REMOVAL OF NANO- AND MICROPLASTICS FROM MARITIME ENVIRONMENT BY USE OF BIODEGRADABLE FLOCCULANTS

Currently, microplastics and their accumulation in open oceans threaten marine wildlife and by extension, also potentially humans. Removal methods for microplastics are thus urgently needed to be developed and adapted to this environment. One solution for removal of plastics from marine environment is proposed in the EU project IN NO Plastic1 and targets the so-called "hot spots": ports, river mouths and industrial areas on shore using sea water as cooling water. These "hot spots" are heavily contaminated by plastics and microplastics and represent the entry point of these into the sea. Within Europe, the location of these industrial hot spots coincides with large industrial cooling water systems (CWS) in power industry located on seashores such as the UNIPER power plant in Rotterdam, The Netherlands and The EDF nuclear power plant in EdF’s Gravelines France- industrial partners in our project. We have investigated at lab scale the feasibility of a coagulation /flocculation process using natural and biodegradable flocculants, iron salts and chitosan, for removal of micro- and nano plastic particles from sea water. A "model" mixture of polystyrene and polyethylene particles ranging from 200-3000 nm, with different surface properties has been utilised. Effects of different coagulants and flocculants, dosage, process conditions, real and synthetic sea water and particle characteristics on removal efficiency have been evaluated. Our results show that a combination of iron coagulants and chitosan, a biodegradable biopolymer of marine origin, was particularly efficient in removing the submicron-sized plastic particles from sea water. The removal efficiency for the optimal combination was above 90%. The kinetics of the process, monitored by photometric dispersion analyser revealed rapid floc formation induced by precipitation of ferric salts, followed by growth into large structures facilitated by the addition of chitosan. The formed flocs exhibited high sedimentation rate, achieving water clarification in less than 45 minutes. The flocculation efficacy was affected by the type of the flocculant and its dose as well as the particle size, material, and the nature of the surface conditioning. Overall, the optimal combination of iron chloride and chitosan exhibited robust performance in different samples of sea water, with different particles and within the whole environmentally relevant pH range. Acknowledgement: We would like to acknowledge funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 101000612, IN NO Plastic project. References: [1] https://www.innoplastic.eu/clean-up-technologies