Constructed wetland technology transfer to Nepal.

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Sanitation in Developing Countries

Background:

• Constructed Wetland (CW) technology has significant potential for wastewater treatment but is underutilized in developing nations.
• Effective wastewater management is crucial for public health and environmental protection in developing countries.

Purpose of the Study:

• To describe and evaluate the transfer of CW technology for wastewater treatment in Nepal.
• To assess the treatment efficiency of CW systems for hospital wastewater, household greywater, and septage.
• To demonstrate CWs as educational tools for raising awareness about environmental issues and solutions.

Main Methods:

• Implementation of three subsurface flow Constructed Wetlands with vertical flow stages for hospital wastewater, household greywater, and septage.
• Performance monitoring and efficiency assessment of two operational CW systems.
• Data collection on pollutant removal rates, including Total Suspended Solids (TSS), Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), Ammonia Nitrogen (NH4-N), Phosphate Phosphorus (PO4-P), and Total Coliforms.

Main Results:

• High median load elimination rates were achieved: TSS (97-99%), BOD5 (97-99%), COD (94-97%), NH4-N (80-99%), and Total Coliforms (99.87-99.999%).
• Variable PO4-P removal rates were observed (5-69%).
• CW systems served effectively as demonstration sites, increasing awareness among the public and decision-makers.

Conclusions:

• Constructed Wetland technology demonstrates high efficiency for various wastewater streams in a developing country context.
• CWs can serve dual roles as effective treatment systems and valuable demonstration sites to promote sustainable sanitation solutions.
• Recommendations are provided to facilitate the wider adoption of CW technology in developing countries.