A new database on urban runoff pollution: comparison of separate and combined sewer systems

2005 ◽  
Vol 51 (2) ◽  
pp. 119-128 ◽  
Author(s):  
H. Brombach ◽  
G. Weiss ◽  
S. Fuchs
Keyword(s):  
Treatment Plant ◽  
Pollution Load ◽  
Combined System ◽  
Concentration Data ◽  
Measured Concentration ◽  
Sewer Systems ◽  
Combined Sewer ◽  
Long Time ◽  
Separate System ◽  
Receiving Waters

For a long time people have questioned what the “best” sewer system is for limiting the pollution load released into the receiving waters. In this paper the traditional separate and combined sewer systems are compared using a pollution load balance. The investigation is based on measured concentration data for a range of pollutant parameters in the sewer from the new database “ATV-DVWK Datenpool 2001”. The approach also accounted for the wastewater treatment plant outflow which contributes to the total pollutant load considerably. In spite of a number of neglected effects, the results show that the separate system is superior to the combined for some parameters only, such as nutrients, whereas for other parameters, e.g. heavy metals and COD, the combined system yields less total loads. Any uncritical preference of the separate system as a particularly advantageous solution is thus questionable. Individual investigations case by case are recommended.

Reduction of Combined Sewer Overflow Pollution Loads by Detention of Sanitary Sewage

1990 ◽  
Vol 22 (10-11) ◽  
pp. 205-212
Author(s):  
W. Schilling ◽  
D. T. Kollatsch
Keyword(s):  
High Strength ◽  
Chemical Transformations ◽  
Storage Tanks ◽  
Combined System ◽  
System A ◽  
Sewer Systems ◽  
Combined Sewer ◽  
Separate System ◽  
Using Data ◽  
Operational Aspects

For mixed combined/separate sewer systems it is proposed, in times of combined sewage overflows (CSO), to store sanitary sewage at the inlet point to the combined system. Thereby, sanitary sewage (with high strength) is kept in the system for further treatment after the storm whereas less-polluted CSO are diverted to the receiving water. By using data of an existing catchment different scenarios are evaluated and the potential benefit of sanitary sewage detention is quantified. This approach is compared to current German CSO regulations. It is more effective than conventional CSO detention if more than 60 % of the population upstream of the CSO diversion are served by a separate system. A key problem of this concept is the control strategy that determines when to activate and empty the storage tanks. A number of criteria are compared. Considerations are also made on operational aspects such as chemical transformations in stored sewage, maximum allowable detention time, and cleansing of storage tanks.

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.

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.

Comparison of the efficiency of best stormwater management practices in urban drainage systems

1999 ◽  
Vol 39 (9) ◽  
pp. 269-276 ◽  
Author(s):  
R. Mehler ◽  
M. W. Ostrowski
Keyword(s):  
Stormwater Management ◽  
Management Practices ◽  
Alternative Methods ◽  
Urban Drainage ◽  
Pollution Load ◽  
Load Model ◽  
Urban Stormwater Management ◽  
Sewer Systems ◽  
Combined Sewer ◽  
Stormwater Management Practices

Increasingly extended and alternative methods for urban stormwater management have been discussed in Germany and elsewhere. Without question an economically and ecologically sound combination of central and decentral measures will be a concept of the future. Yet, at present the introduction of approaches other than traditional combined sewer systems is restricted due to missing planning tools and technologies. Adding a number of frequently used Best Stormwater Management Practices (BSMP's) has widely extended the applicability of an existing stormwater water balance and pollution load model.

scholarly journals Assessing the efficiency of different CSO positions based on network graph characteristics

2013 ◽  
Vol 67 (7) ◽  
pp. 1574-1580 ◽  
Author(s):  
R. Sitzenfrei ◽  
C. Urich ◽  
M. Möderl ◽  
W. Rauch
Keyword(s):  
Treatment Plant ◽  
Spatial Layout ◽  
Construction Costs ◽  
Sewer Systems ◽  
Significant Difference ◽  
Combined Sewer ◽  
The Impact ◽  
And Storage ◽  
Storage Units ◽  
Sewer Networks

The technical design of urban drainage systems comprises two major aspects: first, the spatial layout of the sewer system and second, the pipe-sizing process. Usually, engineers determine the spatial layout of the sewer network manually, taking into account physical features and future planning scenarios. Before the pipe-sizing process starts, it is important to determine locations of possible weirs and combined sewer overflows (CSOs) based on, e.g. distance to receiving water bodies or to a wastewater treatment plant and available space for storage units. However, positions of CSOs are also determined by topological characteristics of the sewer networks. In order to better understand the impact of placement choices for CSOs and storage units in new systems, this work aims to determine case unspecific, general rules. Therefore, based on numerous, stochastically generated virtual alpine sewer systems of different sizes it is investigated how choices for placement of CSOs and storage units have an impact on the pipe-sizing process (hence, also on investment costs) and on technical performance (CSO efficiency and flooding). To describe the impact of the topological positions of these elements in the sewer networks, graph characteristics are used. With an evaluation of 2,000 different alpine combined sewer systems, it was found that, as expected, with CSOs at more downstream positions in the network, greater construction costs and better performance regarding CSO efficiency result. At a specific point (i.e. topological network position), no significant difference (further increase) in construction costs can be identified. Contrarily, the flooding efficiency increases with more upstream positions of the CSOs. Therefore, CSO and flooding efficiency are in a trade-off conflict and a compromise is required.

Modelling the total ammonia impact of CSO and WWTP effluent on the receiving water

1998 ◽  
Vol 38 (10) ◽  
pp. 31-39 ◽  
Author(s):  
Peter Holzer ◽  
Peter Krebs
Keyword(s):  
Treatment Plant ◽  
Rain Event ◽  
Combined System ◽  
Sewer System ◽  
Wwtp Effluent ◽  
Fish Poison ◽  
Combined Sewer ◽  
Total Ammonia ◽  
High Concentrations ◽  
Rain Events

For 25 rain events test runs were performed on a catchment of a small town, where 40% of the person equivalents are connected to a separate sewer system and 60% to a combined one. We investigate the effects of rain events with regard to NH4-loads discharged by the wastewater treatment plant and by a combined sewer overflow. NH4-concentrations in the river caused by these loads are also discussed. NH4 is important as (i) it closely interrelates with NH3 – a fish poison – and (ii) it stands for dissolved compounds that mainly origin from the wastewater. The sewer system is simulated with three different options: with a combined water retention tank connected to the CSO structure, with a sewage retention tank at the interface between the separate and the combined system, and without any retention structure. While the sewage retention tank performs better concerning the integrated load discharged into the river, the combined sewer retention tank is more efficient in decreasing peak values and duration of high concentrations in the river. We also show that NH4 peak concentrations in the river are largely due to a wash-out effect in the main sewer at the beginning of a rain event.

Long term pollution simulation in combined sewer networks

2001 ◽  
Vol 43 (7) ◽  
pp. 83-89 ◽  
Author(s):  
B. Masse ◽  
M. Zug ◽  
J. P. Tabuchi ◽  
B. Tisserand
Keyword(s):  
Conceptual Model ◽  
Combined System ◽  
Sewerage System ◽  
Sewer Network ◽  
Reference Flow ◽  
Combined Sewer ◽  
Stream System ◽  
Long Time ◽  
Sewer Networks

This paper presents results of long term pollution simulations on the example of the sewerage system of Grand-Couronne. This modelling work is part of a study where objective is to develop a method to define the reference flow of a WWTP. The model HYDROWORKS DM™ has been successfully validated in hydraulics and pollution for the sewer network, for long time simulations. A conceptual model has been built to model the pollution in the tank at the outlet of the combined system. One synthetic year of rain has been used to simulate the working of the “up stream system” of the WWTP (combined sewer + tank + separate sewer + pre-treatments) and has been successfully validated by measurements of the 1998-1999 year. If this paper is focused on the “up stream system”, the SIMBA/SIMBAD WWTP model has been successfully calibrated and validated too, and the combination represents a fully validated “Integrated Model” for the sewerage system.

Occurrence and fate of organic pollutants in combined sewer systems and possible impacts on receiving waters

2007 ◽  
Vol 56 (10) ◽  
pp. 141-148 ◽  
Author(s):  
A. Welker
Keyword(s):  
Organic Pollutants ◽  
Wastewater Treatment Plants ◽  
Combined Sewer Overflows ◽  
Sewer Systems ◽  
Flow Surface ◽  
Combined Sewer ◽  
Polycyclic Aromatic ◽  
Receiving Waters ◽  
First Time ◽  
Receiving Water

Selected organic pollutants are classified based on an intensive literature survey. Two wastewater parameters (COD and ammonium) and six selected organic pollutants (polycyclic aromatic hydrocarbons (PAH), diethylhexylphthalate (DEHP), estradiol (E2), ethinylestradiol (EE2), ethylenediamine tetraacetic acid (EDTA) and nitrilo triaceticacid (NTA)) are specified. As a result, for the first time representative concentrations in dry weather flow, surface runoff and effluent of wastewater treatment plants (WWTPs) in combined sewer systems (CSS) are stated. The second part of the paper presents a first estimation of main emission out of a combined sewer system and possible receiving water impacts in terms of (1) annual discharged loads calculated by pollution load simulations in a hypothetical catchment and (2) concentrations calculated in combined sewer overflows (CSO) discharges and resulting receiving water concentrations.

Settleable Solids from Combined Sewers: Settling, Stormwater Treatment, and Sedimentation Rates in Rivers

1994 ◽  
Vol 29 (1-2) ◽  
pp. 95-102
Author(s):  
S. Michelbach ◽  
C. Wöhrle
Keyword(s):  
River Sediments ◽  
Oxygen Demand ◽  
Stormwater Treatment ◽  
Organic Micropollutants ◽  
Sewer Systems ◽  
Settling Behaviour ◽  
Combined Sewer ◽  
Important Pathway ◽  
Receiving Waters ◽  
The Relationship

Settleable solids are an important pathway for pollutants found in river sediments. To study settling behaviour of settleable solids, settling velocity was measured by a settling apparatus. Special measurements were undertaken to determine the relationship between the settling distribution of settleable solids and their pollutant load - organic mass, chemical oxygen demand, heavy metals and organic micropollutants. To calculate where settleable solids from combined sewer systems will settle in receiving waters, the settling distribution is also useful. The results of a three-year research indicate that stormwater treatment by settling is effective in preventing adverse environmental impacts of combined sewage pollutants.

scholarly journals The importance of pollutional loads during wet weather

2019 ◽  
pp. 271-282
Author(s):  
Oddvar Georg Lindholm ◽  
Lars Aaby
Keyword(s):  
Time Series ◽  
Wastewater Treatment ◽  
Wastewater Treatment Plant ◽  
Treatment Plant ◽  
The Other ◽  
Combined Sewer Overflows ◽  
Combined Sewer ◽  
Receiving Waters ◽  
Wet Weather ◽  
Annual Discharge

Wet weather discharges consist mainly of washed out surface pollution in separate sewered areas, but in combined sewered areas; resuspended pipe deposits, surface washoff and sewage, discharging via combined sewer overflows (CSOs). Of the three mentioned sources, resuspended pipe solids is dominating over the other two and may contribute as much as 50 to 90 % of the total amount of the CSO. The CSO in a normal catchment may also on an annual bases be of the same amount, or even twice as much as the effluent from the wastewater treatment plant (WWTP). If the receiving waters are vulnerable to shock loads on a daily base, it is important to be aware that the amount of CSO might, at its most adverse be up to I 00 times more than the effluent from the WWTP during a day. The annual discharge via CSOs in a catchment may easily vary with a factor of up to 8 from the driest to the wettest year, during time series of 20 to 40 years.

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