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This special issue of Ecological Engineering provides an overview of research within the Everglades Stormwater Treatment Areas (STAs) over the past decade to understand the ecology and the biogeochemical processes that affect phosphorus (P) retention in these constructed wetlands. This research was established within the South Florida Water Management District's Restoration Strategies Science Plan (RSSP). The RSSP was developed in 2012, updated in 2018, and produced a total of 21 studies. The goal of RSSP research is improve understanding of the factors contributing to P retention, to support management of the STAs to attain and sustain a stringent outflow total P concentration goal (i.e., the Water Quality Based Effluent Limit or WQBEL) and to maintain the wetland plant communities used to achieve this goal. Compliance with the WQBEL will reduce P loads to the Everglades to support restore and maintain this special ecosystem. This synthesis paper presents an overview of the STAs and their purpose and then summarizes the findings from the publications included in this special issue as well as previous STA related research. From this synthesis, a list of potential management options to enhance P retention in the STAs is presented. • Stormwater Treatment Areas (STAs) built to reduce P in runoff entering the Everglades. • STA discharge must meet strict low P concentration limits. • P biogeochemistry research conducted to support management of the STAs. • P removed by particle settling, biogeochemical processes and plant uptake. • Fauna excretion, bioturbation, and internal loads substantially affect P retention. [ABSTRACT FROM AUTHOR]

Abstract This editorial describes a 12-paper special issue that began with a symposium at EcoSummit 2016 in Montpellier France in August/September 2016 with a focus on ecological engineering and spatial planning in coastal seascapes. The papers in this issue review ideas around experimental design for testing and application of eco-engineering to reduce the impacts of coastal infrastructure and improve ecological outcomes. Similarly, the need for early integration of ecological principles into engineering designs (eco-design) is highlighted as a key factor in the success of impact mitigation (2 papers). Ideas are presented on spatial planning for coastal infrastructure to mitigate and offset impacts at regional scales (3 papers). At more local scales, empirical evidence is presented to support the manipulation of physical complexity on coastal infrastructure through the addition of artificial rock pools and turf mimics, as well as complex crevice and ledge habitat (3 papers). Chemical manipulations of substrate (concrete) are also explored (3 papers) with the aim of increasing the sustainability of structures and improving specific ecological outcomes. While increasing human pressure has pushed our oceans out of balance, this special issue provides practical solutions, supported by case studies and empirical data to begin helping the “feng shui” of our coastal seascape. Highlights • Modern day seascape comprises a mix of natural and built ecosystems • This special issue is on ecological engineering science of coastal development • Many of the 12 papers began at the EcoSummit 2016, Montpellier France • Authors were from United Kingdom, Australia, United States, France, Hong Kong and Chile • Major advances in ecological engineering need to keep pace with coastal development expansion [ABSTRACT FROM AUTHOR]

This editorial describes a 10-paper special issue that arises from the 4th International Conference on Soil Bio- and Eco-Engineering (SBEE2016) ‘The Use of Vegetation to Improve Slope Stability’ held at the University of Sydney, Australia, in July 2016. The conference focused on current topics and progress in slope stability research and the successful application of soil bio-engineering and eco-engineering techniques to stabilizing slopes in a variety of climatic and geomorphic settings. The papers are divided into the following categories: vegetation and slope stability (1 paper); root-soil interactions (5 papers); slope stability modelling (2 papers); eco-engineering and land restoration (2 papers). Most of the papers present case studies documenting bio- and eco-engineering techniques, site-specific investigations or innovative slope stability modelling approaches and two papers are aimed at standardizing data collection and sustainability assessment practices within the discipline. Case studies are presented by scientific researchers, practitioners, geotechnical and civil engineers, biologists, ecologists, geomorphologists, and foresters from North America, Europe, South-East Asia, Australia, and New Zealand. [ABSTRACT FROM AUTHOR]

This editorial describes a 25-paper special issue that began with a symposium at EcoSummit 2016 in Montpellier France in August/September 2016 with a focus on ecological engineering principles applied to the development of large-scale sustainable landscapes and catchments. The papers are divided into the following categories: watershed management (3 papers); wetland creation and restoration (5 papers); monitoring wetlands (3 papers); lake management (2 papers); restoration of wetland and terrestrial landscapes (6 papers); public health (2 papers); and ecotechnological solutions (4 papers). Some of these case studies are purposeful application of ecological engineering principles; others happened or are happening naturally through self-design. Several of the presentations focus on ecological engineering that involves scales of thousands of hectares or even larger catchments to solve ecological and environmental problems. Case studies are presented by scientists and engineering from North America, Europe, and South America. [ABSTRACT FROM AUTHOR]

Ecological restoration has been risen to a national strategic project for China and become an significant way to realize ecological civilization construction. As an important way to measure the effectiveness of ecological restoration engineering, the corresponding evaluation provides a reliable basis for ecological restoration decision-making and ecosystem management. Based on remote sensing technology with the advantages of short revisit time, large monitoring range, high spatial resolution, this paper proposes a remote sensing evaluation method of watershed ecological restoration effect, so as to monitor the implementation effect of ecological restoration engineering in the watershed and technically check whether the expected goals set before the restoration are achieved. The comprehensive ecological restoration engineering of Yongding River has been implemented since 2016, and it was the first focus of the coordinated development of Beijing-Tianjin-Hebei region to make advances in ecology. In this paper, year 2015 and 2020 were selected as the before and the after the ecological restoration engineering of Yongding River. The research object was the riparian zone from Luopoling Reservoir to Daning Reservoir in Yongding River Watershed. After obtaining and processing remote sensing images, ZY-3 images were used to obtain land cover data by means of human-computer interactive interpretation, and Landsat images were used to retrieve NDVI data. Based on these data, the changes of the eight indicators of water resources, water ecology and ecological function in the study area were calculated to evaluate the ecological restoration engineering effect. The results showed that the study area has basically realized the maintenance of ecological water quantity, formed the ecological corridor of Yongding River, and effectively enhanced the ecological function and improved the water environment. By verifying the feasibility of remote sensing evaluation method, this paper could provide relevant decision makers and planners with an effective evaluation method for the ecological restoration engineering effect based on remote sensing data and technology. • Remote sensing images and land cover data were utilized to calculate the indicators before and after ecological restoration. • Ecological restoration engineering effect was evaluated from water resources, water environment and ecological function. • Based on the proposed method, the ecological restoration effect in the study area was proved to be satisfactory overall. [ABSTRACT FROM AUTHOR]

This paper is dedicated to numerical analysis of the influence of vegetation on slope's stability using the calculation of the safety factor of different slopes by a classical shear reduction method with the software PLAXIS in 2D. The soil is modelled as an elastic perfectly plastic material. The shear strength of the soil is also modelled using the Mohr–Coulomb criterion. Slope stability is influenced by vegetation mechanical parameters: plant's root matrix system and surcharge due to presence of trees. Based on 2D finite element method, this paper investigates the combined effects of different rectilinear slope geometries, soil types and vegetation mechanical parameters on the slope's factor of safety. The effects of the roots are modelled by increasing the soil cohesion following a classical Wu model. The additional cohesion depends on the vegetation type and on the depth from soil surface. The analysis examined reinforcement effects of the roots’ systems of four idealised types of vegetation growing on three different types of soil composing the slope. The case study was performed on different slope configurations where slope's height and angle were allowed to vary significantly. Two key parameters of the root matrix system had been considered for the finite element analysis: additional cohesion due to the presence of roots and depth of the root matrix. Moreover, influence of geometrical parameters, height and angle of the slope, on the stability of different slope configurations had been analysed by computing slope's factor of safety. Parametric studies were performed to assess the variation of the factor of safety of a slope in case of different geometrical configurations combined with several types of vegetation coverage. Results showed that the slope angle had the greatest impact on variation of factor of safety. Additional cohesion is regarded as the second most important parameter influencing the factor of safety. These two parameters combined play an important role in shallow failures of slopes and significantly affect stability of a slope regardless of a soil type composing the slope. Results of the current study can help practitioners determine if a slope is at risk by the lack of additional roots cohesion combined with different types of soil and young vegetation. Hence, the proposed method helps evaluate slope's vulnerability and could be efficiently used as management or informative tool for ecological engineers and forest conservative practitioners. [ABSTRACT FROM AUTHOR]

Beitang is an ecologically engineered constructed wetland dominated by human activities and is composed of paddy fields, ponds, ditches, courtyards and other related ecological infrastructure with the functions of agricultural production, hydrological regulation, environmental cleanup and ecological agricultural regulation. The history of Beitang extends back more than 2500 years in China, and it plays a very important role in China's agricultural development. This paper first reviews the history of the development of Beitang; then according to the historical structural features of Beitang, it summarizes Beitang as a pond–ditch–courtyard–farmland ecological engineering composed of constructed breakwaters, sluice gates, and water intakes; courtyards; and farmland and irrigation ditches with the functions of water collection, storage and conveyance. Under different terrain conditions, Beitangs exhibit different characteristics. For example, in flat areas featuring a larger pond capacity, longer shoreline and larger area of farmland, a Beitang can serve more rural areas; in hilly areas featuring a smaller pond capacity and smaller area of farmland, ditches serve as a very important structural unit that can connect ponds for water volume regulation between ponds, increase the irrigated area, and achieve gravity irrigation to as great an extent as possible. Moreover, the paper analyzes the hydrological, nutrient cycling and biological processes as well as other ecological processes associated with this type of pond–ditch–courtyard–farmland-system. The paper also proposes five ecosystem services of Beitang: hydrological regulation, ecological purification, soil and water conservation, production functions and biological diversity protection. Finally, the paper analyzes the reasons for the degradation of Beitang over the past 30 years from the perspectives of institutions, management, concepts and technology, and proposes corresponding countermeasures to protect and restore Beitang. [ABSTRACT FROM AUTHOR]

Abstract: The delta of the Colorado River in Mexico supports about a million hectares of riparian, marsh and estuarine habitats of international importance. Some of these habitats depend on flows of fresh and brackish water from the U.S. and Mexico. Up to now, these flows were the incidental result of water management actions taken to provide water for agriculture and municipal use, protect against flooding, and dispose of saline agricultural return flows. This paper briefly describes the wetlands and documents recent bi-national efforts to provide environmental flows to the delta, codified in Minutes 306, 316 and 319 of the water treaty between the U.S. and Mexico for the utilization of Colorado River water. Providing water for environmental uses in this watershed will be a daunting task given the many competing uses for water and expected diminished flows due to climate change. The paper serves as an introduction to a special issue of Ecological Engineering, Wetlands of the Colorado River Delta, which contributes 17 new research articles to the science based on these diverse aquatic habitats. We hope these studies will be useful to those developing management strategies to preserve and enhance these habitats for the future. [Copyright &y& Elsevier]

Abstract Environmental flow, one of the main restoration measures for regulated rivers, aims to restore and sustain degraded riparian ecosystems and the human wellbeing that depends on these ecosystems with a reasonable magnitude, frequency, duration and timing of water flow. However, efficacies of environmental flows are often restrained by other demands along the river and inappropriate water management, leading to only spatially limited habitats being suitable for ecosystem functioning. This paper presents current restoration measures in the lower reaches of the Tarim riparian ecosystem in Northwest China and analyzes ecohydrological dynamics as a function of environmental flows. The groundwater level oscillation before/after and during the environmental flows (i.e., manmade water diversion) was examined, and the Mann-Kendall test was applied to identify the overall trend of change in groundwater depth from 2003 to 2011. The growth, distribution, health status (referred to as "vitality") and renewal potentials of the dominant tree species Populus euphratica were quantified by using individual-based repeated measurements of P. euphratica morphology in two sampling sites (a 100-ha permanent plot and five random sampling plots with 50-m radii) at Arghan village in the lower reaches of the Tarim River. Based on these measurements, the effects of restoration measures on the groundwater recharge and the revitalization of degraded trees were assessed. The main contribution and achievements of the water diversion project on rehabilitation of the degraded riparian forests were evaluated; further, the limitations and challenges faced by of the restoration project were examined. The results of this research could help establish a reference for monitoring changes in riparian forests in Central Asia and possibly recommend restoration measures for riparian forest ecosystems in arid regions worldwide. [ABSTRACT FROM AUTHOR]

Abstract: Traditionally, protection of the coastal area from flooding is approached from an engineering perspective. This approach has often resulted in negative or unforeseen impacts on local ecology and is even known to impact surrounding ecosystems on larger scales. In this paper, the utilization of ecosystem engineering species for achieving civil-engineering objectives or the facilitation of multiple use of limited space in coastal protection is focused upon, either by using ecosystem engineering species that trap sediment and damp waves (oyster beds, mussel beds, willow floodplains and marram grass), or by adjusting hard substrates to enhance ecological functioning. Translating desired coastal protection functionality into designs that make use of the capability of appropriate ecosystem engineering species is, however, hampered by lack of a generic framework to decide which ecosystem engineering species or what type of hard-substrate adaptations may be used where and when. In this paper we review successful implementation of ecosystem engineering species in coastal protection for a sandy shore and propose a framework to select the appropriate measures based on the spatial and temporal scale of coastal protection, resulting in a dynamic interaction between engineering and ecology. Modeling and monitoring the bio-physical interactions is needed, as it allows to upscale successful implementations and predict otherwise unforeseen impacts. [ABSTRACT FROM AUTHOR]

Abstract: The beneficial effect of vegetation on particle deposition is often stated in arboricultural literature but has rarely been researched in detail. To quantify these filtering effects of façade greening, it is necessary to study the accumulation properties of leaf surfaces on particle adsorption. In this paper attention will be given to a measure technique for particle adsorption on vegetation. The presented preliminary study aims to classify the total amount of particles by counting of particles on ESEM photographs. In the PhD research more attention will be given on the relation between particle reduction and the effect of vegetation on air quality improvements. Two locations were investigated, namely: leaves from near a traffic road and from a woodland. A difference in the particle amount was found at the underside and upper side of the leaves. For example, in a sampling at early autumn for the road location roughly 7000 particles (per 1275×950μm) were counted for the upper side, and, roughly 3200 particles for the underside. Also a difference in particle amount was found between the two different locations, respectively roughly 7000 particles for the upper side of the leaf at the road location and roughly 3300 for the woodland location. The comparison must give more insight into the sink capacity of vegetation, but also between the environments. In the paper, results of counting particles on leaves from both locations are provided via a factorial design approach with four independent factors at two levels (height, leaf, time and environment). The outcome of the factorial design shows that there is a difference between the collecting capacity of the leaf (upper side/underside) and between the environments (road/woodland). Fine and ultra-fine particles (i.e., the fractions that are potentially the most harmful to human health) were more abundantly found on the leaves than coarser particles. Also some energy dispersive X-ray analysis (EDS) of the adhered particles is provided. As the main conclusion of this research, it can be said that counting particles instead of weighing particles on a specific leaf area seems to be a proper way to classify aerosol deposition on vegetation. [Copyright &y& Elsevier]

Abstract: Horizontal subsurface constructed wetlands (HFCWs) are examples of the use of appropriate technology for the sanitation of small communities. The most common problem of HFCWs is clogging; but the exact mechanisms and consequences of clogging in HFCWs are still unclear. This paper describes the methodology followed to acquire and analyse the available data and knowledge to amend the clogging phenomena in constructed wetlands. This manuscript also presents an attempt to integrate and reuse the information extracted from the literature and real experiences, to contribute to the prevention and solution of clogging problem. The management of this information allowed the proposal of an operation and maintenance protocol for clogging. The paper concludes with some recommendations to improve the performance of HFCW technology. [Copyright &y& Elsevier]

Abstract: Eutrophication is a world-wide environmental issue. Lake Taihu is a typical large, shallow, eutrophic lake located in delta of River Changjiang (Yangtze River). A large-scale ecological engineering experiment targeted at water quality improvement was implemented in Meiliang Bay, Lake Taihu. In this special issue, there are six papers related to water purification and algal bloom control techniques applied in this experiment. Four papers address the validity and efficiency of water quality improvement of this ecological engineering and one paper presents a similar but small-size ecological engineering. The others focus on macrophyte restoration, aquatic plant management and recycling exploitation. The editorial paper highlights the main results and conclusions from these papers. [Copyright &y& Elsevier]

Abstract: This paper describes the development and operation of an Environmental Decision Support System (EDSS) to improve the operation and maintenance of horizontal subsurface-flow constructed wetlands (EDSS-maintenance). Constructed wetlands (CWs) allow wastewater treatment in a sustainable manner since they involve low energy consumption, low construction and functioning costs and low environmental impact. However, operation and maintenance activities are essential to guarantee reliability in CWs performance. The definition of operation and maintenance protocols depends on several quantitative and qualitative aspects such as wastewater treatment plant configuration, CW design, influent characteristics, sensitivity of the receiving media, etc. Bearing this in mind and considering the limited technical knowledge about CWs, the need for a new tool to support CW performance is clear. In this sense, EDSSs offer a new approach because they can tackle problems of complex and uncertain systems. The EDSS-maintenance provides operation and maintenance manuals specifically defined for every CW. To achieve it, the required knowledge was implemented within a rule-based system, which forms the backbone of the EDSS. Several features presented in this paper demonstrate how the EDSS-maintenance provides a proper platform to support the necessary collaborative work in the ecological engineering problem of horizontal subsurface flow CWs operation and maintenance. [Copyright &y& Elsevier]

Abstract: This paper describes the development of Taiwan''s localized ecological engineering methods to make the mitigation works more effective. To strengthen the soil and water conservation and protection of the ecological environment, comprehensive mitigation planning is necessary with considerations that include balancing the safety, ecology, and landscape, and treating the whole watershed as a unit. To demonstrate the achievement of the promotion of the ecological engineering methods in Taiwan, this paper illustrates two complete mitigation examples for a debris flow torrent and a stream. Most of the mitigation works have survived and are still stable (with some minor damages) after the two strong typhoons of 2004. We show that the developed ecological engineering methods are very suitable in mitigation and worthwhile for further promotion for Taiwan''s ecological environment. [Copyright &y& Elsevier]

Abstract: Two international meetings on ecological engineering, with a focus on riparian buffer zones, served as the source for selected papers in this special issue: (1) an International Workshop on Efficiency of Purification Processes in Riparian Buffer Zones: Their Design and Planning in Agricultural Watersheds, jointly organised by Hokkaido University, Japan, the National Agricultural Research Center for Hokkaido Region, Japan, Civil Engineering Research Institute of Hokkaido, Japan, and the Institute of Geography, University of Tartu, Estonia, and held from 5 to 9 November 2001 in Kushiro City, Hokkaido, Japan; and (2) an International Conference on Ecological Engineering for Landscape Services and Products, jointly organised by the International Ecological Engineering Society (IEES) and Lincoln University, Christchurch, New Zealand, and held from 25 to 29 November 2001 in Christchurch, New Zealand. At these two meetings, altogether 94 oral presentations (17 from invited speakers) and 15 posters by representatives from 21 countries were presented. The editorial paper highlights trends in investigation of the purification processes in riparian buffer zones as well as planning, design and management aspects of riparian buffers regarding the wide spectrum of their ecological functions; it characterises the two international meetings which served as sources for the selected papers and briefly explains the main aspects of these papers. [Copyright &y& Elsevier]

Ecological services were initially used to quantify the benefits used in valuation of environmental protection, as they helped stakeholders to understand the benefits that ecosystems bring to people. As a result, they increased support for ecological engineering, including ecosystem restoration. However, by failing to account for costs, and particularly for indirect costs such as the tradeoffs among ecosystem services under different land uses, the analyses were incomplete and often provided poor support for policy development and land management to promote environmental conservation. In this paper, we provide a framework for assessing the net value of the benefits provided by ecosystem services (i.e., the benefit that remains after subtracting key costs), taking the Beijing Plains afforestation project as an example. Furthermore, we analyzed the importance of scale effects and marginal changes in ecosystem services assessment, and highlighted the uncertainty of evaluation results caused by basing some of the analysis on market prices, which can change unpredictably. To better support conservation activities and maximize the ecological benefits obtained from an environmental strategy, it’s necessary to obtain accurate estimates of the net value of ecosystem services by accounting for an increasing range of direct and indirect costs, calculated at the same scale as the project implementation and accounting for marginal changes, thereby providing better support for policy development and implementation. [ABSTRACT FROM AUTHOR]

This paper is dedicated to a numerical simulation using a 3D model applied to analyze a hillslope’s stability in an ecological area in Togo. The 3D model is applied to two natural slopes prone to landslides located in Atakora mountains. The slopes are covered by a randomly distributed heterogeneous vegetation. There were four species of timber and one species of firewood present on the studied sites. Samples of soil and root systems were collected and tested in the laboratory in order to determine their properties which were then used as entry parameters for the 3D numerical model. The study examines the influence of natural forest stands and the morphology of the root system on slope’s stability. It was noticed that, close to the tree’s trunk, the additional cohesion due to the presence of the roots had a significant influence on the improvement of the slope’s stability. Moreover, the depth of the root system as well as spatial repartition and the density of trees on a given site have a major impact on the stability of a hillslope. The model proposed here can be used as a decision-making tool in elaboration of forest management plans and strategies. [ABSTRACT FROM AUTHOR]

In a great number of scientific articles on water quality improvement using constructed wetlands (CW) and riparian buffers zones (RBZ) at catchment scale, contradictory results are found. In most cases this is due to underestimating or even ignoring the role of the hydrological factor for water quality improvement. It has often resulted in biased estimates of buffering systems’ efficiency at catchment scale and, consequently, has caused planning and establishment failures, mistakes and inconsistencies in legislative acts and finally, it has influenced stakeholder’s willingness to support these eco-technological measures. In this paper we present a short but critical overview of the potential of CWs and RBZs in water quality improvement at catchment scale and highlight the most important aspects to be considered when planning, establishing and managing these systems. [ABSTRACT FROM AUTHOR]

A series of ecological projects, including forest and dike-pond projects, were constructed in the littoral zone of the Three Gorges Reservoir (TGR) to maintain the ecological safety of this area. Previous ecological designs mainly focused on the functions of ecological engineering for environmental purification, economic value and increased biodiversity. However, the variations in land-use may alter the emissions of greenhouse gases (GHGs), which were ignored in our previous design. In this paper, the carbon sequestration benefits of ecological engineering were evaluated after dynamically monitoring the GHG emissions from different land-use sites during the growing (April-September) and submerged (October-March) seasons. The results showed that CH 4 fluxes in the dike-ponds (3.76 CH 4 -mg m −2 h −1 ) and rice paddies (6.09 ± 1.60 mg-CH 4 m −2 h −1 ) were significantly higher than those in the natural littoral zone (0.77 ± 0.27  mg-CH 4 m −2 mg-CH 4 ·m −2 h −1 ) and forest project (0.57 ± 0.31 mg-CH 4 m −2 h −1 ) during the growing season. There were no significant differences in the CO 2 fluxes from different land-use sites. The emission of N 2 O from different land-use sites was low and ranged from −0.02 to 0.07 mg-N 2 O m −2 h −1 . The growing season contributed to more than 76% of the cumulative annual GHG emissions. Direct GHG emissions and the carbon sequestration ability of species determined the net carbon sinks in the littoral zone. Net carbon sinks in the forest projects with different understory plant communities showed a small variation, with a range of −2.58 to 3.40 t-CO 2 ha −1 year −1 , but the design of the dike-pond projects should favor species that are positive net carbon sinks, e.g., Sagittaria (19.76 t-CO 2 ha −1 y −1 ) and Canna generalis (16.79 t-CO 2 ha −1 y −1 ), rather than those that are negative net carbon sinks, e.g., Trapa natans (−11.79 t-CO 2 ha −1 y −1 ). [ABSTRACT FROM AUTHOR]

Forest plantations can help to reinforce soil and improve hillslope’s stability against shallow landslides. Based on 3D finite element method implemented in SIMULIA software, this paper develops a 3D numerical simulation model to assess impact of forest’s stands structure and 3D root system morphologies on hillslope’s stability. A preliminary analysis is performed to assess the impact of different stand parameters and root morphologies on the slope’s safety factor as well as on the volume of soil mobilized by a landslide. Regarding tree’s root morphology, we found that the overall slope’s stability mainly depends on the depth of root’s system and on additional cohesion provided by the roots. Hence, tap-like block morphology provides the best overall stability improvement. Furthermore, among the stand parameters, inter-tree distance in the slope direction has the greatest influence on the slope’s safety factor. The rectangular pattern of stand distribution exhibits the lowest inter-tree distance in the slope direction and significantly improves slope’s stability. Finally, the volume of soil mobilized during a landslide shows noticeable variations through root block morphologies. However, for a given root morphology, the stand distribution does not cause significant differences in the volume of soil mobilized during a landslide. [ABSTRACT FROM AUTHOR]

This paper investigates the structural properties of four common riparian tree species and their reconfiguration under hydrodynamic loading in a towing tank in foliated and defoliated conditions. 3D tree models were generated by digitizing twenty 0.8–3.3 m tall specimens at branch level. Branch diameters and lengths were measured in order to calculate the one-sided stem area and stem volume over the plant height. The novelty of the investigations originated from the characterization of the reconfiguration which was achieved by combining the contracted width, the deflected height, and the underwater projected area in order to determine the porosity at different velocities. The results showed that the basal diameter could be used to predict the entire total one-sided stem area, although this method was not capable of reproducing the observed non-linear vertical distributions. The flow-induced width contraction contributed significantly to the reduction of the rectangular cross-sectional area occupied by the plant. The porosity of the foliated trees increased at the lower velocities, and then decreased at the higher velocities. Overall, detailed spatial–structural analyses of woody vegetation provided valuable information about plant behaviour under load, and thus are helpful for improving the determination of the physically based parameters of complex vegetative elements which is highly relevant for environmental modelling in order to fill the gap of knowledge concerning the hydrodynamic and aerodynamic flow around trees. [ABSTRACT FROM AUTHOR]

The river is an essential part of water resources, which has unique ecological structure and function. With the rapid socio-economic development, the improper use of water resources has led to a series of structural and functional decline of the river system, such as water pollution, environmental degradation and river shrinkage. How to restore damaged river ecosystems to an ecologically healthy status has become one of the important environmental issues, which is the key to achieve the goal of productivity improvement, ecosystem balance and sustainable development. And also, the structure and function of the river ecosystem should be pre-assessed before the restoration. In this paper, the Liangshui River, a tributary of Daling River in the arid region of western Liaoning Province, is selected as a study site. An assessment index system involving 21 defined indices on structure and function of river ecosystem is firstly established. A mathematical method for comprehensive assessing the structure and function of river ecosystem is proposed based on the Set Pair Analysis (SPA) and Quadrant Method. Then, the evaluation value is gained at the ecosystem level. The result shows that the assessment value of structure and function is −0.513 and −0.208, respectively, which means that the Liangshui River ecosystem is defective in structure and sub-healthy in function. It is necessary to choose potential development emphasized on the structurally rehabilitating of the Liangshui River ecosystem. Based on the above, ecological engineering measures and suggestions are recommended to preserve the health of river ecosystem. [ABSTRACT FROM AUTHOR]

In this paper an effort has been made to theoretically estimation of overall oxygen mass transfer coefficient ( K L ) in field conditions by applying wind correction to the oxygen mass transfer coefficient ( K Lphy ) estimated in a simulated pond in laboratory conditions using physical absorption method. The value of K Lphy (8.44 × 10 −6 m/s) was estimated experimentally by three well-mixed reactors of three different interfacial areas. Further, the value of K Lphy was used to estimate the overall oxygen mass transfer coefficient ( K L ) in field conditions. The K L values in the field condition was estimated for waste stabilization ponds at sewage treatment plants of Kalyani and Bandipur in the state of West Bengal and were estimated to be 1.08 × 10 −5 and 1.19 × 10 −5 , respectively. Study gives a handy approach of application of estimated overall oxygen mass transfer coefficient ( K L ) for rational design of waste stabilization ponds. [ABSTRACT FROM AUTHOR]

This paper investigates changes in the visual perception of a stream landscape due to remediation work (i.e., the construction of a stone revetment, which is a common ecological engineering technique in Taiwan) in the Nan-Shi-Ken stream. Various images of the Nan-Shi-Ken streambank before and after remediation were collected. The visual preference ( P ) and perceived naturalness ( N ), which were selected as indices of visual perception, were quantified using a questionnaire survey. The image characteristics were analyzed by the image spectrum method and presented by the spectrum-frequency slope ( S ). Furthermore, the relationship between S and the visual perceptual reaction was presented. The results of this study demonstrate that P and N increase with increasing vegetative cover on a stone revetment after stream remediation. P and N were highly correlated with S and proportional to S . S provides an index to assess P or N for a stream landscape change due to variation in vegetation. [ABSTRACT FROM AUTHOR]

Abstract: Ecosystem restoration was originally founded upon recovering ecosystems using wildlands as a reference state. More recently there has been interest in shifting to the restoration of ecosystem services – the benefits that natural systems can provide to humans. This shift is resulting in new restoration goals as well as new methodological approaches. The pace at which restoration goals and methods are changing is particularly fast for running-water ecosystems, which calls for a rigorous assessment of the environmental and economic costs and benefits associated with such changes. In this paper, we explore the environmental costs and benefits of an emerging form of urban stream restoration, in which ecosystems are vastly transformed in order to enhance specific ecosystem functions and support desirable services. These projects are usually implemented in highly incised low-order perennial, intermittent, or ephemeral stream reaches. In either case, the stream channel is transformed into a stormwater management structure designed to reduce peak flows and enhance hydraulic retention of stream flow with the goals of reducing bank erosion and promoting retention of nutrients and suspended sediments. Results to date indicate that this novel ecological design approach does modify the hydrologic responses of streams during some storm events, but there is no consistent pattern of nitrogen retention or removal that would lead to net annual benefits. While additional data are needed, results suggest there is the potential for sediment retention, at least during some flows. Ongoing work which includes monitoring both pre- and post-project implementation will help resolve this uncertainty. If sediment retention does occur, it is likely to decrease over time making the lifespan of these highly engineered projects is finite. Furthermore, environmental impacts associated with these projects can include loss or damage of riparian forests and export of sediment pulses during construction which may offset project benefits depending on their lifespan. Therefore, the use of approaches where entire existing ecosystems are modified to enhance a few specific biophysical processes should be limited to the most degraded systems where less invasive techniques, such as upland reforestation, reduced lawn fertilization, or better stormwater management at the source of runoff generation have first been exhausted. [Copyright &y& Elsevier]

Abstract: Subsurface oxygen availability tends to be one of the main rate-limiting factors for removal of carbonaceous and nitrogenous compounds in subsurface flow (SSF) wetlands used for domestic wastewater treatment. This paper reviews the pertinent literature regarding oxygen transfer and consumption in subsurface flow treatment wetlands, and discusses the factors that influence oxygen availability. We also provide first results from a pilot-scale research facility in Langenreichenbach, Germany (15 individual systems of various designs, both with and without plants). Based on the approach given in Kadlec and Wallace (2009), areal-based oxygen consumption rates for horizontal flow systems were estimated to be between 0.5 and 12.9g/m2-d; for vertical flow systems between 7.9 and 58.6g/m2-d; and for intensified systems between 10.9 and 87.5g/m2-d. In general, as the level of intensification increases, so does subsurface oxygen availability. The use of water or air pumps can result in systems with smaller area requirements (and better treatment performance), but it comes at the cost of increased electricity inputs. As the treatment wetland technology envelope expands, so must methods to compare oxygen consumption rates of traditional and intensified SSF treatment wetland designs. [Copyright &y& Elsevier]

Abstract: Constructed wetlands (CWs) have been used in ecological engineering for more than two decades, since 1990. In order to understand the present application and trend of CWs in China, this paper summarized the status quo, prospect and influencing factors in CWs construction, technology application and operation management in China, according to the data obtained by literature survey. Results of the systematic survey showed that CWs technology achieved gradual perfection under pushes of national policies, market demand and technical feasibility, with the capacity of wastewater treatment increasing year by year. However, there were still some problems concerning engineering operation and management. Moreover, the results demonstrated that limited by the economic level, the degree of industrialization and urbanization, climatic conditions as well as land availability, CWs were distributing predominately in the region of 20°13′N–35°20′N in China, where covered the central areas with a subtropical monsoon climate and southern or central areas at province level. In these areas, there were more than 40 plant species, which accounted for 57.14% of the total number of common wetland plants. Most of the CWs composted series or parallel combination forms of the vertical flow and free water surface flow CWs units, and they were suitable to treat more than 20 different types of wastewater. For these CWs, the effluent chemical oxygen demand (COD), biological oxygen demand (BOD), total nitrogen (TN) and total phosphorous (TP) reached in the ranges of 20–60mg/L, 4–20mg/L, 1–20mg/L and 0.2–1mg/L, respectively. The effluents from CWs were reused in more than eight ways, such as for agricultural irrigation, supplying surface water, green belt sprinkling, etc. [Copyright &y& Elsevier]

Abstract: Green roof technology has been adopted in the United States as a specialized roofing system and as a sustainable technology capable of saving energy. Most of the previous thermal performance models for green roofs have had the main goal of quantifying these energy savings. However, until recently, none of the models had been fully validated with laboratory and experimental data including both heat flux and surface temperature data. A recently developed green roof thermal performance model was validated with detailed experimental data from a new experimental apparatus called a Cold Plate, which is specifically designed and built for that purpose. In order to further examine the accuracy of the model, this paper describes the dynamic validation of the model using field data from a green roof installed on a commercial roof in Chicago. The dynamic validation consists of comparing substrate surface temperature, heat flux through the roof, and net radiation. The validated results show that the green roof thermal model predicts the heat and mass transfer appropriately as long as the long-wave radiation data from a weather station are used to reduce a possible bias resulting from the sky condition. [Copyright &y& Elsevier]

Abstract: Ecosystem health is a desired endpoint of environmental management and should be a primary design goal for ecological engineering. This paper describes ecosystem health as a comprehensive, multiscale, measure of system vigor, organization and resilience. Ecosystem health is thus closely linked to the idea of sustainability, which implies the ability of the system to maintain its structure (organization) and function (vigor) over time in the face of external stress (resilience). To be truly successful, ecological engineering should pursue the broader goal of designing healthy ecosystems, which may be novel assemblages of species that perform desired functions and produce a range of valuable ecosystem services. In this way ecological engineering can achieve its goals, embedded in its definition as the “design of sustainable ecosystems that integrate human society with its natural environment for the benefit of both.” It allows the benefits of ecological engineering practices ‘to both humans and the rest of nature’ to be assessed in an integrated and consistent way that will allow us to build a sustainable and desirable future. [Copyright &y& Elsevier]

Abstract: The objective of ecological engineering is to design sustainable ecosystems that integrate human communities and their natural environment for the benefit of both. In this paper, we illustrate how social-ecological modeling can be used as a tool to clarify this objective at a landscape scale for freshwater systems. Coupled social-ecological systems (SESs) are open, dynamic systems subject to both ecological and socioeconomic perturbations. Here we demonstrate the interactive effects of social and technological uncertainties on SES dynamics over time. Additionally, we integrate research on ecosystem stability, social-ecological modeling, and ecological engineering to offer guidance for research at the human-environment interface. Based on a case study of Lake Erie''s Sandusky watershed, we use an integrated human-biophysical model to investigate the influence of two parameters on SES dynamics: (1) regional societal preferences that impact watershed management and (2) technological innovation that alters agricultural nutrient efficiency. Our results illustrate ways in which SES dynamics and optimum management strategies depend on societal preferences within the region, indicating a key area of uncertainty for future investigation. As guidance for SES restoration, our model results also illustrate the conditions under which technological change that increases nutrient efficiency on farms can and cannot create a win-win, or increase both human welfare and SES resistance to eutrophication simultaneously. Using these results, we elucidate the value of ecological engineering and offer guidance for assessments of ecological engineering projects using social-ecological modeling. [Copyright &y& Elsevier]

Abstract: Trees in the city not only have an ornamental function but also a role in improving the ecological function in urban ecosystems that has been substantially disturbed by human activities such as environmental pollution. Today the ecological role of urban greenery is clearer than ever and is included in the new scientific field of ecological engineering, which is the design of sustainable ecosystems that integrate human society with its natural environment for the benefit of both. Trees in an urban environment show many difficulties in surviving in it because the ecological conditions that exist in the cities are worse than these of the nature. One of these seems to be the heavy wind loads. But even though rough surfaces slow down the wind speed, tall buildings can cause wind tunnel effects that stress a tree as much or even more than if it was positioned in an exposed, unprotected site. An urban tree must be able to endure all the damages and loads from the wind throughout its life. The ability of a tree to withstand wind loads of gale forces depends on its shape and its dimensions. The objective of this paper is the evaluation of tree stability based on the aboveground silvicultural characteristics in order to create an empirical index which can correlate tree stability with these features. Silvicultural characteristics that play the greatest role on tree stability are crown ratio (CR), crown asymmetry index (CAI), and tree height (H). Consequently, tree stability index (TSI) is formed by them. According to TSI values, tree stability was classified in three categories (classes): high, moderate and crucial stability. The limits of the transition from one class to another, as the classes themselves are depended on the number of variables that represent silvicultural characteristics. [Copyright &y& Elsevier]

Abstract: In 2007, a constructed wetland system was implemented on the tourist island of Koh Phi Phi in Southern Thailand. This paper presents the process of planning, designing and implementing the system and discusses the performance and operational issues 3 years after implementation. The system is an international lighthouse project showing the potential for aesthetical integration of constructed wetland systems in the built environment. The system comprises a wastewater collection system for the main business and hotel area of the island, a pumping station and a pressure pipe system to the treatment facility, a multi-stage constructed wetland system, and a system for reuse of treated wastewater. The treatment chains consist of vertical-flow, horizontal subsurface flow and free water surface flow units. Because the treatment system is located at the centre of the island, surrounded by resorts, restaurants and shops, the systems are designed with terrains as scenic landscaping. The wastewater is treated to meet the Thai effluent standards for total suspended solids and nitrogen, but because of inadequate pre-treatment and removal of oil and grease prior to the system, the standards for oil and grease and BOD are not met. A number of challenges during construction and operation have caused problems with clogging of the vertical flow constructed wetlands and given rise to odour problems. Safeguards were prepared, but not effectively activated, mainly because no key-person or key-authority took responsibility for managing the system. [Copyright &y& Elsevier]

Abstract: Presented in this paper is a low-carbon assessment for wastewater treatment by a constructed wetland as ecological engineering. Systems accounting by combining process and input–output analyses is applied to track both direct and indirect GHG emissions associated with the wastewater treatment. Based on the detailed assessment procedures and the embodied GHG emission intensity database for the Chinese economy in 2007, the GHG emissions embodied in both the construction and operation stages of a pilot constructed wetland in Beijing are investigated in concrete detail, with parallel calculations carried out for a cyclic activated sludge plant as a typical conventional wastewater treatment system for comparison. With the overall embodied GHG emissions taken into account, the constructed wetland is shown to be remarkably less carbon intensive than the conventional wastewater treatment system, and the contrast in GHG emission structure is also revealed and characterized. According to the results, the ecological engineering of the constructed wetland is considered to be favorable for achieving the low-carbon goal. [Copyright &y& Elsevier]

Abstract: This paper presents a comparative study of two different drainage designs in a 10,930-ha new town development of The Woodlands, Texas. Open surface drainage by shallow grassed swales was used in the first two subdivisions that were developed with ecological approaches. Open surface drainage mimics the natural flow regime and is regarded to mitigate development impacts on watershed. In other later subdivisions, the drainage design shifted back to a conventional stormwater drainage system, that is, curb and gutter, drop inlet, and underground piping, known to concentrate stormwater and lead to downstream flooding. The objective of this study is to compare The Woodlands’ two drainage systems on their correlation with downstream floods. Two sub-watersheds within The Woodlands that used different drainage designs were compared. U.S. Geological Survey stream data from the gauge station at the outlet of each sub-watershed were used for analysis. Geographic Information System was used to quantify the development conditions. Correlation analysis was performed using measured precipitation and streamflow data. Results show that open drainage watershed generated less storm runoff than the conventional drainage watershed, given the similar impervious area in both watersheds. Furthermore, the open surface drainage watershed responded to rainfall in a way similar to its predevelopment natural forest conditions, indicating effective flood mitigation post development. In contrast, in the conventional drainage watershed, the precipitation–streamflow correlations increased enormously after development. The open drainage system presents an advantage over the conventional drainage one in mitigating flood problems in urban development. [ABSTRACT FROM AUTHOR]

Abstract: In coming years society will be forced to adapt to lower energy levels due to projected declines in non-renewable energies. This will increase the challenge to ecological engineers to design sustainable ecosystems, driven by renewable energies to benefit society and the environment. This paper introduces the field of Traditional Ecological Knowledge (TEK) as an important source of ideas, inspiration and designs to help our profession meet this challenge. TEK refers to ecological knowledge and practices of indigenous and local cultures. Because these practices originated and evolved prior to the era of fossil-fuel dominance, they were designed and have continuously adapted to utilize renewable energies and resources. TEK is also well suited to sustainable design due to philosophical differences with Western science and culture. While Western culture views society as apart from and controlling ecosystems, indigenous cultures routinely see themselves as embedded within ecosystems. Because TEK has declined as the influence of Western culture has spread, there is an urgent need to identify and apply this knowledge for future benefit. Collaboration with scientists can help raise the social standing of indigenous people and of TEK within their own communities, thus contributing to cultural survival while maintaining this information. Applications of TEK relevant to ecological engineering including water management and agriculture in the Americas are highlighted. [Copyright &y& Elsevier]

Abstract: This paper aims to investigate the effect of the root architecture on the shear strength increment provided by plant roots in the soil. In situ shear tests were conducted for this purpose. Five plant species –Hibiscus tiliaceus L. (Linden hibiscus), Mallotus japonicus (Thunb.) Muell.-Arg. (Japanese Mallotus), Sapium sebiferum (L.) Roxb. (Chinese tallow tree), Casuarina equisetifolia L. (ironwood), and Leucaena leucocephala (Lam.) (white popinac) – were used in this study. Tensile tests on roots of various diameters and surveys on the root system structure were carried out for each of the plant species tested. The shear strength increments (ΔS) provided by the roots of Linden hibiscus, Japanese Mallotus, Chinese tallow tree, ironwood, and white popinac were 0.34t R, 0.462t R, 0.688t R, 0.3t R, and 0.87t R, respectively, when t R was estimated on the basis of the tensile root strength crossing through the shear plane. The shear strength increment provided by plant roots with conspicuous oblique and vertical roots was greater than that of root structures in which lateral roots were dominant. In comparison with other types of root architecture, the R-type root architecture was found to be the most effective root system against shear failure in the soil. Its shear strength increment was slightly greater than that with the V-type root architecture, followed by the VH-type root architecture. The shear strength increment provided by plants with the H-type root architecture was less effective than that contributed by plant species with other types of root architecture. [Copyright &y& Elsevier]

Abstract: Nearly half a century ago, H.T. Odum envisioned a sustainable approach to systems design where human intervention would be supplementary to nature. He referred to this concept as ecological engineering and suggested that practitioners should receive an education beyond the rigors of engineering. To understand natural processes needed to design, develop, and restore natural systems successfully, Odum suggested ecological engineers should have an expanded knowledge of environmental systems and ecology. Furthermore, he recommended broadening educational exposure to social science and liberal arts. The field of ecological engineering has blossomed in the years since Odum expressed his vision, but universities have not adopted his suggested curriculum, and undergraduate engineering students have generally seen a reduction in social science and liberal arts courses. This paper compares Odum''s vision with the surveyed visions of an international group of ecological engineers, who assessed the value and characteristics of an ecological engineering undergraduate education. The respondents’ perspectives vary with their location, education, and profession; however, most participants in this survey share Odum''s vision, and are dissatisfied with existing curricula. Participants outside of the United States were more confident that something approaching Odum''s vision for a program in ecological engineering could be delivered at the undergraduate level. [Copyright &y& Elsevier]

Abstract: The current energy crisis is a worldwide problem, and developing energy from biomass is considered an effective partial solution. Sheyang Saltern is located in a coastal area in East China. The administration of saltern cooperated with our Halophyte Research Lab to create a Five-year Plan of Biomass Energy on Saline Land. In this plan, 3330ha of salt-tolerant oil plants will be planted on the coastal saline land in Sheyang Saltern, including 2664ha of Ricinus communis and 666ha of Kosteletzkya virginica (L.) presl. These plants will produce biomass energy from land that is not fit for common crops, and thus this plan will not affect crop production. Moreover, the biomass of plants will be fully utilized in a hierarchical way, guided by an ecological engineering design. Thus, more outputs and more profits will be gained by applying this plan. This study uses the emergy analysis to predict and analyze the saltern ecosystem''s ecological potential and compare it with an existing system founded in 2007, a 33.3ha field of the two plants in the saltern. Four main emergy indices of the two ecosystems, EYR, EIR, ELR and ESI, are calculated and compared. To better show the system''s ecological potential, we establish a new emergy index-potential yield ratio (PYR). PYR is designed to measure artificial ecosystems’ potential output capacity. It reflects a system''s potential to transform stored emergy into output emergy using ecological engineering technology. The value of the predicted system''s PYR is as great as 225, indicating that the system has a bright future to develop salt-tolerant oil plants. The system''s future ecological potential and additional ways to utilize the two plants – the use of ricin and tuberous roots, etc. are also discussed in this paper. Our results will be helpful to the government''s policy making, and provides useful information for enterprises. [Copyright &y& Elsevier]

Abstract: Large-scale centralized wastewater treatment systems often prevail in industrial countries and have been regarded as a successful approach during the last century. However, to solve the multifold water-related problems in China with its rapid growth of urbanization and industrialization, complete replication of this centralized, cost- and energy-intensive technology has proved to be extremely limited in scope and success. As one of the most important applications of ecological engineering, constructed wetland (CW) systems for wastewater treatment can offer an optimal alternative and result in beneficial conservation of natural resources with low capital costs and energy consumption, as well as minimal operation and maintenance expenditures. CW technology is particularly suitable for rapidly growing small- and medium-size cities in China. This paper aims at examining the mechanisms of pollutant removal efficiency in these systems and investigating the merits, status and feasibility of using constructed wetland systems to treatment wastewater in China. Additionally, it investigates existing impediments to application and implementation of CWs in China, as well as challenges to future development. [Copyright &y& Elsevier]

Abstract: The work presented in this paper demonstrates housing development as an application of ecological engineering on streamside. The study site consists of terrestrial, riverbank and aquatic zones, on which their correlation and effects were investigated. Interdisciplinary methods involving ecology, hydrology, environment and landscape were applied to achieve maximum benefits for humans and nature. A technical scheme for housing development was established and organized as a hierarchy structure, i.e. determination of problems, establishment of goals, designation of functions, production of plan, and development of designs. The designs and implementation of housing and land consisted of riverbank restoration, vegetation replanting, rainwater purification and landscape protection. Ecological benefit was to be the core of the housing project with consideration of social and economic benefits. [Copyright &y& Elsevier]

Abstract: Spartina alterniflora Loisel (S. alterniflora) is native to the Atlantic and Gulf Coasts of North America and was introduced to China in 1979. Over the years, S. alterniflora played an important role in protecting coastal banks, accelerating sediment deposition, improving local economies, and alleviating natural disasters. As an exotic species, S. alterniflora has a very strong capability of propagation, which has caused some negative effects, such as occupying ecological niches of some seashells and blocking harbors by fast sediment deposition. As a result, ecological control of S. alterniflora in some areas has drawn wide attention from biologists and ecologists in China and abroad. For this paper, we studied the technology of topography and hydrology modification to substitute S. alterniflora with P. asutralis and reported our results in a project applying this technology. Furthermore, we studied various ways to make use of biomass of S. alterniflora and found that such ways were a good alternative to ecological control of S. alterniflora. [Copyright &y& Elsevier]

Abstract: Ecological engineering was defined several decades ago, both in the academic field and in management. However, ecological engineering seems to be re-emerging as an academic field and as a cornerstone concept in French ecologists’ writings. I first summarize Barbault and Pavé''s [Barbault, R., Pavé, A., 2003. Territoire de l’écologie et écologie des territoires. In: Caseau, P. (Ed.), Etudes sur l’environnement: de l’échelle du territoire à celle du continent, Tec et Doc Lavoisier, Paris, pp. 1–49] point of view on why ecological engineering now seems rehabilitated in France. I next propose a definition of ecological engineering, in accordance with the two reasons for its French re-emergence, i.e. the prevalence of the concept of sustainable development and the development of applied ecological sub-disciplines. This leads us to suggest that ecological engineering should be ecological in the broad sense, and not only targeted to the ecosystem level. I end the paper by discussing some problems and characteristics of ecological engineering that stem from this definition. [Copyright &y& Elsevier]

Abstract: This paper describes a constructed wetland treatment system designed to treat wastewater from oil refinery. In 2003, to promote the practical development of constructed wetlands (CWs) used for industrial wastewater treatment in Pakistan, a series of investigations was conducted to evaluate the feasibility of using constructed treatment wetlands to remove pollutants from refinery wastewater. The main objective of the research was to quantify the effect of different filter media on the treatment performance of vertical flow wetlands in the prevailing climate of Pakistan. Wastewater produced from the oil refinery contains high concentrations of organic and inorganic pollutants; therefore it cannot be discharged directly into river without any treatment. Phragmites karka were planted in both containers as a vertical flow wetland to evaluate their efficiencies in the purification of wastewater and their growth in wetlands fed with oil refinery wastewater. The results from a 1-year treatment showed that the purifying efficiency of constructed wetlands for oil-refined wastewater was low at the beginning but it improved gradually with the growth of plants and biofilm. Thus, a gravel-filled wetland and organic compost filled wetland were operated identically with primarily treated refinery wastewater at a hydraulic loading rate of 0.100md−1, intermittently. According to the results, the removal efficiencies for the compost and gravel wetland cells varied as follows during the experimental period of 1 year: total suspended solids (TSS) (51–73% and 39–56%), chemical oxygen demand (COD) (45–78% and 33–61%), biological oxygen demand (BOD) (35–83% and 35–69%) and significant removal of heavy metals, i.e. Fe2+, Cu2+ and Zn2+, was observed. The treatment performances of the compost-filled wetland were better than that of the gravel-filled wetland in terms of removal of COD and BOD. Since this study was a pioneer for implementation of vertical flow constructed wetlands in Pakistan using local sources, it has proved that this eco-technology could also be used effectively for water quality enhancement in Pakistan. [Copyright &y& Elsevier]

Abstract: This paper analyses the purification efficiency and mass removal of organic material, suspended solids, nitrogen and phosphorus in a hybrid constructed wetland (CW) system treating wastewater from a basic school in Paistu, Estonia. The CW consists of two subsurface flow filter beds using lightweight aggregates (LWA): a two-chamber vertical subsurface flow (VSSF) filter bed followed by a horizontal subsurface flow (HSSF) filter bed, with a total area of 432m2. This CW was constructed in summer 2002 by the Centre for Ecological Engineering in Tartu (CEET). Eighteen series of water samples (from 30.10.2003 to 15.10.2005) were undertaken. The analyses show the outstanding purification effect of the system: for BOD7 the average purification efficiency is 91%; for total suspended solids (TSS)—78%, for total P—89%, for total N—63%, and for NH4 77%. The average outlet values for the above-listed parameters were 5.5, 7.0, 0.4, 19.2 and 9.1mgL−1, respectively. According to our results, the purification parameters meet the standards set by the Water Act of Estonia for wastewater treatment plants of 2000–9999 PE: 15, 25, and 1.5mgL−1 for BOD7, TSS and total P, respectively. The results show that hybrid CW systems consisting of subsurface flow filter beds can work efficiently in conditions of changing hydraulic loading and relatively cold climate. We did not find significant differences between the removal efficiency, mass removal, and values of the first-order rate-constant k for most water quality indicators during the warm (May–October) and cold (November–April) periods. Locally produced LWA as a filter material in CWs has shown good hydraulic conductivity and phosphorus sorption capacity (k =17.1±12.4myr−1). The Paistu CW, with its proper design and outstanding purification results, can be considered one of the best systems in Estonia. [Copyright &y& Elsevier]