Bioremediation of a Sewage-Contaminated Tropical Swamp Through Bioaugmentation with a Microalgae-Predominant Microbial Consortium

Bioaugmentation has many applications as a bioremediation technique. It is usually performed by bacteria but microalgal consortia also have great potential for bioremediation. This study evaluated the ability of a microbial consortium with predominance of microalgae (MCPM) to decontaminate the water of the Mallorquín tropical swamp. The Mallorquín Swamp is a natural water reservoir, essential for the ecological and hydric balance of the region, as well as for the fishermen, but has received sewage for more than 20 years. Microalgae for bioremediation purposes were isolated from the swamp, selected, cultured in bioreactors, and poured back into the Mallorquín waters. After bioaugmentation, there was a significant reduction in the BOD5 (98%), nitrates (58%), enterococci (92%), and total coliforms (100%). Notably, despite the MCPM bioaugmentation, the original richness and abundance of phytoplankton in the Mallorquín swamp was not disrupted. These results confirm the benefits of phycoremediation as an effective tool for on-site bioremediation of natural water bodies and show an effective phycoremediation at a large scale without altering the autochthonous microalgae community. This constitutes the first report of a successful MCPM intervention performed at this scale in a natural swamp in Colombia.