Environmental Engineering for hydrology in civil

Environmental Engineering

1. ELITTE COLLEGE OF ENGINEERING NAME : SUJIT MONDAL PAPER : ENVIRONMENTAL ENGINEERING - II PAPER CODE : CE(PC)505 TOPIC : COMBINED SEWERAGE SYSTEM YEAR : 3 rd SEMESTER : 5 th DEPARTMENT : B.TECH IN CIVIL ENGINEERING ROLL NO : 34601322016 REGISTRATION : 223460120069

2. ELITTE COLLEGE OF ENGINEERING combined sewerage system A combined sewer system  collects rainwater runoff, domestic sewage, and industrial wastewater into one pipe . Normally, it can transport all of the wastewater to a treatment plant. Sometimes the amount of runoff exceeds the capacity of the system .

3. ELITTE COLLEGE OF ENGINEERING This system carries a mixture of indoor sewage and storm sewage is called integrated sewage pipes. Compacted pipelines often contain large pipelines or tunnels, due to the large volumes of storm water that have to be carried out during wet weather. They are very common in older cities but are no longer being built and are not being built as part of new sewage treatment plants. Because wastewater treatment plants cannot handle large amounts of storm water, sewage must pass through treatment plants during wet weather and be sent directly to receiving water. This concentrated sewage, which contains untreated indoor sewage, causes recurring water pollution problems and is a very problematic source of pollution. In some large cities, the problem of compacted sewage has been reduced by diverting sewage into a large septic tank or underground tunnel. After temporary storage, it can be treated by disinfection and disinfection before being fed to the receiving body of water, or it can be treated at a nearby wastewater treatment plant at a rate that will not load the area. Another integrated waste management method involves the use of swirl concentrators. This sewage is controlled by cylinder-shaped devices that form the effect of a vortex, or whirlpool. The vortex helps to stabilize impurities in a very small amount of water for treatment.

4. ELITTE COLLEGE OF ENGINEERING . Situation for Adoption Rainfall is even throughout the year . Both the sanitary sewage and the storm water have to be pumped . The area to be severed is heavily built-up and space for laying pipes is not enough . E active or quicker owes have to be provided . If the sewers are laid along with the overall development of the area, a combined system is preferred.

5. ELITTE COLLEGE OF ENGINEERING . Advantages of Combined Sewer Systems: Cost-Effective: Combined sewer systems are often more cost-effective to implement initially since they require only one set of pipes to carry both wastewater and storm water. This can result in lower construction and maintenance costs compared to separate sewer systems . Efficient Use of Infrastructure: By combining wastewater and storm water into a single system, combined sewer systems make efficient use of existing infrastructure. This can be especially beneficial in older cities where retrofitting separate sewer systems may be challenging or costly . Increased Water Supply : During periods of heavy rainfall, combined sewer systems can capture storm water runoff and redirect it to treatment facilities. This additional water can be treated and used for non-potable purposes such as irrigation or industrial processes, effectively increasing the available water supply.

6. ELITTE COLLEGE OF ENGINEERING 2. Limited Treatment Efficiency : Since combined sewer systems transport both wastewater and storm water together, treatment facilities may struggle to effectively treat the combined flow during heavy rainfall. The increased volume and dilution of pollutants can reduce treatment efficiency, resulting in less effective removal of contaminants before discharge. 3. Environmental Impact: CSOs can have a detrimental impact on water quality and ecosystems. The release of untreated sewage and storm water can introduce excess nutrients, pathogens, and pollutants into rivers, lakes, and oceans, leading to water pollution and ecological damage. This can harm aquatic life, compromise biodiversity, and affect the overall health of ecosystems. 4. Maintenance Challenges : Combined sewer systems require regular maintenance to prevent blockages and ensure proper functioning. The presence of debris, sediment, and other materials carried by storm water can increase the risk of pipe clogging and reduce system efficiency. Regular inspections, cleaning, and maintenance efforts are necessary to address these challenges . Disadvantages of Combined Sewer Systems : Risk of Overflow: One significant disadvantage of combined sewer systems is the risk of overflow during heavy rain events. When the volume of water exceeds the system’s capacity, a combined sewer overflow (CSO) may occur, leading to the discharge of untreated sewage and storm water into nearby water bodies. This poses environmental and health risks, as it can contaminate water sources and harm aquatic ecosystems .

7. ELITTE COLLEGE OF ENGINEERING Large networks of underground pipes, mostly in urban areas. Collection of Blackwater, brown water, greywater and storm water. The system contains three types of sewer lines: Main line (primary): the centre of the system, all other lines empty into it . Branch lines (secondary): extend from the main . House laterals (tertiary): bring wastewater from the houses to the branch lines.

8. ELITTE COLLEGE OF ENGINEERING Design Wastewater is transported to a centralised treatment facility by gravity. Depending on topography, sewer pumping stations are necessary. Primary sewers are laid beneath roads, at minimal depths of 1.5 to 3 m to avoid damages caused by traffic loads It must be designed to maintain “self-cleansing” velocity that no particles accumulate Access manholes are set at regular intervals along the sewer, at pipe intersections, at changes in pipeline direction and at drops When the required slope cannot be maintained, a pumping station must be installed

9. ELITTE COLLEGE OF ENGINEERING Costs The initial cost is high (50 to 80% more than simplified sewer systems) Maintenance costs are high compared to decentralised systems and consists mainly inspection, unblocking and repair Extension of the system can be difficult and costly Applicability Suitable for urban areas with resources to implement, operate and maintain the system Appropriate when a centralized treatment facility is available Infiltration may hamper the performance combined sewers

10. ELITTE COLLEGE OF ENGINEERING Health Aspect Provide a high level of higiene and confort for the user The ultimate health and environmental impacts are determined by the treatment provided by the downstream wastewater treatment facility.