REMOVAL OF MICROCYSTIN USING ARTIFICIAL FLOATING ISLANDS IN RESIDENTIAL WASTEWATER

Microcystin, a toxin produced by cyanobacteria, is a concern in both fresh and brackish water. The growth of cyanobacteria, though a natural occurrence, has become more intense and widespread due to increased agricultural activities. Elevated microcystin levels in aquatic environments due to cyanobacterial blooms pose ecological and health risks, impacting water quality and causing harm to wildlife and humans through physical contact, ingestion, and inhalation of algal aerosols. Research showed that not only can microcystins cause acute poisoning, but also have the potential to promote cancers, particularly liver cancer, with chronic exposure. Artificial Floating Islands (AFIs) are an increasingly popular phytoremediation technology used in many water bodies including rivers, lakes, and reservoirs. These systems consist of floating hydroponic structures on the water surface, where emergent plants are inserted in a buoyant mat supported by a floating component, with the crowns and shoots growing above water while the root systems grow deep into the water column. AFIs have been reported to be efficient, environmentally friendly, and cost-effective methods in treating a wide range of pollutants, including nutrients (organic and inorganic), toxic metals, color dyes, personal care products and other toxins. However, the capability of AFIs in removing microcystin has not been thoroughly explored in previous research. In this study, we deployed an AFI system at the equalization basin of the Plymouth Wastewater Treatment Plant, Plymouth, OH. The AFI system was installed in three linear structures, offering a multi-layer setup intercepting the majority of water flow between the basin’s supply and return line. Two aquatic macrophyte species native to Ohio, Carex comosa and Eleocharis obtusa, were used to construct the AFIs. Raw water samples were collected weekly from mid-August to mid-November, and microcystin concentrations were measured using the enzyme-linked immunosorbent assay (ELISA). Specific objectives of this study include temporal analysis of microcystin variations in the residential wastewater and investigation of the potential for AFIs to remove microcystin. Preliminary results showed that AFIs could potentially remove microcystin from wastewater. The removal of microcystin is affected by temperature, pH, and conductivity of the water.