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Stormwater wet detention ponds hold a permanent pool of water and offer many beneficial uses including flood mitigation, pollution prevention, downstream erosion control, increased aesthetics, and recreational uses. Although the removal of nutrients is generally low for stormwater wet detention ponds in urban areas, floating treatment wetlands (FTWs) can be installed to offer an innovative solution toward naturally removing excess nutrients and aiding in stormwater management. To improve the stormwater reuse potential, this study assessed nutrient, microcystin, and chlorophyll-a interactions in three Florida stormwater wet detention ponds with recently implemented FTWs. Both episodic (storm events) and routine (non-storm events) sampling campaigns were carried out at the three ponds located in Ruskin, Gainesville, and Orlando. The results showed a salient negative correlation between total phosphorus and microcystin concentrations for both storm and non-storm events across all three ponds. The dominant nutrient species in correlation seemed to be total phosphorus, which correlated positively with chlorophyll-a concentrations at all ponds and sampling conditions, with the exception of Orlando non-storm events. These results showed a correlation conditional to the candidate pond and sampling conditions for microcystin and chlorophyll-a concentrations.

Lake Okeechobee, located in south Florida and originated about 6000 years ago during oceanic recession, is the second largest freshwater lake contained entirely within the United States. During recent years, four major hurricanes, Irene (1999), Frances (2004), Jeanne (2004), and Wilma (2005), made landfall near Lake Okeechobee. As a result, the lake's hydrodynamic patterns, water level, and water quality have been extensively influenced by hurricanes in the past decade. The direct landfall of Hurricane Wilma on the Lake Okeechobee area led to a drastic structural change to the ecosystem, resulting in an abrupt population decrease of submerged aquatic vegetation (SAV). During the same time period, south Florida also suffered from intermittent droughts in 2000–2001 and 2006–2008 due to climate variability. Drought stress and hurricane impacts induce complex ecosystem responses, including pervasive changes in species composition and productivity that may persist as changes in habitat, lake trophic state, light penetration depth, water levels, and nutrient cycling. After the 2006–2008 drought, decreased turbidity due to reduced sediment hydrodynamics, along with the increased runoff and nutrient inflows to the aquatic ecosystem, led to a range of ecological responses associated with gradual increases in primary productivity and the recovery of SAV in lake shore environments. The ecosystem then recovered after the population increase of SAV, triggering active ecodynamics among phytoplankton, zooplankton, and fish that had abruptly vanished after successive hurricanes in 2004 and 2005. To address such a unique structural change in the lake ecosystem, this study developed a structurally dynamic model to quantify the ecodynamics of the four main aquatic system organisms (SAV, phytoplankton, zooplankton, and fish) based on a thermodynamics index (exergy) and elucidated the ecosystem recovery pathways under the coupled impact of hurricanes and droughts.

Rapid urbanization and climate variability impacts increase with more extreme precipitation and drought events, challenging stormwater management in terms of both flood control and water quality. Traditional stormwater wet detention ponds have limited capacity to remove nutrient pollutants, specifically nitrogen, and the changing environment may exacerbate the problem. The use of floating treatment wetlands (FTWs) may become a viable best management practice to increase the efficiency for on-site removal of nitrogen pollution from traditional stormwater wet detention ponds before release into neighboring aquatic systems or to the groundwater. This study, which is deemed a companion study of the early ecological engineering practice of FTWs, presents a system dynamics model to improve understanding of the nitrogen cycle in relation to FTWs-based subtropical stormwater wet detention ponds. The model was calibrated and validated based on surface water samples collected in a thorough field campaign with R-squared values of 0.83 and 0.97, respectively. Final simulation runs with sensitivity analysis were conducted to investigate scientific questions about the experimental design and effects of urbanization impacts on the biological nitrogen cycling in stormwater ponds.

Floating treatment wetland (FTW) is one of the emerging best management practices (BMPs) for stormwater treatment where macrophytes provide a suitable root-zone environment for microorganisms that allow the plants to remove nutrients through direct uptake into their tissue. In this study, four floating mats with native Florida aquatic macrophytes were deployed in a 340 m2 subtropical stormwater wet detention pond. A fountain in the pond and peat moss used to hold the substrate for plant species on the floating mats are both assumed to add nutrients to the water column. The aim of this study was to evaluate the performance of nutrient removal through the four floating mats and explore associated effects of simultaneous hydrological and biological controls related to various hydrobiogeochemical processes for nutrient removal in a multimedia pond environment. Nutrient concentrations in both inlet and outlet were monitored continuously over 13 months, with episodic (storm events) and routine (non-storm events) sampling plans carried out in parallel to justify the efficacy of the FTWs. Nutrient values within the water column and the sediment were compared before (Phase I) and after (Phase II) the deployment of the FTWs to prove the proposed hypotheses. An additional phase (Phase III) after the removal of the FTWs was added to enhance the understanding of ecosystem response. For non-storm events, phosphorus removal was substantial because of the increase in the initial concentrations, presumably due to resuspension of nutrients into the water column from the fountain operation; about 47.7% total phosphorus (TP) and 79.0% orthophosphate (OP) were removed. The removal rates of total nitrogen (TN), nitrite– and nitrate–nitrogen ( NO x – N = N O 2 − – N + N O 3 − – N ) , and ammonia–nitrogen (NH3–N) were also calculated as 15.7, 20.6, and 51.1%, respectively. Without the uptake by plants, the nutrient removal decreased to different degrees when comparing those in non-storm events during Phase II. Considering plant species, nutrient uptake and assimilation by soft rush (Juncus effusus) was much higher than that by pickerelweed (Pontederia cordata) through both leaves and roots in this case. For soft rush, uptake rate in spring is much higher than that in fall. About 77.0 g N and 8.8 g P were removed from pond water via uptake and assimilation during the second phase. Despite organic nitrogen accumulation due to the pickerelweed leaf debris sedimentation, the organic nitrogen concentration in pond water was still kept at a low level, which implies that the ecosystem is capable of efficiently managing the withered plants and circulating nutrients.

Stormwater wet detention ponds hold a permanent pool of water and offer many beneficial uses including flood mitigation, pollution prevention, downstream erosion control, increased aesthetics, and recreational uses. The reduction efficiency of nutrients is generally low in stormwater wet detention ponds in many urban areas. To enhance nutrient reduction, floating treatment wetlands (FTWs), which are a new best management practice (BMP) in stormwater management, can be installed in wet detention ponds to offer an innovative solution toward naturally removing excess nutrients and aiding in stormwater management. This study assesses nutrient reduction in three Floridian stormwater wet detention ponds where FTWs have recently been installed. Both episodic (storm event) and routine (nonstorm event) sampling campaigns were carried out at the three ponds located in Ruskin, Gainesville, and Orlando. Most notably, nutrient reduction rates after installation of the FTWs reached levels of 33% for total nitro...

In this study, a new-generation subsurface upflow wetland (SUW) system packed with the unique sorption media was introduced for nutrient removal. To explore the interface between hydraulic and environmental performance, a tracer study was carried out in concert with a transport model to collectively provide hydraulic retention time (7.1 days) and compelling evidence of pollutant fate and transport processes. Research findings indicate that our pollution-control media demonstrate smooth nutrient removal efficiencies across different sampling port locations given the appropriate size distribution conversant with the anticipated hydraulic patterns and layered structure among the sorption media components. The sizable capacity for nutrient removal in this bioprocess confirms that SUW is a promising substitute for an extension of traditional on-site wastewater treatment systems.

On-site sewage treatment and disposal systems, commonly referred to as a septic systems, consist basically of a septic tank and soil adsorption field or drainfield. It may represent a large fraction of nutrient loads and pathogen impacts in vadose zone and groundwater systems. It includes not only nitrogen (N) and phosphorus (P), but also pathogen indicators such as fecal coliform and Escherichia coli, which indicate the presence of other disease-causing bacteria flowing into the aquatic system and potentially adversely affecting public health. Constructed wetlands, an effective small-scale wastewater treatment system with low energy and maintenance requirements and operational costs, will cover current needs for nutrient and pathogen removal. In our study, a next-generation subsurface upflow wetland system that is filled with green sorption media (e.g., mixes of recycled and natural materials) along with selected plant species was tested as a substitute for the conventional drainfield in septic ...

Constructed wetlands have been popular in ecological engineering regime; yet, modeling the physical, chemical, and biological processes within these wetlands is a long-standing challenge in the past decades. In concert with our field-scale pilot testing of a new-generation subsurface upflow wetland (SUW) system, this article highlights an advancement of modeling the SUW system with a layer-structured compartmental simulation model. This is the first wetland model of its kind to address the complexity between plant nutrient uptake and medium sorption. Such a system dynamics model using STELLA® as a means for a graphical formulation was applied to illustrate the essential mechanism of the nitrification and denitrification processes within a sorption medium-based SUW system, which can be recognized as one of the major passive on-site wastewater treatment technologies in this decade. Model calibration and validation received fairly good R-squared values of 0.9998 and 0.9644, respectively. Such good a...

In this study, a new-generation subsurface upflow wetland (SUW) system packed with a unique sorption media was introduced for nutrient removal in a domestic wastewater treatment process. To explore the interface between hydraulic and environmental performance, a tracer study was carried out in concert with a transport model to collectively provide hydraulic retention time (7.1 days) and compelling evidence of pollutant fate and transport processes. Research findings indicate that our pollution-control media demonstrates smooth nutrient removal efficiencies across different sampling port locations given the appropriate size distribution conversant with the anticipated hydraulic patterns and layered structure among the sorption media components. The sizable capacity for nutrient removal in this bioprocess confirms that the SUW is a promising substitute or an extension of traditional onsite wastewater treatment systems. Constructed wetlands have been popular in ecological engineering regime; yet modeling the physical, chemical, and biological processes within these wetlands with respect to the knowledge gained in a tracer study has been a long-standing challenge in past decades. The second part of this chapter highlights an advancement of modeling the SUW system with a layer-structured compartmental simulation model. This is the first wetland model of its kind in the world to address the complexity between plant nutrient uptake and sorption media. Such a system dynamics model using STELLA® as a means for a graphical formulation was applied to illustrate the essential mechanism of the nitrification and denitrification processes within a sorption media-based SUW system, which can be recognized as one of the major passive onsite wastewater treatment technologies in this decade.

Floating treatment wetland (FTW) is one of the emerging best management practices (BMPs) for stormwater treatment where macrophytes provide a suitable root-zone environment for microorganisms that allow the plants to remove nutrients through direct uptake into their tissue. In this study, four floating mats with native Florida aquatic macrophytes were deployed in a 340-m 2 subtropical stormwater wet detention pond. A fountain in the pond and peat moss used to hold the substrate for plant species on the floating mats are both assumed to add nutrients to the water column. This chapter presents the basic performance evaluation of nutrient removal through the four floating mats and explores associated effects of simultaneous hydrological and biological controls related to various hydrobiogeochemical processes for nutrient removal in a multimedia pond environment. Nutrient concentrations in both inlet and outlet were monitored continuously over 13 months, with episodic (storm events) and routine (nonstorm events) sampling plans carried out in parallel to justify the efficacy of the FTWs.

The major causes of nutrient problems are widely acknowledged to be nonpoint sources of pollution from both urban and rural areas, including conventional septic tanks or onsite sewage treatment and disposal systems (OSTDS). In this chapter, an extensive literature review of the myriad of alternative passive and non-passive technologies available leads to a new constructed wetland technology that is designed as a subsurface upflow wetland (SUW) with innovative subsurface hydraulic flow patterns, green reactive sorption media, and various plant species. The biosorption-activated media (BAM) are used before the standard drainfield design, and the SUW is used to replace the conventional drainfield. The SUW must have a seepage area for the effluent if reuse of the water is not planned. The SUW system installed at Central Florida underwent intensive sampling for system performance, modeling of the processes, pollutant transport and fate measures, and an assessment for integration of the planning, design, installation, maintenance, and management functions for future implementation and certification testing. Such an SUW system has proven advantageous relative to the conventional OSTDS. The average effluent nitrates are less than 10 mg L − 1 and fecal and E. coli data indicate that their removal is significant for all cases in the field campaign.

This study presents an integrated k-means clustering and gravity model (IKCGM) for investigating the spatiotemporal patterns of nutrient and associated dissolved oxygen levels in Tampa Bay, Florida. By using a k-means clustering analysis to first partition the nutrient data into a user-specified number of subsets, it is possible to discover the spatiotemporal patterns of nutrient distribution in the bay and capture the inherent linkages of hydrodynamic and biogeochemical features. Such patterns may then be combined with a gravity model to link the nutrient source contribution from each coastal watershed to the generated clusters in the bay to aid in the source proportion analysis for environmental management. The clustering analysis was carried out based on 1 year (2008) water quality data composed of 55 sample stations throughout Tampa Bay collected by the Environmental Protection Commission of Hillsborough County. In addition, hydrological and river water quality data of the same year were acquired from the United States Geological Survey's National Water Information System to support the gravity modeling analysis. The results show that the k-means model with 8 clusters is the optimal choice, in which cluster 2 at Lower Tampa Bay had the minimum values of total nitrogen (TN) concentrations, chlorophyll a (Chl-a) concentrations, and ocean color values in every season as well as the minimum concentration of total phosphorus (TP) in three consecutive seasons in 2008. The datasets indicate that Lower Tampa Bay is an area with limited nutrient input throughout the year. Cluster 5, located in Middle Tampa Bay, displayed elevated TN concentrations, ocean color values, and Chl-a concentrations, suggesting that high values of colored dissolved organic matter are linked with some nutrient sources. The data presented by the gravity modeling analysis indicate that the Alafia River Basin is the major contributor of nutrients in terms of both TP and TN values in all seasons. With this new integration, improvements for environmental monitoring and assessment were achieved to advance our understanding of sea–land interactions and nutrient cycling in a critical coastal bay, the Gulf of Mexico.

The conventional decentralized sewage collection, treatment, and disposal systems are no longer able to fully respond to the needs of handling removal of nutrients.. Without proper sorption and nitrification/denitrification, a large fraction of nutrient loads such as nitrogen and phosphorus flowing into aquatic system may adversely affect the water quality and public health. Constructed wetland, a cost-effective small-scale wastewater treatment system with low energy and maintenance requirements and operational costs, may well fit the current needs. A subsurface constructed wetland system as designed as a performance-based passive on-site sewage treatment and disposal system (OSTDS) was proved effective after receiving septic wastewater flow. With the aid of a suite of locally adapted and selected plant species, such an OSTDS was configured to handle 189 cubic meters per day (50 GPD) influent using green sorption media at the test center located on the main campus of University of Central Florida (UCF). During the test run, results indicate that wetland 1, which was planted with Canna, achieved the best removal efficiency of 97.1 %, 98.3 %, 99.98 % and near 100.0 % for TN, TP, fecal coli and E.Coli, respectively. Keyword: Wastewater treatment, Nutrient control, Ecological engineering, Sustainability engineering, Green Technology, Environmental health