systems. An assessment of the removal efficiencies for both wet biofiltration and dry pond treatment facilities was undertaken. Motorway-derived contaminants, including V, Cr, Mn, Co, Ni, Cu, Zn, Mo, Cd, Sb and Pb, were measured in unfiltered stormwater collected during the initial stages of a storm event using inductively coupled plasma mass spectrometry (ICP-MS). Results suggest that a higher level of motorway-derived heavy metal contamination exists in stormwater runoff from a road section with a higher average daily traffic density. In addition, a comparison of both sites shows a higher percentage removal efficiency of heavy metals in stormwater from the biofiltration facility.

A combination of retention pond and reed bed was tested for its effectiveness in reducing non-point source runoff pollution from an urban area. This paper presents data on the development of reed plants (Phragmites australis Cav. Trin .), on the effectiveness of runoff purification and on the accumulation of contaminants in the pond sediment and the reed bed for the years 1993–1995. P. australis was well established and grew according to normal development. The measured length and biomass values of P. australis were larger on sand than on gravel and coarse materials. Toxic levels of heavy metals in the plants were not reached. Harvested plants can be composted. The purification system is effective within the following ranges: The rate of retention of suspended solids and heavy metals varies between 16% and 91%. For chemical oxygen demand the average values is 25%. Poor retention rates usually occur along with very low input concentrations. Generally retention within the reed bed is higher than in the pond. Between 1993 and 1995 the concentration of contaminants within the organic layer of the reed bed increased by 50% for lead and by 90% for poly aromatic hydrocarbons. Until 1994 the concentrations of mineral oil hydrocarbons also increased by 60%. Between 1994 and 1995 however the concentration of mineral oil hydrocarbons in the reed bed decreased rapidly by more than 50%: Mineral oil hydrocarbons underlie biological degradation within the reed bed. In the pond sediment a significant accumulation of heavy metals, poly aromatic hydrocarbons and mineral oil hydrocarbons has also been found. The concentrations of these contaminants are still far from inhibiting the function of the system.

The purification capacity and seasonal variability of two newly created reed bed systems was monitored over 1 year. In one of the systems treating domestic wastewater, the reduction in the concentrations of chemical oxygen demand (COD), total N, total P and fecal coliform bacteria (FC) ranged from 80 to 99%. In the second system, treating a mixture of domestic and agricultural wastewater produced by a cheese dairy, treatment efficiency ranged between 13 and 99%. The removal rates did not show any seasonal pattern for domestic wastewater, in contrast to the mixture of domestic and agricultural wastewater with increased removal rates in the summer. Bacteria which are involved in N metabolism was estimated by the most probable number-test (MPN). In both reed bed systems the MPN of proteolytic bacteria, ammonifiers, nitrifiers and denitrifiers/g DW of gravel substrate were of the orders of magnitude of 10 4 –10 6 , 10 5 –10 7 , 10 1 –10 5 and 0–10 3 , respectively. On the basis of the microbial assemblage there is a need to improve the conditions for both nitrification and denitrification to enhance the efficiency of N removal.

Lagoon systems generally represent an effective wastewater treatment process for small communities in rural regions. However, sensitive receiving waters promote an increasing need for algal removal and effluent polishing. The study's main objective was to delineate a reed bed process feasible for upgrading lagoon systems. Results are given for two types of small constructed wetlands which have been investigated over a period of several years. The stress is upon the seasonal differences and the effect of dry or wet weather operation. Design, construction and maintenance of the wetlands are described. The reed beds produced high effluent qualities in terms of suspended solids, algae, COD and hygienic aspects. During summer about 50% of influent concentration of chlorophyll and about 60% of suspended matter could be filtered by a subsurface flown constructed wetland. Furthermore, a buffering of pH value and temperature could be observed after the passage of the wetlands.

The present study consists of assessing the efficiency of a macrophyte (Phragmites australis) system in wastewater purification in an arid climate. The experimental system is made up of three beds differing in length (30, 40 and 50 m) and implanted with Phragmites australis. Wastewater inflow through these beds is horizontal with a flow of 10 l.s−1. Retention time varies between 1 and 4 h. The frequency of irrigation is weekly. The studied parameters are: the organic load (COD and TSS), nutrients (total Kjeldhal nitrogen: TKN and total phosphorus: TP) and the parasitical load (helminth eggs). Water, soil and plants are the three components of the experimental system we analyzed. Results reveal that in the output, the decrease in organic load, nutrients and parasitical load is very sharp in the large bed (COD: 62%, TKN: 43%, TP: 14%, helminth eggs: 93%). However, in the small bed (30 m), the decrease is slight (COD: 48%, TKN: 23%, TP: 5%, helminth eggs: 88%). Concerning parasitical load, the study shows that the three beds are effective in eliminating helminth eggs, even with a very short retention time (1–4 h). The quality of the effluent of the reed bed system should be classified within category B according to WHO guidelines (1989) for crops irrigation. Soil sample analysis from entrance to exit shows a decreasing gradient of nitrogen (N), phosphorus (P), organic carbon (Org.C), organic matter (OM) and parasitical helmith eggs. The gradient becomes more significant in the largest bed with decreasing rate, reaching respectively 49%, 44%, 37%, 40% and 100% for TKN, TP, Org.C, OM and helminth eggs. As for the plant material, the composition of major elements (nitrogen and phosphorus) of Phragmites aerial parts shows the same evolution. While the decreasing rate of nitrogen in the leaves reaches 50% in the largest bed, it does not exceed 8% in the smallest bed. Mean aerial productivity of the studied reed beds was estimated at 134 tons dry weight.ha−1. The aerial biomass exported contains only 5–6% of nitrogen and 10–12% of phosphorus with regard to their load at the influent.

The objective of an engineered reed bed is to manage the natural growth of the reeds in order to optimise the processing of the wastewater to be purified. Downflow reed beds, with two treatment stages, have been added in front of a previously installed horizontal flow bed on a dairy farm to treat parlour washings and standing yard wastewater. Recent results have shown that the BOD is being reduced from an average of 1006 mg/litre at the inlet to only 57 mg/litre at the exit from the small final lagoon.