Water quality modelling – Qualsoc application Essay Example
Water quality modelling – Qualsoc application Essay Example

Water quality modelling – Qualsoc application Essay Example

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  • Pages: 5 (1285 words)
  • Published: November 27, 2017
  • Type: Article
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Stormwaters refer to the precipitation that collects in storage systems, which can be either natural or man-made, during and immediately following a storm.

The original sewer systems were created to transport sewage and stormwater together to the treatment plant at the same time, resulting in combined sewer overflows (CSOs) (Porteous, 2000). In areas with combined sewers, during a storm, the sewer system can surpass its maximum capacity. As a result, the design of the sewer system allows surplus water to overflow directly into bodies of water without undergoing treatment. This prevents the overflow from occurring through household appliances such as toilets and sinks.

The paths of waste waters from an urban area, along with stormwater, are depicted in Figure 1. The figure also showcases the representation of combined sewer overflows (CSOs) and separate sewer systems.The urban area is shown in Figure 1, which


depicts both separate sewer systems and combined sewer systems. (EPA, Internet 1)

Managing the contamination of overflow water in urban areas caused by stormwater and combined sewage overflows is crucial for maintaining proper water quality. This type of overflow water contains pathogens, debris, and industrial wastes, which can pose a significant health risk and limit recreational activities (Jrgensen & al, 1995).

The purpose of water quality modelling is to enable environmental planners and managers to predict the impact of stormwater overflows on water quality.

The use of river water quality models in research, as well as the design and evaluation of water quality management measures, is extensive. These mathematical models are consistently enhanced to tackle emerging concerns regarding surface water pollution.

QUALSOC is a software that

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is created for the purpose of predicting the optimal level of the CSO weir.


The data from the QUALSOC software is available in Appendix 1, 2, and 3.

The histogram is a type of graph used to represent data.

Below, you can find a 3-D histogram of the DWJ multiples against the BOD concentrations and percentile river flows, created using the aforementioned data.

The BOD concentrations are highest for Q5 and lowest for Q50.

2. BOD downstream has 1 to 12 DWF multiples.

From the data sheets obtained through QUALSOC, the highlighted data in pages and

The BOD concentrations downstream from the sewer vary based on the DWF multiple (ranging from 1 to 12) and quartile (including Q5, Q10, Q25, Q50).

The actual overflow setting is multiplied by 3 in DWF.

Appendix 1, 2, and 3, pages 6, 7, and 8, exhibit the computed values with QUALSOC. The needed ssosetting is 1296 m/day. Consequently, after evaluating the DWF, the ratio ssosettinbg/DWF amounts to 1.56:

The text below, including the and their contents, is:


The ideal configuration for DWF.

The results of calculated mass balance at different percentile river flow are shown on pages 7 and 8 of the Appendix.

> Q5 flow

Applying a factor F of 2 reduces the BOD concentration to 5mg/l or less, resulting in a concentration of 4.7mg/l that falls within the range specified by factors F 3 and 2.

The "Q10 flow" is aligned to justify.

The BOD concentration is reduced to 4.9mg/l from an initial concentration of 5mg/l or less when

a factor F of 3 is used.

The text "

> Q25 flow

" remains unaltered.

To lower the BOD concentration to 5mg/l or below, a factor F of 10 (5mg/l) is needed.

The text is already unified andwhile keeping the and their contents:

> Q50 flow

An NRA target with a factor F higher than 12 would result in a BOD concentration of 5mg/l. However, the QUALSOC software can only calculate up to a maximum of 12 DWF, so the factor F for the NRA target has not been determined.

The maximum overflow is 100m.

The flow of the receiving stream or river is at its lowest (5%) during Q5. The discharge of the CSO has a significant impact on the chemistry and biological community of the receiving stream or river, especially during low flow. Therefore, it is crucial to ensure that the BOD concentration remains at a minimum of 5mg/l for this percentile. To achieve this goal, a DWF multiple ranging from 2 to 3 should be used.

The DWF multiple for achieving it is 3 at Q10, 10 at Q25, and greater than 12 at Q50.

The DWF multiple of the actual weir setting has been calculated as F=1.56, indicating that this setting is below the recommended minimum optimum setting for Q5. Nonetheless, this system allows for a BOD concentration of 5mg/l or less to be attained at Q5, which is deemed acceptable.

The histogram illustrates that Q5, Q10, Q25, and Q50 have BOD concentrations within the NRA recommendation for F values under specific limits. In particular, Q5 complies with the recommendation for F

below 3, while Q10 adheres to the recommendation for F below 4. Similarly, Q25 meets the recommendation for F below 11, and Q50 surpasses the limit of the QUALSOC software's recommendation.

At this site, the weir overflow setting is 1296 m/day. However, the anticipated maximum overflow is only 100 m. This implies that during a rainy period, the highest amount of water overflowing through the weir will be 100 m. Consequently, the 100 m of CSO water will mix with the receiving water without causing significant impact. The DWF measures at 829.92 m/day, making the expected maximum overflow more than 8 times smaller compared to the DWF. Since a weir setting at 1.56 DWF can provide satisfactory BOD concentration, it will also yield satisfactory results for a volume that is 8 times smaller.

6. The methods have limitations.

The QUALSOC software enables the operator to anticipate the effects of a CSO on the BOD concentration in a freshwater body. It determines the best setting for the CSO weir based on a specific BOD value.

Despite the limitations of this method, it is commonly used for general screening purposes to provide rough estimates without statistical testing or providing a degree of confidence. However, the QUALSOC model can be routinely utilized when the discharge of the CSO is not significant. In the given example, with a small discharge of 100m, the use of QUALSOC is justified.

This design model is limited to only the flow level and does not consider many biochemical processes. It is a 1-D model and allows any type of operator to use it, but it does not take

into account the dynamic of the receiving water. The answers provided by this 1-D model are limited to steady state conditions and only consider the acute effect of the CSO on the receiving water.

The QUALSOC model is designed to accommodate a population of up to 2000. Therefore, it cannot be utilized for towns exceeding this population limit. This restriction hinders its applicability and necessitates the need for a different model in larger towns, making it economically disadvantageous.

The model described can be used together with other models as well. In fact, it has been shown recently that combining models of different dimensions is advantageous (Pollert ; Stri??nsky, 2003).

The following text is unified:


The Urban Waste Water Treatment Regulations (Northern Ireland)- Guidance Note was published by the Department of the Environment in 1999 (source:

; Department of the Environment. 1999. The Urban Waste Water Treatment Regulations (Northern Ireland)- Guidance Note.

).The text in the given states that Jrgensen et al. (1995) conducted a study on the general assessment of potential combined sewer overflow (CSO) reduction using real-time control. The study was published in Water Science & Technology, volume 32, issue 1, pages 249-257. The paragraph is centrally aligned.The following text is a citation in HTML format:

; Pollert, J., Stri??nsky, D. 2003. Combination of Computational Techniques- Evaluation of CSO Efficiency for Suspended Solids Separation. Water Science ; Technology. Vol. 47 No 4 pp 157-166.

; Porteous, A. 2000. Dictionary of Environmental Science and Technology. (Third Edition). John Wiley ; Sons, Ltd.

(Source: Porteous, A. 2000. Dictionary of Environmental Science and Technology. Third Edition. John

Wiley & Sons, Ltd.)

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