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.

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.

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.

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.

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.

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.

Methods for studying dissolved oxygen levels in coastal and estuarine waters receiving combined sewer overflows

1995 ◽  
Vol 32 (2) ◽  
pp. 95-103
Author(s):  
José A. Revilla ◽  
Kalin N. Koev ◽  
Rafael Díaz ◽  
César Álvarez ◽  
Antonio Roldán
Keyword(s):  
Dissolved Oxygen ◽  
Coastal Waters ◽  
Computational Cost ◽  
Oxygen Deficit ◽  
Alternative Methods ◽  
Coastal Zones ◽  
Combined Sewer Overflows ◽  
Sewer Systems ◽  
Combined Sewer ◽  
High Computational Cost

One factor in determining the transport capacity of coastal interceptors in Combined Sewer Systems (CSS) is the reduction of Dissolved Oxygen (DO) in coastal waters originating from the overflows. The study of the evolution of DO in coastal zones is complex. The high computational cost of using mathematical models discriminates against the required probabilistic analysis being undertaken. Alternative methods, based on such mathematical modelling, employed in a limited number of cases, are therefore needed. In this paper two alternative methods are presented for the study of oxygen deficit resulting from overflows of CSS. In the first, statistical analyses focus on the causes of the deficit (the volume discharged). The second concentrates on the effects (the concentrations of oxygen in the sea). Both methods have been applied in a study of the coastal interceptor at Pasajes Estuary (Guipúzcoa, Spain) with similar results.

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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