World Environmental and Water Resources Congress 2017: Water, Wastewater, and Stormwater; Urban Watershed Management; and Municipal Water Infrastructure

This study investigates the performances of granular activated carbon (GAC) in batch studies for the removal of refractory compounds and NH₃-N using raw leachate from a local landfill (China). The adsorbent was made up of coconut shell waste. The surface modification of GAC with ozone was undertaken to improve its performance. The results showed that ozone-modified GAC removed COD (75%) and/or NH₃-N (74%), compared to as-received GAC (COD: 43%; NH₃-N: 50%) at the same COD and/or NH₃-N concentration of 8,000 and 2,620 mg/L, respectively at 30 g/L of dose, pH 8 (for COD removal) or pH 9 (for NH₃-N removal), 200 rpm of agitation speed and 20 min of contact time. However, treatment using ozone-modified GAC still could not generate effluents that complied with the COD and the NH₃-N effluent limit of lower than 200 and 5 mg/L respectively, suggesting that a subsequent treatment is still required to meet the legislation.

Activated sludge systems are commonly used for treating sewage and industrial wastewater. The activated sludge process is a complex process involving physical, chemical and biological processes. A rapid evaluation of the effluent water quality in activated sludge systems would help engineers improve operation conditions and consequently bring economic benefits to wastewater treatment plant. In this study, computational fluid dynamics (CFD) was used to inform an activated sludge model (ASM1) for the chemical and biological processes, serving to provide a rapid evaluation of effluent water quality. The CFD-ASM1 was validated with the use of measured data, such as the effluent concentrations of chemical oxygen demand, ammonium, and nitrate, from a full-scale activated sludge tank. This study also studied the impacts of air flow rate and bubble size on air volume fraction distribution in the activated sludge tank using the CFD-ASM1. The model developed in this study can further serve as a tool to optimize operation conditions (e.g., air flow rate and bubble size) of activated sludge systems at a low cost.

This paper reports on ongoing research into the potential use of a macro-pervious pavement system in central Scotland as a source of local irrigation water for use in the summer months. Chemical analysis revealed that, after the first application of de-icing salt in winter, the water has a sodium content which is too high for harvesting for irrigation use and that it remains so until the salt is flushed out by spring rains. However water collected in May was used in a growth trial and plants irrigated with this water showed no significant difference in growth compared to control plants irrigated with de-ionised water. With a view to facilitating maintenance of the system, a preliminary growth trial was used to investigate the effects of disposing of the liquid sludge from the system’s separator channels on adjacent planted areas. The results showed that there seems to be no deleterious effects on the plants used but further work would be required if long term effects are to be ruled out.

The objective of this paper is to present an experimentally validated mechanistic model to predict the oxygen transfer rate coefficient (Kla) in aeration tanks for different water temperatures. Using experimental data created by Hunter and Vogelaar, the formula precisely reproduce experimental results for the standardized Kla at 20 ⁰C, comparatively better than the current model used by ASCE 2-06 based on the equation Kla₂₀ = Kla.(θ)^(20-T) where T is in ⁰C. Currently, reported values for θ range from 1.012 to 1.047. Because it is a geometric function, large error can result if an incorrect value of θ is used. Establishment of such value for an aeration system can only be made by means of series of full scale testing over a range of temperatures required. The new model predicts oxygen transfer coefficients to within 1% error compared to observed measurements. This is a major breakthrough since the correct prediction of the volumetric mass transfer coefficient (Kla) is a crucial step in the design, operation and scale up of bioreactors including wastewater treatment plant aeration tanks, and the equation developed allows doing so without resorting to multiple full scale testing for each individual tank under the same testing condition for different temperatures. The effect of temperature on the transfer rate coefficient Kla is explored in this paper, and it is recommended to replace the current model by this new model given by: where T is in degree Kelvin, and the subscripts refer to degree Celsius; E, ρ, σ are properties of water. Furthermore, using data from published data on oxygen solubility in water, it was found that solubility bears a linear and inverse relationship with the mass transfer coefficient.

Geysers in sewer systems are receiving considerable attention due to the public safety concerns. There have been relatively limited studies on geyser formation process and its association with air release from pressurized pipes, consequently very few relevant mitigation measures have been proposed. A large physical model was initiated to study the geysering flow through standpipes and to examine key parameters which may have great influence on geysers. Air-control plates and throttled vent pipes were found to be remarkably effective in alleviating geyser intensity and pressure oscillations in the present study. For vent pipes with diameter d = 0.04 m and 0.06 m, adding an air-control plate with an orifice (d₁ = 0.01 m) resulted in much weaker water jets through the orifice and the pressure peak was also reduced by about 70% and 55%, respectively. If cover blow-off occurred in the air release process, a much larger pressure spike could emerge, with the peak about 3.5 times as large as that without cover blow-off.

Stormwater runoff poses potential flooding and pollution concerns in urban areas such as Los Angeles. The potential impacts of urban stormwater have given rise to solutions such as low impact developments (LID) to remove pollutants from entering river/ocean and provide groundwater replenishment/water supply benefits. The Broadway Neighborhood Stormwater Greenway (Project) is a joint partnership between City of Los Angeles, California State Water Resources Control Board, Water Replenishment District of Southern California, Santa Monica Bay Restoration Commission, and Geosyntec Consultants, to develop a neighborhood system of LID stormwater capture/infiltration in South Los Angeles. The Project is located in public right-of-way and retrofits segments of the Broadway neighborhood with stormwater LID designed to capture, infiltrate and treat stormwater runoff, recharge groundwater, and help address Los Angeles River-total maximum daily load (TMDL) water quality requirements. Total Project cost was $4.9 million and has four levels of LID: parcel based (19 residential rain gardens/infiltration trenches); street-ends (eight dry wells); commercial green streets (four parkway infiltration swales); and sub-regional infiltration gallery (417,000-gallon underneath parking). Water quality monitoring with continuous flow meters are installed to quantify water quality/groundwater recharge. Design drainage area is approximately 45 acres and benefits from a total of tributary area of 220 acres. With its particular location above the “Los Angeles Forebay”, the project is expected to recharge on average 41 acre-feet/year into the underlying Central Groundwater Basin. The Project meets TMDL requirements for the design drainage area through the removal of pollutants such as trash, bacteria, and metals. The Project provides educational, ecological, community benefits leading to a healthier, vibrant neighborhood.

Wastewater disposal systems are designed to meet minimum dilution requirements within a regulatory mixing zone-a limited region around the discharge structure where initial dilution of the effluent occurs. We present a design case study of a multiport diffuser for a 1 MGD dense discharge into a shallow 60-foot wide river. CORMIX mixing zone modeling software was used to design the diffuser to achieve dilution to meet water quality criteria within a mixing zone for regulatory compliance. An iterative design process was employed using the CORMIX mixing zone model and the CorHyd internal diffuser hydraulics model. CORMIX simulates the multiport diffuser as a line source to predict downstream water column dilution values needed for regulatory compliance. CorHyd is used to (i) calculate port and pipe velocities, (ii) verify uniform discharge distribution from the ports, and (iii) determine the diffuser head requirements. To decrease the diffuser-induced near-field acceleration zone and enhance mixing, a fanned unidirectional multiport diffuser was designed. The diffuser riser lengths vary to conform to the river bathymetry. The riser ports were fitted with duckbill valves to maintain high port velocity over a range of effluent discharge rates. The design was optimized for dilutions at the mixing zone with port geometry, exit velocity, and spacing that allows individual plumes to merge by the end of the near-field and minimizes the potential for scouring the river bed.

Sediments containing mercury from historical mining operations in California’s Coastal range have initiated multiple implementation programs to reclaim and mitigate the risk to human health and the environment. At a former historical mining district in Colusa County, California, approximately 22,000 cubic yards of mercury-impacted material was successfully removed and stabilized in an on-site repository. Common lithologies in the area include detrital serpentines, sandstone, and mudstone; and groundwater beneath the district is primarily geothermal. The implementation of integrated stormwater pollution prevention and construction quality assurance plans provided the framework for site stabilization and mitigation of mercury-laden sediment discharge to nearby waterbodies. Depending on excavation contour and slopes, certain best management practices (BMPs) were installed to promote the stabilization of sediment on the areas where mining-related waste rock was removed. Practices included facines, straw mats, hydroseed using local vegetation seed mixes, and hay bale dams; that were evaluated for performance before and during the rainy season. Hydroseed methods above and below straw matting for future potential seeding methods in the area were implemented. Success for stabilization will be measured by multiple site visits during the rainy season and the use of vegetative surveys before and after stabilization using a variety of methods (biological surveys, drone photography, and GPS).

A study has been conducted to develop wetland eco-systems and cost-effective alternatives to the discharge of Alexandria’s partially treated wastewater into coastal lagoons, lakes and to provide sustainable solutions for wastewater recycling. A pilot wetland facility, in conjunction with a biofilm aeration facility, was constructed at Lake Maryout by Alexandria coast, where primary treated wastewater of 50,000 m³/day is being handled. The satisfactory results of water quality parameters of the pilot wetland effluent were compared with the performance of the wastewater-natural treatment facility located at Arcata Bay, CA. The results provide motivations for further large scale wetland applications in the available land of Maryout Valley where fresh water supplies are low. Highlights are presented on use of safe wastewater sludge and bio-solids for restoration of constructed and natural wetlands, which serve for coastal defense; e.g. at the Nile Rosetta headland, San Francisco Bay, and the Central Wetlands in Louisiana, USA.

Sustainable development gears towards preserving the environment and conserving the rapidly diminishing natural resources such as natural resources. This research seeks to assess the performance of crushed recycled concrete aggregates (RCA) from Trinidad and Tobago as sub-base materials in permeable pavement systems (PPS) applicable to urban stormwater management systems across the Caribbean small island developing states (SIDS). Presently, research is lacking regarding the performance of RCA in PPS. These pavement systems are being considered as a natural resource conservation attempt, in addition to reducing surface water flooding in several towns and cities across these SIDS. The project includes laboratory experimental assessment of PPS using RCA versus virgin aggregates (limestone from Trinidad and Tobago and basalt from St. Lucia) from a stormwater quality, geotechnical and hydrologic viewpoint. Stormwater is being collected from various towns and cities across the islands and applied uniformly over the pilot scaled permeable pavements using a purpose-built rainfall simulator. The permeable pavements stormwater treatment efficiencies are being evaluated for the removal and retention of nutrients (nitrates and phosphates), heavy metals (zinc, lead, copper, iron and manganese), suspended solids and turbidity. Hydrologic performances are also being assessed through numerous simulated storm events at various intensities. All pavements have handled 15-minute high intensity rainfall inputs (in excess of 222 mm/h) with 100% infiltration (no surface runoff) recorded. In terms of total suspended solids (TSS) removal, results showed that removal efficiencies varied from 31 to 85% with the RCA test rig recording the highest average TSS trapping efficiency of 58%. The test pavement with RCA in the subbase has performed similarly or better than those with virgin aggregates.

Phosphate, ammonium and nitrates are forms of nutrients; they are released from different sources. The eutrophication of water bodies contributes in speeding the unusual growth of algae because of discharge of high levels of nutrient. Recently, many filtration and treatment systems were developed and used for different removal processes. Due to enhanced operational aspects for the up-flow, continuous, granular Media filter; researchers became more interested in further developments regarding this technology and its performance for nutrient removal from wastewater. Environmental factors significantly affect the filtration process performance, and understanding their impact will help to maintain the nutrient removal process. Phosphate removal by phosphate sorption materials PSMs and nitrogen removal biologically are the methods of nutrient removal that have been discussed in this paper. Hence, the focus on the factors that have an influence on these processes is the scope of this work. The findings showed there are several factors that influence nutrients removal processes. The size, shape and roughness of the filter media particles play a crucial role in supporting biofilm formation. On the other hand, their effect on the reactivity of surface between the media and phosphate ions. Many studies alluded to factors that have significant influence on the biological removal of nitrogen such as dissolved oxygen, temperature and pH; this is due to the sensitivity of biological processes. While the phosphate removal by PSMs showed that it is less affected by these factors. This work provide researchers a comprehensive approach regarding the study of nutrient removal in up-flow filtration systems.

Wet oxidation using hydrogen peroxide (1, 3, and 5% H₂O₂) at raised temperatures has been used to oxidize pharmaceutical wastewater derived from contraceptive pill production. Model wastewater containing ethinyl estradiol (40 µg/ml), levonorgestrel (25 µg/ml), cyproterone (25 µg/ml), gestodene (10 µg/ml), and desogestrel (50 µg/ml) was formulated based on the average concentration of hormones measured in the first wash of an equipment cleaning process. Higher temperatures for wet oxidation ranging from 100 to 150°C were anticipated to enhance the oxidizing capability of this hydroxyl-radical-mediated advanced oxidation. At mild oxidation treatments (1% H₂O₂ at 100°C), only sensitive species showed minor degradation by HPLC chromatogram. Desogestrel was easily removed even with this mild oxidizing, but the other hormones were more stable. Fortunately, higher temperatures generated much higher hormone degradation rates. For instance, 5% H₂O₂ at 150°C destroyed all the hormones in the model wastewater within 5 min. We assume highly reactive hydroxyl radicals produced the rapid mineralization of the spiked hormones.

From 2008 to 2013, South Korea had carried out a river improvement project named Four River Project for flood protection and water supply during drought. In addition, the replacement wetlands were created in riverside at the same time as Four River Project to consider the environment of the river. However, the management problem of replacement wetlands has been encountered because the evaluation of the wetland functions for the conservation of the river environment was not done properly after creation of replacement wetland. So, it is necessary to evaluate the functions of the replacement wetlands and to establish a management plan of the wetlands. The wetland functions could be evaluated in hydrological, ecological and geological aspects. To do this, we compare and analyze the wetland function between replacement wetlands before/after Four River Project to evaluate the wetland function and establish a wetland management plan. Also, we evaluate the wetland functions associated with hydrological, biogeochemical, plant habitat, and animal habitat variables for the suggestion of the wetland management plan. Therefore, we expect that this study could be used as an idea for management plan of future replacement wetlands with climate change.

Over the past 20 years, the built-up area of the urban has been expanded significantly, and the urbanization rate rises from 29.37% (1996) to 56.1% (2015), at the same time, along with the impervious area increased sharply and the infiltration channel was blocked in the most area of the urban, manly wetlands was destroyed, river channel was occupied and changed it use, which changes the city’s original ecological and hydrological characteristic, result to waterlogging disasters, runoff pollution, loss of stormwater resources, water ecological environment destruction and other prominent stormwater problems in water environment. In order to release above problems in the process of urbanization, the national state and local department has issued a series of code and policy documents in the past 20 years and to explored a new model of stormwater management. This paper the development of stormwater management of China was described systematically in recently 20 years from several points, including the national policy, technological changing andmanagement methods, it may provide a reference to developing countries about stormwater management in rapid urbanization.

The municipal water infrastructure in the U.S. include 54,000 community water systems (CWS), more than 15,000 wastewater treatment facilities, and 20,000 wastewater pipe systems, and the associated distribution and collection piping networks and, storage reservoirs or ponds, in the comprehensive manner. A current estimate on this water infrastructure’s sustainable management, to the applicable standards and operational requirements, would cost more than a US$650-billion (or, it could be more than a trillion-US$) in the next twenty (20) years. The spending-to-need-ratio is projected to drastically decline to 26% by 2040, thus, it is an immediate necessity that the utilities need alternative way(s) of financing for and undertaking the needed improvements or this asset renewal. The energy requirements are significant from the potable water processing to wastewater processing to clean water; on an average, a 5,000 kWh per million-gallon-treated is spent. The non-revenue water at the utilities is a significant financial drain, at more than 25% per year; those non-revenue water losses must be controlled. Other local economic losses due to failed water infrastructure assets and/or interrupted water processing and supplies, are also significant at a good number of cities and towns. The design-build (DB) or design-bid-build (DBB) have been the typical way of executing water infrastructure projects; however, the other proven project delivery models are: public private partnership (PPP or P3); construction manager at risk (CMAR); or performance contracting (PC). This work is focused on the performance contracting model of qualification, development, and delivery of water infrastructure asset renewal and management. Performance contracting integrates critical and all elements of the asset renewal project development and completion, in a comprehensive manner, as follows: project qualification, preliminary review with a cash-flow; project design by the expert engineer-of-the-record-team; bid-pricing; financing supported by verified savings; project construction with no-change-order(s); one-contact-of-responsibility by the qualified provider; complete training; and, measurement and verification. Thus, this paper elucidated performance contracting delivery of water infrastructure asset renewal projects with supporting case studies.

Monitoring surface water temperatures (T_w) in lakes, rivers, and reservoirs is a key component of environmental management and influences water quality by affecting bio-geo chemical reaction rates, altering the saturation concentration of dissolved oxygen (DO), and influencing the susceptibility of fish to disease. Temperatures in the Tigris River, one of the largest rivers in the Middle East, are influenced by factors such as heat fluxes at the air-water and human activities such as direct discharge of water to the river. However, modeling and management of water temperature is limited by a paucity of in-situ data, which prevents calibration of models. In this study, we infill data gaps by estimating T_w using the thermal bands of both the Landsat 5 TM and Landsat 7 ETM+ sensors. These satellite-based estimates, typically measured once or twice a month with 60-120m resolution, are then used to develop a regression model that relates daily water temperature to daily air temperature and river flow. These estimates are used to define the T_w boundary conditions for a hydrodynamic and water quality model of the Tigris River based on a 2D implementation of the CE-QUAL-W2 (W2) numerical model. Initial results suggest that there is a significant agreement between modeled and remotely estimated data of T_w. Results suggest that short-wave solar radiation is the most important factor that controls seasonal T_w variations. However, anthropogenic influence is observed as a result of return irrigation flows and flows from Tharthar Lake.

Available options for treating log yard stormwater would appear to be relatively expensive based on two recently completed projects in Washington State. In 2013–2014, multimillion dollar treatment facilities were constructed at the waterfront log handling facilities of the Port of Tacoma and the Port of Olympia. However, a more cost-effective approach was implemented at a northern California sawmill site in late 2015. In all cases, treatment was required to reduce concentrations of chemical oxygen demand (COD) to meet the U.S. Environmental Protection Agency (EPA) COD benchmark (120 mg/L). This paper summarizes the state of the practice for treating log yard stormwater and describes the lessons learned from the more economical approach used at the northern California sawmill.

This paper presents a procedure to identify priority areas for the stormwater management plans based on the identification of hydrologically sensitive areas. The procedure uses secondary data from topographic information, such as soil slope and areas of contribution, the classification of land use and soil characteristics and defines a topographic index. After determining the index, it established a hydrological sensitivity threshold, which identified which areas of a watershed are more likely to be saturated during rainfall events. Then, the areas of the watershed identified as hydrologically sensitive areas (HAS) and that potentially generate pollutants were classified according to their suitability to different types of stormwater management and structures. The specification of these management measures were made from the use of information about the class of land use of the watershed area, the distance of the areas over the drainage systems and the amount of contribution areas upstream the river. The procedure was applied to the Alto Descoberto Basin.

Wastewater is transitioning from being viewed as a waste to being utilized as a resource in the production of reclaimed water. Reclaimed water, obtained through waste stabilization pond treatment technologies, has the potential to offset potable water needs for irrigation purposes as well as fertilizers for crop growth. In developing countries, where waste stabilization ponds are widely used, a major issue is the lack of maintenance which can lead to considerable amounts of sludge piled at the bottom of the pond. This sludge accumulation reduces the treatment capacity of the waste stabilization pond and possibly, the treatment efficiency which is vital for reuse purposes. Improving the hydraulic performance of waste stabilization ponds is an important management strategy that assures protection of public health and the environment. It also maximizes the potential reuse of valuable resources found in the reclaimed water. In cases for which desludging of the pond is a challenge, retrofitting pond inlet can offer an alternative to improve pond hydraulic performance. This option is a low-cost substitute which offers improved retention times based on the types of retrofit. In this study, two inlets retrofit geometries are investigated using computational fluid dynamics. The improvements in retention times observed make this approach a viable solution in places where desludging is not a priority in pond management.

Traditional continuous water supply systems are designed based on certain fundamental assumptions such as controlled population growth, need based withdrawals, responsible citizenship etc. Non-adherence or violation of these assumptions would render the dream of continuous water supply a mirage despite good intentions and engineering practices. Converting distribution networks designed for intermittent supply to continuous supply can further complicate this issue. Transitioning intermittent systems to continuous water supply, especially when the water utility is not able to ensure adherence of the fundamental assumptions, require not only good hydraulic engineering solutions but also sound engineering management solutions. The transition time can be very high ranging anywhere from several months to few years. This presentation will discuss the differences between traditional continuous water supply systems, intermittent water supply systems and future continuous water supply systems transitioned from intermittent water systems, and describes the necessary hydraulic engineering solutions as well as the engineering management solutions. The hydraulic engineering solutions include design of network elements based on both demand driven and pressure dependent flow models. Engineering management solutions include pressure and flow control solutions, air management solutions, and the feedback control loop for effective transitioning from intermittent water supply to continuous water supply.

Seawater desalination results in a concentrated brine that must be safely disposed of. The commonly-used reverse osmosis (RO) process generates concentrate with a salinity about twice that of the intake seawater. This level of salinity would be toxic to many marine organisms so the concentrate must be quickly diluted to safe levels. The California Ocean Plan (Plan) has recently been amended to include new regulations on desalination discharges. These include the definition of a brine mixing zone (BMZ), numeric salinity limits, and assessment of marine organism mortality due to shear and turbulence in the discharge. In this paper we review and summarize the changes in the Plan and provide a case study for a proposed desalination plant in an environmentally sensitive location in Northern California to ensure compliance with the Plan and to support environmental review under the CEQA/NEPA process. Discussed is modeling of the plume dynamics and dilution, predictions of salinity within the BMZ, and assessments of biota mortality due to entrainment into the jets of the proposed diffuser.

The Philadelphia Water Department’s combined sewer overflow (CSO) long-term control program, “Green City, Clean Waters”, aims to reduce wet-weather overflows from its combined sewer outfalls including those along the tidal Delaware and Schuylkill Rivers. Hydrologic and hydraulic models of the combined sewer collection system are used to estimate CSO volume and frequency under average annual hydrologic conditions. A “typical year” rainfall time-series has previously been developed for use in models to evaluate the effectiveness of current and proposed CSO control measures under average annual conditions. Recent efforts to improve model accuracy during the implementation phase of the program have led to the development of a “typical year” tide time-series to represent average annual dynamic tidal boundary conditions. The “typical year” tide is developed using observed water level data for the period from 1901 to the present. The observed tidal water levels can be seen to result from predictable astronomical influences as well as certain large scale meteorological conditions. The astronomical influences result in a predictable diurnal tidal cycle that is independent of the occurrence of rainfall events in the “typical year.” The meteorological influences, however, are expected to be correlated to certain rainfall events and need to be analyzed in order to identify average annual conditions in the development of a “typical year” tide time-series. While the “typical year” tide is developed from a single station, there is a significant time lag of the tide along the Delaware and Schuylkill Rivers. A harmonic analysis is performed on nearby tide stations to estimate timing and water level adjustments needed for developing boundary conditions for all tidal outfall locations. The result is a “typical year” tide time-series for each of five tidal zones.

Secondary settling tanks (SSTs) or secondary clarifiers are integral to the performance of the activated sludge process which is the most commonly used biological method of wastewater treatment. The SST’s purpose is to separate the biosolids from and return them to the reactor. SST research was first performed more than 100 years ago and many significant advances have been made. CFD clarifier models were introduced in 1970s and fully developed in the 1980s and 1990s. Recent CFD models have provided new insight and better SST designs. To continue this progress we studied the major influential SST design factors using a numerical Quasi 3-D SST model to verify several published SST studies. The papers provided the input and design parameters for the model, such as tank geometry, loading rates and density currents to determine their effect efficiency. Model outputs were compared to field data and simulation results in the original papers. Our results showed differences and similarities between the Quasi 3-D model and the simulation outcomes in the published papers. The Quasi 3-D model showed many opposite trends in efficiency as a function of loading rates. Future work is focusing on (1) the development of a systematic and repeatable rheological measurement protocol, (2) the development of a more reliable rheological model under the guidance of this protocol, and (3) the development of a new 3D clarifier model coupled with the new rheological model.

This paper presents a case study of rainwater harvesting potential in a small residential city located in the semi-arid Southern California through implementation of low impact development (LID) devices. To model the rainwater capture potential, a storm water management model of the existing storm system is developed using PCSWMM, a modeling platform based on the EPA SWMM model. The model looks at the effect of the 2-year and 10-year 24-hour design storm under 3 different scenarios considering–(1) a single rain barrel, (2) five rain barrels, and (3) a storage tank in each residential lot. Results show that using either a single or five rain barrels captures a relatively small amount of rainwater. However, a storage tank per lot increases the city’s rainwater capture efficiency and from a single storm the city can collect more than 3.5% of its annual reclaimed water volume.

This study uses advanced mathematical modeling techniques to evaluate a novel mainstream anaerobic wastewater treatment scheme that offers the possibility of low energy treatment while achieving target effluent goals (TN≤ 10mg/L; TP≤ 1 mg/L). The main components of the scheme consist of anaerobic membrane bioreactors (AnMBRs) for BOD and TSS removal, adsorptive filter media for phosphorus removal and Anammox process for nitrogen removal. Simulation results suggest that, AnMBR operation removed about 80% of the influent COD, providing a permeate (biodegradable COD/N ~ 1.25) that is suitable for Anammox operation. The removal efficiencies of TN, TP and TCOD in the effluent was 93%, 86%, and 95% respectively which is comparable to a high performing BNR plant. Further comparison of the treatment scheme with conventional aeration intensive systems in terms of sludge generation, chemical requirement, operational cost and energy, we conclude that the proposed configuration has great potential for full-scale implementation.

The storm water investment strategy evaluation (StormWISE) model is applied in Philadelphia as a case study in deploying green stormwater infrastructure (GSI) to reduce CSO flows. Previous work reported on revisions to StormWISE’s hydrology and cost components to adapt the optimization model for intense urbanization in Philadelphia using EPA’s SWMM model to calculate runoff volume reduction from deploying GSI. This paper further extends StormWISE’s hydrology components using a more detailed SWMM model and using it’s sewer flow rate time series to calculate annual CSO volume reductions. Analysis of results shows nonlinear hydrological response that be explained by exploring three different underlying physical processes that cause nonlinearities. A nonlinear statistical model is developed through regression analysis of the simulation results. A revised StormWISE model incorporates the statistical model and applies it to Philadelphia’s Wingohocking Sewershed to generate cost minimizing GSI deployment strategiesto achieve CSO reduction targets.

Rain gardens and other bioretention SCMs have proven to be an effective means to mitigate increased stormwater runoff. Present research has focused on infiltration as the key volume reduction mechanism, but the inclusion of evapotranspiration (ET) in the design of SCMs is a viable removal method. Design guidelines for soil in rain gardens are often restrictive. Tailoring the soil media to site specific conditions, or using on-site soils, to promote either infiltration or ET can be beneficial to increase both volume and pollutant removal. A bench scale study was designed at Villanova University to assess the quantity and quality removal capabilities of five different USDA soil types. This paper will focus on comparing the nutrient removal capabilities of the different soil types. Nutrient removal was studied through three means: non-continuous weighing lysimeters in the field, and batch and column experiments in the laboratory. Each method measures the performance of five soil types: loamy sand, sandy loam, loam, silt loam, and clay loam. The depth of soil media and flow path were also analyzed for each soil type through two different lysimeter configurations: vertical 46 cm deep columns and horizontal 20 cm deep boxes at a 2.5% slope. Three dosed storm simulations compare the influent and effluent concentrations of TKN, TN, NO₂, NO₃, TKP, and PO₄ in each lysimeter. In addition, cation exchange capacity and batch isotherm relationships were measured for each soil type. The results of this research provide a performance comparison as it relates to nutrient removal for various soil mixes in rain gardens.

In trying to deal more effectively with urban stormwater runoff, recent research has been focused on implementing smart stormwater systems that optimize volume collection and removal performance. Several green infrastructure technologies on the Villanova University campus have been recently retrofitted to include real-time control to achieve this improved volume removal goal. These systems utilize the physical processes present in green infrastructure (infiltration, evapotranspiration, etc.) tomanipulate the hydrologic timing to optimize performance through actively controlled inflows and discharges from the system. The control is implemented through a cloud-native platform developed by OptiRTC, a technology firm focused on control of stormwater infrastructure. A modeling study was completed of a real-time controlled green and gray roof system on the Villanova University campus. The study site is comprised of an existing extensive green roof and an adjacent gray roof that has been retrofitted to capture excess runoff from the system. Stored runoff is actively released onto the green roof during dry periods to fully utilize the evapotranspiration potential of the green roof while increasing total capture from the system. The system as a whole demonstrates how forecast information, remote sensing, and self-learning components can be integrated into a green infrastructure system to optimize performance. The long-term continuous simulation compared performance of the green roof system to the performance prior to being retrofitted, allowing for the benefit of the real-time control to be evaluated.

The use of green stormwater infrastructure (GSI) continues to grow as an important source of stormwater management in cities across the United States. Designing GSI systems often includes implementing pretreatment practices in order to avoid clogging, reduce maintenance, and increase the life span of the infrastructure. Often, arbitrary design guidelines are adopted for these pretreatment practices with unknown consequences on the longevity and performance of the subsurface systems. This preliminary study outlines a methodology by identifying key site selection, sampling procedures, and device selection in order to ultimately better understand GSI performance in Philadelphia. By sampling two stormwater management practices (SMPs) during simulated runoff tests and natural rain events at set sampling locations throughout the flow path in the SMP, we aim to characterize stormwater flow by measuring its particle size distribution. With different measurements of particle size distribution throughout the SMP, we aim to understand the SMP’s longevity and performance as well as identify the needs for pretreatment protocol adjustments.

This article shows the design and development of a reactive early warning model as part of a reactive early warning system for urban flash flood management in the city of Barranquilla, Colombia. The system is divided into four components: (i) measuring equipment with rainfall and flow rate gauges, datalogging and transmission, (ii) a system for database processing and a web interface, (iii) a numerical rainfall-runoff model in PCSWMM calibrated and validated, and (iv) a reactive early warning model for determining the hazard level, and for making decisions of alertness along the main streets. Twelve (12) rainfall gauges were installed in the city, covering around 150 Km². The numerical model in PCSWMM was calibrated and validated with rainfall and flow rate data measured in a typical subcatchment of the city. A time of concentration equation was developed from the characteristics of the subcatchment such as slope and length. A pilot urban watershed was selected to test the system, from which hazard alerts every minute with forecasting of up to 40 minutes ahead on the lower parts of the watershed were determined. That time may allow people to make prompt decisions regarding their mobility over the city and reducing accidents caused by flash floods.

This study evaluated the effect of rainfall intensity on the volume reduction of stormwater in combined sewers through the use of permeable pavements. Three types of permeable pavements (concrete, asphalt, and interlocking blocks) were installed at three alleys in St. Louis: one type of pavement material for each alley. These three alleys are close to each other in a single family residential neighborhood. Flows in the combined sewers that collect storm runoff from the alleys were measured before and after installation of the permeable pavements. The stormwater flows were separated from the measured total flows in the combined sewers and normalized by the amount of rainfalls. The measured rainfalls were put in four categories by their intensities. Results showed that the rainfall intensity affected reduction of storm runoffs. Reduced volume reduction of storm runoff were correlated to increased rainfall intensities. The percentage reduction for each type of pavement were reported in the study.

The hydrologic and pollutant removal effectiveness of structural stormwater control measures (SCMs) is subject to a significant amount of variability, attributable to the episodic and stochastic nature of stormwater flows. This variability can be seen by the range of an SCM’s “percent removal” metric-the proportion of the influent that does not appear in the effluent–as estimated across varying precipitation characteristics. As the percent removal metric is commonly used in practice for the selection and design of SCMs for post-development runoff control, and for estimating progress toward total maximum daily load (TMDL) waste load allocations (WLAs), the variability in performance confounds straightforward cost-effectiveness calculations. This research presents alternate methods for characterizing SCM performance, discusses the use of these methods for cost-effectiveness estimation, and compares the outcomes to the cost-effectiveness as estimated using a static percent removal value. The importance of the SCM performance method employed on the selection of the “optimal” SCM is discussed, as is the effect of the various methods on progress toward a TMDL waste load allocation.

The California Statewide Trash Amendments require that Phase I MS4 Permittees initiate retrofit programs to eliminate Trash in discharges from MS4s through the implementation of Trash Control BMPs. In addition, development projects are also required to incorporate LID BMPs that provide the full retention of the 85^th-percentile storm runoff. This paper assesses how green infrastructure impacts compliance with the 100-year level of flood protection. Based on the findings of a literature review, two separate case studies were developed to assess the hydraulic impacts of green infrastructure. The implementation of infiltration chambers in an interior drainage pond located in the City of Oxnard resulted in a slight increase of the pond volume (1.3%) due to the loss in hydrostatic pressures on the outlet flap gate. Typical MS4 maintenance of catch basins are performed once to twice every year, when catch basins are 25% to 50% full. A 2D hydraulic model for the western part of the City of Simi Valley showed that a blockage factor of 25% would result in an additional 33 parcels in a designated flood zone. Maintenance and design recommendations are proposed to address these findings.

Bioretention systems are commonly understood to include permeable media with a significant organic component and plants. Although the number and variety of plants and soil composition varies widely, the microbiological community that develops within the soil and plant zone is thought to be important to system performance, especially in the inter-storm period. During this time, many pollutants are transformed, assimilated and incorporated into new vegetative growth. These inter-storm processes play an important role in regenerating the removal capabilities and permeability of the filtration media. While there is no defined method to assess the biological community dynamics in bio retention systems this study was performed to perhaps serve as a foundation to develop a method to assess biological population and diversity as a “health” indicator for bio retention systems. To identify and quantify the microbiological community present in common stormwater filtration treatment systems, samples of filter media were collected and subjected to microscopy analysis. Microscopy analysis included counts for protozoa, fungi, nematodes and bacteria. These counts demonstrate nutrient cycling capacity, predatory food abundance, nutrient retention and transportation, soil structure, aerobic conditions, and provide a general indication of diversity, population balance and soil health. The types and amounts of organisms present in planted bioretention systems (containing organic media) and non-planted conventional sand filter systems (containing inorganic media) were compared to assess the impact of vegetation and organic material on the biological community. The results from this study should provide a better understanding of how biological activity and ultimately pollutant removal processes are affected based on the presence of vegetation and organic material in different stormwater filtration systems.

Critical infrastructures (e.g., water supply) are by definition essential for society and their damage, destruction or disruption may have significant negative impact on public health and the security of the citizens. Primary disasters such as natural hazards or man-made hazards can influence critical infrastructures and can lead to secondary disasters. Secondary disasters are caused by the consequences of primary disasters, which means for example the unavailability or pollution of drinking water resulting from disastrous events like a hurricane. To provide drinking water in any phase of a disaster, municipalities need to provide an emergency water-supply strategy. This study shows the needs of hospitals and health care facilities and the need of water for sewage systems to avoid a risk for public health. However, the main vulnerability is the distribution of emergency water supply.

The Metropolitan St. Louis Sewer District (MSD) Combined Sewer Overflow Long-Term Control Plan (CSO LTCP) was approved by the Missouri Department of Natural Resources on June 1, 2011. The LTCP is identified in MSD’s federal Consent Decree (CD) which became effective in April, 2012. MSD’s efforts to comply with the CD are referred to as MSD Project Clear. MSD Project Clear includes a $100 million green infrastructure (GI) program in portions of the District that flow directly to the Mississippi River outfalls. One component of the GI program is the “Rainscaping Small Grants Program,” which offers up to $3,000 per grant to private landowners to install rainscaping solutions on their property. Funds are available to private residences, community organizations, schools, churches, etc. located in the program area. This program allows MSD to outreach and educate the public as well as creating greater community and sewer system benefits than MSD would be able to accomplish alone. The program encourages simple techniques to reduce the overall impact of stormwater such as rain gardens, lawn alternatives, pervious pavement, green roofs, and rainwater harvesting. Naturally reclaiming the stormwater by using rainscaping techniques improves curb appeal, increases property values, reduces sewer overflows, minimizes basement backups, and attracts birds and butterflies. MSD began the Rainscaping Small Grants Program in 2014, and completed the first full round in 2015, collectively awarding 53 grants. This year, MSD will again partner with the Missouri Botanical Garden to continue the program.

This paper presents the results regarding an experimental and numerical study about a buried PVC pipe and its interaction with the surrounding soil. The interaction between a buried pipe and the composite soil has been simulated by using elastoplastic finite element models to determine the levels of deformation in the pipe and settlement in the soil. A series of loading configuration tests were conducted, using a prototype trench, in which a flexible pipeline was buried in composite soil layers of known properties. The resulting data from these tests were used to validate output mathematical models using a Mohr Coulomb Plasticity model in one case, and a Dragger Prager model in the second to simulate the stress-strain behaviours of a composite soil and a buried PVC pipe. The pipe–soil interactions were found to be influenced by the pattern of soil and bedding layers, thereby establishing that the properties of the soil play a significant role in determining levels of deformation and displacement of a sewer pipe cross-section. The use of ABAQUS, a finite elements package, and selection of the appropriate model to simulate soil elastoplastic behaviour, has confirmed the importance, significance and sensitivity of the soil material properties on the numerical simulation accuracy when compared with experimental data.

Four conceptual stormwater systems have been designed using City of Toronto and City of Pickering standards. The four systems have been inputted into EPA SWMM 5.1 and simulated against IDF curve-based design storms, as well as Toronto’s historic rainfall data ranging from 2005 to 2015. From analyzing the simulation outputs, it is noted that many of the design assumptions lead to systems performing below expectations when tested directly against the design storm. In some cases, peak flow rates, flow velocities and flow areasall exceed the expected values from the initial design. There are several factors that may contribute to this. The first notable factor would be an incorrectly assumed time of concentration, leading to a design storm that is not representative of an actual “worst case scenario” storm. The second notable factor is the inclusion of all pipes in a dynamic network, as opposed to the simplistic Manning’s approach taken by the design. These two factors are explored and their potential impacts are discussed in relation to real world situations where storms are far less likely to mimic the chosen design storm.

Delineation of urban catchment areas is important in the decision making of stormwater management, city planning, and urban flooding mitigation. We propose a new method using inverse modeling to identify the area and location of the urban catchment. The method is applied to the city of Shanghai, China.

The current research is a partnering effort between Southern Illinois University Carbondale and City of Las Vegas to assess the vulnerability to drought, extreme heat, and extreme precipitation. This study focuses on precipitation and usesdifferent climate scenarios from the high-resolution North American Regional Climate Change Assessment Program (NARCCAP) climate model data to evaluate the existing stormwater infrastructure of the Gowan Watershed in the Las Vegas valley. Six NARCCAP modelsconsidered in the study have shown the Gamma distribution as the best fitted from Kolmogorov Smirnov best fit test. Delta change method is adopted to quantify the effect of climate change on storm depth. U.S. Army Corps of Engineers HEC-HMS model is used to evaluate the changes in peak flow, storage, and outflow within the watershed. The findings of the analysis show that the drainage facility of the study area is vulnerable to the related climate change impacts. This study helps to quantify the effect of climate change on design storm depth of urban watershed.

The decanter is one of the core unit in the traditional SBR process, in order to dissolve the decanter limit problem impose to the traditional SBR, the new process SBR without decanter is proposed in this article. This new type of SBR modified the original tank structure, utilizing fixed weir as the effluent pattern. We made a comparative analysis for effluent water quality between fixed weir SBR and original SBR. As a result, making the water level stable inside of water tank is a good method to raise the water quality of effluent. In conclusion, we believe that the fixed weir SBR can become one replaced type of SBR in the future.