scholarly journals Dynamics of pollutant discharge in combined sewer systems during rain events: chance or determinism?

2014 ◽  
Vol 69 (8) ◽  
pp. 1751-1758 ◽  
Author(s):  
A. Hannouche ◽  
G. Chebbo ◽  
C. Joannis
Keyword(s):  
Suspended Solids ◽  
Rain Event ◽  
Sewer Systems ◽  
Spatial Consistency ◽  
Combined Sewer ◽  
Diverse Origin ◽  
Deterministic Processes ◽  
Rain Events ◽  
Event Flow ◽  
Pollutant Discharge

A large database of continuous flow and turbidity measurements cumulating data on hundreds of rain events and dry weather days from two sites in Paris (called Quais and Clichy) and one in Lyon (called Ecully) is presented. This database is used to characterize and compare the behaviour of the three sites at the inter-events scale. The analysis is probed through three various variables: total volumes and total suspended solids (TSS) masses and concentrations during both wet and dry weather periods in addition to the contributions of diverse-origin sources to event flow volume and TSS load values. The results obtained confirm the previous findings regarding the spatial consistency of TSS fluxes and concentrations between both sites in Paris having similar land uses. Moreover, masses and concentrations are proven to be correlated between Parisian sites in a way that implies the possibility of some deterministic processes being reproducible from one catchment to another for a particular rain event. The results also demonstrate the importance of the contribution of wastewater and sewer deposits to the total events' loads and show that such contributions are not specific to Paris sewer networks.

A statistical approach to pollutant emissions from combined sewer systems

1997 ◽  
Vol 36 (8-9) ◽  
pp. 95-100 ◽  
Author(s):  
Robin G. Veldkamp ◽  
Jan B. M. Wiggers
Keyword(s):  
Suspended Solids ◽  
Statistical Approach ◽  
Low Frequency ◽  
Pollutant Emissions ◽  
Frequency Of Occurrence ◽  
Single Event ◽  
Sewer Systems ◽  
Impervious Area ◽  
Combined Sewer ◽  
Kjeldahl Nitrogen

This research is based on CSO emissions from Dutch sewer systems. During the years 1982 to 1989 research was done on several sewer systems, all of them equiped with a single overflow weir. Pollutant emissions were calculated from the measurements, whereby each storm was considered as a single event. Extreme emissions have a detrimental, sometimes even desastrous effect on water quality. Such extreme emissions are the result of heavy storms, giving it a low frequency of occurrence. From the measurements a statistical model was developed enabling the user to forecast extreme waste emissions with a certain return period in a range of 2 to 10 years. Five pollutants are put in the model: BOD, COD, Kjeldahl nitrogen, total phosphate and suspended solids. The model operates with standardized emission values in kg per ha of impervious area. When the model is used in practice the runoff area to the specific overflow under consideration has to be known.

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.

Efficiency evaluation of an installed swirl separator

1994 ◽  
Vol 21 (6) ◽  
pp. 924-930 ◽  
Author(s):  
Jean-Pierre Villeneuve ◽  
Eric Gaume ◽  
France Michaud
Keyword(s):  
Suspended Solids ◽  
Suspended Sediments ◽  
Efficiency Evaluation ◽  
Line Treatment ◽  
Treatment Facility ◽  
Alternative Technologies ◽  
Sewer Systems ◽  
Public Work ◽  
Combined Sewer ◽  
On Line

Municipalities try to limit overflow of their sewer systems by various technologies such as storage in basins and transfer of the water after the storm to a treatment facility, storage and decantation, on-line treatment of overflows, or by alternative technologies like porous roadways or runoff infiltration. The swirl separator, proposed by the American Public Work Association, is an attractive device, because it requires little supervision and maintenance. However, only few results exist about its efficiency for treating combined sewer overflow. The purpose of the present field study was to determine the performance of an existing device (the Québec swirl regulator). The results, presented herein, show that up to 25% of the suspended solids transported during storms can be eliminated, but most of the liquid–solid separation seems to take place in the upstream collecting pipe. Key words: combined sewers, overflows, water treatment, suspended sediments.

GROSS SOLIDS IN SEWER SYSTEMS: TEMPORAL AND CATCHMENT BASED RELATIONSHIPS

1994 ◽  
Vol 30 (1) ◽  
pp. 63-71 ◽  
Author(s):  
C. Jefferies ◽  
R. M. Ashley
Keyword(s):  
Suspended Solids ◽  
Daily Variation ◽  
Critical Factor ◽  
Observation Point ◽  
Dry Period ◽  
Sewer Systems ◽  
Combined Sewer ◽  
Predictive Methods ◽  
Different Types ◽  
High Degree

The behaviour of gross and visible solids was studied at two combined sewer overflow sites using the WRc Gross Solids Sampler. At one of the sites the daily variation of gross solids during dry weather was determined. There was found to be close correspondence between the variations of gross and suspended solids in the sewage. A relationship was developed between the load of gross solids and that of suspended solids at the observation point in dry weather. This relationship is presented for use with other predictive methods. A chart is presented which differentiates with a high degree of reliability the gross solids production of two different types of catchments, one being a collector sewer catchment, the other being a trunk. The rate of gross solids production has been found to be a critical factor in differentiating between the catchments. A consistent and further differentiation in the accumulation of gross solids is presented on the basis of antecedent dry period, greater than 24h allowing considerably greater accumulations than shorter dry periods.

The Influence of System-Specific Properties on the Pollutant Discharge of Combined Sewer Systems

1993 ◽  
Vol 27 (5-6) ◽  
pp. 185-196 ◽  
Author(s):  
M. Moens ◽  
L. Vos ◽  
J. Zuidervliet
Keyword(s):  
Model Fitting ◽  
Sewer System ◽  
Frequency Distributions ◽  
Sewer Systems ◽  
Practical Research ◽  
Combined Sewer ◽  
Calculation Results ◽  
Pollutant Discharge ◽  
Near Future ◽  
Quality Policy

The water quality policy in the Netherlands regarding discha ges from sewer systems into surface water will in the near future aim at the pollutant discharge instead of the overflow frequency. Recent practical research has shown that system-specific properties are the main influencing factors for the sediment behaviour of sewer systems. Based on this knowledge the pollutant discharge concept EMOR has been developed. A detailed description is given of the background of this concept and of how to work with it. The calculation results Include frequency distributions for the COD, peak discharges and annual load, overflow quantities, overflow frequencies, etc. An objective calculation method is provided to express the influence in the so-called depositing factor, which can be determined for a single sewer as well as for a complete sewer systems. Application of this factor in the EMOR-concept makes it possible to use a schematization of the sewer system into a multireservoir model without losing the influence of the system specific properties. Model fitting has demonstrated that with the application of the EMOR concept a reliable prediction can be made for the pollutant discharge.

Organic carbon biodegradability and heterotrophic bacteria along a combined sewer catchment during rain events

1998 ◽  
Vol 37 (1) ◽  
pp. 25-33 ◽  
Author(s):  
M. Seidl ◽  
P. Servais ◽  
M. Martaud ◽  
C. Gandouin ◽  
J. M. Mouchel
Keyword(s):  
Organic Carbon ◽  
Suspended Solids ◽  
Heterotrophic Bacteria ◽  
Oxygen Demand ◽  
Bacterial Biomass ◽  
Combined Sewer Overflows ◽  
Sewer System ◽  
Urban Catchment ◽  
Combined Sewer ◽  
Rain Events

The aim of this study was the evaluation of fluxes of organic carbon and biodegradability of waste waters during rain events in order to better predict the impacts of combined sewer overflows (CSO). The combined sewer system studied was located in a densely populated urban catchment adjacent to Paris. Five subcatchments of different size, have been monitored during several rain events for suspended solids, conductivity, ammonium, chemical and biological oxygen demand. In addition, two of these subcatchments have been evaluated for dissolved and particulate organic carbon, their biodegradable fractions, and the total bacterial biomass. Several indexes, indicate a lower degradability of waste water during dry weather at the downstream stations, accompanied by an increase of bacterial size and bacterial biomass. A further decrease of biodegradable organic carbon related to rain intensity can be seen at all stations. Our results show a higher proportion of refractory organic carbon during rain events than during dry weather with a possible contribution of the in-sewer sediments to the bacterial wet weather flux.

Wastewater transfer during dry and wet weather in Parisian combined sewer

2009 ◽  
Vol 4 (1) ◽  
Author(s):  
M. Kafi ◽  
M.C. Gromaire ◽  
M. Saad ◽  
G. Chebbo
Keyword(s):  
Great Part ◽  
Rain Event ◽  
Transport Capacity ◽  
Combined Sewer ◽  
Daily Cycles ◽  
Wet Weather ◽  
The Difference ◽  
Solid Transport ◽  
Water Volumes ◽  
Rain Events

The study of wastewater transfer in dry and wet weather was made following various approaches: in dry weather (relationship between pollutant loads and flows, evolution of the nature of particulate and dissolved pollutants, variations of VSS/SS and of SS/TKNd ratios); in wet weather (evaluation of the proportion of wastewater effluent during the rain event from conductivity and water volumes). Results obtained from dry weather show that the dilution by parasitic waters allows to explain a great part of the concentration variations observed at OPUR outlets. Moreover, the difference in the nature of wastewater produced during the day and the variation in the solid transport capacity, leading to erosion and/or sedimentation can also explain the daily cycles of wastewater concentrations. Indeed, results obtained from wet weather, show, whatever the size of the catchment, that there is direct correspondence between the volumetric and the conductivity methods. This indicates that wastewater volumes, at outlets during rain events, do not appear to be affected by the hydrodynamics of wet weather, whatever the size of the catchment.

Caractérisation des eaux usées de débordements de réseau unitaire

1985 ◽  
Vol 12 (3) ◽  
pp. 527-537 ◽  
Author(s):  
Paul Lessard ◽  
Pierre Lavallée
Keyword(s):  
Water Quality ◽  
Rain Event ◽  
Combined Sewer Overflows ◽  
Drainage Basins ◽  
Combined Sewer ◽  
Different Types ◽  
Rain Events ◽  
The Impact ◽  
The City

In 1981, the City of Québec signed a protocol with the Québec Ministry of Environment permitting the study of the impact of combined sewer overflows (CSO) during rain periods on the St-Charles River. One of the main study objectives was to characterize CSO, both quantitatively and qualitatively. Five main drainage basins, representative of the study area, were selected and sampled during nine rain events. Certain appraisals were made to explain the importance of the water quality variations during rain events in combined sewers, dry weather period influence on runoff quality, and "first-flush" phenomenon. Two principal conclusions have been drawn from these data: (1) the major part of the pollutant load routed through a combined sewer network during a rain event is generated by surface runoff and dragging of sewage deposits and (2) the overall water quality of CSO doesn't seem to vary much from one basin to another, even if the percentages associated with different types of land use (residential, commercial, industrial, etc.) are different. Key words: urban runoff, combined sewer overflow, rainfall, quality, concentration, load.

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