DEPARTMENT OF CIVIL ENGINEERING, UAP: STUDY VISITS TO DASHERKANDI SEWAGE TREATMENT PLANT

The Department of Civil Engineering at the University of Asia Pacific (UAP) organized a site visit to the Dasherkandi Sewage Treatment Plant for Level 4 students on November 9, 2024. A group of 28 students, accompanied by 12 faculty members, departed from the university at 8:30 a.m. and arrived at the plant by 9:15 a.m. Upon arrival, the group was warmly welcomed by the plant's engineering team, which included Md. Momtajur Rahman (Executive Engineer), Md. Habibur Rahman Roni (Assistant Engineer), Md. Imam Hossain (Sub-Assistant Engineer), Md. Kamal Uddin (Sub-Assistant Engineer), Manmatha Roy (Sub-Assistant Engineer), Md. Mahamudul Hassan Riead (QHSE Engineer), Md. Sahinur Rahman (Chemist), and Md. Nasir Uddin Tushar (Maintenance Engineer).

Before beginning the field tour, QHSE Engineer Mahamudul Hassan Riead provided an informative presentation, giving an overview of the plant’s design, functions, and environmental significance. This introduction helped students gain essential background knowledge, enhancing their understanding of the processes they would observe during the field trip.
With a sewage treatment capacity of 500,000 tons per day, the plant is the largest individual sewage treatment plant in South Asia. The plant can treat sewage for nearly five million people in Dhaka City. The plant is in Khilgaon, near Aftabnagar. The plant was designed and built by Chengdu Engineering Corporation, a subsidiary of Hydro China Corporation (Power China). The plant has a sludge drying-burning system and is the first modern STP and sludge drying-incinerator in Bangladesh. The plant treats sewage from Hatirjheel, Badda, Banani, Gulshan and Aftabnagar area.

The field trip was organized into two groups, with one led by Mahamudul Hassan Riead, QHSE Engineer, and the other by Md. Habibur Rahman Roni, Assistant Engineer. This structure allowed students to engage closely with different components of the treatment facilities, examining each stage of the process in detail. The guided tours provided a comprehensive view of the plant's operations, enabling students to observe firsthand how each treatment unit functions and contributes to the overall sewage treatment process.
The Dasherkandi Sewage Treatment Plant operates through several treatment phases, beginning with the sewage lifting station, which pumps wastewater from lower levels to initiate treatment. This lifted sewage then goes through Coarse and Fine Screens to remove large debris, such as plastic and organic waste, followed by the Vortex Grit Chamber, which separates out heavier grit and sand particles. This screening and grit removal protects downstream equipment and reduces wear. Next, the wastewater flows into the Primary Sedimentation Tank, where heavier organic solids settle out, and forming primary sludge.

In the AAO (Anaerobic-Anoxic-Oxic) process, wastewater flows through multiple biological treatment stages. The process reduces organic pollutants and nutrients like nitrogen and phosphorus. The Oxic Zone, in particular, is aerated by blowers that introduce air, supplying oxygen to support aerobic bacteria. These bacteria break down organic pollutants and nutrients, reducing biochemical oxygen demand (BOD) and nutrient levels, such as nitrogen. The blowers maintain optimal oxygen levels in this stage, essential for effective biodegradation and pollutant removal.
The treatment also includes comprehensive sludge management. The primary sludge is initially reduced from about 95% moisture to 78% using dewatering techniques. This semi-dry sludge is then incinerated, converting it into fly ash, which can be repurposed. During incineration, flue gas generated is treated through purification systems to remove harmful emissions, ensuring safe release into the atmosphere. The plant ultimately discharges treated water into the Gojari Canal, significantly reducing pollution and protecting local water quality.

Students were also given the opportunity to visit the plant’s laboratories and control room, where they observed the full operational and monitoring systems in action. This hands-on experience highlighted how different units within the facility are managed and controlled for optimal performance. Following the site visit, a seminar titled “Career Growth in Environmental Sustainability: Fundamentals of Wastewater Management and Industrial Reuse” was conducted by Engr. Md. Masud Rana Shahin. This session provided valuable insights into selecting appropriate wastewater treatment technologies and introduced key reuse methods such as MBR (Membrane Bioreactor), RO (Reverse Osmosis), and ZLD (Zero Liquid Discharge). Additionally, it explored the applications and job opportunities within Bangladesh's environmental sector.
The site visit enriched students' understanding of how theoretical concepts are practically implemented and allowed them to explore the complexities of wastewater treatment in depth. The seminar also encouraged students to consider various career pathways in environmental engineering, inspiring them to contribute to sustainable development and resource management.