World Environmental and Water Resources Congress 2019: Water, Wastewater, and Stormwater; Urban Water Resources; and Municipal Water Infrastructure

The water quality and quantity benefits of green roofs have been well documented. However, the transfer of the sun’s heat through the roof to the building envelope has not been as well studied. This project addresses the knowledge deficit by testing thermal flux between the surface and the bottom of the green roof media operated under simulated winter and summer conditions and under saturated and dry conditions. Initial studies evaluated replacing expanded shale with crumb rubber. The results showed that when the surface was approximately 65 C, the temperature against the building envelope were 29 C for crumb rubber and 39 C for conventional media. Under saturated conditions, the initial measurements showed that crumb rubber still transfers less heat to the roof compare to the conventional material. Rubber also retained water longer, which kept the heat away from the roof due to slow evaporation of water. This translates to a considerable amount of energy saving in urban areas by using recycled tires as green roof materials. Further research will investigate other components of green roof media and the impact of vegetation on heat transfer, with the goal of improving existing models of building roof performance when a green roof is added.

A daily water balance model is developed for California State University Long Beach campus to investigate rain water saving potential of a rain water tank system. When it rains, the model stores runoff from 28,225 m² roof top area in the tank and uses it for landscape irrigation. The model evaluates the performance of tanks ranging from 10,000 L to 100,000 L in size for the historical driest, average, and wettest years. Results show that in an average rainfall year, runoff volume stored in a 100,000 L tank can supply 50 days of irrigation demand (< 52,000 L/day) of cool grass turf on North campus. However, whenever the rainfall was more than 10% of average annual rainfall, a large fraction of the rain water was lost as overflows from the 100,000 L tank. Reliability of tank system increases with tank sizes but is highly dependent on the annual volume of rainfall.

Controlling stormwater runoff from impervious surfaces in urban areas presents two main engineering challenges: (1) the handling a large volume of water in a short period of time and (2) the presence of many contaminants. Controlling water quality of infiltrating stormwater is difficult. Bone char has been shown to have a high affinity for copper, zinc, cadmium, arsenic, and lead ions. We investigated the potential of amending bioswale soil with bone char to decrease the dissolved metal transport from parking lot runoff in Detroit, MI. The role of temperature on the sorption rate and capacity of bone char in cold climates must be considered. Various amounts of bone char were added to 40 mL of 500 ppm copper solution (pH ~5.5) in centrifuge tubes and placed on rotators at room temperature. Additional experiments were conducted in tube racks placed at room temperature (25°C), in a refrigerator (5°C), and in a hot water bath (40°C). Copper concentrations were measured with colormetric techniques using a spectrophotometer and were confirmed with ICP-MS analysis. Copper concentrations were measured weekly for 60 days and showed a large effect with temperature. After 60 days, the 5°C, 25°C, 40°C samples had 32%, 88%, and 100% sorption, respectively. The mass loading after 60 days was 64, 176, and 200 mg Cu/g bone char for 5°C, 25°C, 40°C, respectively. These results demonstrate that bone char is a promising bioswale soil amendment to aid sorption of copper and other metals, although temperature effects must be accounted for in design.

Much more attention and focus should be paid on studying the curb inlet interception efficiency and its design because curb inlet is an important component for road-bioretention facilities. It allows the runoff from the road surface to get into bioretention and influences the performance of the road-bioretention strip directly. Most of the currently used curb inlet interception efficiency equations were based on simple theoretical derivation with assumptions and revised coefficients or exponents using experimental data. The experiments were conducted under varying upstream inflows rather than rainfall situations. In this study, the updated FullSWOF-ZD program, based on the open source overland flow simulation program FullSWOF_2D, was tested with 20 different road configurations (varying longitude and cross slopes) of locally depressed Texas type D curb inlets and 10 undepressed cases. The FullSWOF-ZD program simulates the complete overland flow processes and then quantify the curb inlet efficiency under the constant rainfall and constant upstream inflow conditions. One thousand road modeling cases with different longitudinal slopes, cross slopes, and curb inlet lengths were established and modeled. The curb inlet intercepted flow percentage (P_ci) during the simulation period was summarized and discussed. The results show that P_ci is 100% at the beginning of the rainfall, then decreases and reaches to equilibrium, and then P_ci increases when rainfall stops. The curb inlet efficiency (E_ci) for all cases were summarized and compared with HEC-22 calculated results. The advantage and limitation of HEC-22 method were summarized and discussed based on a comparison of calculated and simulated E_ci.

Winter snowmelt and stormwater runoff contain large concentrations of deicing salts. Past research has shown that NaCl has the potential to reduce the permeability of soils, defeating the purpose of green infrastructure. To understand the behavior of NaCl and its alternatives, our research compared three alternative deicing salts [sodium acetate (NaAc), calcium chloride (CaCl₂), and calcium acetate (Ca(Ac)₂)] to NaCl for their effects on infiltration, retention/release of metals, and fertility. The results suggest that chloride-based salts reduced the infiltration rate whereas the acetate-based salts had minimal impact. Calcium-based salts, especially CaCl, resulted in less copper uptake, compared to Na-based salts. After completing the infiltration tests, soils were tested for calcium, magnesium, potassium, pH, and phosphorus, total nitrogen (TN), total carbon (TC), sodium, and metals (copper and zinc). The soil test results confirmed that deicing salts resulted in less copper retention on the soil.

The age of “smart storm water” pushes the existing stormwater infrastructure to be retrofitted with sensors, controllers, and actuators for improving system performance. Real-time control enables the development of smarter stormwater systems by controlling distributed system components like gates, pumps, and valves to adapt to changing storm events. Once the watershed is controlled, how to coordinate these dispersed controllers to achieve best global results need more theoretical support. To meet this demand, a better fundamental understanding of the coordination between local control and system-level control are needed. This paper explores the potential of using controlled smart stormwater system simulation to improve our knowledge. By presenting this modeling work, simulation outcomes of controlled stormwater systems are obtained before they become reality. Using three simulated control cases that were designed to reduce downstream peak water depth, we observed that the best at local controlled storm water sites might not be expanded to optimal system-level, watershed-scale control. Finally, a campus open-source storm water RTC simulation framework called PySWUU is compiled at the University of Utah for future hydrologic-hydraulic modeling.

Urbanization increases the amount of impervious surfaces and adversely affects the quality and quantity of surface and ground water resources. Imperviousness leads to decreased infiltration, increased surface runoff, and washed off pollutants in the stormwater runoff. Stormwater management strategies such as low impact development (LID) are control measures designed to restore the natural hydrologic flow and improve the quality of stormwater. Although LID practices have shown improved quality of urban stormwater, their performance is highly dependent on local conditions such as design parameters (media, plants, retention time) and climate. In this study, pilot-scale experiments were performed to assess the removal efficiency of different sand and bioretention media. A synthetic water and four different media, including limestone sand as native soil, were tested to identify the optimal bioretention design. The results of water quality analyses suggested that limestone sand showed significantly higher removal efficiencies, especially for the removal of heavy metals.

Although bioretention systems are very effective at reducing peak flows and improving water quality, recent studies have shown that nutrients and metals can leach from the bioretention soil and cause degradation of receiving waters in bioretention systems with an underdrain. Mycorrhizae, particularly endomycorrhizae which enhances the root system of plants, may increase nutrient and metals uptake in bioretention systems. To evaluate whether mycorrhizae improve nutrient uptake, column studies were conducted with mycorrhizae-inoculated soil, a proprietary soil inoculated with mycorrhizae and bacteria, and bioretention soil (as a control). Ten tests were conducted with stormwater, and influent and effluent were analyzed for total phosphorus, phosphate, total nitrogen, nitrate, ammonia, copper, and zinc. Results indicate the plant root network was more extensive in soils inoculated with mycorrhizae and initially reduced nutrient and metals leaching, but this trend reversed halfway through testing when leaching from the inoculated columns became higher than the control. Variation in results were not as pronounced in the proprietary soil, which consistently retained total phosphorus and phosphate, but leached nitrogen. Other factors such as soil type, presence of other soil microbial populations, and wetting/drying cycles may have a larger impact on nutrient uptake than presence of mycorrhizal fungi.

Infrastructure compliant stormwater management (ICSM) strategy is an approach where stormwater runoff volume above the capacity of existing drainage systems can be managed using water sensitive urban design (WSUD) technologies. This new approach could support the growth needed in urban landscapes of developing countries in Asia. A trial catchment in Dhaka, Bangladesh, was considered and an essential element of ICSM strategy was the assumption that the existing stormwater drainage infrastructure of Dhaka City has a capacity limit equivalent to 1 year ARI rainfall events. Rainfall beyond this capacity is responsible for serious flooding; it can be successfully managed by employing infiltration based WSUD technologies. The study showed that with infiltration based WSUD technologies in place, an acceptable level of nuisance flooding will only be experienced in 100 years rainfall events and complete flood security can be provided for 50 and 20 years levels.

Construction of impervious surface by replacing natural vegetation increases surface runoff and is traditionally managed by channeling storm water to an outlet. However, traditional methods create problems such as downstream erosion and flooding, reduction in ground water storage, and increase in pollutant loads. This study presents an analysis on reduction of runoff quantity and pollutant loads by retrofitting urban stormwater management system. Retrofitting was done by using combinations of green infrastructures such as rain cisterns, infiltration trenches, permeable pavement, and roof disconnections. A part of University of Nevada Las Vegas campus area was selected as study area. A design rainfall of 6-hour duration with a return period of 100 years was used to analyze flooding and design retrofits. Storm water management model was used to model infiltration and flow routing in the existing storm water network with system of conduits and storage units. Runoff and pollutant response was analyzed by dividing the area into subcatchments based on existing structures and stormwater inlets. Pollutant loads were modeled using buildup and washoff equation for two different land uses and routed through drainage systems. Results were validated by using the runoff quantity and pollutant loads from previous studies. Cost estimates of retrofits were calculated using stormwater calculator. Green infrastructures such as permeable pavement, infiltration basin, rain cisterns, and rooftop disconnections were suggested as retrofits to solve the problem of flooding. The results showed that impermeable pavements and infiltration basins were most effective for parking lots and reduced the runoff by as high as 90% and pollutant loads by 57%. The runoff coefficient was reduced significantly up to 94% for catchments with high percentage of replaceable impervious cover such as parking lots. Roof cisterns were suggested as an option to control runoff from buildings. The total installation cost of retrofits was estimated to be 5.2 million dollars. Retrofitting with green infrastructures could be helpful for planners to reduce runoff and pollutant loads.

Providing sustainable wet weather solutions while enhancing local neighborhoods is Blueprint Columbus’ innovative approach to “Clean Streams, Strong Neighborhoods”. The pioneer project for Blueprint Columbus is the South Side Settlement Heritage Park (SSSHP). In addition to addressing local nuisance flooding, providing tangible social benefit to the neighborhood, the SSSHP provides lessons learned for design, construction, and maintenance for other Blueprint projects. The SSSHP provides water quality for 6 acres and manages approximately 10 MG of runoff annually while reducing local flooding. The park has stormwater bio-retention basins, pervious pavement basketball court, picnic shelter area, playground, and a walking path. The city started park construction in 2015 and completed it in 2016. Regular inspection has occurred for the past 2 years to evaluate the bio-retention vegetation, performance, and O&M requirements.

TOPKAPI (tographic kinematic approximation and integration) model is a distributed hydrological model with physical mechanism developed by Prof. Ezio Todiniin and his team in Italy at the beginning of the 21st century. It can fully consider the spatial variability of rainfall, topography, vegetation, soil, and other factors. The TOPKAPI model is simple in structure and in parameter composition, so it has great advantages in real-time flood forecasting in river basins. On the basis of introducing the basic principle and structure characteristics of the TOPKAPI model, this paper explains the terrain data, hydro-meteorological data, soil, land use, and other data needed for the application of TOPKAPI model and the acquisition ways or approaches of the data. Then it analyzes the application of TOPKAPI model in the world, especially the application of flood forecasting in China. Finally, the TOPKAPI model is compared with TOPMODEL model, SWAT model, and lumped Xin'anjiang model. It points out that TOPKAPI model has great application potential in real-time flood forecasting, but it is inadequate in the areas where human activities are intense. It is necessary to combine other methods or models to improve the simulation process and the simulation effect, and it is also need to develop concurrent application versions of the network to meet the need of real-time flood forecasting of some departments at the same time. The research results may provide some reference for the improvement of TOPKAPI model and its application and popularization in real-time flood early warning and forecasting in China.

Bioswales and catch basin inserts are two current “buzz words” in the field of the environmental engineering. Bioswales are a “U” or “V” shaped depression in the landscape designed to: (1) reduce stormwater runoff volumes by increasing infiltration rates and (2) improve water quality by capturing sediment and sorbing contaminants. Catch basin inserts are runoff-filters with a sediment trap and various sorption media filters installed under an individual sewer grate with the goal of filtering particles and dissolved pollutants (both organic and inorganic) from stormwater before entering a sewer system. Both of these techniques improve the quality of stormwater runoff and these techniques have independently shown the potential to be effective. However, efficiencies of the processes are reduced in some situations due to poor management practices or insufficient design criteria. We first collected runoff samples from various locations around Detroit, MI, near the Wayne State University campus (parking lot runoff entering bioswales, street runoff entering storm sewers, etc.) to quantify appropriate concentrations of pollutants to use in our testing. We then tested various sorbent materials from commercial catch basin inserts and other promising sorbents (e.g., bonechar) with synthetic urban runoff to quantify the potential pollutant removal using inserts. Various amounts of sorbents were added to synthetic runoff solutions in 50 mL centrifuge tubes and measured for metal concentrations over time. We also evaluated some potential design flaws in bioswales and catch basin inserts and provided some recommendations to improve the efficiency of the processes and update best management practices.

Urban runoff/stormwater poses flooding and pollution hazards in metropolitan areas. The impacts of contaminated urban stormwater have given rise to low impact development (LID). City of Los Angeles (City)—LA Sanitation (LASAN) has installed thirty five (35) rain gardens in the University Park neighborhood to capture and infiltrate stormwater. The 35 rain gardens with a total volume of about 46,000 gallons, dimensions of 4'–7’ wide by 15' long by 4' deep (void ratio of 0.40). Key elements of the project includes cooling the urban environment with removal of impervious surfaces and adding native vegetation planting; infiltration media to remove pollutants and increase water supply; parkway sediment trap basins to remove pollutants like trash, bacteria, metals, suspended solids, oil, and grease; new Curb-O-Let model inlet system to capture stormwater; easy to maintain pollutants/trash in the sediment trap area. With treatment of dry/wet-weather runoff, water carrying pollutants of concern were prevented from discharging into the Ballona Creek/Santa Monica Bay watershed. Overall project was a success on terms of successful implementation and for demonstrating the use of rain gardens along the City’s right-of-way. The relative success of the Project in achieving its objectives may provide a basis for future broader-scale regional programs in implementing similar types of rain gardens, particularly as part total maximum daily load (TMDL) implementation plan. However their future implementations of rain gardens should seek ways to maximize their drainage areas and use larger size footprints. The rain gardens LID approach’s is demonstrated in Los Angeles, CA.

Green infrastructure (GI) controls surface runoff and restores pre-development hydrological conditions in a more environmental-friendly way. However, shallow groundwater restricts the implementation of GI due to possible groundwater contamination, groundwater flooding, and decline of surface runoff control efficiency. Thus, it is challenging to strike a balance between surface runoff control and groundwater protection. Some design methods have been proposed, but knowledge on how to allocate GI to maximize the benefits and minimize the problems is limited. This study utilized a loosely-coupled hydrological model, named SWMM-MODFLOW, to examine the impact of spatial allocation of GI on surface hydrological performance (e.g., peak and volume reduction of surface runoff and flow of catchment outlet) and groundwater table dynamics (e.g., maximum height of groundwater mound) at an urban catchment at the Kitsap County, Washington State, of the U.S. GI showed good performance in surface runoff reduction even in shallow groundwater environment. It enhanced the formation of groundwater mound but the effect was localized. Porous pavements showed better performance than bioretention cells, particularly in the peak and volume reduction of surface runoff. Bioretention cells allocated aggregately showed slightly better runoff reduction than that allocated distributedly, and GI in upstream areas generated greater groundwater mound than that in downstream areas. The results of this study provide some references for allocating GI in the catchment scale considering surface and subsurface hydrology in shallow groundwater environment.

The main reason for pollution of landscape water system is pollutant invading like raining, raise dust of air, and life waste. With lacking of recycling in the water body, this will lead to the low dissolved oxygen inside of water. As a result, the water body will lose self-cleaning capability gradually. There are many methods to increase dissolved oxygen, traditional method is utilizing surface aerator, but it has many disadvantages. A modification for traditional aerator is proposed in this article, it has high efficiency in aeration and can force water recycling. In this article, we made a comparative analysis between new push flow aerator and traditional surface aerator. The conclusion is new type of aerator is much more helpful to increase the efficiency of oxygenating and enhance the diffusing effect than traditional one.

Use of chlorine and ammonia for water disinfection to produce monochloramines as the most favorable disinfection species, faces several challenges. Addition of stoichiometric amount of chlorine and ammonia will not necessarily lead to formation of the target concentration of monochloramine and this is because of the various factors affecting monochloramine formation such as pH, chlorine to nitrogen ratio, temperature, and poor mixing. Inadequate mixing of chlorine and ammonia in water pipelines in direct injection system, yields in reduction of disinfection efficiency, and bacterial growth in distribution systems. The goal of current research is to examine the effect of mixing on monochloramine formation in the main stream of a pipeline. In this study a straight section of a 4 inch pipe is built with the length of 120 ft and water flow-rates ranging from 40 GPM to 317 GPM pass through the pipe. NaCl salt is added to pipeline and coefficient of variation (COV) of the conductivity of water is used, to measure sufficient mixing in the pipe to define appropriate sampling distance. Afterwards, chlorine and ammonia are injected at the upstream of the pipeline. There are two sources of chlorine with concentrations of 6.5 g/L and 86.0 g/L, to analyze effect of dilution ratios. Various injection velocities are tested and different flow rates are investigated to evaluate the effect of turbulence on chemical mixing for both salt and chemical addition. The concentration of monochloramine and dichloramine as the inorganic chloramine species is monitored at the 76 ft downstream of the injection points within 30 min and 24 hr of sampling. The results are compared with the expected monochloramine formation from the stoichiometric amount and monochloramine recovery under well mixed condition. Results show that monochloramine recoveries are not as high as the condition with adequate mixing, however, increase in the flow rate improves mixing and thus the recoveries.

A vast number of synthetic organic and inorganic chemicals are constantly being developed for industrial, domestic, and agricultural applications. Some of these chemicals present adverse health effects, even at trace levels. Such chemicals when introduced to environmental subsystems including surface water are termed as contaminants of concern. Examples include polycyclic aromatic hydrocarbons (PAHs) and engineered nanomaterials (ENMs). While PAHs have been detected in significant quantities in marine sediments, their presence in fresh surface water system sediments is yet to be established. Furthermore, there is lack of cohesive research effort aimed at characterizing the ENMs in surface waters. This can be due to the lack of analytical techniques for characterizing ECCs in surface water environmental samples. The current study introduces thermal desorption extraction techniques for characterizing PAHs in urban creek sediments creeks. The study suggests potential use of the approach characterizing ENMs.

Adopted in June 2011, Philadelphia Water Department’s (PWD) Green City, Clean Waters initiative seeks to establish a long-term plan for the control of combined sewer overflows (CSOs) through investments in green stormwater infrastructure (GSI), combined with traditional sewer infrastructure, and expanded treatment plant capacity. Green City, Clean Waters is a 25-year plan proposing to create natural landscapes to absorb stormwater runoff from impervious surfaces. Over the past seven years, PWD has implemented a variety of GSI systems within the combined sewer area of Philadelphia. These systems have been designed to manage more than 31 million gallons of stormwater runoff from each one-inch storm event, effectively diverting over 1.3 billion gallons of polluted water from entering Philadelphia’s waterways. For maximum impact, GSI is being implemented on a block-by-block scale to take full advantage of the economic, social, and environmental benefits associated with introducing green space into a highly urbanized environment.

The aim of this work was to study the adsorption of chromium (Cr⁶⁺) from textile wastewater through carbonized banana (CBP) and orange peels (COP) as low-cost natural adsorbents. Synthetic textile wastewater was made within the range of 0.05–10 mg/L of Cr (IV). The adsorption performance of the CBP and COP was studied with respect to the adsorbent dosage (0.1–5 grams) and the contact time (30–240 minutes) individually and collectively in batch systems at 20°C and pH of 7. Freundlich isotherm model and pseudo-second order kinetic model have adequately described the biosorption mechanism and distribution of adsorption particle observed from the high coefficient correlation. Maximum uptake capacity achieved for both peels within 90 minutes with an adsorbent dose of 0.5 gr of CBP and 1 gr of COP for concentration below 1 mg/L. Therefore, CBP and COP could be used as an effective biosorbent to treat textile wastewater.

Environmental impacts of concentrate management from desalination projects is a major consideration in deciding for an appropriate concentrate management strategy and mitigation methods. The concentrate management technology of each plant should be developed in view of the desalination plant location, potential environmental impacts, and possible mitigation options. This paper examines the advantages and disadvantages of different concentrate management strategies in view of the characteristics of the concentrates from desalination processes and potential environmental impacts for each concentrate management alterative. The quality of the concentrate depends on the amount of chemicals used (i.e., anti-scaling agents, surfactants, acids for pH adjustment, and salts removed from feed water). Therefore, concentrate produced by the desalination processes can impact the land, marine environment, energy demand and greenhouse gas emissions, groundwater quality as well as demands for chemicals, and noise emissions. The aim of this study is to develop an assessment method by analyzing the potential impacts in view of the criteria associated with each alternative. The general concentrate management options include discharge to oceans and bays, discharge to surface waters and sanitary sewers, deep well injection, land disposal, and evaporation ponds. In view of the potent toxicity and persistence of emerging contaminants, innovative and cost-effective treatment technologies are needed, especially for the emerging organic contaminants (EOCs) that may be retained in the concentrate. The results of this study can be used as a decision making tool for preliminary screening of options for concentrate management strategies appropriate depending on the location of the desalination plants.

Membrane processes have been adopted by water treatment industries and utilities. The management of concentrate from desalination plants is a challenge due to relatively high levels of both organic and inorganic contaminants. Because of the increasing concern over environmental impacts of concentrates from desalination processes and regulations of pollution control, concentrate management has been shifting towards minimizing the concentrate quantity, potential recovery of materials from concentrate, and improving the concentrate quality. Concentrate quality from different plants could be significantly different in terms of types and levels of compounds present. The removal efficiencies of membrane processes for with low molecular weight contaminants are low, and most data available for the removal of these types of contaminants indicate variable treatment performance. Even with treatment developments, and developments in membrane processes; the concentrate characteristics could be variable. In addition to development of treatment processes for unregulated emerging organic compounds, chemicals used for cleaning may also affect the contaminant-removal efficiency. Types of membrane modules used may affect removal efficiency, which subsequently affects the quality of the concentrates. This paper reviews the treatment options for concentrates from desalination plants for development of integrated water management strategies, to reduce the quantity of concentrates, and for materials recovery.

The municipal wastewater (as generated) and the wet-weather flows are provided with secondary or up to tertiary wastewater treatment in the U.S. as per the applicable national pollutant discharge elimination system (NPDES) regulatory requirements and, thus, the final effluents are discharged back to watershed(s). These final effluents are suitable for industrial reuse; and, based on the quality of these regulated effluents, this water resource is started being noticed as “nonrevenue water”. Currently, those regulated municipal wastewater effluents are considered U.S.-wide for indirect potable reuse (IPR) or direct potable reuse (DPR). This review is focused on DPR of municipal treated wastewater effluents. This paper includes a review of the: quality of treated wastewater effluents of the fifty (50) capital cities of the U.S.; advanced water treatment systems (AWTSs) for DPR; the current law, policy, and regulatory requirements (as available and selected) on DPR; the AWTSs’ product-water quality; and, costs of DPR (as available). Recommendations are included on utilization of an effective preliminary water treatment step as part of AWTS, the DPR (concept) for effective usage of AWTS product water, and consideration of AWTS toward a separately regulated entity. The application of DPR can play a significant role toward an effective municipal water-infrastructure.

Phosphorus pollution in waterways continues to pose both environmental and human health problems. Increased phosphorus levels in waterways promote algal blooms that have diverse environmental effects, including the blocking of sunlight to underwater organisms, and increased oxygen consumption resulting in dead zones. Additionally, toxic blue-green algae can lead to sickness or even death in humans and animals. While some current products have shown promising results in phosphorus removal from wastewater, the cost of such systems is very high and unrealistic for the majority of homeowners with on-lot systems. The more cost-effective alternative to biological or electrochemical removal of phosphorus may be by adsorption. This project will consider the theory of chemical adsorption in phosphorus removal, along with future lab tests to help later determine which adsorptive media will prove most effective. This research is timely as regulations are forthcoming as a result of legal challenges being filed in hopes of forcing the Environmental Protection Agency (EPA), along with several states (including Pennsylvania), to require enforceable permit limits on phosphorus pollution in waterways from wastewater treatment.