Aquatic macrophytes in domestic wastewater treatment is receiving growing attention over last few years. Duckweed-based pond system my be a feasible option for organic matter and nutrient removal, particularly for country, like India where sunshine is available in plenty for photosynthesis.
Links:
[1] http://admin.indiaenvironmentportal.org.in/feature-article/experimental-investigation-nutrient-removal-efficiency-duckweed-covered-wastewater
[2] http://admin.indiaenvironmentportal.org.in/category/author/sunil-sharma
[3] http://admin.indiaenvironmentportal.org.in/category/author/m-kuraishi
[4] http://admin.indiaenvironmentportal.org.in/category/journal/indian-journal-environmental-protection
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/sewage-treatment-technology
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/jodhpur-t
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/sanitation
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/india