Floating Treatment Wetlands provide a space efficient, economically viable
alternative to traditional Constructed Treatment Wetlands for wastewater
treatment and water purification. Current Floating Treatment Wetland systems
are planted with native wetland plants adapted to the conditions in wetlands.
These native wetland plants provide wastewater remediation and water quality
improvements, but the plants themselves require disposal off-site and provide
only limited useable products. The efficiency of Floating Treatment Wetland
systems is greatly reduced over winter, due to low temperatures and
microbiological activity. In this experiment we show the possibility of growing
‘Little Gem’ lettuce in Floating Treatment Wetland systems instead of native
wetland plants, with similar and sometimes better water treatment properties
than Phragmites australis planted systems. The most efficient batch
(26/04/2019) reduced phosphate loading by 82-89% after 7 days in lettuce
planted systems, while Phragmites systems reduced phosphate loading by 47
56% after 7 days which represents a significant difference (p<0.05). Phragmites
systems were slow to establish and provide water quality treatment properties.
We propose the testing of hybrid systems with intercropping, a system where
both plants are grown in one growing season, in order to maximise treatment
efficiency and produce useful agricultural products for consumption either by
humans or animals.