Receiving Water Quality Research Articles

From Panther Island to Beyond: Resilient Urban Infrastructure to Protect and Enhance Receiving Water Quality

From Panther Island to Beyond: Resilient Urban Infrastructure to Protect and Enhance Receiving Water Quality

Effects of Wastewater Disinfection on Human Health

Wastewater disinfection is practiced with the goal of reducing risks of human exposure to pathogenic microorganisms. Ideally, this goal is to be met without introducing other risks, such as those that could be associated with disinfection by-products. The purpose of this research was to assess the effects of wastewater disinfection on human health.Fecal coliforms and enterococci were both critically examined in terms of their ability to function as indicator organisms. Both bacterial groups were observed to be easily inactivated by chlorine and UV, and both indicators were observed to be relatively sensitive to these disinfectants, as compared with the remaining bacterial population. These observations are even more important when it is recognized that these indicator species represent a small fraction of the total bacterial population in wastewater effluent samples. Total culturable bacteria (TCB) were suggested as a possible alternative to coliform bacteria and enterococci as bacterial indicators. TCB represents a larger fraction of the bacterial population. However, the TCB assay requires a longer incubation time than is required for either coliforms or enterococci, and provides essentially no specificity in the analysis of water samples.Taken together, and when considered in conjunction with previously published research, the results of these experiments illustrate several important limitations of common disinfection processes as applied in the treatment of municipal wastewaters. In general, it is not clear that disinfection processes, as commonly implemented, are effective for control of the risks of disease transmission, particularly as associated with viral pathogens. Microbial and chemical quality in receiving streams may not be substantially improved by the application of these methods; under some circumstances, it could be argued that disinfection may actually yield a decrease in effluent and receiving water quality. Decisions regarding the need for effluent disinfection must account for site-specific characteristics, but it is not clear that disinfection of municipal wastewater effluents is necessary or beneficial for all facilities. When direct human contact or ingestion of municipal wastewater effluents is likely (i.e., close to an outfall or in cases of discharge to bathing areas or food production areas), disinfection appears to be necessary. Under these circumstances, the data from these experiments illustrate clear advantages of UV irradiation over chlorination in terms of microbial quality, as well as chemistry and toxicology. This advantage is more evident in effluents that contain appreciable quantities of ammonia-N or organic-N.This title belongs to WERF Research Report SeriesISBN: 9781843396734 (Print)ISBN: 9781780403274 (eBook)

Urban Stormwater Temperature Surges: A Central US Watershed Study

Impacts of urban land use can include increased stormwater runoff temperature (Tw) leading to receiving water quality impairment. There is therefore a need to target and mitigate sources of thermal pollution in urban areas. However, complex relationships between urban development, stormwater runoff and stream water heating processes are poorly understood. A nested-scale experimental watershed study design was used to investigate stormwater runoff temperature impacts to receiving waters in a representative mixed-use urbanizing watershed of the central US. Daily maximum Tw exceeded 35.0 °C (threshold for potential mortality of warm-water biota) at an urban monitoring site for a total of five days during the study period (2011–2013). Sudden increases of more than 1.0 °C within a 15 min time interval of Tw following summer thunderstorms were significantly correlated (CI = 95%; p < 0.01) to cumulative percent urban land use (r2 = 0.98; n = 29). Differences in mean Tw between monitoring sites were significantly correlated (CI = 95%; p = 0.02) to urban land use practices, stream distance and increasing discharge. The effects of the 2012 Midwest USA drought and land use on Tw were also observed with maximum Tw 4.0 °C higher at an urban monitoring site relative to a rural site for 10.5 h. The current work provides quantitative evidence of acute increases in Tw related to urban land use. Results better inform land managers wishing to create management strategies designed to preserve suitable thermal stream habitats in urbanizing watersheds.

EFFICACY OF PHRAGMITE KARKA PLANT IN CONSTRUCTED WETLAND SYSTEM

Wetlands, either constructed or natural, offer a cheaper and low-cost alternative technology for wastewater treatment. A constructed wetland system that is specifically engineered for water quality improvement as a primary purpose is termed as a ‘Constructed Wetland Treatment System’ (CWTS). In the past, many such systems were constructed to treat low volumes of wastewater loaded with easily degradable organic matter for isolated populations in urban areas. However, widespread demand for improved receiving water quality, and water reclamation and reuse, is currently the driving force for the implementation of CWTS all over the world. Recent concerns over wetland losses have generated a need for the creation of wetlands, which are intended to emulate the functions and values of natural wetlands that have been destroyed. Natural characteristics are applied to CWTS with emergent macrophyte stands that duplicate the physical, chemical and biological processes of natural wetland systems. The number of CWTS in use has very much increased in the past few years. The use of constructed wetlands is gaining rapid interest. Most of these systems cater for tertiary treatment from towns and cities. They are larger in size, usually using surface-flow system to remove low concentration of nutrient (N and P) and suspended solids. However, in some countries, these constructed wetland treatment systems are usually used to provide secondary treatment of domestic sewage for village populations. These constructed wetland systems have been seen as an economically attractive, energy-efficient way of providing high standards of wastewater treatment by the help of Phragmite karka plant.
 Typically, wetlands are constructed for one or more of four primary purposes: creation of habitat to compensate for natural wetlands converted for agriculture and urban development, water quality improvement, flood control, and production of food and fiber.

Spatially-Distributed Cost-Effectiveness Analysis Framework to Control Phosphorus from Agricultural Diffuse Pollution.

Best management practices (BMPs) for agricultural diffuse pollution control are implemented at the field or small-watershed scale. However, the benefits of BMP implementation on receiving water quality at multiple spatial is an ongoing challenge. In this paper, we introduce an integrated approach that combines risk assessment (i.e., Phosphorus (P) index), model simulation techniques (Hydrological Simulation Program–FORTRAN), and a BMP placement tool at various scales to identify the optimal location for implementing multiple BMPs and estimate BMP effectiveness after implementation. A statistically significant decrease in nutrient discharge from watersheds is proposed to evaluate the effectiveness of BMPs, strategically targeted within watersheds. Specifically, we estimate two types of cost-effectiveness curves (total pollution reduction and proportion of watersheds improved) for four allocation approaches. Selection of a ‘‘best approach” depends on the relative importance of the two types of effectiveness, which involves a value judgment based on the random/aggregated degree of BMP distribution among and within sub-watersheds. A statistical optimization framework is developed and evaluated in Chaohe River Watershed located in the northern mountain area of Beijing. Results show that BMP implementation significantly (p >0.001) decrease P loss from the watershed. Remedial strategies where BMPs were targeted to areas of high risk of P loss, deceased P loads compared with strategies where BMPs were randomly located across watersheds. Sensitivity analysis indicated that aggregated BMP placement in particular watershed is the most cost-effective scenario to decrease P loss. The optimization approach outlined in this paper is a spatially hierarchical method for targeting nonpoint source controls across a range of scales from field to farm, to watersheds, to regions. Further, model estimates showed targeting at multiple scales is necessary to optimize program efficiency. The integrated model approach described that selects and places BMPs at varying levels of implementation, provides a new theoretical basis and technical guidance for diffuse pollution management in agricultural watersheds.

Development of integrated catchment and water quality model for urban rivers

This paper presents the development of an urban river water quality model which considers the physical-biochemical processes within rivers and the incorporated urban catchment rainfall-runoff process developed with the time–area method. Unlike other models that simulate the hydrological and receiving water quality processes in the rural areas of the watershed scale, the model developed here is typically efficient for simulating the water quality response to nonpoint loadings from urban drainage systems, where the hydrological process is disturbed by artificially pumped discharge in wet-weather periods. This model is employed to assess the river water quality restoration in Nanfei River in Hefei City, China, where the model is calibrated against the measured data (i.e., the COD, the BOD5, the NH3-N, and the DO) in 2010, and the model parameters are suggested. It is shown that the nonpoint pollutants from the urban catchments contribute 34%-47% of the total pollutant inputs (i.e., the COD, the BOD5, and the NH3-N), despite their low flow component of 13.4%. Apart from the improvement of the wastewater treatment plant effluent (i.e., Grade IV of the Surface Water Quality Standard), a nonpoint loading reduction of 27.2%, 25.1%, and 35.3% of the COD, the BOD5, and the NH3-N are anticipated to meet the designated surface water quality standards of Grade V.

Climate Variation Overwhelms Efforts to Reduce Nitrogen Delivery to Coastal Waters

We calculated watershed nitrogen (N) retention (inputs–outputs)/inputs) each year from 1999–2013 for nine sub-watersheds along an urban–rural gradient near Baltimore MD to determine how land use and climate influence watershed N flux. Retention is critical to efforts to control coastal eutrophication through regulatory efforts that mandate reductions in the total maximum daily load (TMDL) of N that specific water bodies can receive. Retention decreased with urbanization as well as with increases in precipitation with retention decreasing from an average of 91% in the forested sub-watershed to 16% in the most urban sub-watershed. Export was 23% higher, and retention was 7% lower in winter (November–April) than during the growing season. Total N delivery to Baltimore Harbor varied almost threefold between wet and dry years, which is significant relative to the total annual export allowed for all non-point sources to the harbor under the TMDL. These results suggest that expectations for TMDLs should consider watershed land use and climate variability, and their potential for change if they are to result in improvements in receiving water quality.

Event-based design tool for construction site erosion and sediment controls

This paper provides additional discussion surrounding the novel event-based soil loss models developed by Trenouth and Gharabaghi (2015) for the design of erosion and sediment controls (ESCs) for various phases of construction – from pre-development to post-development conditions. The datasets for the study were obtained from three Ontario sites – Greensborough, Cookstown, and Alcona – in addition to datasets mined from the literature for three additional sites – Treynor, Iowa, Coshocton, Ohio and Cordoba, Spain. Model performances were evaluated for each of the study sites, and quantified using commonly-reported statistics. This work is nested within a broader conceptual framework, which includes the estimation of ambient receiving water quality, the prediction of event mean runoff quality for a given design storm, and the calculation of the required level of protection using adequate ESCs to meet receiving water quality guidelines. These models allow design engineers and regulatory agencies to assess the potential risk of ecological damage to receiving waters due to inadequate soil erosion and sediment control practices using dynamic scenario forecasting when considering rapidly changing land use conditions during various phases of construction, typically for a 2- or 5-year design storm return period.

Water Quality Trading with Equitable Total Maximum Daily Loads

Waste Load Allocation (WLA) strategies usually intend to find economic policies for water resource management. Water quality trading (WQT) is an approach that uses discharge permit market to reduce total environmental protection costs. This primarily requires assigning discharge limits known as total maximum daily loads (TMDLs). These are determined by monitoring organizations with respect to the receiving water quality and remediation capabilities. The purpose of this study is to compare two approaches of TMDL assignment for WQT policy in small catchment area of Haraz River, in north of Iran. At first, TMDLs are assigned uniformly for the whole point sources to keep the concentrations of BOD and dissolved oxygen (DO) at the standard level at checkpoint (terminus point). This was simply simulated and controlled by Qual2kw software. In the second scenario, TMDLs are assigned using multi objective particle swarm optimization (MOPSO) method in which the environmental violation at river basin and total treatment costs are minimized simultaneously. In both scenarios, the equity index and the WLA based on trading discharge permits (TDP) are calculated. The comparative results showed that using economically optimized TMDLs (2 scenario) has slightly more cost savings rather than uniform TMDL approach (1 scenario). The former annually costs about 1 M$ while the latter is 1.15 M$. WQT can decrease these annual costs to 0.9 and 1.1 M$, respectively. In other word, these approaches may save 35 and 45% economically in comparison with command and control policy. It means that using multi objective decision support systems (DSS) may find more economical WLA, however its outcome is not necessarily significant in comparison with uniform TMDLs. This may be due to the similar impact factors of dischargers in small catchments. Conversely, using uniform TMDLs for WQT brings more equity that makes stakeholders not feel that much envious of difference between TMDL and WQT allocation. In addition, for this case, determination of TMDLs uniformly would be much easier for monitoring. Consequently, uniform TMDL for TDP market is recommended as a sustainable approach. However, economical TMDLs can be used for larger watersheds. Keywords—Waste load allocation (WLA), Water quality trading (WQT), Total maximum daily loads (TMDLs), Haraz River, Multi objective particle swarm optimization (MOPSO), Equity.

Identifying objectives for sustainable stormwater management in urban Indian perspective: a case study

During 1900s, the only imperative for stormwater management was removal. With increasing urbanisation and degradation of receiving water quality, however, it has become essential to manage stormwater in a holistic, sustainable way. Yet the various factors in developing countries make the management of stormwater a very difficult task. The purposes of this study are to identify the constraints and problems of stormwater in typical urbanised cities of India. This study also presents a preliminary attempt to define objectives for developing a decision-making system for sustainable stormwater management. Relevant literature for defining the objectives is studied and a case study of Pune city in India has been taken for further analysis. The quantity and quality of stormwater and other related data has been collected to identify the constraints of existing system. Lastly, objectives are defined which could be further used to develop assessment criteria and a decision support system.

Comparing quantitative precipitation forecast methods for prediction of sewer flows in a small urban area

Due to the relatively small spatial scale, as well as rapid response, of urban drainage systems, the use of quantitative rainfall forecasts for providing quantitative flow and depth predictions is a challenging task. Such predictions are important when consideration is given to urban pluvial flooding and receiving water quality, and it is worthwhile to investigate the potential for improved forecasting. In this study, three quantitative precipitation forecast methods of increasing complexity were compared and used to create quantitative forecasts of sewer flows 0–3 h ahead in the centre of a small town in the north of England. The HyRaTrac radar nowcast model was employed, as well as two different versions of the more complex STEPS model. The STEPS model was used as a deterministic nowcasting system, and was also blended with the Numerical Weather Prediction (NWP) model MM5 to investigate the potential of increasing forecast lead-times (LTs) using high-resolution NWP. Predictive LTs between 15 and 90 min gave acceptable results, but were a function of the event type. It was concluded that higher resolution rainfall estimation as well as nowcasts are needed for prediction of both local pluvial flooding and combined sewer overflow spill events.Editor D. Koutsoyiannis; Guest editor R.J. MooreCitation Schellart, A., Liguori, S., Krämer, S., Saul, A., and Rico-Ramirez, M.A., 2014. Comparing quantitative precipitation forecast methods for prediction of sewer flows in a small urban area. Hydrological Sciences Journal, 59 (7), 1418–1436. http://dx.doi.org/10.1080/02626667.2014.920505

Stormwater Quality Characteristics in (Dutch) Urban Areas and Performance of Settlement Basins

Stormwaters, flowing into storm sewers, are known to significantly increase the annual pollutant loads entering urban receiving waters and this results in significant degradation of the receiving water quality. Knowledge of the characteristics of stormwater pollution enables urban planners to incorporate the most appropriate stormwater management strategies to mitigate the effects of stormwater pollution on downstream receiving waters. This requires detailed information on stormwater quality, such as pollutant types, sediment particle size distributions, and how soluble pollutants and heavy metals attach themselves to sediment particles. This study monitored stormwater pollution levels at over 150 locations throughout the Netherlands. The monitoring has been ongoing for nearly 15 years and a total of 7,652 individual events have been monitored to date. This makes the database the largest stormwater quality database in Europe. The study compared the results to those presented in contemporary international stormwater quality research literature. The study found that the pollution levels at many of the Dutch test sites did not meet the requirements of the European Water Framework Directive (WFD) and Dutch Water Quality Standards. Results of the study are presented and recommendations are made on how to improve water quality with the implementation of Sustainable Urban Drainage Systems (SUDS) devices.

Revised design criteria for stormwater facilities to meet pollution reduction and flow control requirements, also considering predicted climate effects

There is a need to revise existing design methods for stormwater pollutant treatment, flow transport and detention facilities. The aim is to increase the accuracy in predicting the performance compared with design only based upon areal and volumetric functions and to optimize design by considering more site-specific data, receiving water quality criteria and forecasted climate effects. During the latest years, flow proportional concentration data from in- and outlets from wet ponds and constructed wetlands, have been compiled. Furthermore, other kind of data from the specific facilities have been compiled, such as areas, volumes, proportion of vegetation, outlet design details and length:width ratio. The parameters are used to revise design methods and are implemented in the operative stormwater and recipient software model StormTac. Design criteria and parameters for calculating design flow and sizing required detention volume are also presented. The climate effects on some of the studied parameters, e.g. design flow and inlet concentration, are discussed. The paper presents the climate factor based upon the hypothesis that it is a function of the design rain duration and reoccurrence time.

Chemical Characterization and Toxicity of Bridge Deck Runoff and Impacts to Receiving Water Quality

AbstractIn this study, the chemical and microbiological characteristics of bridge deck runoff were evaluated at four bridge locations in the state of Nebraska. These bridges represent a range of annual average daily traffic (AADT) and receiving stream characteristics. In addition to runoff sampling, dry weather water quality and sediment quality was evaluated to determine if bridges influence dry weather water quality. Bridge deck runoff was determined to be not toxic using a 48-h acute toxicity assay with fathead minnows (Pimephales promelas). The results determined no significant differences in water and sediment quality upstream and downstream of the bridge at each of the four locations, indicating that bridges do not influence the receiving water quality or sediment during dry weather. The bridge deck runoff was found to contain a number of chemical constituents, and metals and nutrients were detected most frequently. The quality of bridge deck runoff was determined to be similar to that of roadway ru...

Characteristic length scales and time-averaged transport velocities of suspended sediment in the mid-Atlantic Region, USA

[1] Watershed Best Management Practices (BMPs) are often designed to reduce loading from particle-borne contaminants, but the temporal lag between BMP implementation and improvement in receiving water quality is difficult to assess because particles are only moved downstream episodically, resting for long periods in storage between transport events. A theory is developed that describes the downstream movement of suspended sediment particles accounting for the time particles spend in storage given sediment budget data (by grain size fraction) and information on particle transit times through storage reservoirs. The theory is used to define a suspended sediment transport length scale that describes how far particles are carried during transport events, and to estimate a downstream particle velocity that includes time spent in storage. At 5 upland watersheds of the mid-Atlantic region, transport length scales for silt-clay range from 4 to 60 km, while those for sand range from 0.4 to 113 km. Mean sediment velocities for silt-clay range from 0.0072 km/yr to 0.12 km/yr, while those for sand range from 0.0008 km/yr to 0.20 km/yr, 4–6 orders of magnitude slower than the velocity of water in the channel. These results suggest lag times of 100–1000 years between BMP implementation and effectiveness in receiving waters such as the Chesapeake Bay (where BMPs are located upstream of the characteristic transport length scale). Many particles likely travel much faster than these average values, so further research is needed to determine the complete distribution of suspended sediment velocities in real watersheds.

Variability of Metal Composition and Concentrations in Road Dust in the Urban Environment

Urban road dust comprises of a range of potentially toxic metal elements and plays a critical role in degrading urban receiving water quality. Hence, assessing the metal composition and concentration in urban road dust is a high priority. This study investigated the variability of metal composition and concentrations in road dust in 4 different urban land uses in Gold Coast, Australia. Samples from 16 road sites were collected and tested for selected 12 metal species. The data set was analyzed using both univariate and multivariate techniques. Outcomes of the data analysis revealed that the metal concentrations in road dust differ considerably within and between different land uses. Iron, aluminum, magnesium and zinc are the most abundant in urban land uses. It was also noted that metal species such as titanium, nickel, copper and zinc have the highest concentrations in industrial land use. The study outcomes revealed that soil and traffic related sources as key sources of metals deposited on road surfaces.

Striking the Balance between Nutrient Removal, Greenhouse Gas Emissions, Receiving Water Quality, and Costs

This Water Environment Research Foundation study considered the relationship between varying nutrient-removal levels at wastewater treatment plants, greenhouse gas emissions, receiving water quality (measured by potential algal production), and costs. The effluent nutrient concentrations required by some U.S. permits are very low, approaching the technology-best-achievable performance. This study evaluated five different treatment levels at a nominal 40 ML/d (10 mgd) flow. Greenhouse gas emissions and costs increase gradually up to the technologies' best-achievable performance, after which they increase exponentially. The gradual increase is attributed to additional biological treatment facilities, increased energy and chemical use, and additional tertiary nitrogen and phosphorus removal processes. Within the limited focus of this study, the evaluation shows that a point of diminishing return is reached as nutrient-removal objectives approach the technology-best-achievable performance, where greenhouse gas emissions and cost of treatment increases rapidly while the potential for algal growth reduce marginally.

Utilization of Glyphosate‐Containing Herbicides on Pervious Paving Systems: Laboratory‐Based Experiments to Determine Impacts on Effluent Water Quality

Pervious paving (PPS) model rigs have been used in laboratory‐based experiments to determine the impact of a glyphosate‐containing herbicide (GCH) on the ability of the PPS to retain and biodegrade pollutants. Using three concentrations of GCH (7200, 720, and 72 mg L−1) and used engine oil, it was found that hydrocarbon in the effluent increased with time, and with increasing GCH concentration. Turbidity increased and pH decreased with time, with the highest application of GCH declining by a whole pH unit to become slightly acidic. For Zn, Cu, and Pb, values for the lowest concentration of GCH, whilst slightly higher than the control mirrored its temporal trend and the highest concentration of GCH decreased with time. For the medium GCH concentration, however, Zn and Pb increased toward the end of the monitoring period. Dissolution experiments appeared to confirm speculation that the surfactant in the GCH may be forming an emulsion with the oil facilitating the release of metals associated with the oil. Particulate‐associated pollutants possibly released from the aggregate may be desorbed as the pH declined in the PPS rig. This raises concerns for receiving water quality, particularly with UK legislation encouraging the use of sustainable drainage systems and therefore PPS.

Toxicity of urban highway runoff in Shanghai to Zebrafish (Danio rerio) embryos and luminous bacteria (Vibrio qinghaiensis.Q67)

Pollution from urban highway runoff has been identified as one of the major causes of the deterioration of receiving water quality. The purpose of this study is to assess the toxicity of urban storm water samples in Shanghai using the zebrafish (Danio rerio ) embryo test and the bacterial luminescence (Vibrio qinghaiensis ) assay. The toxicity of highway runoff from seventeen storm events was investigated in both grab and composite samples. Zebrafish embryos were exposed to the runoff samples and development parameters including lethality, spontaneous movements in 20 s, heart beat rate, hatching rate, and abnormality of zebrafish embryos were observed after 24, 48, 72, and 96 h of exposure. Inhibition rates of luminescence intensity were also recorded. The results showed that in the zebrafish embryo toxicity tests, both grab and composite samples increased the lethality, reduced the percentage with spontaneous movements and heart beats, inhibited the hatching of embryos, and induced morphological abnormalities. In the Vibrio qinghaiensis toxicity test, all the grab samples inhibited the luminescence, while some of the composite samples promoted it, which indicated that different types of toxicants might have been affecting the species. The multivariate statistics analysis indicated that heavy metal (zinc, manganese, and copper) and PAHs might mainly contribute to the toxicity of runoff samples.

Science to Support Management of Receiving Waters in an Event-Driven Ecosystem: From Land to River to Sea

Managing receiving-water quality, ecosystem health and ecosystem service delivery is challenging in regions where extreme rainfall and runoff events occur episodically, confounding and often intensifying land-degradation impacts. We synthesize the approaches used in river, reservoir and coastal water management in the event-driven subtropics of Australia, and the scientific research underpinning them. Land-use change has placed the receiving waters of Moreton Bay, an internationally-significant coastal wetland, at risk of ecological degradation through increased nutrient and sediment loads. The event-driven climate exacerbates this issue, as the waterways and ultimately Moreton Bay receive large inputs of nutrients and sediment during events, well above those received throughout stable climatic periods. Research on the water quality and ecology of the region’s rivers and coastal waters has underpinned the development of a world-renowned monitoring program and, in combination with catchment-source tracing methods and modeling, has revealed the key mechanisms and management strategies by which receiving-water quality, ecosystem health and ecosystem services can be maintained and improved. These approaches provide a useful framework for management of water bodies in other regions driven by episodic events, or where novel stressors are involved (e.g., climate change, urbanization), to support sustained ecosystem service delivery and restoration of aquatic ecosystems.