Screening of cyanobacteria producing exopolymers as bioflocculant for microplastics water removal

, Faria Marisa, Henriques Sérgio, Cordeiro Nereida.

Discovered in the early of the 20th century, plastic has become a material used in all industry sectors as it is a low-cost, durable, inert, and corrosion-resistant product. Around 1 million plastic bottles are purchased every minute around the world [1]. In 2021, its expected that number reach half a trillion, with less than half of those bottles ending up getting recycled [1]. Unfortunately, most of this non-recycled plastic is disintegrated into smaller sized low molecular-weight polymer fragments – microplastics - through various mechanical actions and degradation in the environment. Microplastics have become into a serious problem due to their potential negative effects - from its size to the chemicals released - on the marine ecosystem and biota. In the recent years, the scientific community turned its focus to the development of sustainable methodologies to remove them from the contaminated water [2]. The flocculation technique is the most conventional approach to remove the suspended solids in wastewater treatment with high efficiency. However, inorganic, and organic flocculants are employed in this process and most of them stay in the wastewater after treatment and may cause ecological damage [3]. Cyanobacterial-based extracellular substances have been shown encouraging properties suitable to be applied in industry as gums, bioflocculants, biosorbents and bioemulsifiers [4]. Following our interest on microbial-based biomaterials and the development of an efficient way to remove the microplastics of contaminated water, the main purpose of this research is to assess the bioflocculant activity of different cyanobacteria-based extracellular substances to remove plastic debris of contaminated water and compare with the bioflocculant activity of commercial extracellular substances. These assessments allowed the evaluation of the potential of cyanobacterial-based exopolymers as bioflocculants and their applicability in bioremediation.

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