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The Dasherkandi Sewage Treatment Plant, South Asia's largest, is a major project funded by China and operated by Dhaka WASA. Located near Aftabnagar in Dhaka, the facility processes 500 million liters of polluted water daily, aiming to enhance the water quality of Hatirjhil and Balu River. This plant connects to a vast drainage network encompassing various Dhaka neighborhoods including Tejgaon, Gulshan, Banani, and parts of Dhanmondi and Gulistan, ultimately treating 20% of Dhaka's sewage. Advanced automated systems at the plant convert sewage into fly-ash.
It is the largest modern SWTP plant which include sewage treatment, sludge treatment, and final disposal system all at the same place working harmoniously
State-of-art Technology used at DSWTP
State-of-art Technology used at DSWTP
The plant is divided into three areas based on their functions: the sewage treatment area, the sludge treatment area, and the plant management area. The sewage treatment area includes the inlet pump station, coarse screen, fine screen, vortex grit chamber, primary sedimentation tank, AAO tank, secondary sedimentation tank, ultraviolet disinfection tank, and effluent sampling chamber, among others. The sewage lifting station is located on the south side of the Rampura Bridge, where sewage from the mentioned areas is lifted and waste larger than 25mm is separated from the water.
Essentially, waste is separated from water in three stages. Initially, waste larger than 25mm is removed at the lifting station. Then, at the project area, waste between 5mm and 25mm is separated. Finally, through a rotational process, waste smaller than 0.125mm, including fine particles like sand, is removed from the sewage water. From there, the sewage passes through a coarse screen after removing plastic waste and solid materials. Then, the sewage is lifted and sent to a fine screen for further removal, followed by the vortex grit chamber. The primary sedimentation tank collects suspended solids at the bottom and stores them in the primary settling sludge.
The entire process, a first in Bangladesh, involves a biological method where additional oxygen helps clean the water by multiplying bacteria and breaking down organic matter containing carbon and ammonia. Finally, the water passes through UV rays, which help purify the water and remove harmful germs. Additionally, there is a tunnel for home and mobile toilet sewage that does not connect with the drainage system.
At the primary level, the plant removes 60% of the sewage from the water, and at the secondary level, it cleans the remaining 40%. The thoroughly cleaned water then passes through UV rays, which kill all germs, rendering the water as clean as drinking water. In the future, there are plans to build a water treatment plant to utilize this water in the business sector.
When the water arrives at the project area from the lifting station, it is stored in three sections: clean, process, and storage. The water cleaning process is automated and progresses step-by-step, monitored by CCTV cameras around the clock to ensure continuous observation.
All about the Dasherkandi Sewage Treatment Plant
All about the Dasherkandi Sewage Treatment Plant
Transforming Dhaka: The Dasherkandi Sewage Treatment Plant's Impact on Public Health, Economy, and Environment
Transforming Dhaka: The Dasherkandi Sewage Treatment Plant's Impact on Public Health, Economy, and Environment
This project has significantly reduced water pollution in downtown Dhaka, enhancing the quality of life for local residents. During its construction, this project generated thousands of jobs and boosted the local economy by procuring equipment and materials worth approximately 300 million yuan. Villagers from Dasherkandi have expressed their delight and gratitude since the DSTP became operational. According to one local, the plant has led to a decrease in various diseases, such as mosquito bites, malaria, and diarrhea. Many residents who were unemployed before the plant's construction found jobs during its development. "For us, it’s a good thing, and I hope to benefit more in the future," a villager shared. (Businesswire, 15 July, 2023)
Besides, the project also aims to reduce the water pollution of the Shitalakshya River at the intake point of Phase-1 and Phase-2 of Sayedabad water treatment plant. At the Sayedabad point there is already a water treatment plan. After starting of this project, it helps to woks better for the water treatment plant which helps to provide clean water at a locality.
During our visit to the area behind the project where water is directly supplied, we spoke with local residents. They reported better water quality, noting that they can now swim in it and use it for household purposes without experiencing unpleasant odors now. However, some residents reported allergies and issues with fish farming, attributing these problems to the treated water. We also learned that some cattle died after eating grass near the water body, though it's unclear if the water or another factor caused their deaths. Additionally, residents mentioned a bad smell from smoke produced by burning sewage. Previously, the land was used for agriculture, which is no longer possible, but the project has created new job opportunities for local youth, who are pleased with these changes.
Previously, the water here was black and dirty and now people can swim in clean water.
During our visit to the area behind the project where the treated water is directly supplied, local residents reported improved water quality. They now enjoy activities like swimming and using the water for household purposes without encountering the bad odors they previously faced. However, some locals have raised concerns, including allergies and problems with fish farming, which they attribute to the water from the treatment plant. Additionally, there have been reports of cattle dying after consuming grass grown near the water body, though it has not been confirmed that these issues are linked to the water quality or any harmful substances in it. Residents also mentioned a persistent bad smell from smoke produced by burning sewage. While the land was previously used for agriculture, which is no longer viable, the project has created new job opportunities for young people in the community, who are pleased with this development.
Before the plant was built, the area faced water supply issues as WASA could not provide water consistently. Now, with a new connection line to clean water, residents no longer experience any water supply problems.
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