A new model of Algal Turf Scrubber for bioremediation and biomass production using seaweed aquaculture principles

Abstract

An increase in the use of macroalgal biomass for different applications is required in development of efficient cultivation systems and low-cost culture media. With this in mind, the present work proposes modifications to the Algal Turf Scrubber (ATS) system inducing the establishment of a monospecific culture of Ulva ohnoi through a seeding process, speeding up the maturation time and increasing efficiency and productivity. Bench-scale units of Seeded Algal Turf Scrubber (sATS) were built to test different types of algal attachment substrates (nylon and jute fiber) and water flow conditions (stagnant and continuous) besides evaluating of coverage rate, daily growth rate, and nutrient removal capacity. The results were promising. The coverage rate by U. ohnoi seedlings was higher when nylon substrate was combined with continuous water flow (74.41 ± 6.79%). Changes in nutrient concentration demonstrated a dose-dependent pattern with complete removal of P-PO43− in 24 h at all concentrations tested when the system had 18 days of maturation and N-NH4+ was completely removed in 24 h at all concentrations tested in both maturation times (18 and 47 days). Daily growth rates presented satisfactory values, reaching maximum of 4.8 ± 0.6% day−1. In conclusion, it was demonstrated that the bench-scale sATS system was successful to enable cultivation of U. ohnoi by seeding, resulting in good quality biomass production and efficient nutrient removal, thus justifying upscale experiments.