Integrated Constructed Wetland Research Articles

Adaptive neuro-fuzzy inference system for real-time monitoring of integrated-constructed wetlands.

Monitoring large-scale treatment wetlands is costly and time-consuming, but required by regulators. Some analytical results are available only after 5 days or even longer. Thus, adaptive neuro-fuzzy inference system (ANFIS) models were developed to predict the effluent concentrations of 5-day biochemical oxygen demand (BOD5) and NH4-N from a full-scale integrated constructed wetland (ICW) treating domestic wastewater. The ANFIS models were developed and validated with a 4-year data set from the ICW system. Cost-effective, quicker and easier to measure variables were selected as the possible predictors based on their goodness of correlation with the outputs. A self-organizing neural network was applied to extract the most relevant input variables from all the possible input variables. Fuzzy subtractive clustering was used to identify the architecture of the ANFIS models and to optimize fuzzy rules, overall, improving the network performance. According to the findings, ANFIS could predict the effluent quality variation quite strongly. Effluent BOD5 and NH4-N concentrations were predicted relatively accurately by other effluent water quality parameters, which can be measured within a few hours. The simulated effluent BOD5 and NH4-N concentrations well fitted the measured concentrations, which was also supported by relatively low mean squared error. Thus, ANFIS can be useful for real-time monitoring and control of ICW systems.

Enzyme activities in pilot-scale constructed wetlands for treating urban runoff in China: temporal and spatial variations

Two pilot-scale integrated constructed wetland (ICW) systems were constructed to assess the feasibility of treating urban runoff in Hefei, P.R. China. Each ICW consisted of a down-flow chamber (50 m2, planted with Canna indica), an up-flow chamber (50 m2, planted with Iris pseudacorus), and a horizontal subsurface-flow chamber (50 m2, planted with Acorus calamus) in series. Substrate enzyme activities, growth of vegetation, and contaminant removal efficiencies were monitored during a one-year period. These two systems, achieved an average efficiency of 64.8% for total phosphorus (TP), 59.6% for total nitrogen (TN), 52.7% for ammonium (NH4+-N), and 72.7% for chemical oxygen demand (COD). There were significant correlations between the phosphatase (PP) activity and the removal efficiencies of TP and COD, as well as between the urease (UR) activity and TN removal. The activities of both nitrate reductase (NR) and PP were the highest in down-flow chamber (DFC), and then in up-flow chamber (UFC) and horizontal subsurface-flow chamber (HFC), successively. Meanwhile, the maximum enzyme activities of DFC and UFC occurred in summer or autumn when plants were in the vigorous growing stage. Furthermore, the enzyme activities of both PP and UR were significantly correlated with all growth parameters of C. indica in DFC. Significant correlations existed between the root number of I. pseudacorus, and PP and UR activities in UFC. In HFC, there were no significant correlations between the enzyme activities (PP, UR, and NR) and all growth parameters of A. calamus.

Nitrogen transformations and mass balance in an integrated constructed wetland treating domestic wastewater.

Nitrogen (N) transformations and removal in integrated constructed wetlands (ICWs) are often high, but the contributions of various pathways, including nitrification/denitrification, assimilation by plants and sediment storage, remain unclear. This study quantified the contributions of different N removal pathways in a typical multi-celled ICW system treating domestic wastewater. Findings showed near complete average total N retention of circa 95% at 102.3 g m⁻² yr⁻¹ during the 4-year period of operation. Variations in total N and NH4-N removal rates were associated with effluent flow volume rates and seasons. According to the mass balance estimation, assimilation by plants and sediment/soil storage accounted for approximately 23% and 20%, respectively, of the total N load removal. These were the major N removal route besides microbial transformations. Thus, the combination of plants with high biomass production offer valuable opportunities for improving ICW performance. The retrieval and use of sequestered N in the ICW sediment/soils require coherent management and provide innovative and valuable opportunities.

Integrated constructed wetlands for treatment of dairy operation runoff in Eastern Tennessee during first year establishment

Integrated constructed wetlands (ICWs) were implemented to reduce nutrient and sediment transport from a confined-animal dairy operation in East Tennessee. The objectives of this study were to (1) characterize first flush concentrations of potential pollutants from a typical confined animal dairy operation, and (2) determine if two ICWs have acted as hydrologic and physicochemical buffers in agricultural drainages during the establishment phase (first year after construction). Nine events between the two ICWs were sampled within the first year of construction and flow rates were continuously measured at the inlets and outlets. First flush sampling showed that phosphorus concentrations exceeded critical levels in six of the eight sampled events and nitrogen concentrations exceeded critical levels in half of the sampled events. Suspended solids, organic carbon, and phosphate were the most commonly detected pollutants of concern carried by runoff leaving the dairy operation. The documented performance of ICWs indicated that the practices generally reduced sediment and nutrient concentrations in runoff flowing to receiving waterways during wet weather conditions during the first year following construction and acted to buffer hydrologic pulses by reducing peak flow rates. In four sampled storm events spanning the time of late summer through winter, a total of over 2200kg of suspended solids and 0.22kg of nitrogen were retained in one ICW. Organic carbon was exported from the ICW practices during most events. Overall, the practice removed significant amounts of suspended solids and nitrogen, and event-based phosphorus.

Design of a novel constructed treatment wetland system with consideration of ambient landscape

A ‘fan-shape’ constructed wetland (CW) system is designed to treat domestic wastewater as well as to provide an aesthetically pleasing and environmentally sensitive landscape with ornamental plants for recreation. The system consists of two-stage subsurface horizontal flow CW cells with dewatered alum sludge cakes as the main substrate to ensure the treatment efficiency. The system is located in a new countryside village in Northwest China. The paper presents the design considerations of the CW together with the surrounding landscape to create an integrated CW (ICW). The study attempts to show how the wastewater infrastructure of CW can be an attractive feature in a community; bringing utility and beauty together, and serving needs for education, recreation and habitat conservation, through integrating engineering and landscape design.

Assessment of long-term phosphorus retention in an integrated constructed wetland treating domestic wastewater.

Due to the nature of the phosphorus (P) removal mechanisms associated with constructed wetlands, the sustainability of P treatment is usually of high interest. As a result, a 4-year dataset from a typical multi-celled integrated constructed wetland (ICW) located at Glaslough in Co. Monaghan, Ireland was evaluated to determine the effects of long-term P loadings and hydrological inputs on P treatment. The ICW was intensively monitored year-round from February 2008 through March 2012 for total P and molybdate reactive phosphate (MRP). Domestic wastewater was loaded at 16.4 ± 0.96 g m(2) year(-1) for total P and 11.2 ± 0.74 g m(2) year(-1) for MRP. Average mass reductions over the monitoring period were 91.4 and 90.1%, respectively. The area-based kinetic coefficients (K(20)) of 11.8 for total P and 15.6 m year(-1) for MRP indicated a high area-specific retention rate. The ICW appeared to have a sustained capacity for P adsorption and retention, but the treatment was influenced mainly by external hydrological inputs and fluctuations in wastewater loadings. Linear regression analyses showed a reduction in mass retention of both total P and MRP with increased effluent flow volumes. Monthly mass reductions exceeded 90% when the effluent flow volumes were less than 200 m(3) day(-1). When monthly effluent flow volumes exceeded 200 m(3) day(-1), nonetheless, mass reductions became highly variable. Designs and management of ICW systems should adopt measures to limit external hydrological loadings in order to maintain sufficient P treatment.

Nitrogen Removal along Vertical direction by Plant Biological Membrane System

Based on the equipment of integrated constructed wetlands (ICWs) with independent intellectual property rights. Plant biological membrane system (PBMS) was constructed to purify nitrogen of sanitary sewage. PBMS includes palm silk, non-woven and floating plant (Trifolium repens L.). Total nitrogen (TN), ammonia nitrogen (NH3-N) was investigated to evaluate the effects of the layered purification and resistance to the outside impact. The results showed that layered purification occurred along the flowing vertical direction. The average removal rate of TN, NH3-N and total dissolved solids was 65.6%, 60.7% and 38.7%, respectively. The TN and NH3-N removal load of the lower, middle and upper layer were 1.0, 0.8, 0.7g/ (m2.d) and 0.8, 0.8, 0.3g/ (m2.d), respectively. The higher concentration of inflow the stronger resists impact load capability. The TN and NH3-N average removal load of the lower, middle and upper layer were 4.1, 1.88, 1.57 times and 3.13, 1.25, 1 time than those of the stable phase, respectively.

Groundwater Quality Impacts from a Full‐Scale Integrated Constructed Wetland

AbstractThe concept of integrated constructed wetlands (ICW) promotes in‐situ soils to construct and line wetland cells. The integrity of soil material, however, may provide a potential pathway for contaminants to flow into the underlying groundwater. This study assessed the extent of groundwater quality deterioration due to the establishment of a full‐scale ICW system treating domestic wastewater in Ireland. The ICW is located at Glaslough in Co. Monaghan, Ireland. It consists of two sedimentation ponds and a sequence of five shallow vegetated wetland cells. The ICW cells were lined with 500‐mm thick local subsoil material, which comprised a mixture of alluvium, organic soils, tills, and gravel. Groundwater samples and head data were collected from eight piezometers, which were installed around the ICW cells. The groundwater and wetland water samples were analysed for water quality parameters such as bulk organic matter, nutrients, and pathogens. Overall, the quality of groundwater underlying the ICW system recorded some contamination with bulk organic matter and some inorganic nutrients. Significantly higher contaminant concentrations were recorded in monitoring wells upgradient and near to the distal wetland cells than downgradient ones, which were near to the proximal cells. For the downgradient piezometers, concentrations seldomly exceeded the natural background levels. Detailed analyses through the application of chemometrics models indicated that the source of contamination was largely of geogenic origin. Findings suggest that ICW systems pose a minimal risk to the groundwater quality; the greatest risk was associated with the distal wetland cells.

Removal of antibiotics and antibiotic resistance genes in rural wastewater by an integrated constructed wetland

Integrated constructed wetlands (ICWs) are regarded as one of the most important removal technology for pollutants in rural domestic wastewaters. This study investigated the efficiency of an ICW consisting of a regulating pool, four surface and subsurface flow-constructed wetlands, and a stabilization unit for removing antibiotics and antibiotic resistance genes (ARGs) from rural domestic wastewaters. The results showed that antibiotics leucomycin, ofloxacin, lincomycin, and sulfamethazine, and ARGs sul1, sul2, tetM, and tetO were the predominant antibiotics and ARGs in the influent, respectively. The ICW system could significantly reduce most of the detected antibiotics and ARGs with their aqueous removal rates of 78 to 100 % and >99 %, respectively. Based on the measured concentrations, the total pollution loadings of antibiotics were 3,479 μg/day in the influent and 199 μg/day in the final effluent. Therefore, constructed wetlands could be a promising technology for rural wastewater in removing contaminants such as antibiotics and ARGs.

Performance evaluation of an integrated constructed wetland used to treat a contaminated aquatic environment

The treatment performance of an integrated constructed wetland (ICW) that was in operation for 3 years was evaluated. Artificial neural network modeling was used to predict contaminant treatment efficiencies based on easily measured field parameters. The estimates for average yearly removals of total phosphorus (TP), total nitrogen (TN), chemical oxygen demand (COD), and total suspended solids (TSS) were 0.81 ± 0.18, 7.17 ± 1.62, 63.80 ± 17.41, and 126.12 ± 48.61 g m−2 d−1, respectively. Removal velocities of contaminants were determined from analyses of inlet–outlet datasets. The areal removal rate constants were 0.46, 0.73, 0.44, and 0.82 m d−1 for TP, TN, COD, and TSS, respectively. The presence of high background concentrations of contaminants (TP: 0.01 mg L−1, TN: 0.13 mg L−1, COD: 6.43 mg L−1, TSS: 14.83 mg L−1) indicated that the water in the ICW was mesotrophic. Statistical methods (i.e., principal component analysis (PCA), forward selection, and correlation analysis) were used to select optimal input subsets for different contaminants. These data subsets were subsequently used for model development. To find the optimal network architectures, a genetic algorithm was introduced to the learning processes. The models were competent at providing reasonable matches between the measured and the predicted effluent concentrations of TP (R2 = 0.9711), TN (R2 = 0.8875), COD (R2 = 0.9359), and TSS (R2 = 0.9164). The results of the models provided information that will be useful for the design and modification of constructed wetlands.

Performance of a pilot-scale constructed wetland for stormwater runoff and domestic sewage treatment on the banks of a polluted urban river

To examine the performance of a constructed wetland system on stormwater runoff and domestic sewage (SRS) treatment in central east China, two parallel pilot-scale integrated constructed wetland (ICW) systems were operated for one year. Each ICW consisted of a down-flow bed, an up-flow bed and a horizontal subsurface flow bed. The average removal rates of chemical oxygen demand (CODCr), total suspended solids (TSS), ammonia (NH4(+)-N), total nitrogen (TN) and total phosphorus (TP) were 63.6, 91.9, 38.7, 43.0 and 70.0%, respectively, and the corresponding amounts of pollutant retention were approximately 368.3, 284.9, 23.2, 44.6 and 5.9 g m(-2) yr(-1), respectively. High hydraulic loading rate (HLR) of 200 mm/d and low water temperatures (<15 °C) resulted in significant decrease in removals for TP and NH4(+)-N, but had no significant effects on removals of COD and TSS. These results indicated that the operation of this ICW at higher HLR (200 mm/d) might be effective and feasible for TSS and COD removal, but for acceptable removal efficiencies of nitrogen and phosphorus it should be operated at lower HLR (100 mm/d). This kind of ICW could be employed as an effective technique for SRS treatment.

Integrated constructed wetlands: hotspots for freshwater coleopteran diversity in the landscape of Ireland

Constructed ponds are small water bodies that have an enormous biodiversity potential. The creation of this habitat can be seen as a valuable ecological enhancement tool, as ponds can host a great number of species. Integrated constructed wetlands (ICWs) are a type of surface-flow constructed wetland formed by interconnected ponds that integrate their water treatment capabilities with other functions such as biodiversity enhancement, carbon sequestration and landscape fit, by virtue of mimicking natural wetlands. ICWs have been shown to have the potential to enhance freshwater macroinvertebrate diversity in Ireland, especially Coleoptera diversity, in agricultural areas due to their unique design adaptability. A total of 67 water beetle taxa were found to inhabit the 15 studied ponds in the Annestown River catchment, Co. Waterford. Furthermore, when the taxa that have the potential to inhabit ICW ponds in Ireland were included a total of 82 water beetle taxa was obtained, which represents 26% of the known Irish aquatic lentic coleopteran fauna and includes several species of conservation interest. If the potential of these small water bodies to support water beetle diversity and that of other aquatic macroinvertebrates is to be maximised, particular attention should be paid to enhancing the range of mesohabitats within the ICW system.

Systemic solutions for multi-benefit water and environmental management

The environmental and financial costs of inputs to, and unintended consequences arising from narrow consideration of outputs from, water and environmental management technologies highlight the need for low-input solutions that optimise outcomes across multiple ecosystem services. Case studies examining the inputs and outputs associated with several ecosystem-based water and environmental management technologies reveal a range from those that differ little from conventional electro-mechanical engineering techniques through methods, such as integrated constructed wetlands (ICWs), designed explicitly as low-input systems optimising ecosystem service outcomes. All techniques present opportunities for further optimisation of outputs, and hence for greater cumulative public value. We define ‘systemic solutions’ as “…low-input technologies using natural processes to optimise benefits across the spectrum of ecosystem services and their beneficiaries”. They contribute to sustainable development by averting unintended negative impacts and optimising benefits to all ecosystem service beneficiaries, increasing net economic value. Legacy legislation addressing issues in a fragmented way, associated ‘ring-fenced’ budgets and established management assumptions represent obstacles to implementing ‘systemic solutions’. However, flexible implementation of legacy regulations recognising their primary purpose, rather than slavish adherence to detailed sub-clauses, may achieve greater overall public benefit through optimisation of outcomes across ecosystem services. Systemic solutions are not a panacea if applied merely as ‘downstream’ fixes, but are part of, and a means to accelerate, broader culture change towards more sustainable practice. This necessarily entails connecting a wider network of interests in the formulation and design of mutually-beneficial systemic solutions, including for example spatial planners, engineers, regulators, managers, farming and other businesses, and researchers working on ways to quantify and optimise delivery of ecosystem services.

Integrated Constructed Wetlands (ICW) working at the landscape scale: The Anne Valley project, Ireland

Availability of clean water in Europe has become a topic of great concern. The Water Framework Directive (WFD) is putting pressure on EU Member States to provide water quality of a high standard throughout the Union. An effective way of tackling this problem is to use Integrated Constructed Wetlands (ICWs) at the landscape scale. Over the last 23years, 15 ICWs have been constructed within the Anne Valley catchment in Waterford, Ireland, to address both point-source and diffuse pollution at the catchment scale. ICWs address a diversity of pollution problems including the treatment of sewage effluent from small villages, wastewater from livestock and waste material from creameries. A series of aerial photographs shows the development of these wetlands within the catchment over time. A catchment scale GIS is currently being developed in Ireland to address the WFD concerns. The integration of ICWs into these catchment models will provide a mechanism for measuring their effectiveness at the landscape scale and for identifying strategic sites for their implementation.

Facilitating implementation of landscape-scale water management: The integrated constructed wetland concept

This research addressed measures necessary to overcome barriers to the implementation of integrated resource management solutions delivering multiple ecosystem services, using the case of the Anne Valley integrated constructed wetlands (ICWs) in County Waterford, Ireland. The benefits of ICWs are reviewed, and feedback from interviews with a range of people from farming, national government and policy, business, County Council and other perspectives, is analysed using the STEEP framework. Whilst we acknowledge bias in interviewee selection, there is considerable local support for ICWs reflecting multiple social, environmental and economic benefits. Indeed, the Irish government has published design guidance for ICWs. However, there remain disconnects between some regulatory and other bodies, which appear to be related to their tradition of looking at issues from a more narrow, discipline-specific perspective. These barriers are not unique to Ireland, but representative of the areas of cultural change necessary to enable more connected ways of thinking, technological development and implementation and its subsequent licensing and regulation. The experience therefore has generic relevance not merely for the broader pervasion of the benefits of ICWs across Ireland and the wider world, but also in evaluating and implementing the efficacy of similar multi-benefit solutions.

Statistical Modeling of Contaminants Removal in Mature Integrated Constructed Wetland Sediments

Multiple regression models, principal component analysis, redundancy analysis, and the self-organizing map (SOM) model were applied to assess the effects of physico-chemical parameters on the treatment performance of contaminated wetland sediments in replicate integrated constructed wetland (ICW) mesocosms treating either farmyard runoff or domestic wastewater. Dissolved oxygen concentration and conductivity were correlated with the reduction of ammonia–nitrogen (NH4–N) and/or molybdate reactive phosphorus (MRP), and the redox potential and conductivity were related to chemical oxygen demand (COD) removal. SOM was selected as the prediction model to provide numerical estimations for the performance of ICW mesocosms. The model was validated, indicating that NH4–N, MRP, and COD removal can be predicted by input variables that are quick and cost-effective to measure. The SOM model is an appropriate method for monitoring the performance of mature ICWs as a source of contaminants such as nitrogen and phosphorus. Although no reduction in the overall performance was observed for ICW Sites 7 and 11, this laboratory-scale study provides valuable warning signs regarding the loss of contaminant removal for ICW systems that have been in operation for a relatively long time.

Characterising infiltration and contaminant migration beneath earthen-lined integrated constructed wetlands

The concept of integrated constructed wetlands (ICW) uses in situ soils to construct and line their cells. The integrity of soil materials, however, may provide a potential pathway for contaminants to flow into the subsoil. In this study, the rates of infiltration and contaminants loading occurring beneath a full-scale ICW treating domestic wastewater were evaluated over an 18-month period. The ICW is located at Glaslough in Co. Monaghan, Ireland. It consists of two sludge cells and a sequence of five shallow vegetated wetland cells. The ICW cells were lined with 500mm thick local subsoil materials. Infiltration water was collected from zero-tension pan lysimeters, which were placed within the soil-liners of the first three ICW cells and analysed for water quality parameters such as chemical oxygen demand, ammonia-nitrogen, nitrate-nitrogen, and molybdate reactive phosphate. Infiltration rates were 4.3×10−9, 3.7×10−9 and 1.0×10−8ms−1 from the first three ICW cells. The variation among locations was small. The apparent hydraulic conductivity of the soil liner, calculated with empirical water budgets, ranged between 3.5×10−9 and 9.8×10−9ms−1across the cells. In the first two cells of the ICW, less than 0.5% of the influent contaminant loading to the cells was lost through infiltration to subsoil. Overall, the amount of infiltration and contaminant loading occurring beneath the ICW cells increased from the proximal cells to the distal one. Higher contaminant loading was recorded in the third cell, which received partially treated wastewater. This implies that each ICW cell has the potential to impact differently on the underlying groundwater and that the potential for groundwater contamination from ICW systems was minimal in the first ICW cells, when compared to the last one.

The use of integrated constructed wetlands (ICW) for the treatment of separated swine wastewaters

The use of constructed wetlands for the treatment of wastewater is an approach that has received increasing attention over the last 30 years due to their innate ability to deal with a wide range of highly variable influent types. The treatment of swine wastewater is an on-going issue due to its generally higher nutrient concentrations and the limited land available to owners. The implementation of the European Union Nitrates Directive and Water Framework Directive is currently placing considerable pressure on agriculture in EU member states with its focus on the improvement and sustained quality of surface waters. The limit of 170 kg of organic nitrogen/ha/annum imposed by the Nitrates Directive can cause severe difficulties for wastewater management in the piggery industry in Ireland, where spreadlands are already receiving high application rates of organic N. A replicated mesocosm integrated constructed wetland (ICW) approach was examined for the effective treatment of anaerobically digested separated swine wastewater with emphasis on nutrient removal. These mesocosm systems are based on operations identified in the available literature as well as on the ICW Concept pioneered in Ireland. The removal efficiency yielded substantial results over an 18 month period and highlighted high mass removal of ammonia–nitrogen (98.1–99.9%) from the influent. The removal recorded in all operational replicates throughout the study period showed that wetlands based on the ICW concept may very well prove to be a viable and sustainable approach for the treatment of swine wastewaters in Ireland whilst successfully addressing both the Nitrates and Water Framework Directives.

A review of the potential of surface flow constructed wetlands to enhance macroinvertebrate diversity in agricultural landscapes with particular reference to Integrated Constructed Wetlands (ICWs)

Integrated Constructed Wetlands (ICWs) constitute an alternative way of cleansing water in agricultural areas to conventional water treatment plants. These pond systems integrate their water treatment capabilities with other functions such as biodiversity enhancement, carbon sequestration and landscape fit, by virtue of mimicking natural wetlands. ICWs have shown to have potential to enhance macroinvertebrate diversity in agricultural areas due to their unique design flexibility. We suggest that ICWs characterised by adequate shore sloping and presence of complex habitat mosaics, as well as other design considerations, would maximise the potential of these systems to enhance macroinvertebrate diversity. In addition, it would be highly beneficial to increase the total ICW area and to increase the total number of ponds in a system accordingly from a minimum of four to at least five. This article also highlights the need not only to develop policies that focus on the creation of ICWs but also to foster a number of management practices that rely on the active involvement of farmers. The inclusion of additional ponds in selected ICW systems could be the means to inform local communities as to the importance, attractiveness and conservation value of ponds.

Integrated Constructed Wetlands (ICW): Ecological Development in Constructed Wetlands for Manure Treatment

In Flanders (Belgium), treatment systems based on constructed wetlands have been successfully implemented to treat the liquid fraction of separated pig manure, resulting in water that meets the stringent discharge criteria. As these systems have proven their nutrient removal performance, attention has moved towards the concept of biodiversity development from a perspective of Integrated Constructed Wetlands (ICWs). The spontaneous colonization of constructed wetlands with macroinvertebrates was examined to quantify the added biological value presented by a farmyard treatment wetland. In total, 17 taxa were found. The diversity of macroinvertebrates increased along the water treatment path in the system and was higher in summer than in autumn. Several pollution sensitive taxa like Orthetrum, Ischnura, and Cloeon were found at the last basins of the treatment wetland chain. Most species were insects, since their adults can easily aerially colonize these recently constructed systems. Water quality was assessed using the Multimetric Macroinvertebrate Index Flanders (MMIF), and showed a general increase towards the end of the treatment. The MMIF increased significantly with decreasing nutrient levels. ICWs adequately combine the treatment of wastewater with supporting and enhancing biodiversity in agricultural landscapes.