Hello P. Rakshit, Look at ...

Hello P. Rakshit,

Look at natural, fully functioning wetland and riparian ecosystems.  Periphyton and diatoms do much of the "cleaning" of water- including some heavy metals- by chemical and biological processes (adsorption, chelation, etc.).  

My old company, Watershed Consulting, LLC, out of Montana, is deploying Floating Treatment Wetlands as part of waste-water treatment systems.  These islands essentially create tremendous surface area on which those beneficial organisms attach.  These manufactured wetlands can be made to different sizes to match your site and locally adapted plant species can be planted through the matrix. Different than heavily engineered approaches which require perpetual maintenance, these systems grow over time and after some time can become self-maintaining.  Scale is important.  If you want to treat large urban areas, modern wastewater treatment facilities do that.  But for smaller areas, look to wetlands-- either manufactured like FTW or enhancing natural wetlands on the landscape where algae and periphyton thrive.

Good luck,

Pedro Marques- Restoration Programs Manager- Big Hole Watershed Committee, Montana, USA