Proposed Greywater Treatment Plant at Vavuniya Campus, University of Jaffna
Introduction
Water scarcity and environmental sustainability are pressing issues globally, and educational institutions are not exempt from these challenges. In response to these concerns, the Faculty of Applied Sciences at Vavuniya Campus, University of Jaffna, has embarked on an innovative project to design and implement a greywater treatment plant for its hall of residence. This initiative aims to treat and reuse wastewater, thereby reducing water consumption and minimizing environmental impact.
Understanding Greywater
Greywater refers to wastewater generated from domestic activities such as bathing, laundry, and washing dishes. Unlike blackwater, which contains sewage, greywater is relatively cleaner and can be treated and reused for purposes like irrigation. The proposed treatment plant at Vavuniya Campus focuses solely on greywater, ensuring that no kitchen or toilet water contaminates the system.
Project Overview
The greywater treatment system is designed to serve a hostel accommodating approximately 400 male students. With each student using around 100 liters of water per day for sanitation, the facility generates an estimated 40 cubic meters of greywater daily. To handle this volume, the treatment plant is designed with a capacity of 45 cubic meters per day, incorporating a safety factor to account for variations in water usage.
The Treatment Process: Constructed Wetlands
The proposed treatment system utilizes constructed wetlands, which are engineered systems that mimic natural wetlands’ water filtration processes. These wetlands use vegetation, soil, and microbial activity to treat greywater. The system at Vavuniya Campus includes:
- Primary Treatment: Existing collection pits serve as pre-treatment tanks, capturing and partially treating the greywater.
- Constructed Wetlands: Two subsurface flow systems, each handling 22.5 cubic meters per day, further treat the greywater. The wetlands are designed with a bed of washed river gravel, providing a medium for plant roots and microorganisms to thrive and treat the water.
- Reuse: Treated water is reused for irrigating campus vegetation, promoting water conservation and reducing the demand on freshwater resources.
Construction and Design Details
Key aspects of the constructed wetlands include:
- Safe Location: Ensuring the wetland is protected from flooding and integrated into the landscape.
- Rainwater Diversion: Preventing rainwater from entering and overwhelming the system.
- Filter Media: Using fine to medium gravel for filtration, with coarser gravel at inlet and outlet zones.
- Inlet Structures: Distributing incoming water evenly to avoid clogging.
- Freeboard: Providing a 20 cm distance from the bed surface to the top edge to manage water flow.
- Plant Species: Utilizing local species such as cattail, sedge, rush, and reeds to enhance treatment efficiency.
Conclusion
The proposed greywater treatment plant at Vavuniya Campus, University of Jaffna, is a testament to the institution’s commitment to sustainability and environmental stewardship. By treating and reusing greywater, the campus not only addresses water scarcity but also sets a precedent for other educational institutions to follow. This project exemplifies how innovative engineering solutions can contribute to a more sustainable future.
