Abstract: A floway system for a building roof includes a substrate for supporting a periphyton culture that removes nutrient pollution from surface water and isolates the building envelope from solar-induced heat. The substrate is seedable to form a floway. a harvester for harvesting periphyton from the substrate. Water desired to be bioremediated is channeled to an inlet of the periphyton culture. A gutter system includes a sector for collecting cleansed water from an outlet of the periphyton culture having a drain for permitting water to be emptied therefrom and a sector for collecting periphyton harvested from the substrate therein. An element is provided for directing material exiting the periphyton culture outlet selectively between the water-collecting sector and the periphyton-collecting sector.

Abstract: A floway system for a building roof includes a substrate for supporting a periphyton culture that removes nutrient pollution from surface water and isolates the building envelope from solar-induced heat. The substrate is seedable to form a floway. A basin is provided for holding water to be treated, and a pump for pumping water therefrom to the floway inlet. At the floway outlet is positioned an effluent-collection gutter, which channels effluent to a collection vessel. Algal biomass can be harvested. A flexible divider is positioned in the gutter along the long axis, a top edge of securable adjacent the floway outlet so that, during harvesting, algal biomass is scraped into a distal section of the gutter, and thence to a biomass collection basin. The harvester can include a scraper and mechanism for traveling down the floway. The harvester can also move between adjacent floways and to the building roof.