scholarly journals Impact of Combined Sewer Systems on the Quality of Urban Streams: Frequency and Duration of Elevated Micropollutant Concentrations

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 850 ◽  
Author(s):  
Ulrich Dittmer ◽  
Anna Bachmann-Machnik ◽  
Marie A. Launay
Keyword(s):  
Aquatic Organisms ◽  
Urban Streams ◽  
Base Flow ◽  
Storm Events ◽  
Urban Catchment ◽  
Mixing Ratios ◽  
Sewer Systems ◽  
Wwtp Effluent ◽  
Wide Range ◽  
Combined Sewer

Water quality in urban streams is highly influenced by emissions from WWTP and from sewer systems particularly by overflows from combined systems. During storm events, this causes random fluctuations in discharge and pollutant concentrations over a wide range. The aim of this study is an appraisal of the environmental impact of micropollutant loads emitted from combined sewer systems. For this purpose, high-resolution time series of river concentrations were generated by combining a detailed calibrated model of a sewer system with measured discharge of a small natural river to a virtual urban catchment. This river base flow represents the remains of the natural hydrological system in the urban catchment. River concentrations downstream of the outlets are simulated based on mixing ratios of base flow, WWTP effluent, and CSO discharge. The results show that the standard method of time proportional sampling of rivers does not capture the risk of critical stress on aquatic organisms. The ratio between average and peak concentrations and the duration of elevated concentrations strongly depends on the source and the properties of the particular substance. The design of sampling campaigns and evaluation of data should consider these characteristics and account for their effects.

Origins and characteristics of urban wet weather pollution in combined sewer systems: the experimental urban catchment “Le Marais” in Paris

1998 ◽  
Vol 37 (1) ◽  
pp. 35-43 ◽  
Author(s):  
Marie-Christine Gromaire-Mertz ◽  
Ghassan Chebbo ◽  
Mohamed Saad
Keyword(s):  
Waste Water ◽  
Sewer System ◽  
Urban Catchment ◽  
Rainfall Events ◽  
Sources Of Pollution ◽  
Sewer Systems ◽  
Combined Sewer ◽  
Wet Weather ◽  
Wet Weather Flow ◽  
Different Sources

An experimental urban catchment has been created in the centre of Paris, in order to obtain a description of the pollution of urban wet weather flows at different levels of the combined sewer system, and to estimate the contribution of runoff, waste water and sewer sediments to this pollution. Twenty-two rainfall events were studied from May to October 1996. Dry weather flow was monitored for one week. Roof, street and yard runoff, total flow at the catchment outlet and waste water were analysed for SS, VSS, COD and BOD5, on both total and dissolved fraction. Results show an evolution in the characteristics of wet weather flow from up to downstream: concentrations increase from the catchment entry to the outlet, as well as the proportion of particle-bound pollutants and the part of organic matter. A first evaluation of the different sources of pollution establishes that a major part of wet weather flow pollution originates from inside the combined sewer, probably through erosion of sewer sediments.

scholarly journals Assessing dry weather flow contribution in TSS and COD storm events loads in combined sewer systems

2011 ◽  
Vol 63 (12) ◽  
pp. 2983-2991 ◽  
Author(s):  
M. Métadier ◽  
J. L. Bertrand-Krajewski
Keyword(s):  
Time Series ◽  
Oxygen Demand ◽  
Seasonal Effect ◽  
Storm Events ◽  
Combined System ◽  
Time Step ◽  
Urban Catchment ◽  
Sewer Systems ◽  
Continuous Discharge

Continuous high resolution long term turbidity measurements along with continuous discharge measurements are now recognised as an appropriate technique for the estimation of in sewer total suspended solids (TSS) and Chemical Oxygen Demand (COD) loads during storm events. In the combined system of the Ecully urban catchment (Lyon, France), this technique is implemented since 2003, with more than 200 storm events monitored. This paper presents a method for the estimation of the dry weather (DW) contribution to measured total TSS and COD event loads with special attention devoted to uncertainties assessment. The method accounts for the dynamics of both discharge and turbidity time series at two minutes time step. The study is based on 180 DW days monitored in 2007–2008. Three distinct classes of DW days were evidenced. Variability analysis and quantification showed that no seasonal effect and no trend over the year were detectable. The law of propagation of uncertainties is applicable for uncertainties estimation. The method has then been applied to all measured storm events. This study confirms the interest of long term continuous discharge and turbidity time series in sewer systems, especially in the perspective of wet weather quality modelling.

Erosion resistance and behaviour of highly organic in-sewer sediment

2013 ◽  
Vol 69 (3) ◽  
pp. 672-679 ◽  
Author(s):  
I. Seco ◽  
M. Gómez Valentín ◽  
A. Schellart ◽  
S. Tait
Keyword(s):  
Organic Content ◽  
Natural Environments ◽  
Time Varying ◽  
Storm Events ◽  
Dry Period ◽  
Sewer Systems ◽  
Organic Sediment ◽  
Combined Sewer ◽  
Tank Design ◽  
High Organic Content

Reliable prediction of time-varying pollutant loads in combined sewer systems during storm periods can aid better management of the release of pollution into natural environments as well as enhancing storage tank design. Better understanding of the behaviour of sewer sediments is crucial for the development of models that adequately describe the transport of in-sewer solids and accurately predict the changes in pollutant concentration within combined sewers during storm events. This paper reports on the results of a test programme to examine the erosion of highly organic sewer sediment under the application of time-varying shear stress. The tests were carried out with and without supplying oxygen, and varying simulated dry-weather periods. The aim was to investigate the behaviour of real in-sewer sediment with a high organic content (around 80%) in an attempt to improve prediction of the transport rates under the particular Mediterranean conditions of long dry-period/build-up and intense rainfall/wash-off, and understand how this environment affects the erosional resistance and subsequent sediment release. Results have been compared with previous work on lower organic content sewer sediments and artificial organic sediment.

scholarly journals The new German standard on constructed wetland systems for treatment of domestic and municipal wastewater

2018 ◽  
Vol 78 (11) ◽  
pp. 2414-2426 ◽  
Author(s):  
Jaime Nivala ◽  
Manfred van Afferden ◽  
Ralf Hasselbach ◽  
Guenter Langergraber ◽  
Pascal Molle ◽  
...  
Keyword(s):  
Municipal Wastewater ◽  
Domestic Wastewater ◽  
Secondary Treatment ◽  
Sewer Systems ◽  
Wide Range ◽  
Combined Sewer ◽  
Operations And Maintenance ◽  
German Standard ◽  
First Time ◽  
Raw Wastewater

Abstract The German Association for Water, Wastewater and Waste e.V. (DWA) has published a new standard for the dimensioning, construction, and operation of constructed wetlands for treatment of domestic and municipal wastewater. The changes to the standard are based on a wide range of experience gained in recent years in Germany and Europe. For the first time ever, the standard has been officially translated and published in English. This paper summarizes the new standard for secondary treatment of domestic wastewater with classical one-stage unsaturated vertical flow (VF) wetlands, VF wetlands with lava sand for treatment of wastewater from combined sewer systems, and actively aerated VF and horizontal flow (HF) flow wetlands. Two-stage unsaturated VF wetlands treating raw wastewater (French VF wetlands), are also included in the new standard. HF wetlands are no longer described in the standard for secondary treatment of domestic wastewater. This does not exclude their application. Existing HF wetland systems in Germany may continue to be operated so long as effluent parameters are met and proper operations and maintenance is ensured. This paper gives an overview of the new design standard, including key information on wastewater type and loading, as well as primary attributes of each wetland design.

First estimation of occurrence and fate of organic substances in combined sewer systems with pollution load simulations

2007 ◽  
Vol 2 (2) ◽  
Author(s):  
A. Welker
Keyword(s):  
Waste Water Treatment ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Pollutant Emissions ◽  
Waste Water Treatment Plant ◽  
Organic Substances ◽  
Pollution Load ◽  
Sewer Systems ◽  
Wwtp Effluent ◽  
Combined Sewer

Emissions of selected organic substances from a hypothetical combined sewer system are calculated by pollution load simulation. The results are subsequently discussed. First, representative concentrations of chemical oxygen demand (COD), ammonium (NH4-N) and eight selected organics (polycyclic aromatic hydrocarbons (PAH), isoproturone, Di(2-ethylhexyl)phthalate (DEHP), ibuprofen, 17-ß-estradiol (E2), 17-a-ethinylestradiol (EE2), ethyl-enediamine tetraacetic acid (EDTA), nitrilo triaceticacid (NTA)) in dry weather flow, surface runoff and effluent of WWTP in combined sewer systems are stated based on a literature survey. The second part of the paper presents pollution load simulations and first calculations of possible dis-tributions of organics in combined sewer systems for a hypothetical catchment. Different scenarios of annual discharge loads of main emission matrices of the catchment (waste water treatment plant (WWTP) effluent and combined sewer overflow (CSO)) are compared to determine significant dis-charge points. The results of the pollution load simulations show that generally discharges from the WWTP dominate the total emissions of combined sewer systems. Nevertheless, emissions from CSOs are not negligible in some cases (e.g. for estradiol). In summary, the results give first indications about possible strategies to reduce pollutant emissions from combined sewer systems. The paper also formulates recommendations for the selected organic compounds.

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.

Methods for Calculation of Annual and Extreme Overflow Events from Combined Sewer Systems

1984 ◽  
Vol 16 (8-9) ◽  
pp. 311-325 ◽  
Author(s):  
N B Johansen ◽  
P Harremoës ◽  
M Jensen
Keyword(s):  
Extreme Event ◽  
Short Term ◽  
Sewer Systems ◽  
Extreme Load ◽  
Combined Sewer ◽  
Receiving Waters ◽  
Water Problems ◽  
Source Of Pollution ◽  
Receiving Water

Overflow from combined systems constitute an increasing source of pollution of receiving waters, as compared to daily wastewater discharges which undergo treatment to a still higher extent. The receiving water problems from overflows are significant both in a long term scale (mean annual load) and in a short term scale (extreme event load). A method for computation of both annual and extreme load is presented. It is based on historical rain series and the use of a time-area model and simple pollutant mixing model in runoff calculation. Statistical calculations for both mean annual load and extreme events have been applied to the computed overflow series. Based on the computerized method simple manual calculations methods have been developed, resulting in graphs and tables for annual load and extreme load.

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