The College of Science and Technology is a residential college with the students residing in the 923 bedded hostels with an additional 132 bedded hostel due for completion in 2023. Further the college offers 91 units (364 residents) of on campus accommodation for its staff and family. The wastewater from the water closets is managed using the conventional septic tank system but the greywater from the kitchens and bathrooms of the students? hostels as well as the staff residences are directly discharged into the environment. Most part of the grey water and storm water from the area eventually discharges into a natural depression(pond) found in the low-lying area of the college campus.
The lack of proper management of the grey water as well as discharge of untreated greywater into the pond has resulted in the formation of foul order and development of unsightly locations which has become a breeding ground for mosquitoes and such other vectors. In addition, the runoff generated from the watershed during the monsoon is also collected in the same pond. The outflow from the pond presents high risk of landslide occurrences and threat to stability of the building located below the pond.

To address these issues, the proposed project will explore the eco-technological natural wastewater treatment system for treatment of the grey water. The system will make use of aquatic plants that are locally available such as Lactusa virosa(wild lettuce), Echinochloa colona(jungle rice), Osmunda cinnamomea (cinnamon fern), murdannia keisak(marsh dewflower), and P. australis(common reed). When the wastewater passes through the plants? rhizosphere, microbiological degradation occurs, which effectively removes the water pollutants. The project will seek the advice of officials at the National Biodiversity Centre to ensure that the use of any invasive species of plants is avoided.
The treatment efficiency of the proposed system will be evaluated by conducting water quality test of the influent and effluent samples. The major works includes the design and construction of sewer network, the treatment system including the equalization basin and constructed wetland and the development of the source of disposal. The treated effluent from such natural treatment system maybe safely discharged into a receiving water body(streams, rivers, lakes, etc), or disposed on the land for irrigation, as overland flow or allowed to seep into the ground. The proposed project will use the existing depression available near the treatment site for disposal of the effluent.
Since the college campus and Phuentsholing in general severely lacks beautiful spaces for leisure and enjoyment, the pond will be developed in to an engineered system to serve as a robust ecosystem of aquatic flora and fauna. The site around the pond will also be developed into a small theme park enhancing the beauty of the area, which will in turn impact the quality of life of the residents. In the development of the park, inspiration will be drawn from the gardens of the Royal Bhutan Flower Exhibition and Ludrong park etc. A terraced garden, footpaths, small pedestrian bridge, benches and such other amenities will be designed. On the completion of the project, a natural treatment system for wastewater treatment using the most suitable aquatic plants which are locally available will be developed and installed. A network of drainage to transport the wastewater from the source to the treatment plant will be designed and constructed. Additionally storm water drains will also be constructed for safe disposal of runoff from the area. The area around the pond will be area of nature based leisure facilities on campus and sanctuary for aquatic flora and fauna. In the non-rainy season, the water from the pond can be used for irrigation of the vegetable gardens of the residents
The project site will also be useful for teaching learning on the campus, creating environmental awareness and as pilot system that can be adopted by other communities..