Aerobic microbial transformations of pipe and silt trap sediments from combined sewers

1999 ◽  
Vol 39 (2) ◽  
pp. 233-249 ◽  
Author(s):  
Jes Vollertsen ◽  
Thorkild Hvitved-Jacobsen ◽  
Iain McGregor ◽  
Richard Ashley
Keyword(s):  
Organic Matter ◽  
Dissolved Oxygen ◽  
Conceptual Model ◽  
Combined Sewer Overflow ◽  
Organic Fraction ◽  
Combined Sewer ◽  
Receiving Waters ◽  
Oxygen Utilisation ◽  
Fast Settling ◽  
The Impact

Organic matter in sediments from pipes and silt traps in combined sewers was divided into fractions with different settling velocities. Biodegradability of organic matter for these fractions was characterised based on results from a conceptual model of aerobic transformations of resuspended sediments calibrated on oxygen utilisation rates. Pipe sediments as well as silt trap sediments were investigated and no differences between these deposits were detected. It was found that the largest fraction of organic matter is associated with material which settles relatively fast and only a small part is associated with relatively slow settling material. However, the fast settling organic matter was found to be rather slowly biodegradable compared to the slow settling organic fraction. Because the biodegradability of the organic matter discharged during combined sewer overflow (CSO) events is of significant importance to the impact on the dissolved oxygen concentrations in receiving waters, the biodegradability of sewer sediments is argued to be taken into account for detailed characterisation when dealing with CSO impacts.

Wastewater quality changes during transport in sewers – an integrated aerobic and anaerobic model concept for carbon and sulfur microbial transformations

1998 ◽  
Vol 38 (10) ◽  
pp. 257-264 ◽  
Author(s):  
T. Hvitved-Jacobsen ◽  
J. Vollertsen ◽  
N. Tanaka
Keyword(s):  
Organic Matter ◽  
Organic Fraction ◽  
Model Concept ◽  
Combined Sewer ◽  
Wastewater Quality ◽  
Receiving Waters ◽  
Oxygen Utilisation ◽  
Fast Settling ◽  
The Impact ◽  
Aerobic And Anaerobic

Organic matter in sediments from pipes and silt traps in combined sewers was divided into fractions with different settling velocities. Biodegradability of organic matter for these fractions was characterised based on results from a conceptual model of aerobic transformations of resuspended sediments calibrated on oxygen utilisation rates. Pipe sediments as well as silt trap sediments were investigated and no differences between these deposits were detected. It was found that the largest fraction of organic matter is associated with material which settles relatively fast and only a small part is associated with relatively slow settling material. However, the fast settling organic matter was found to be rather slowly biodegradable compared to the slow settling organic fraction. Because the biodegradability of the organic matter discharged during combined sewer overflow (CSO) events is of significant importance to the impact on the dissolved oxygen concentrations in receiving waters, the biodegradability of sewer sediments is argued to be taken into account for detailed characterisation when dealing with CSO impacts.

Development of a Methodology to Determine the Pollution Discharged by a Combined Sewer Network

1990 ◽  
Vol 22 (10-11) ◽  
pp. 15-22 ◽  
Author(s):  
M. Cherrered ◽  
B. Chocat
Keyword(s):  
Urban Runoff ◽  
Pollution Source ◽  
Relative Effect ◽  
Actual State ◽  
Combined Sewer Overflow ◽  
Combined Sewer Overflows ◽  
Combined Sewer ◽  
Receiving Waters ◽  
Sewer Overflow ◽  
The Impact

Until a few years ago, there was not much research in France into Combined Sewer Overflow phenomena in storm weather. The water of urban runoff has always been considered “clean” and one considered that the dilution of dry weather flows in storm water decreased the impact of the pollution generated by overflows. Now, with increased urban development and realization of the importance of pollution caused by urban runoff, the problem can be considered differently. Indeed, some quality studies of receiving waters show that combined sewer networks represent an important pollution source for the natural environment, due to the increasing relative effect of combined sewer overflow discharge into receiving waters. Thus, combined sewer overflows have until recently been the least known part of the sewer system. In this present communication, methodology to estimate combined overflows has been elaborated after exploitation of data resulted from ten French real case studies where such problems were observed. This study has been realized in four steps:- A bibliography study to discover the actual state of the problem in terms of existent methods concerning both experimentation and modelling and to define the needs of the research.- Ten French studies have been selected, analysed, and used to define the different methods used, and to show methodological lacunas from the observations and results realized. Elements of improvement have been proposed.- Methods and new propositions have been defined and a coherent methodological diagram has been realized to compare and test these methods.- Computer tools have been conceived and tested in the ten study cases.

Considering the impact of intermittent discharges when modelling overflows

1998 ◽  
Vol 38 (10) ◽  
pp. 23-30
Author(s):  
Sarah Jubb ◽  
Philip Hulme ◽  
Ian Guymer ◽  
John Martin
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Preliminary Investigation ◽  
Oxygen Demand ◽  
Sediment Oxygen Demand ◽  
Combined Sewer Overflows ◽  
River Hydraulics ◽  
Combined Sewer ◽  
The Impact ◽  
Curve Equation

This paper describes a preliminary investigation that identified factors important in the prediction of river water quality, especially regarding dissolved oxygen (DO) concentration. Intermittent discharges from combined sewer overflows (CSOs) within the sewerage, and overflows at water reclamation works (WRW) cause dynamic conditions with respect to both river hydraulics and water quality. The impact of such discharges has been investigated under both wet and dry weather flow conditions. Data collected from the River Maun, UK, has shown that an immediate, transient oxygen demand exists downstream of an outfall during storm conditions. The presence of a delayed oxygen demand has also been identified. With regard to modelling, initial investigations used a simplified channel and the Streeter-Phelps (1925) dissolved oxygen sag curve equation. Later, a model taking into account hydrodynamic, transport and dispersion processes was used. This suggested that processes other than water phase degradation of organic matter significantly affect the dissolved oxygen concentration downstream of the location of an intermittent discharge. It is proposed that the dynamic rate of reaeration and the sediment oxygen demand should be the focus of further investigation.

The influence of biodegradability of sewer solids for the management of CSOs

2005 ◽  
Vol 51 (2) ◽  
pp. 89-97 ◽  
Author(s):  
R. Sakrabani ◽  
R.M. Ashley ◽  
J. Vollertsen
Keyword(s):  
Weather Conditions ◽  
Bulk Water ◽  
Combined Sewer Overflows ◽  
Sediment Erosion ◽  
Combined Sewer ◽  
Utilisation Rate ◽  
Laboratory Device ◽  
Receiving Waters ◽  
Oxygen Utilisation ◽  
Wet Weather

The re-suspension of sediments in combined sewers and the associated pollutants into the bulk water during wet weather flows can cause pollutants to be carried further downstream to receiving waters or discharged via Combined Sewer Overflows (CSO). A typical pollutograph shows the trend of released bulk pollutants with time but does not consider information on the biodegradability of these pollutants. A new prediction methodology based on Oxygen Utilisation Rate (respirometric method) and Erosionmeter (laboratory device replicating in-sewer erosion) experiments is proposed which is able to predict the trends in biodegradability during in-sewer sediment erosion in wet weather conditions. The proposed new prediction methodology is also based on COD fractionation techniques.

Impact of dissolved oxygen concentration on membrane filtering resistance and soluble organic matter characteristics in membrane bioreactors

2008 ◽  
Vol 57 (2) ◽  
pp. 161-165 ◽  
Author(s):  
Kyung-Nan Min ◽  
Sarina J. Ergas ◽  
Anna Mermelstein
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Dissolved Oxygen ◽  
Weight Fraction ◽  
Total Resistance ◽  
Soluble Organic Matter ◽  
Aerobic Conditions ◽  
Do Concentration ◽  
The Impact ◽  
Molecular Weight Fractions

This study investigated the impact of dissolved oxygen (DO) concentration on membrane filtering resistance, soluble organic matter (SOM) and extracellular polymeric substance (EPS) characteristics in a membrane bioreactor (MBR). A laboratory-scale MBR was operated under DO limited (0.2 mg L−1 DO) and fully aerobic (3.7 and 5.4 mg L−1 DO) conditions. Membrane filtering resistance was determined for the mixed liquor suspended solids (MLSS) and for resuspended microbial biomass after removing SOM. Regardless of the DO concentration, the cake resistance (Rc) was approximately 95 percent of the total resistance (Rt). The membrane cake resistance was found to decrease significantly after removing the SOM. The total resistance caused by the resuspended biomass was 29 percent of that caused by the MLSS under DO limited conditions, while the total resistance caused by resuspended biomass was 41 to 48 percent of that caused by the MLSS under fully aerobic conditions. Under DO limited conditions, SOM in the MLSS contained a larger amount of high molecular weight compounds, leading to higher cake resistance than under fully aerobic conditions. There was significant variation in the molecular weight fractions of the EPS, with no clear relationship with DO concentration. There was also no distinct relationship between membrane filtering resistance and molecular weight fraction of the EPS.

Storm tank against combined sewer overflow: Operation strategies to minimise discharges impact to receiving waters

2014 ◽  
Vol 12 (3) ◽  
pp. 219-228 ◽  
Author(s):  
Anna Llopart-Mascaró ◽  
Ramon Farreny ◽  
Xavier Gabarrell ◽  
Joan Rieradevall ◽  
Alicia Gil ◽  
...  
Keyword(s):  
Combined Sewer Overflow ◽  
Combined Sewer ◽  
Receiving Waters ◽  
Sewer Overflow

The feasibility of flocculation in a storage sedimentation basin

1999 ◽  
Vol 39 (2) ◽  
pp. 75-83 ◽  
Author(s):  
W. De Cock ◽  
P. Blom ◽  
G. Vaes ◽  
J. Berlamont
Keyword(s):  
Numerical Model ◽  
Velocity Gradient ◽  
Settling Velocity ◽  
Pollution Load ◽  
Combined Sewer Overflows ◽  
Combined Sewer ◽  
Efficiency Increase ◽  
Receiving Waters ◽  
Sedimentation Basins ◽  
The Impact

For the Flemish situation, storage sedimentation basins are one of the best ‘end-of-pipe’ solutions to reduce the impact of combined sewer overflows on the receiving waters. In some cases, when the spilled pollution load is too high, the settling efficiency of the basin has to be improved. Adding coagulants could be a reasonable alternative for building larger basins. To estimate the effect of enhancing the settling by flocculation, a floc growth and break-up model is worked out and is implemented in the numerical model Phoenics. The evolution of the floc dimensions and the sedimentation behaviour of the particles in the basin is calculated for different inflow rates and initial settling velocity profiles. Finally, the efficiency increase by mixing (creating a higher velocity gradient) in the agitation chamber or by adding coagulants in the trunk sewer upstream of the basin is also investigated.

Detention of Sanitary Sewage as a Method to Reduce Combined Sewer Overflow Pollution Loads

1991 ◽  
Vol 24 (6) ◽  
pp. 217-224 ◽  
Author(s):  
Dirk-Th Kollatsch ◽  
J. Bünzel
Keyword(s):  
High Efficiency ◽  
Control Strategies ◽  
Flow Characteristics ◽  
Combined Sewer Overflow ◽  
Pollution Load ◽  
Combined Sewer ◽  
Receiving Waters ◽  
Control Devices ◽  
Sewer Overflow ◽  
Pollution Loads

Sanitary sewage yields the basic and most important pollution load diverted to receiving waters during combined sewer overflow (CSO). To reduce overflow pollution loads, it is proposed to store waste water in sanitary sewage detention tanks (SST). For high efficiency those SSTs should be filled and emptied by pumps or gates, operated by control devices. Control strategies have to be worked out depending on different situations and parameters (catchment, rain and flow characteristics).

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