Performance of a high-rate sedimentation process for combined sewerage treatment in wet weather

2006 ◽  
Vol 1 (1) ◽  
Author(s):  
K. Suzuki ◽  
T. Fujihashi ◽  
S. Kosanda ◽  
H. Hinuma ◽  
R. Hata
Keyword(s):  
Treatment Plant ◽  
High Rate ◽  
Test Facility ◽  
Test Results ◽  
Combined Sewer Overflows ◽  
Sedimentation Process ◽  
Coagulation And Flocculation ◽  
Combined Sewer ◽  
Mixing Method ◽  
Wet Weather

A novel high-rate sedimentation process has been developed for directly treating combined sewer overflows (CSOs). This was done using a test facility at an actual wastewater treatment plant in Tokyo. Pilot test results, carried out 13 times, from December 2002 to July 2003 in wet weather, suggested that the process was suitable for treatment of CSOs. The performance of the process was favorable at 50 m3/(m2 ·h) up to 880 mg/L influent TSS, removing between 78 % and 91 % of TSS at loading and between 64 % and 85 % of BOD5 also at loading. The pilot testing clarified that a decrease in the influent alkalinity due to rain water caused a drop in the pH after FeCl3 addition and thus improved coagulation, with a significant decrease in the effluent TSS. Mixing, coagulation and flocculation were carried out in a baffling type mixing tank to enable uniform mixing without any short-passes. Coagulation conditions in this mixing method were evaluated and results clarified that rapid mixing was required momentarily after each addition of FeCl3 and polymer, i.e. to diffuse these additives into the influent.

scholarly journals The importance of pollutional loads during wet weather

2019 ◽  
pp. 271-282
Author(s):  
Oddvar Georg Lindholm ◽  
Lars Aaby
Keyword(s):  
Time Series ◽  
Wastewater Treatment ◽  
Wastewater Treatment Plant ◽  
Treatment Plant ◽  
The Other ◽  
Combined Sewer Overflows ◽  
Combined Sewer ◽  
Receiving Waters ◽  
Wet Weather ◽  
Annual Discharge

Wet weather discharges consist mainly of washed out surface pollution in separate sewered areas, but in combined sewered areas; resuspended pipe deposits, surface washoff and sewage, discharging via combined sewer overflows (CSOs). Of the three mentioned sources, resuspended pipe solids is dominating over the other two and may contribute as much as 50 to 90 % of the total amount of the CSO. The CSO in a normal catchment may also on an annual bases be of the same amount, or even twice as much as the effluent from the wastewater treatment plant (WWTP). If the receiving waters are vulnerable to shock loads on a daily base, it is important to be aware that the amount of CSO might, at its most adverse be up to I 00 times more than the effluent from the WWTP during a day. The annual discharge via CSOs in a catchment may easily vary with a factor of up to 8 from the driest to the wettest year, during time series of 20 to 40 years.

Vortex separator: dimensionless properties and calculation of annual separation efficiencies

1996 ◽  
Vol 33 (9) ◽  
pp. 277-284 ◽  
Author(s):  
Gebhard J. Weiß ◽  
Steven Michelbach
Keyword(s):  
Steady Flow ◽  
Separation Efficiency ◽  
Scale Effects ◽  
Treatment Plant ◽  
Transfer Model ◽  
Test Results ◽  
Combined Sewer Overflows ◽  
Combined Sewer ◽  
Vortex Separator ◽  
The Given

Vortex separators as new devices for combined sewer overflows (CSOs) claim good efficiencies which can be confirmed by laboratory tests. Such model tests are usually performed in reduced scale and under steady-flow conditions. This paper describes a possible way to transfer model test results to the prototype scale. As a first step, the most essential parameters must be accounted for using a proper dimensional analysis which also considers scale effects. It will result in dimensionless efficiency curves which allow prediction of prototype efficiencies, yet valid for steady flow only. To take into account the variability of annual inflow as well as dynamic effects like filling and emptying of a particular separator, the efficiency characteristics of the separator are combined with a quantity-quality simulation model. Such a numerical model is able to compute inflow and outflow hydrographs and pollutographs and to account for the catchment data at the given site. It allows the computation of annual pollutant loads as well as of the percentage of sewage sediment fed to the treatment plant, i.e. an annual separation efficiency.

scholarly journals Analysis of Combined Sewer Flow Storage Scenarios Prior to Wastewater Treatment Plant

2018 ◽  
Vol 25 (4) ◽  
pp. 619-630 ◽  
Author(s):  
Grażyna Sakson ◽  
Marek Zawilski ◽  
Agnieszka Brzezińska
Keyword(s):  
Wastewater Treatment ◽  
Wastewater Treatment Plant ◽  
Storage Tank ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Real Time Control ◽  
Combined Sewer Overflows ◽  
Combined Sewer ◽  
Receiving Waters ◽  
Wet Weather

Abstract Combined sewer systems in cities are increasingly equipped with additional storage facilities or other installations necessary for keeping the wastewater treatment plants from overloading during wet weather and reducing combined sewer overflows into receiving waters. Effective methods for reducing such negative phenomena include the temporary storage of wet weather flow in an end-of-pipe separate tank or in a sewer system. In this paper, four scenarios of wastewater storage for the Group Wastewater Treatment Plant (GWWTP) in Lodz (Poland) have been analysed: a storage in a separate single tank located in GWWTP, a storage in the bypass channel in GWWTP, in-sewer storage, and a combination of the aforementioned variants, also with real time control (RTC) system introduced. The basic calculations were performed using the EPA’s SWMM software for the period of 5 years (2004-2008). The chosen solution - storage in a separate storage tank - has been verified based on the inflow dataset from the years 2009-2013. The specific volume of the separate storage tank should be at least 22 m3 per hectare of impervious catchment area, but it could be reduced if additional in-sewer storage with RTC were introduced. Both options allow the effective protection of receiving waters against discharge of untreated sewage during wet weather.

Implementation of Hamilton-Wentworth Region’s Pollution Control Plan

1996 ◽  
Vol 31 (3) ◽  
pp. 453-472 ◽  
Author(s):  
M. Stirrup
Keyword(s):  
Wastewater Treatment ◽  
Pollution Control ◽  
Wastewater Treatment Plant ◽  
Treatment Plant ◽  
Control Measures ◽  
Storm Events ◽  
Combined Sewer Overflows ◽  
Control Plan ◽  
Combined Sewer ◽  
Sewer Overflows

Abstract The Regional Municipality of Hamilton-Wentworth operates a large combined sewer system which diverts excess combined sewage to local receiving waters at over 20 locations. On average, there are approximately 23 combined sewer overflows per year, per outfall. The region’s Pollution Control Plan, adopted by Regional Council in 1992, concluded that the only reasonable means of dealing with large volumes of combined sewer overflow in Hamilton was to intercept it at the outlets, detain it and convey it to the wastewater treatment plant after the storm events. The recommended control strategy relies heavily on off-line storage, with an associated expansion of the Woodward Avenue wastewater treatment plant to achieve target reductions of combined sewer overflows to 1–4 per year on average. The region has begun to implement this Pollution Control Plan in earnest. Three off-line detention storage tanks are already in operation, construction of a fourth facility is well underway, and conceptual design of a number of other proposed facilities has commenced. To make the best possible use of these facilities and existing in-line storage, the region is implementing a microcomputer-based real-time control system. A number of proposed Woodward Avenue wastewater treatment plant process upgrades and expansions have also been undertaken. This paper reviews the region's progress in implementing these control measures.

Long-Term Simulation of Pollutant Loads in Treatment Plant Effluents and Combined Sewer Overflows

1990 ◽  
Vol 22 (10-11) ◽  
pp. 69-76 ◽  
Author(s):  
A. Durchschlag
Keyword(s):  
Waste Water Treatment ◽  
Treatment Plant ◽  
Storm Water ◽  
Water Runoff ◽  
Storage Tanks ◽  
Combined Sewer Overflows ◽  
Storm Water Runoff ◽  
Combined Sewer ◽  
Hydraulic Load ◽  
Water Tanks

As a result of urbanization, the pollutant discharges from sources such as treatment plant effluents and polluted stormwaters are responsible for an unacceptable water quality in the receiving waters.In particular, combined sewer system overflows may produce great damage due to a shock effect. To reduce these combined sewer overflow discharges, the most frequently used method is to build stormwater storage tanks. During storm water runoff, the hydraulic load of waste water treatment plants increases with additional retention storage. This might decrease the treatment efficiency and thereby decrease the benefit of stormwater storage tanks. The dynamic dependence between transport, storage and treatment is usually not taken into account. This dependence must be accounted for when planning treatment plants and calculating storage capacities in order to minimize the total pollution load to the receiving waters. A numerical model will be described that enables the BOD discharges to be continuously calculated. The pollutant transport process within the networks and the purification process within the treatment plants are simulated. The results of the simulation illustrate; a statistical balance of the efficiency of stormwater tanks with the treatment plant capacity and to optimize the volume of storm water tanks and the operation of combined sewer systems and treatment plants.

An application of Austrian legal requirements for CSO emissions

2011 ◽  
Vol 64 (5) ◽  
pp. 1081-1088 ◽  
Author(s):  
Manfred Kleidorfer ◽  
Wolfgang Rauch
Keyword(s):  
Model Calibration ◽  
Model Building ◽  
Treatment Plant ◽  
Cost Effective ◽  
Combined Sewer Overflows ◽  
Sewer System ◽  
Legal Requirements ◽  
Innovative Methods ◽  
Combined Sewer

The Austrian standard for designing combined sewer overflow (CSO) detention basins introduces the efficiency of the combined sewer overflows as an indicator for CSO pollution. Additionally criteria for the ambient water quality are defined, which comprehend six kinds of impacts. In this paper, the Austrian legal requirements are described and discussed by means of hydrological modelling. This is exemplified with the case study Innsbruck (Austria) including a description for model building and model calibration. Furthermore an example is shown in order to demonstrate how – in this case – the overall system performance could be improved by implementing a cost-effective rearrangement of the storage tanks already available at the inflow of the wastewater treatment plant. However, this guideline also allows more innovative methods for reducing CSO emissions as measures for better usage of storage volume or de-centralised treatment of stormwater runoff because it is based on a sewer system simulation.

Model-based comparison of two ways to enhance WWTP capacity under stormwater conditions

2009 ◽  
Vol 60 (7) ◽  
pp. 1875-1883 ◽  
Author(s):  
M. Ahnert ◽  
J. Tränckner ◽  
N. Günther ◽  
S. Hoeft ◽  
P. Krebs
Keyword(s):  
Treatment Plant ◽  
Combined Sewer Overflows ◽  
Worst Case ◽  
Wwtp Effluent ◽  
Combined Sewer ◽  
Total Ammonia ◽  
Rain Events ◽  
Simulated Time ◽  
Simulated Time Series ◽  
Receiving Water

Two different approaches to increase the fraction of combined water treated in the wastewater treatment plant (WWTP) which would otherwise contribute to combined sewer overflows (CSO) are presented and compared based on modelling results with regard to their efficiencies during various rain events. The first option is to generally increase the WWTP inflow according to its actual capacity rather than pre-setting a maximum that applies to worst case loading. In the second option the WWTP inflow is also increased, however, the extra inflow of combined water is bypassing the activated sludge tank and directly discharged to the secondary clarifier. Both approaches have their advantages. For the simulated time series with various rain events, the reduction of total COD load from CSOs and WWTP effluent discharged to the receiving water was up to 20% for both approaches. The total ammonia load reduction was between 6% for the bypass and 11% for inflow increase. A combination of both approaches minimises the adverse effects and the overall emission to the receiving water.

Toxicity and pollutant impact analysis in an urban river due to combined sewer overflows loads

2010 ◽  
Vol 61 (1) ◽  
pp. 207-215 ◽  
Author(s):  
A. Casadio ◽  
M. Maglionico ◽  
A. Bolognesi ◽  
S. Artina
Keyword(s):  
Water Quality ◽  
Impact Analysis ◽  
Waste Water Treatment ◽  
Treatment Plant ◽  
Quality Data ◽  
Waste Water Treatment Plant ◽  
Combined Sewer Overflows ◽  
Water Quality Data ◽  
Combined Sewer ◽  
Sewer Overflows

The Navile Channel (Bologna, Italy) is an ancient artificial water course derived from the Reno river. It is the main receiving water body for the urban catchment of Bologna sewer systems and also for the Waste Water Treatment Plant (WWTP) main outlet. The aim of this work is to evaluate the Combined Sewer Overflows (CSOs) impact on Navile Channel's water quality. In order to collect Navile flow and water quality data in both dry and wet weather conditions, two measuring and sampling stations were installed, right upstream and downstream the WWTP outflow. The study shows that even in case of low intensity rain events, CSOs have a significant effect on both water quantity and quality, spilling a considerable amount of pollutants into the Navile Channel and presenting also acute toxicity effects. The collected data shown a good correlations between the concentrations of TSS and of chemical compounds analyzed, suggesting that the most part of such substances is attached to suspended solids. Resulting toxicity values are fairly high in both measuring points and seem to confirm synergistic interactions between heavy metals.

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.

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