The transfer of solids in combined sewer networks

1995 ◽  
Vol 31 (7) ◽  
pp. 95-105 ◽  
Author(s):  
G. Chebbo ◽  
A. Bachoc ◽  
D. Laplace ◽  
B. Le Guennec
Keyword(s):  
Organic Matter ◽  
Suspended Solids ◽  
Rainfall Event ◽  
Bed Load ◽  
Surface Slope ◽  
Rainfall Events ◽  
Sediment Deposits ◽  
Combined Sewer ◽  
Stress Variations ◽  
Sewer Networks

Suspended solids are the main vectors of pollution in combined sewer wet weather flows. In spite of being very fine, they decant rather quickly except in the case of light rainfall events rich in organic matter. The part originating from sewer sediment deposits provides a large proportion of organic matter mass. By analysing the content and the volume of sewer deposits at different points from upstream to downstream, it emerges that the main source of this contribution is probably located in man-entry sewers. In one of these, sewer trunk no. 13 in Marseilles, five hundred metres of which were monitored continuously for sediment build-up over three years, the deposit volume grows mainly during certain rainfall events and its surface slope tends to an equilibrium with the (millimetric) particle size. Theoretical bed-load and suspension thresholds have been validated, then analysed for various situations and sections. A typology of the vulnerable areas, in several networks, has been drawn up, as well as a study of shear stress variations during a rainfall event. The sediment deposits seem to occur in particular hydraulic discontinuity zones where transport capacities can drop sharply.

Technical solutions envisaged in managing solids in combined sewer networks

1996 ◽  
Vol 33 (9) ◽  
pp. 237-244 ◽  
Author(s):  
Ghassan Chebbo ◽  
Dominique Laplace ◽  
André Bachoc ◽  
Yves Sanchez ◽  
Benoit Le Guennec
Keyword(s):  
Large Scale ◽  
Suspended Solids ◽  
Drainage Area ◽  
Bed Load ◽  
Urban Drainage ◽  
Combined Sewer ◽  
Wet Weather ◽  
Technical Solutions ◽  
Dry Weather Flow ◽  
Sewer Networks

Solids in combined sewer networks represent two important technical questions: - the clogging of man-entry sewers, and - pollution in urban wet weather discharges, whose main vectors are generally suspended solids. In this paper, we shall present first, curative technical solutions which avoid or remove deposits in man-entry sewers. We shall discuss the partial extraction of the largest solids; selective trapping of bed load solids, which form deposits; and the displacement of deposits using dry weather flow flushing waves. We shall then examine technical solutions to control pollution in urban wet weather discharges. This will show that decantation is an efficient means of fighting pollution. However, it is not always feasible because it involves large scale investments. Complementary methods should, therefore, be developed and used at different points in the water's passage through an urban drainage area.

Comparison of Parameters Characterizing Organic Matter in a Combined Sewer During Rainfall Events and Dry Weather

1999 ◽  
Vol 71 (4) ◽  
pp. 408-417 ◽  
Author(s):  
Pierre Servais ◽  
Martin Seidl ◽  
Jean-Marie Mouchel
Keyword(s):  
Organic Matter ◽  
Rainfall Events ◽  
Combined Sewer

Modelling of suspended sediment in a weir reach using EFDC model

2015 ◽  
Vol 73 (7) ◽  
pp. 1583-1590 ◽  
Author(s):  
Gijung Pak ◽  
Kristine Joy B. Mallari ◽  
Jongrak Baek ◽  
Deokwoo Kim ◽  
Hwansuk Kim ◽  
...  
Keyword(s):  
Water Quality ◽  
Suspended Solids ◽  
Water Quality Management ◽  
Total Suspended Solids ◽  
Rainfall Event ◽  
Hydraulic Structures ◽  
Rainfall Events ◽  
Efdc Model ◽  
Environmental Fluid ◽  
Modelling System

Construction of hydraulic structures often leads to alteration of river dynamics and water quality. Suspended solids entering the upstream of the weir cause adverse effects to the hydroecological system and, therefore, it is necessary to build a modelling system to predict the changes in the river characteristics for proper water quality management. In this study, the discharges and total suspended solids upstream and downstream of the Baekje Weir installed in Geum River, Korea, was modelled using the environmental fluid dynamics code (EFDC) model. The resulting trend of four rainfall events shows that as rainfall increases, the total suspended solids (TSS) concentration increases as well. For the two larger events, at the upstream of the weir, TSS was observed to decrease or remain constant after the rainfall event depending on the lowering of the open gate. At the downstream, TSS supply was controlled by the weir during and after the rainfall event resulting in decline in the TSS concentration. The modelling produced good results for discharge based on %Diff. (4.37–6.35), Nash–Sutcliffe efficiency (NSE) (0.94–0.99) and correlation coefficient (r) (0.97–0.99) values as well as for TSS with acceptable values for %Diff. (12.08–14.11), NSE (0.75–0.81) and r (0.88–0.91), suggesting good applicability of the model for the weir reach of the river in the study site.

scholarly journals Impact of a high rainfall event on the water level, current velocity, and total suspended solids in tidal flats environments of the estuarine Cruces River wetland, south-central Chile

2021 ◽  
Vol 49 (1) ◽  
pp. 188-192
Author(s):  
Mario Manzano ◽  
Eduardo Jaramillo ◽  
Mario Pino
Keyword(s):  
Surface Waters ◽  
Suspended Solids ◽  
Environmental Variability ◽  
Total Suspended Solids ◽  
Tidal Flats ◽  
Rainfall Event ◽  
Rainfall Events ◽  
Central Chile ◽  
South Central ◽  
Coseismic Subsidence

The effects of a sudden rainfall (40 mm d-1) event on the surface waters covering muddy tidal flats were studied during April 2016 at the estuarine Cruces River wetland in south-central Chile (~40ºS). The study area included flooded vestigial tree trunks, which is evidence of coseismic subsidence associated with the 1960 Valdivia earthquake as a source of environmental variability. The tidal flat with vestigial tree trunks registered the fastest and highest depth of inundation. In contrast, the tidal currents velocity and total suspended solids' concentrations were higher at the flat without trunks. Sudden rainfall events can significantly modify the characteristics of surface waters above sedimentary intertidal surfaces, where structures such as flooded trunks are present.

Sewer Sediment and its Relation with the Quality Characteristics of Combined Sewer Flows

1990 ◽  
Vol 22 (10-11) ◽  
pp. 247-257 ◽  
Author(s):  
M. Verbanck
Keyword(s):  
Suspended Solids ◽  
Particulate Material ◽  
Main Trunk ◽  
Rainfall Events ◽  
Combined Sewer ◽  
First Results ◽  
Sandy Material ◽  
Complex Phenomena ◽  
Pollution Emissions ◽  
Dry Weather Flow

Combined sewer lines in the centre of Brussels are laid at very slack gradients, resulting during dry-weather in a systematic deficit of the load of particulate material at the outlet. The first results of a data collection programme are documented, with regard to the influence of in-sewer deposits upon pollution emissions. The monitoring of suspended solids load in the Main Trunk showed the extent of sediment deposition/resuspension processes in the system. Over a long period of time, the accumulation of deposits on sewer inverts is clearly noticeable. The total volume of deposition in the network also appears to be much more influenced by rainfall events than by human sewer-cleaning practices. Particle size analyses of sewer sediment samples have shown that most deposits in running sewers are composed of sandy material, which reduces the hydraulic capacity, but is suspected to have only slight adverse pollutional impact. Samples with finer material and higher organic contents were however found in some protected locations, not submitted to continuous dry-weather flow. From the experience gained in this study, it is strongly believed that the acquisition of detailed field data is essential in order to assess correctly the complex phenomena involved.

scholarly journals Acoustic measurement and morphological features of organic sediment deposits in combined sewer networks

2017 ◽  
Vol 112 ◽  
pp. 279-290 ◽  
Author(s):  
Iacopo Carnacina ◽  
Frédérique Larrarte ◽  
Nicoletta Leonardi
Keyword(s):  
Morphological Features ◽  
Acoustic Measurement ◽  
Sediment Deposits ◽  
Organic Sediment ◽  
Combined Sewer ◽  
Sewer Networks

Spatial variability of characteristics and origins of urban wet weather pollution in combined sewers

2005 ◽  
Vol 52 (3) ◽  
pp. 53-62 ◽  
Author(s):  
M. Kafi-Benyahia ◽  
M.G. Gromaire ◽  
G. Chebbo
Keyword(s):  
Heavy Metals ◽  
Organic Matter ◽  
Suspended Solids ◽  
Spatial Scales ◽  
Urban Runoff ◽  
Urban Catchment ◽  
Rainfall Events ◽  
Wet Weather ◽  
Wet Weather Flow ◽  
Dry Weather Flow

An experimental on-site observatory of urban pollutant loads in combined sewers was created in the centre of Paris to quantify and characterise the dry and wet weather flow in relation to spatial scale. Eight rainfall events were studied from April 2003 to May 2004. Samples were analysed for suspended solids, organic matter, nitrogen and heavy metals. Results confirm the extent of wet weather pollution. They have shown the relative homogeneity of SS and organic matter characteristics from one urban catchment area to another. Two groups of heavy metals were identified. The first one concerns Cu, which has a higher concentration in wet weather flow (WWF) than in dry weather flow (DWF), and runoff. The second includes Cd, Pb and Zn, where higher concentrations were measured in urban runoff than in WWF and DWF. A first evaluation of contribution of wastewater, urban runoff and sewer deposit erosion sources to wet weather pollution was established and has highlighted the contribution of wastewater and sewer deposits to this pollution. However, it has shown that sewer deposit erosion remains an important source of wet weather pollution at different spatial scales.

Coupling acoustic devices for monitoring combined sewer network sediment deposits

2014 ◽  
Vol 69 (8) ◽  
pp. 1653-1660 ◽  
Author(s):  
I. Carnacina ◽  
F. Larrarte
Keyword(s):  
Flow Patterns ◽  
Complex Environments ◽  
Velocity Measurements ◽  
Sediment Deposits ◽  
Combined Sewer ◽  
Acoustic Techniques ◽  
Sediment Interface ◽  
Sewer Networks ◽  
Good Agreement

Combined sewer networks display some unique features that are not easily reproducible in the laboratory and have yet to be well understood. The transport of organic and mobile sediments, present in large quantities despite the use of optimal design practices, dramatically changes sewer flow patterns and the interaction between flow and sediment. To understand both the flow patterns and transport features of these complex environments, it is therefore necessary to install instrumentation in situ. For this paper, two distinct acoustic techniques were coupled in order to measure both the sediment interface and velocity. For this purpose, a 2 MHz rotating head acoustic profiler and a 10 MHz acoustic Doppler velocimeter (ADV) were jointly installed to survey the position of sediment deposits and measure velocity patterns. Results were compared with measurements recorded in different environments, where both coarser and finer soft deposits were present. These results typically showed good agreement between the interfaces detected using velocity measurements on coarse deposits, while the presence of soft deposits demonstrated the need for coupling measurements techniques that can correctly assess the sediment interface.

Study on the performance of an up-flow aerated biofilter (UAB) in municipal wastewater treatments

1994 ◽  
Vol 30 (11) ◽  
pp. 25-33 ◽  
Author(s):  
Yoshimasa Watanabe ◽  
Satoshi Okabe ◽  
Tomochika Arata ◽  
Yuji Haruta
Keyword(s):  
Organic Matter ◽  
Suspended Solids ◽  
Municipal Wastewater ◽  
Unique Feature ◽  
Aeration Rate ◽  
Loading Rates ◽  
Hydraulic Loading ◽  
Running Cost ◽  
And Performance ◽  
Activated Sludge Systems

A comprehensive wastewater treatment system that accomplishes oxidation of organic matter, nitrification, and denitrification was developed, and its characteristics and performance were investigated. A municipal wastewater was treated by an up-flow aerated biofilter (UAB), in which biofilms were developed on stainless meshes installed horizontally. This UAB exhibited a great potential ability of oxidation of organic matter, SS stabilization, and nitrification due to a unique aeration mechanism giving high DO concentrations with relatively low aeration rates. Another unique feature of the UAB was that attached biofilms on stainless meshes physically filtered out and/or adsorbed suspended solids in the wastewater in addition to the biological oxidation of organic matter. A stable nitrification could be achieved at HRT=10 hours corresponding to a hydraulic loading of 86 L m−2 d−1 and at a ratio of aeration rate to wastewater flow rate (A/W) of 2, which is considerably low as compared to aeration rates of typical activated sludge systems. This UAB system also could handle relatively high hydraulic loading rates. The UAB used in this study still have enough space to install more stainless meshes so as to reduce hydraulic loading rates resulting in the reduction of HRT and aeration rate, which leads to improvement of the system performance as well as reduction of the running cost.

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.

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