Advancing sludge treatment: Anaerobic digestion and biogas utilization at Guheshwori WWTP

The Bagmati River in the Kathmandu Valley was heavily polluted due to the release of untreated sewage. In 2013, the authorities published an action plan to make the holy river sewage-free by 2020. As an important step, it was decided to increase wastewater treatment capacities, and WABAG was awarded the contract for the rehabilitation and expansion of the existing wastewater treatment plant at Guheshwori in Kathmandu, Nepal. The project also included a new sustainable sludge management system comprising anaerobic digestion and the use of the produced biogas for power generation, making the WWTP essentially energy neutral. The existing plant remained operational during the project execution.

• Scope: WABAG undertook the design and engineering, construction, equipment supply, installation, testing, and commissioning of the Guheshwori WWTP. This comprehensive reconstruction and expansion project involved rehabilitating existing structures, such as the oxidation ditch and secondary clarifier, while also adding new aeration tanks and clarifiers to double the plant’s capacity from 16.2 MLD to 32.4 MLD.
• Treatment Process: The plant employs an activated sludge process, wastewater filtration, and disinfection by electro chlorination. It features an advanced anaerobic sludge digestion system, including two digesters for biogas utilization, contributing to energy-neutral operations. Additionally, an odour removal unit has been installed to ensure air quality.
• Impact: The newly expanded WWTP is designed to meet stringent international water quality standards. After treatment, the discharged water can be safely released into the Bagmati River for various non-potable uses, significantly benefiting the environment. This facility will serve over 300,000 people, helping to revive the Bagmati River and create a healthier ecosystem.