Comparative Analysis of the Behaviour of Marine Litter in Thermochemical Waste Treatment Processes

Abstract

Plastic in the ocean, especially plastic on the ocean surface is not only researched intensively but also photos and reports rise awareness of the challenge in the general public. While research is concerned with the fate of marine litter in the environment, recycling of these materials after collection is rarely addressed, mainly because there is neither considerable data on composition nor a suggested process to do so. This study is the first to analyse and evaluate chemical recycling (pyrolysis, gasification) and energy recovery (incineration) of marine litter. Two heterogenous marine litter samples from Sylt and Norderney, North Sea, Germany, were analysed, consisting of six different material groups. Agricultural mulch foil was used as reference material. The thermochemical treatment processes were reproduced by thermogravimetric analysis. Furthermore, pyrolysis trials on a semi-technical scale were conducted and the residues were analysed by proximate, ultimate and X-ray fluorescence analysis. The results indicate that heterogeneous and weathered material mixtures can be treated by thermochemical processes. Finally, the pyrolysis condensates are discussed as substrate for biotechnological upcycling. In summary, we present a comprehensive approach from the material characterisation of marine litter to the analysis of three different thermochemical treatment processes and the possibility to use the generated pyrolysis condensate for subsequent upcycling. The data collected form the basis for the evaluation and application of possible treatment options for the collected marine litter.

An Overview of the Current Trends in Marine Plastic Litter Management for a Sustainable Development

“…The most used laboratory methods for marine plastic litter identification based on mass determination consist of: Fourier-transform infrared (FT-IR) spectroscopy [18,19,21,48], thermogravimetry [71], differential scanning calorimetry (DSC) [17], and density measurement [45]. These methods enable the identification of the most abundant marine plastic litter, such as PP-PE copolymer, PE, PP, PET, PVC and PS [11,17,19,21,45,65]. The thermoplastic polymers debris is characterized by melting points ranging from 120 • C to 140 • C, degradation temperatures within 300 • C and 500 • C, and a high heating value of 43.9 MJ kg −1 , similar to other natural gases [71].…”

“…Fishing nets are predominantly made from poly(amide) (PA) [52] and poly(ethylene) (PE) [68]. Also, small plastic debris identified in areas where artisanal fishing takes place, is composed of poly(propylene) (PP), low-density poly(ethylene) (LDPE), and poly(ethylene terephthalate) (PET) [11,18]. These items can persist in the marine environment for a long time, posing threats to marine life and the ecosystem.…”

“…Hee et al [11] reported an innovative approach to utilize the condensable fractions, generated by the pyrolysis process, of two heterogenous marine plastic litter batches collected from the North Sea and agricultural mulch foil, as reference, for biotechnological upcycling. Thermogravimetric analysis (TGA) conducted to simulate pyrolysis mass losses of investigated marine plastic litter revealed values of 79 wt% for marine plastic litter Sylt, 88 wt% for Norderney, and 91 wt% for mulch foil.…”

Integrated User-Oriented Service for 3D Printing Environments with Recycled Material from Maritime Plastic Waste

“…The valorization of marine plastics is also a relevant research issue, with different approaches proposed; these include incineration and energy recovery [27,28], landfilling [29] and reuse/recycling [30,31]. This is consistent with plastic generation in Europe in 2019: 57.9 million tons of plastic were generated, of which 29.1 million tons were collected for treatment.…”

Special Issue on “Advanced Technology of Waste Treatment”

“…In a complementary study, Rieger et al [12] focused on plastics from waste electrical and electronic equipment (WEEE) and the comprehensive chemical characterization of the pyrolysis products. Finally, Hee et al [13] used marine litter waste as feedstock for chemical recycling (pyrolysis, gasification) and energy recovery (incineration) with special emphasis on the potential of the pyrolysis condensate for subsequent upcycling.…”