Wetland Cells Research Articles

A macro-level life cycle environmental-economic impact and benefit assessment of sponge cities in China

Urban runoff source control facilities (URSCFs) are integral components of Sponge City (SC), playing a pivotal role in providing ecosystem services and managing water quality and quantity. To accurately assess the performance of URSCFs, it is crucial to quantify their environmental and economic impacts. However, previous studies have predominantly focused on location-specific case studies, lacking a macro-level perspective necessary for informing public policy development pertaining to SC initiatives. This study aims to bridge this gap by conducting a macro-level life cycle assessment across China's 16 initial pilot SCs, categorized into three zones based on their annual rainfall volume control rate α (i.e., Zone II (80 % to 85 % for α), Zone III (75 % to 85 % for α), and Zone IV (70 % to 85 % for α)). By simulating five rainfall drainage scenarios, we delve into the environmental benefits of SC construction. The results indicate that Zone III incurs the highest environmental and economic costs during the construction phase, followed by Zones II and IV. In Zone III, bioretention contribute significantly to the environmental impact and economic cost, while constructed wetland and detention cells are the key contributors for Zone II. During the operation phase, Zone III demonstrates the largest environmental and economic benefits, with Zone IV and II trailing behind. The investment payback period for SCs in all zones is less than eight years, with Zone IV recovering costs the fastest (3.9 years) and Zone II the slowest (7.5 years). Facilities like detention cells, green roofs, and permeable pavements tend to have longer payback periods. Based on our findings, we recommend that Zone II exercise caution in constructing detention cells, permeable pavements, and wetlands, while Zone III should carefully consider green roofs and bioretention to optimize SC investments. Due to the fewer URSCFs constructed in Zone IV, it exhibits the lowest environmental impact compared to Zones II and III. Our research provides valuable insights to support policymaking with regards to future SC planning and development.

The Prado Wetlands: 24 years of river diversion treatment wetlands reducing nitrate and phosphate while increasing an endangered bird

Nitrate pollution of surface water from farms and urban runoff is widespread – impairing drinking water supplies, recreation, and wildlife habitat. The scale of the problem in rivers has overwhelmed most watershed-based best management practices. A new paradigm is needed. In this paper we highlight the 119 ha (294 acres) Prado Wetlands in southern California, USA as an example of a gravity-enabled, free surface flow vegetated wetlands to treat a river – the nitrate-rich, effluent-dominated Santa Anna River. The wetland treats ∼1–2 m3/s of the 7.1 m3/s (250 cfs) flow of the river in 28 wetland cells in two parallel trains (residence time 2–4 d, hydraulic loading rate 10–20 cm/d). The cleaner water is returned to the river and infiltrated downstream into a managed groundwater basin supplying 2.4 million customers. Since 1998, ∼1200 t of nitrate-N have been permanently removed from the river and released as N2-gas into the air. Over 24 years, in the warm summers an average of 6.1 mg-N/L entered the wetland and 3.7 mg-N/L flowed out, a removal efficiency of 57%. In the cooler winters, an average of 6.4 mg NO3-N/L entered and 2.6 mg NO3-N/L flowed out, a removal efficiency of 45%. Individual months varied widely in concentration removal efficiency from 7% (winter) to 98% (high summer). Areal summer removal averaged 137 mg NO3-N/m2/d and the apparent “k” was around 46 m/y. All-year rates were 129 mg NO3-N/m2/d or 47 g/m2/y, a reasonable performance considering the size of the system and its configuration for both nitrate removal and duck hunting (i.e., more open water). Annual average nitrate removal efficiency increased substantially over time (45 to 72% for 1998–2004 versus 2016–22) and is attributed to an increase in hydraulic residence time, upgraded internal plumbing, and increased winter temperatures (+3C°). Prado Wetlands also removes phosphorus, though not as well as nitrate; average warm season removal efficiency was 23% (inflow 1.20 mg PO4-P/L, outflow 0.93 mg PO4-P/L). The aerial removal rate was high at 23 mg P/m2/d or 8.5 g/y, probably due to the high inflowing P-concentrations and the hard water. Wildlife was also enhanced. Least Bell's Vireo (Vireo belli pusillus), an endangered bird in the Prado Basin, increased from 19 pairs (1998) to a recent average of 444 pairs due to habitat improvement and reduction of cowbird parasitism. Results from the Prado Wetlands show that cleaning up rivers via diversion through wetlands benefits both water quality and wildlife.

Transport and Attenuation of an Artificial Sweetener and Six Pharmaceutical Compounds in a Sequenced Wetland-Steel Slag Wastewater Treatment System

The occurrence of pharmaceutically active compounds (PhACs), nutrients, and an artificial sweetener acesulfame in wastewater, and subsequent removal in an engineered system comprising aerobic wetland, anaerobic wetland, and steel slag cells, were investigated. The PhACs evaluated in this study covered a range of octanol–water partition coefficients (log Kow = 0.07–2.45) and acid dissociation constants (pKa = 1.7–13.9) and included carbamazepine, caffeine, sulfamethoxazole, ibuprofen, and naproxen. The mean flow rate in the system was 0.89 m3 day−1 (0.02 to 4.27 m3 day−1), representing a hydraulic retention time of 5 days. The removal efficiencies of PO4-P, NH3-N, and cBOD5 in the treatment system were >99, 82, and 98%. The removal efficiencies for the PhACs and acesulfame were classified into four groups, including those that were (a) efficiently removed (caffeine by >75%); (b) moderately removed (ibuprofen by 50–75%); (c) poorly removed (sulfamethoxazole and naproxen by 25–50%); and (d) recalcitrant (carbamazepine and acesulfame by <25%). Variability in concentrations and treatment efficiencies was observed in different sampling events, which may be due to variations in input concentrations or changes in the flow rate. The addition of a steel slag cell increased the overall removal efficiency of the studied compounds, except for carbamazepine.

Recycled clay bricks and palm kernel shell as constructed wetland substrate for wastewater treatment: An engineered closed circuit circular economy approach

Wastewater treatment using green technologies contributes significantly to a circular economy. Constructed wetlands (CW) using green substrates or recycled materials are low-cost cleaner technologies that further contribute to a closed circuit. This study assessed the performance of two recycled materials, Waste Clay Brick (WCB) and Palm Kernel Shells (PKS), as suitable substrates in a CW for wastewater treatment. Five (5) horizontal subsurface flow constructed wetlands (HSSF CW), designed and fabricated using galvanized steel, were set up for the treatment of domestic wastewater (sewage). The wetland cells were packed with small (WCBS, PKSS) or large (WCBL or PKSL) particle size substrates with one cell using sand as control. The CW operated under two hydraulic loading rates (HLR), 50l/d (HLR-1) and 80l/d (HLR-2). Overall, the effluent quality of HLR-1 was relatively better than HLR-2. pH and turbidity of effluent were satisfactory and within the Ghana Environmental Protection Agency (EPA) guidelines for discharge of wastewater into surface water bodies. For both hydraulic loading rates, the highest removal efficiencies of BOD5 (73.97%), COD (71.89%), TSS (90.82%), TP (71.13%), TN (49.41%) were recorded for WCB. Coliform removal was highest in the Palm Kernel Shell (98.6%), followed by the control (97.39%). Wastewater treatment efficiency decreased with increasing wastewater loading rates for all parameters in Waste Clay Brick and BOD5 and TP in Palm Kernel Shell. WCB demonstrated superior treatment potential compared to PKS for all parameters except coliform removal.

Metal fluxes at the sediment-water interface in a free water surface constructed wetland.

Metal biogeochemistry in the sediment, water, and the sediment-water interface (SWI) was studied in a free water surface constructed wetland. Concentrations of labile copper (Cu), zinc (Zn), sulfate, chloride, and dissolved organic carbon (DOC) were measured with the diffusive gradients in thin film (DGT) and peeper. A good agreement between peeper- and DGT-measured metals was observed for Cu (regression r2 = 0.3, 95% CI of the slopes > 0), but not for Zn (95% CI of the slopes overlapped with 0), which was attributed to the different complexed compounds between Cu and Zn in porewater. The depth profile of labile metals in sediment porewater varied with time and was consistent with the solid-phase metal deposition, showing higher concentrations in the surface layer (3 to - 3cm) than in the bottom layer (- 4 to - 13cm). The depth-averaged labile Cu and Zn concentrations measured by DGT were 1.0 and 3.1µg/L, and labile sulfate, chloride, and DOC concentrations measured by peeper were 1.8, 3.6, and 2.1mg/L, respectively. A sharp decrease in sulfate occurred in September when sulfate concentrations became the lowest among sampling months. This was caused by the seasonal sulfur cycles in the wetland, where the dominant sulfur reaction is sulfate reduction in warm seasons and sulfide oxidation in cold seasons. Different metal-removal mechanisms were observed in the two wetland cells; sulfur dynamics controlled the removal processes in the cell without frequent disturbance but failed to influence metal removal in the cell with frequent disturbance due to the interruption of anoxic layers. The flux ratios that compare labile element concentrations between the water column and the SWI (R-Cu, R-Zn, R-DOC, R-sulfate, and R-chloride) were generated to determine metal diffusive fluxes at the interface. Labile Zn was mostly transported from the water to the SWI during all seasons (R-Zn < 1 for all months except January). Labile Cu moved from the SWI to the water during the warm months (R-Cu < 1), which was explained by the bioturbation-induced transport of organic matter based on the positive correlations between R-Cu and R-DOC. In general, sediment can serve either as a sink or a source depending on the environmental conditions, metal speciation, and presence of living organisms. Metal flux at the SWI is a key component in the biogeochemical cycling of a constructed wetland.

Reciprocating subsurface-flow constructed wetlands: a microcosm treatability study.

Two batch-loaded microcosm treatability studies of eight days' duration (192 hours) were conducted concurrently from July 26 through August 3 in an environmentally controlled greenhouse at the Tennessee Valley Authority's (TVA) Constructed Wetlands Research Facility in Muscle Shoals, Alabama, USA. These, the first of five treatability studies, were conducted in batch-loaded wetland microcosms, with and without reciprocation. Reciprocation refers to the process of filling and draining paired wetland cells on a recurrent and timed basis to facilitate passive aeration of fixed microbial biofilms during the drain phase and oxygen depletion during the fill phase. The study was designed to simultaneously evaluate the influence of three treatment parameters with respect to removal dynamics of chemical oxygen demand (COD), total ammonia-nitrogen (TAN), nitrate-nitrogen, and orthophosphorus. The treatment parameters evaluated included four COD concentrations, two reciprocation cycle times, and the presence or absence of reed canary grass (Phalaris arundinacea), a plant with an anoxic rootzone. Temperature, pH, dissolved oxygen, electrical conductivity, redox potential, and evapotranspiration were also monitored. Results showed that treatments with reciprocation vs. no reciprocation provided significantly enhanced aerobic and anoxic treatment of wastewater and improved removal of COD and ammonium, irrespective of initial COD concentrations or planted vs. not planted with P. arundinacea. Treatments with P. arundinacea had less accumulation of nitrate nitrogen; less than 0.4 mg/L., while reciprocating treatments without P. arundinacea accumulated from 15-26 mg/L nitrate nitrogen over the 192-hour treatment period.

Stormwater Retention of an In-Series System Composed of a Green Roof, Constructed Wetland, and Bioretention Cell for a Single-Family Home

The need to develop a sustainable approach to stormwater management is rapidly becoming a priority as urban development and climate change alters urban hydrologic cycles. Green infrastructure (GI) is widely viewed as a sustainable method to managing stormwater. However, rarely have in-series systems of GI been monitored, even though most stormwater regulations require these practices to be installed. Additionally, studies on the effectiveness of GI in residential settings is lacking. This paper examines how an extensive green roof, constructed wetland (CW), and bioretention cell integrated in-series on a home in Rockville, Maryland, affected site hydrology during 116 storm events that occurred from July 2014 to June 2016. The effects of season, antecedent substrate water content, storm characteristics (size, intensity, and frequency), and green roof vegetation development (leaf area index and percent cover) on retention were evaluated. Collectively, the green roof, CW and bioretention cell stored 6,930.7 mm of stormwater over the 2-year study period. Given a total input of 19,019.1 mm over all storm events, the three systems collectively reduced site runoff by approximately 36.4%. Event size was the single biggest predictor of retention for all systems. When evaluating each system independently, the CW retained the most runoff (37.6% or 337.3 mm/m2 of water). Findings provide insight on the benefits of implementing GI in-series on residential properties.

Spatiotemporal water quality variability in a highly loaded surface flow wastewater treatment wetland.

This study evaluates spatiotemporal relationships between water quality parameters (WQPs), nutrients, suspended solids, and biochemical oxygen demand (BOD) concentrations within an engineered wastewater treatment wetland system in the Georgia Piedmont, USA. We explored factors related to treatment efficiency within a heavily loaded 630-m2 surface flow wetland system over a 2-yr period. Relationships between temperature, dissolved oxygen (DO), and oxidation-reduction potential (ORP) were observed; relationships were also seen between these WQPs and nutrient concentrations. Because temperature, DO, and ORP affect nitrogen (N) cycling rates, seasonal trends in N forms were evident in the system. Organic N and inorganic/organic phosphorus concentrations correlated with solids concentrations in the vegetated system without exhibiting seasonal trends. Surface water within the vegetated section generally exhibited anoxic conditions, leading to removal of nitrate-N within the system; however, limited mineralization and nitrification occurred, which greatly limited overall N removal. Plant selection and lack of maintenance likely led to high solids and BOD contributions to treatment wetland surface water, which varied substantially between and along monitored transects. Because so few studies have investigated treatment dynamics within treatment wetland cells, focusing solely on influent/effluent characterization, radical spatiotemporal variability may be the norm as opposed to the commonly accepted assumptions of relatively uniform pollutant degradation across treatment wetland cells. This spatiotemporal variability in WQPs underscores the dynamic nature of treatment wetlands and the need for routine maintenance, including sludge removal and plant harvesting.

A Review on Constructed Treatment Wetlands for Removal of Pollutants in the Agricultural Runoff

Constructed wetland (CW) is a popular sustainable best management practice for treating different wastewaters. While there are many articles on the removal of pollutants from different wastewaters, a comprehensive and critical review on the removal of pollutants other than nutrients that occur in agricultural field runoff and wastewater from animal facilities, including pesticides, insecticides, veterinary medicine, and antimicrobial-resistant genes are currently unavailable. Consequently, this paper summarized recent findings on the occurrence of such pollutants in the agricultural runoff water, their removal by different wetlands (surface flow, subsurface horizontal flow, subsurface vertical flow, and hybrid), and removal mechanisms, and analyzed the factors that affect the removal. The information is then used to highlight the current research gaps and needs for resilient and sustainable treatment systems. Factors, including contaminant property, aeration, type, and design of CWs, hydraulic parameters, substrate medium, and vegetation, impact the removal performance of the CWs. Hydraulic loading of 10–30 cm/d and hydraulic retention of 6–8 days were found to be optimal for the removal of agricultural pollutants from wetlands. The pollutants in agricultural wastewater, excluding nutrients and sediment, and their treatment utilizing different nature-based solutions, such as wetlands, are understudied, implying the need for more of such studies. This study reinforced the notion that wetlands are effective for treating agricultural wastewater (removal &gt; 90%) but several research questions remain unanswered. More long-term research in the actual field utilizing environmentally relevant concentrations to seek actual impacts of weather, plants, substrates, hydrology, and other design parameters, such as aeration and layout of wetland cells on the removal of pollutants, are needed.

Temporal deposition of copper and zinc in the sediments of metal removal constructed wetlands

The objective of this study was to explore the effects of time, seasons, and total carbon (TC) on Copper (Cu) and Zinc (Zn) deposition in the surface sediments. This study was performed at the H-02 constructed wetland on the Savannah River Site (Aiken, SC, USA). Covering both warm (April-September) and cool (October-March) seasons, several sediment cores were collected twice a year from the H-02 constructed wetland cells from 2007 to 2013. Total concentrations of Cu and Zn were measured in the sediments. Concentrations of Cu and Zn (mean ± standard deviation) in the surface sediments over 7 years of operation increased from 6.0 ± 2.8 and 14.6 ± 4.5 mg kg-1 to 139.6 ± 87.7 and 279.3 ± 202.9 mg kg-1 dry weight, respectively. The linear regression model explained the behavior and the variability of Cu deposition in the sediments. On the other hand, using the generalized least squares extension with the linear regression model allowed for unequal variance and thus produced a model that explained the variance properly, and as a result, was more successful in explaining the pattern of Zn deposition. Total carbon significantly affected both Cu (p = 0.047) and Zn (p < 0.001). Time effect on Cu deposition was statistically significant (p = 0.013), whereas Zn was significantly affected by the season (p = 0.009).

Assessing the Surface Water Quality of Ana Sagar Lake and its Bioremediation in Modified Constructed Wetland

The present study evaluates the potential of an integrated Constructed Wetland and Microbial Fuel Cell (CW-MFC) in removing Chemical Oxygen Demand (COD), Total Dissolved Solids (TDS), nitrate and phosphate along with generating electricity from the polluted water of Ana Sagar Lake, Ajmer. Two vertical downward flow CW-MFCs have been investigated (with and without plant) in batch mode for a period of 12 months. The performance of CW-MFC with the plant (system A) was better than the CW-MFC without the plant (system B), both in terms of COD, TDS, nitrate and phosphate removal and electricity generation. Dracaena trifasciata plant species were used in this study. The maximum power density of 157 mW/m2, current density of 0.65 mA/m2, COD removal efficiency (72%), TDS reduction (74%), nitrate removal (69%) and phosphate removal (69%) were obtained with System A. The germination rate of Vigna radiata seeds was 100% with the effluent from system A. At the end of the experiment the FTIR analysis revealed the structural changes occurring on the CW-MFC media (sand) after removal of pollutants present in the lake water.

Long term evaluation of a pilot scale multimodal algal bioprocess for treatment of municipal wastewater

The feasibility of Multimodal Algal-bacterial Bioprocess (MAB) for the treatment of primary clarified municipal wastewater was demonstrated at a pilot-scale MAB system (0.2 m3/d) installed and operated in Corvallis, Oregon, USA for one year. The system consisted of an anaerobic reactor; mixotrophic and phototrophic ponds followed by algal settlers and a final wetland cell (WC). The wastewater treatment performance was monitored weekly over the one-year period in terms of onsite parameters as pH, dissolved oxygen (DO), oxidation reduction potential (ORP), electrical conductivity (EC), total dissolved solids (TDS),turbidity and chemical parameters (COD, Nitrate-N, Amm.-N and reactive phosphorus). Algal biomass production and algal community analysis in the MAB was determined regularly. A continuous improvement in the mean DO (1.57–13.98 mg/L) and ORP (−140 to +86 mV) was observed throughout the study period. Higher mean pH (8.62) and DO (14 mg/L) in the ponds indicated high algal photosynthesis. The pilot-scale system maintained an average low final effluent turbidity (14.2 NTU), TSS (<30 mg/L) and COD concentrations (~78.3 mg/L) and achieved removal of nitrogen as Amm.-N (76%) and Nitrate-N (34%), phosphorus (DRP: 51%) throughout the experimental period. Particularly in summer, the overall treatment performance was high (70% COD removal; 78% Amm.-N removal; 38% Nit.-N removal; 53% DRP removal) owing to high algal-bacterial activity. The community analysis showed a predominance of diatoms and cyanophycean members in the winter and chlorophycean members especially species Chlorella (~80%) during summer. The average biomass productivities (VSS) in the treatment ponds ranged from 6.75 g/m2/d during winter to 11.47 g/m2/d during summer. Overall, the MAB can effectively treat municipal wastewater; produce quality final effluent and algal bioproducts with minimum energy inputs.

Preliminary Assessment of Vertical-flow Heterogeneous Media Constructed Wetland Cells for Treating Aquaculture Effluent

Adequacy of quality freshwater and wastewater management are the major challenges facing aquaculture industries globally. This study presents a preliminary work aimed at assessing the performance of laboratory-scaled heterogeneous constructed wetlands (HCWs) cells with stratified layers of different filling for treating aquaculture wastewater. The frustum shaped plastic HCWs were planted with Cinnamon fern (Osmunda cinnamomea L.) and operated at the pre-setup stage for about three weeks. The effluents were recirculated twice at hydraulic retention times (HRTs) of 24, 48 and 72 hrs and analyzed for turbidity, pH, total phosphorus (TP), TSS, COD, BOD5 and total ammonia nitrogen (TAN). Ranges of reduction efficiencies obtained were: Turbidity (44.4 to 80.3%), TSS (-12.8 to 36.6%), COD (8.7 to 31.2%), BOD5 (3.7 to 31.6%), TP (33.3 to 58.1%) and TAN (-3.7 to 92.6%). The pH was reduced from 7.9 to a slightly alkaline value of 7.2. There were strong correlations in the treatment pattern due to the cell configurations. A significant effect (p

Phytoremediation of Heavy Metals From Mixed Domestic Sewage Through Vertical- Flow Constructed Wetland Planted with Canna Indica and Acorus Calamus

The removal of contaminants from sewage wastewater through constructed wetlands is becoming increasingly popular worldwide. Constructed wetland (CW) is a man-made structure for wastewater treatment that uses natural processes associated with wetland vegetation, soils, and their associated microbial combinations. This study investigated the performance of experimental vertical flow constructed wetland (VFCW) cells to remove heavy metals (HMs) from primary treated sewage. The primary treated sewage was collected from the sewage treatment plant (STP) in the campus of Indira Gandhi National Tribal University, Amarkantak, India. Sewage wastewater samples were collected from all cells of the experimental VFCW and analyzed for four heavy metals (Zn, Fe, Cu, and Cr). The plant species results show that the removal efficiency of the Canna indica L. for Zn, Fe, Cu, and Cr was 95%, 92%, 96%, and 93 % and Acorus calamus L.were 89 %, 80 %, 91 %, and 47 % respectively. These macrophytes with the substrate (gravel and sand) have presented a wide range of tolerance to all the selected metals and therefore can be used for field-scale constructed wetland removal of heavy metals from sewage wastewater.

Reciprocating Subsurface Wetlands for Drainage Water Treatment A Case Study in Egypt (Dept.C)

A new patented constructed wetlands treatment technology for enhanced nutrients reduction has been developed by Tennessee Valley Authority. This new treatment technology is known as Reciprocating Flow Constructor Wetland (RFCW) through increasing oxygen content in the treatment processes. The RFCW has a process of operating two adjacent subsurface flow gravel beds by alternately draining and filling the wastewater on a recurrent basis to achieve tertiary levels of wastewater treatment. In Egypt, A pilot-scale RFCW was built near Lake Manzala as a demonstration of low cost treatment technology to treat a portion of Bahr El-Baqar drain wastewater that carries drainage water contains domestic and industrial pollution loads. The pilot wetland consists of one sedimentation basin followed by two subsurface flow cells working in a fill-empty sequence mechanism. The treatment capacity is 100 m per day. Treatment detention time is 4 days including 2 days in the gravel bed RFCW cells. Objectives of this paper are to describe operational flow inside the alternate cells, and to evaluate the treatment performance of reciprocating wetland for such polluted drainage water and to estimate removal rate constants (K) of the treated pollutants applying mixed flow reactor model. Water samples were collected from both influent and effluent wetland cells. Samples were analyzed to measure concentrations and loads of DO, BOD, TSS, NH4-N, NO3-N, TP, Fe, and FC. Results showed that RFCW managed to polish pollutants of drainage influent especially ammonia and nitrates reaching a limit which it could be used in a safe manner for the agricultural purpose or dumping it into Lake Manzala without negative impacts on its ecosystem.

Metal-sulfide dynamics in a constructed wetland in the Southeastern United States

The Tritium Processing Facility at the Savannah River Site releases effluent containing copper (Cu), zinc (Zn), and lead (Pb) to the H-02 constructed wetland for remediation before the final release. Sediment cores were collected in the wetland cells in both summer and winter. Concentrations of total metals in all sediment layers and acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) in surface sediments were determined. Total metal concentrations suggested most metals removed from surface water were retained by the organic-rich flocculent in the top sediment layers instead of being transported to the deeper sulfide mineral layers. The seasonal difference of AVS and SEM indicated a season-related sulfur cycle and metal removal process in the wetland cells. SEM-Zn was the major contributor to total SEM. Metals accumulating in surface sediments were mainly sequestered in AVS and SEM extractable phases including metal-sulfides and organic matter complexes. The general SEM/AVS ratio was > 1, demonstrating the metals associated with sediments were potentially mobile and/or bioavailable, which becomes a concern for the long-term sustainability of the constructed wetland. The disturbance event in the sediment triggered the release of total metals, which were mostly in particulate form and were not bioavailable. Due to the high levels of reduced ion (Fe) in the sediment, the released particulate metals were likely to form metal-scavenging particulate Fe3+ oxyhydroxides under oxic conditions.

Prioritizing coastal wetlands for marsh bird conservation in the U.S. Great Lakes

Human activity surrounding the Laurentian Great Lakes basin has significantly degraded coastal wetland habitats, resulting in severe marsh bird population declines and reduced coastal resilience to changing environmental conditions. Given the need to conserve remaining coastal wetlands for wildlife and people, we developed a spatial prioritization to identify the most important U.S. Great Lakes coastal wetlands for 14 marsh bird species. We modeled occurrence and relative abundance of each species using boosted regression trees, a machine learning algorithm, to relate standardized monitoring data to ten remotely-sensed environmental covariates. We then used Zonation conservation planning software to rank every wetland cell based on its importance for the suite of marsh bird species. Evaluation of the drivers of marsh bird occurrence and abundance revealed that open water, herbaceous wetland, latitude, longitude, and impervious surface were the most important predictors across focal species. The high-priority wetlands for marsh birds (defined as grid cells ranked in the top 20%) occurred along the shores of eastern Lake Ontario, western Lake Erie/St. Clair, Saginaw Bay, Green Bay, northern lakes Michigan and Huron, and western Lake Superior. Overall, less than half (42%) of high-priority coastal wetlands across the Great Lakes basin are currently under some level of protection, with Lake Ontario priority wetlands being the least protected (25%). Our findings represent an opportunity to improve coastal wetland conservation in a region where wetland loss and degradation continue to threaten marsh bird populations and the integrity of one of the world's largest freshwater ecosystems.

BOD Treatment in HSSF Constructed Wetlands Using Different Media (Set-up stage). (Dept. C)

Municipal wastewater treatment through horizontal subsurface flow (HSSE) constructed wetlands using three different treatment media (gravel, pieces of plastic pipes, and shredded tire rubber chips) were investigated in Samaha wastewater treatment plant, Dakahlia, Egypt. This study focused on the wetland set up stage during the first months of wetland operation. In this stage media porosity, bacterial biofilm, and plants roots growth were in progress and it was prior to the operational steady state stage. Objectives of this paper are to study the change in media porosity of HSSF wetland cells, to evaluate the use of different bed media on BOD treatment and to study the relationship between wetland hydraulic properties and pollutant removal rates during set up stage. The results showed that after 180 days of operation the wetland cells had reached steady porosity. Also, plastic cell gave more BOD reduction than gravel and rubber cells by average values of 4.83% and 8.66% respectively.

APEX simulation: Water quality of Sacramento Valley wetlands impacted by waterfowl droppings

Since most wetlands in the Sacramento Valley of California are dependent on artificial water delivery, supplying water for wetland management is the greatest challenge to wetland managers, especially during drought years. Efforts are needed to improve the security of water supplies for optimal habitat management and water quality improvement. This study contributes to these efforts by developing an eco-hydrologic model (Agricultural Policy/Environmental Extender [APEX]) of this wetland system, which has key components evaluated in the wetland simulation, including wetting and drying of wetland soils, competition and response of wetland species to wetland hydrology, settling of sediment, and nitrogen (N) removal. APEX model calibration (April of 2017 to May of 2018) and validation (June of 2018 to August of 2018) resulted in a percentage bias (PB) of 9.8% and –8.5%, respectively, for total volume of water holding in four serially connected wetlands. The N contents in the wetland waterbody were calibrated and validated using the monitored values collected during 2017 to 2018 and 2015 to 2016, respectively. All PB values for calibration and validation were over 35%. The calibrated model was used to evaluate the effects of wetland management and increasing temperature on N removal. Moreover, an additive regression model (ARM) was developed based on bird survey data and used to analyze bird dropping seasonal patterns and access their impacts on water quality in the studied wetlands. Based on the results of the model, the wetland water quality was influenced by waterfowl populations and eventually governed by water availability in each wetland cell. The N removal by wetlands was negatively affected by the volume of irrigation water. Moreover, increasing temperature caused a decrease in waterfowl population, which led to decreased N concentration by up to 42%. Overall, the results indicate that the developed model can be effectively used to quantify the effects of wetland management on water balance, water quality, and vegetation and to describe the nexus of wetland management, water use, and ecosystem service functions of managed wetlands.

Design and performance of a coarse media, high hydraulic load polishing wetland for steel industry wastewater.

This paper presents the design of a constructed wetland (CW) system in an area with limited land availability, resulting in high hydraulic loads. The CW was constructed to act as a buffering/ polishing step after stabilization ponds for steel industry wastewater post-treatment. A pilot test with two different filter media (50-100mm vs 40-60mm diameter) indicated that a flow rate increase from 49.5 m3/h to 122.4 m3/h would lead to a head loss increase from 2.9cm to 8.7cm, and more than double that for the finer gravel. This was substantially higher than the calculated theoretical values, though the relation with flow rate was similar. Four full scale wetland cells (CW1, CW2, CW3 and CW4) were constructed using the coarser gravel. A design value of total head loss of 1.01m over the total system length, with a design flow of 36,000 m3/day, was expected based on pilot test results. During the first operation year (September 2017 to July 2018), the pond-CW system has received wastewater already meeting required discharge standards. The effluent from the CWs had consistently lower concentrations of all measured variables, and met the predicted values for biochemical oxygen demand (BOD5), total nitrogen (TN) and NH4 +-N. Highest removal efficiencies were achieved for NH4 +-N (>90%), Mn (>60%) and Fe (45%) with removal efficiencies for TN (14%), BOD5 and chemical oxygen demand (COD) (around 30%). Concentrations of phenol, CN- and Cr6+ were below 10, 4 and 3μg/l, respectively, in in- and outflows. An appreciated benefit of the wetland was the 'green element' in the industrial landscape.