scholarly journals The Role of Sewer Network Structure on the Occurrence and Magnitude of Combined Sewer Overflows (CSOs)

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2675
Author(s):  
Julian Reyes-Silva ◽  
Emmanuel Bangura ◽  
Björn Helm ◽  
Jakob Benisch ◽  
Peter Krebs
Keyword(s):  
Network Structure ◽  
Mitigation Strategies ◽  
Mitigation Measures ◽  
Storm Events ◽  
Combined Sewer Overflows ◽  
Untreated Wastewater ◽  
Intense Storm ◽  
Combined Sewer ◽  
Sewer Overflows

Combined sewer overflows (CSOs) prevent surges in sewer networks by releasing untreated wastewater into nearby water bodies during intense storm events. CSOs can have acute and detrimental impacts on the environment and thus need to be managed. Although several gray, green and hybrid CSO mitigation measures have been studied, the influence of network structure on CSO occurrence is not yet systematically evaluated. This study focuses on evaluating how the variation of urban drainage network structure affects the frequency and magnitude of CSO events. As a study case, a sewer subnetwork in Dresden, Germany, where 11 CSOs are present, was selected. Scenarios corresponding to the structures with the lowest and with the highest number of possible connected pipes, are developed and evaluated using long-term hydrodynamic simulation. Results indicate that more meshed structures are associated to a decrease on the occurrence and magnitude of CSO. Event frequency reductions vary between 0% and 68%, while reduction of annual mean volumes and annual mean loads ranged between 0% and 87% and 0% and 92%. These rates were mainly related to the additional sewer storage capacity provided in the more meshed scenarios, following a sigmoidal behavior. However, increasing network connections causes investment costs, therefore optimization strategies for selecting intervention areas are needed. Furthermore, the present approach of reducing CSO frequency may provide a new gray solution that can be integrated in the development of hybrid mitigation strategies for the CSO management.

scholarly journals A review of combined sewer overflows as a source of wastewater-derived emerging contaminants in the environment and their management

2021 ◽  
Author(s):  
Bruce Petrie
Keyword(s):  
Wastewater Treatment ◽  
Illicit Drugs ◽  
Emerging Contaminants ◽  
Treatment Strategies ◽  
Storm Events ◽  
Combined Sewer Overflows ◽  
Untreated Wastewater ◽  
Combined Sewer ◽  
Sewer Overflows ◽  
The Impact

AbstractEmerging contaminants such as pharmaceuticals, illicit drugs and personal care products can be released to the environment in untreated wastewater/stormwater mixtures following storm events. The frequency and intensity of combined sewer overflows (CSOs) has increased in some areas due to increasing urbanisation and climate change. Therefore, this review provides an up-to-date overview on CSOs as an environmental source of emerging contaminants. Other than compounds with high removal, those chiral species subject to enantioselective changes (i.e. degradation or inversion) during wastewater treatment can be effective markers of CSO discharge in the environment. A proposed framework for the selection of emerging contaminants as markers of CSOs is outlined. Studies have demonstrated that CSOs can be the main source of emerging contaminants with high removal efficiency during wastewater treatment (e.g. > 90%). However, the impact of CSOs on the environment is location specific and requires decision-making on their appropriate management at catchment level. This process would be aided by further studies on CSOs which incorporate the monitoring of emerging contaminants and their effects in the environment with those more routinely monitored pollutants (e.g. pathogens and priority substances). Mitigation and treatment strategies for emerging contaminants in CSOs are also discussed.

Implementation of Hamilton-Wentworth Region’s Pollution Control Plan

1996 ◽  
Vol 31 (3) ◽  
pp. 453-472 ◽  
Author(s):  
M. Stirrup
Keyword(s):  
Wastewater Treatment ◽  
Pollution Control ◽  
Wastewater Treatment Plant ◽  
Treatment Plant ◽  
Control Measures ◽  
Storm Events ◽  
Combined Sewer Overflows ◽  
Control Plan ◽  
Combined Sewer ◽  
Sewer Overflows

Abstract The Regional Municipality of Hamilton-Wentworth operates a large combined sewer system which diverts excess combined sewage to local receiving waters at over 20 locations. On average, there are approximately 23 combined sewer overflows per year, per outfall. The region’s Pollution Control Plan, adopted by Regional Council in 1992, concluded that the only reasonable means of dealing with large volumes of combined sewer overflow in Hamilton was to intercept it at the outlets, detain it and convey it to the wastewater treatment plant after the storm events. The recommended control strategy relies heavily on off-line storage, with an associated expansion of the Woodward Avenue wastewater treatment plant to achieve target reductions of combined sewer overflows to 1–4 per year on average. The region has begun to implement this Pollution Control Plan in earnest. Three off-line detention storage tanks are already in operation, construction of a fourth facility is well underway, and conceptual design of a number of other proposed facilities has commenced. To make the best possible use of these facilities and existing in-line storage, the region is implementing a microcomputer-based real-time control system. A number of proposed Woodward Avenue wastewater treatment plant process upgrades and expansions have also been undertaken. This paper reviews the region's progress in implementing these control measures.

scholarly journals Pollution Loads Discharged from Combined Sewer Overflows: Theoretical Approach and Long Term Numerical Assessment

1992 ◽  
Vol 23 (1) ◽  
pp. 27-48 ◽  
Author(s):  
Paolo Mignosa ◽  
Alessandro Paoletti
Keyword(s):  
Theoretical Approach ◽  
Rainfall Regime ◽  
Combined Sewer Overflows ◽  
Event Simulation ◽  
Numerical Assessment ◽  
Combined Sewer ◽  
On Line ◽  
Sewer Overflows ◽  
Two Parameters

The paper describes a theoretical analysis and a numerical assessment of pollutant loads discharged from Combined Sewer Overflows (CSOs) - with or without stormwater tanks – into the environment. The theoretical approach was based on certain simple assumptions, reasonably valid if the time scale of the problem involved is long enough (month/ year), in that single-event simulation is not interesting at all. Two main parameters related to the rainfall regime were found to be significant: the total volume of water discharged from the structure and the effective mixing factor between sanitary sewage and storm runoff. A numerical assessment of these two parameters was then made, on an annual basis, by means of a long-term rainfall series recorded in Milan, Italy. Both the “simple” CSO structure and the CSO coupled with stormwater tanks (on-line or off-line) were considered. The resulting graphs make it possible to evaluate the total annual load discharged from CSOs into the environment and the potential reduction obtained by adding a storage capacity to the overflow. This estimation could be of interest for persistent pollutants (phosphorus, heavy metals) discharged into low-recirculation bodies (lakes, estuaries, lagoons, closed seas).

scholarly journals A Detention Reservoir Reduced Combined Sewer Overflows and Bathing Water Contamination Due to Intense Rainfall

Water ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 3425
Author(s):  
Marco Romei ◽  
Matteo Lucertini ◽  
Enrico Esposito Renzoni ◽  
Elisa Baldrighi ◽  
Federica Grilli ◽  
...  
Keyword(s):  
Environmental Concern ◽  
Treatment Options ◽  
Heavy Rain ◽  
Rain Event ◽  
Storm Events ◽  
Combined Sewer Overflows ◽  
Bathing Water ◽  
Combined Sewer ◽  
Sewer Overflows ◽  
The Impact

Combined sewer overflows (CSOs) close to water bodies are a cause of grave environmental concern. In the past few decades, major storm events have become increasingly common in some regions, and the meteorological scenarios predict a further increase in their frequency. Consequently, CSO control and treatment according to best practices, the adoption of innovative treatment solutions and careful sewer system management are urgently needed. A growing number of publications has been addressing the quality, quantity and types of available water management and treatment options. In this study, we describe the construction of an innovative detention reservoir along the Arzilla River (Fano, Italy) whose function is to store diluted CSO wastewater exceeding the capacity of a combined drain system. River water sampling and testing for microbial contamination downstream of the tank after a heavy rain event found a considerable reduction of fecal coliform concentrations, which would have compounded the impact of stormwater on the bathing site. These preliminary results suggest that the detention tank exerted beneficial environmental effects on bathing water by lowering the microbial load.

Influence of changes of the wastewater composition on the applicability of UV-absorption measurements at combined sewer overflows

2003 ◽  
Vol 47 (2) ◽  
pp. 73-78 ◽  
Author(s):  
K. Stumwöhrer ◽  
N. Matsché ◽  
S. Winkler
Keyword(s):  
Calibration Procedure ◽  
Uv Absorption ◽  
Storm Water ◽  
Poor Correlation ◽  
Storm Events ◽  
Combined Sewer Overflows ◽  
Rainfall Events ◽  
Combined Sewer ◽  
Sewer Overflows ◽  
Absorption Measurements

The applicability of UV-absorption measurements at combined sewer overflows was investigated under different storm water conditions. Three specific rainfall events of different intensity, different duration and different intervals between the events were investigated. An individual evaluation of each single event resulted in an acceptable correlation between the UV absorption and the pollution measured as COD. A combined evaluation of the different events exhibited a very poor correlation which could not be used as pollution control parameter. Since the calibration procedure of the spectrometer used was not flexible enough to distinguish between different wastewater matrices from the different storm events the applicability of this type of spectrometer for the control of storm water overflows is questionable.

scholarly journals Urban Runoff Characteristics in Combined Sewer Overflows (CSOs): Analysis of Storm Events in Southeastern Spain

Water ◽  
2017 ◽  
Vol 9 (5) ◽  
pp. 303 ◽  
Author(s):  
Juan García ◽  
Pablo Espín-Leal ◽  
Antonio Vigueras-Rodriguez ◽  
Luis Castillo ◽  
José Carrillo ◽  
...  
Keyword(s):  
Urban Runoff ◽  
Storm Events ◽  
Combined Sewer Overflows ◽  
Southeastern Spain ◽  
Combined Sewer ◽  
Sewer Overflows

Urban Storm Water Discharges: Effects upon Communities of Sessile Diatoms and Macro-Invertebrates

1990 ◽  
Vol 22 (10-11) ◽  
pp. 147-154 ◽  
Author(s):  
G. D. Willemsen ◽  
H. F. Gast ◽  
R. O. G. Franken ◽  
J. G. M. Cuppen
Keyword(s):  
Organic Pollution ◽  
Constant Flow ◽  
Combined Sewer Overflows ◽  
Sewer System ◽  
Sewer Systems ◽  
Combined Sewer ◽  
Receiving Waters ◽  
Sewer Overflows ◽  
Urban Storm

From 1985 to 1987, long-term and more or less permanent effects of discharges from combined or separate sewer systems on communities of sessile diatoms and macro-invertebrates in receiving waters have been studied. Sessile diatoms and/or macro-invertebrates have been investigated on 46 locations, spread all over The Netherlands. The results were related to the type of sewer system, the discharges, and the characteristics of the receiving water, and compared with results from sample(s) taken from a corresponding water not influenced by sewer overflows, the reference water. In general, communities of sessile diatoms and macro-invertebrates indicate a more severe organic pollution and disturbance of receiving waters compared with reference waters. In the immediate vicinity of the overflows these communities were more disturbed than at some distance. In small ditches, effects were more pronounced compared with large waterbodies and waters with a constant flow regime. Finally, effects of combined sewer overflows were more pronounced than effects of discharges from separate sewer systems, except for locations in industrial areas.

Selecting a series of storm events for a model-based assessment of combined sewer overflows

2018 ◽  
Vol 15 (5) ◽  
pp. 453-460 ◽  
Author(s):  
Johannes Leimgruber ◽  
David B. Steffelbauer ◽  
Gerald Krebs ◽  
Franz Tscheikner-Gratl ◽  
Dirk Muschalla
Keyword(s):  
Storm Events ◽  
Combined Sewer Overflows ◽  
Model Based ◽  
Combined Sewer ◽  
Sewer Overflows

A STRATEGY FOR MONITORING THE IMPACTS OF COMBINED SEWER OVERFLOWS ON THE OHIO RIVER

1994 ◽  
Vol 30 (1) ◽  
pp. 167-175
Author(s):  
Alan H. Vicory ◽  
Peter A. Tennant
Keyword(s):  
National Policy ◽  
The United States ◽  
Ohio River ◽  
Combined Sewer Overflows ◽  
Treatment Technology ◽  
Design Storm ◽  
Combined Sewer ◽  
Sewer Overflows ◽  
Definition Of ◽  
And Control

With the attainment of secondary treatment by virtually all municipal discharges in the United States, control of water pollution from combined sewer overflows (CSOs) has assumed a high priority. Accordingly, a national strategy was issued in 1989 which, in 1993, was expanded into a national policy on CSO control. The national policy establishes as an objective the attainment of receiving water quality standards, rather than a design storm/treatment technology based approach. A significant percentage of the CSOs in the U.S. are located along the Ohio River. The states along the Ohio have decided to coordinate their CSO control efforts through the Ohio River Valley Water Sanitation Commission (ORSANCO). With the Commission assigned the responsibility of developing a monitoring approach which would allow the definition of CSO impacts on the Ohio, research by the Commission found that very little information existed on the monitoring and assessment of large rivers for the determination of CSO impacts. It was therefore necessary to develop a strategy for coordinated efforts by the states, the CSO dischargers, and ORSANCO to identify and apply appropriate monitoring approaches. A workshop was held in June 1993 to receive input from a variety of experts. Taking into account this input, a strategy has been developed which sets forth certain approaches and concepts to be considered in assessing CSO impacts. In addition, the strategy calls for frequent sharing of findings in order that the data collection efforts by the several agencies can be mutually supportive and lead to technically sound answers regarding CSO impacts and control needs.

Methods of Estimating the Discharge of Gross Solids from Combined Sewer Systems

1992 ◽  
Vol 26 (5-6) ◽  
pp. 1295-1304 ◽  
Author(s):  
C. Jefferies
Keyword(s):  
Research Centre ◽  
Combined Sewer Overflows ◽  
Water Research ◽  
Sewer Systems ◽  
Combined Sewer ◽  
Sewer Overflows ◽  
The Uk

Visible pollution discharged from two combined sewer overflows were studied using passive Trash Trap devices and the UK Water Research Centre Gross Solids Sampler. Relationships are presented for the number of visible solids and the mass of gross solids discharged during an event. The differences in the behaviour of the overflow types are reported on and they are categorised using the Trash Traps.

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