Infiltration and inflow in combined sewer systems: long-term analysis

2002 ◽  
Vol 45 (7) ◽  
pp. 11-19 ◽  
Author(s):  
G. Weiß ◽  
H. Brombach ◽  
B. Haller
Keyword(s):  
Surface Runoff ◽  
Treatment Plant ◽  
Drainage System ◽  
Polluted Water ◽  
Special Focus ◽  
Stormwater Treatment ◽  
Sewer Systems ◽  
Combined Sewer ◽  
Insight Into

A study was conducted on 34 German combined sewer systems including combined sewer overflow (CSO) tanks and treatment plant to show up actual hidden reserves and bottlenecks in stormwater treatment. The study gave also a general insight into the water pathways in urban hydrology. A special focus was given to undesired non-polluted water infiltrating into the sewer, labelled infiltration and inflow (I/I) or infiltration inflows, which is widely underestimated. It leads to a bad performance of the drainage system although the parasite waters are themselves non-polluted. In existing combined systems, pollution control can be considerably improved by reducing I/I. It is equivalent to the reduction of surface runoff e.g. by a separate drainage as frequently proposed alternative. Artificial infiltration of surface runoff may even increase infiltration inflows.

Separate and combined sewer systems: a long-term modelling approach

2009 ◽  
Vol 60 (3) ◽  
pp. 555-565 ◽  
Author(s):  
Giorgio Mannina ◽  
Gaspare Viviani
Keyword(s):  
Cost Benefit Analysis ◽  
Treatment Plant ◽  
Cost Benefit ◽  
Sewer System ◽  
Sewer Systems ◽  
System Versus ◽  
Combined Sewer ◽  
Wet Weather ◽  
Wet Weather Flow

Sewer systems convey mostly dry weather flow, coming from domestic and industrial sanitary sewage as well as infiltration flow, and stormwater due to meteoric precipitations. Traditionally, in urban drainage two types of sewer systems are adopted: separate and combined sewers. The former convey dry and wet weather flow separately into two different networks, while the latter convey dry and wet weather flow together. Which is the best solution in terms of cost-benefit analysis still remains a controversial subject. The present study was aimed at comparing the pollution loads discharged to receiving bodies by Wastewater Treatment Plant (WWTP) and Combined Sewer Overflow (CSO) for different kinds of sewer systems (combined and separate). To accomplish this objective, a comparison between the two systems was carried out using results from simulations of catchments characterised by different dimensions, population densities and water supply rate. The analysis was based on a parsimonious mathematical model able to simulate the sewer system as well as the WWTP during both dry and wet weather. The rain series employed for the simulations was six years long. Several pollutants, both dissolved and particulate, were modelled. The results confirmed the uncertainties in the choice of one system versus the other, emphasising the concept that case-by-case solutions have to be undertaken. Further, the compared systems showed different responses in terms of effectiveness in reducing the discharged mass to the RWB in relation to the particular pollutant taken into account.

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.

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.

Settleable Solids in a Combined Sewer System, Settling Characteristics, Heavy Metals, Efficiency of Storm Water Tanks

1993 ◽  
Vol 27 (5-6) ◽  
pp. 153-164 ◽  
Author(s):  
S. Michelbach ◽  
C. Wöhrle
Keyword(s):  
Heavy Metals ◽  
Settling Velocity ◽  
Urban Runoff ◽  
Stormwater Treatment ◽  
Sewer System ◽  
Sewer Systems ◽  
Combined Sewer ◽  
Combined Sewer System ◽  
Water Tanks ◽  
The Relationship

Sedimentation and transportation of mineral and organic pollutions in combined sewer systems are not completely understood. For better understanding, samples of sediment, slime and urban runoff were taken from the combined sewer system of Bad Mergentheim. The settling velocity of settleable solids was measured with a settling apparatus. Typical settling curves for sediment, slime and wastewater were put together. Some of the samples were analysed for heavy metals and organic micro-pollution. By this the relationship between settling velocity and the load of heavy metals can be shown. The gained data are of interest for the design of clarifier tanks for stormwater treatment.

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 Evaluating three commonly used infiltration methods for permeable surfaces in urban areas using the SWMM and STORM

2021 ◽  
Author(s):  
Frida E. Å. Parnas ◽  
Elhadi M. H. Abdalla ◽  
Tone M. Muthanna
Keyword(s):  
Urban Areas ◽  
Sandy Soils ◽  
High Sensitivity ◽  
Field Measurements ◽  
Infiltration Rate ◽  
Infiltration Capacity ◽  
Infiltration Process ◽  
Sewer Systems ◽  
Combined Sewer

Abstract Climate change and urbanization increase the pressure on combined sewer systems in urban areas resulting in elevated combined sewer overflows, degraded water quality in receiving waters, and changing stream flows. Permeable surfaces offer infiltration potential, which can contribute to alleviate the runoff to combined sewer systems. The variation in urban soil characteristics and the initial moisture conditions before a rainfall event are important factors affecting the infiltration process and consequently runoff characteristics. In this study, the urban hydrological models SWMM and STORM are used to evaluate the Green-Ampt, Horton, and Holtan infiltration methods for three urban sandy soils. A sensitivity analysis was carried out on a set of key parameter values. In addition, long-term simulations were conducted to evaluate the ability to account for initial soil moisture content. The results showed that the Holtan method's ability to account for both available storage capacity and maximum infiltration rate, as well as evapotranspiration in the regeneration of infiltration capacity, gave the best result with regards to runoff behaviour, especially for long-term simulations. Furthermore, the results from the urban sandy soils with different infiltration rate at saturation, together with a high sensitivity to the degree of sensitivity for maximum infiltration rate under dry conditions and minimum infiltration rate under wet conditions, indicate that field measurements of infiltration rate should be carried out at saturation for these soils.

Stormwater Treatment in Combined Sewer Systems in Germany

1992 ◽  
Vol 26 (7-8) ◽  
pp. 1841-1849
Author(s):  
R. Pecher
Keyword(s):  
Design Process ◽  
Stormwater Treatment ◽  
Sewer System ◽  
Sewer Systems ◽  
Combined Sewer ◽  
Combined Sewer System

The use of stormwater detention tanks and their effect on combined sewer system are discussed. The design process is outlined, with particular attention to the most recent ATV guidelines.

Rehabilitation Concept for the Emscher System

1994 ◽  
Vol 29 (1-2) ◽  
pp. 283-291 ◽  
Author(s):  
D. Londong ◽  
M. Becker
Keyword(s):  
Land Subsidence ◽  
River Flow ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Drainage System ◽  
Learning By Doing ◽  
West Germany ◽  
Hard Coal ◽  
Stormwater Treatment ◽  
Natural Form

The densely populated Emscher basin (~ 800 km2) is embedded between the Ruhr and Lippe rivers in the North-West Germany. The sewerage from 2.5 million inhabitants, from a diversity of industrial plants and storm water is conveyed by a combined open sewer system to a central sewage treatment plant located at the mouth of the Emscher. The use of the natural drainage system as an open sewer was due to severe land subsidence caused by underground hard coal mining, which had a most deteriorating influence on flow conditions. After closing down most mines, land subsidence has been greatly reduced: consequently the open sewer concept can be abandoned and a general rehabilitation of the Emscher system is now in progress. The rehabilitation concept is based on the separation of natural river flow and sewage, which will be conveyed via modified combined systems to decentralized treatment plants. A step-wise programme is necessary to complete the basic system rehabilitation through “learning by doing”. The realization period is expected to be 25-30 years. For the construction of sewer systems and plants, including stormwater treatment facilities, and for the reconstruction of the surface drainage system in a natural form, including flood retention measures, the expected investment cost amounts to about 8 billion DM (~ 4.7 billion US $).

Evaluation of total emissions from treatment plants and combined sewer overflows

1998 ◽  
Vol 37 (1) ◽  
pp. 333-340 ◽  
Author(s):  
Joachim Guderian ◽  
Andreas Durchschlag ◽  
Jürgen Bever
Keyword(s):  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Design Flow ◽  
Simulation Tool ◽  
Combined Sewer Overflows ◽  
Flow Management ◽  
Sewer Systems ◽  
Optimal Value ◽  
Combined Sewer

Based upon the connection of a simulation program for combined sewer systems with the IAWQ-Activated Sludge Model No.1 the new simulation tool GEMINI was developed, which allows the calculation of sewer and sewage treatment plant as a unit. Some obtained results are presented in an example. They suggest, that for every treatment plant a rate of inflow is determinable, which leads to a minimum of total emissions out of sewer and treatment plant. The optimal value of sewage treatment plant inflow in the example is distinctly greater than the design flow rate fixed in German design rules. So it is recognizable that a rigid flow management for sewer and treatment plant does not always fulfil the aim of minimization of total emissions.

scholarly journals Innovative use of lamella clarifiers for central stormwater treatment in separate sewer systems

2013 ◽  
Vol 69 (8) ◽  
pp. 1606-1611 ◽  
Author(s):  
Gebhard Weiss
Keyword(s):  
Settling Tank ◽  
Treatment Plant ◽  
Simulation Method ◽  
Structural Flexibility ◽  
Stormwater Treatment ◽  
Treatment Efficiency ◽  
The Past ◽  
Sewer Systems ◽  
Small Footprint

Lamella settlers have been used in the past few years for the sedimentation of particles in wastewater and stormwater applications. A new and very innovative approach for the treatment of stormwater flows is proposed which extends the portfolio of solutions beyond traditional settling tanks. Surface runoff is stored in a sewer or a basin and finally treated in a small but continuously operated lamella clarifier. The low throughput flow will yield good treatment efficiency at a small footprint. The possibilities of using existing storage volume in a storm sewer, as well as the structural flexibility of the arrangement are decisive benefits. As a large operational advantage, the lamellae may be cleaned mechanically, e.g. by pivoting under water. Finally, the flow and the sludge which will be sent to the downstream treatment plant will be minimized. A new comparative simulation method is proposed in order to assess an equivalent degree of stormwater treatment, either by achieving an equal annual volume of treated stormwater or, more directly, an equal amount of spilled pollutant load. The new solution is compared with a traditional settling tank according to current German design rules. Additionally, a case study from a real installation will be presented.

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