Life Cycle Assessment Applied to End-of-Life Scenarios of Sargassum spp. for Application in Civil Construction

Abstract

Environmental risks and vulnerabilities in coastal regions include the massive deposits of brown algae of the genus Sargassum in regions such as the Caribbean, Gulf of Mexico, and northern Brazil. Efforts have been made to turn this problem into an opportunity by seeking new uses for this biomass in the sectors of food, agriculture, health, biofuels, bioremediation, and civil construction. Thus, this study aimed to produce quantitative data for different end-of-life scenarios of the Sargassum algae, seeking for potential applications of this macroalgae in the civil construction sector. For this purpose, we conducted a life cycle assessment (LCA) study of the Sargassum algae, in its natural destination, and evaluated its potential impact. This evaluation was then compared to the possible impacts of alternatives to their end of life, such as landfill disposal, drying and grinding to use as fibers or particles, burning the biomass to generate energy and fly ash, using a consequential LCA and the indicators of the ReCiPe 2016 method. For each of the proposed scenarios, the functional unit of 1 kg of the three types of unprocessed Sargassum algae that are found in the Brazilian deposits (natans I, natans VIII, and fluitans) was considered separately, and also for a composition that is closer to that found in the Brazilian deposits (50% fluitans, 15% natans I, and 35% natans VIII). The results for both natural decomposition scenarios demonstrated a dominant contribution to the categories of impact for climate change, marine eutrophication, and land use, thus justifying the search for new initiatives for the use of the algae. The burning process showed a significant contribution to most of the indicators, with emphasis on the massive generation of particulate, inherent to the biomass burning process; however, it showed a reduction in the magnitude of climate change emissions from around 47% to less than 2%. Finally, the proposed scenario of processing Sargassum biomass to obtain particles presented prevalence of magnitude for potential impact in most of the proposed indicators, due to the processes with high electricity consumption, but keeping climate change emissions’ relative reduction from 47% to 6%. Thus, new studies may further investigate the potential of application of these materials in different products and components of civil construction.

The Use of Sargassum spp. Ashes Like a Raw Material for Mortar Production: Composite Performance and Environmental Outlook

“…The sargassum biomass (Figure 2) used to produce ash was collected in the municipality of Carutapera-MA (Brazil), specifically in the region of São Pedro beach. According to Bueno et al, (2023) [25], the composition of the brown algae found in this region is as follows: Sargassum fluitans III (50%), Sargassum natans I (15%), and Sargassum natans VIII (35%). The sargassum ash was obtained by means of a 10013 Jung resistive oven with 7000 W, a burning temperature of 500 • C for two hours, and a heating rate of 10 • C/min.…”

“…Secondary data were used for the LCI. Information on sargassum ash, as well as its decomposition on beaches and landfills, was collected from the study by Bueno et al, (2023) [25]. Data relating to other processes were obtained from Ecoinvent 3.7.1.…”

“…It has tools that allow users to see an overview of the potential environmental impacts associated with the production systems of composite materials with the incorporation of algae. Bueno et al, (2023) [25], conducted an LCA study of different disposal scenarios for sargassum, including comparing different end-of-life alternatives and their respective potential impacts on landfilling; drying and processing fibers and/or particles for further use; and burning biomass for energy generation and ash production. For this research, an LCA evaluation and indicators of the ReCiPe 2016 methodology were used.…”

The Potential Use of the Pelagic Seaweed <em>Sargassum spp.</em> as an Alternative Lignocellulosic Raw Material for Particleboards: Technical Viability and Life Cycle Assessment

“…The LCA was carried out with the GaBi 6 software, using secondary databases, with Eucalyptus production and the MDP panel production inputs and output taken from the "SICV Brasil" LCA database [sicv.acv.ibict.br]. The processing for sargassum was taken from Bueno et al [42] and the other Ecoinvent 3.7.1 processes. Table 2 presents the secondary data used for multilayer particleboards's LCA.…”

The Use of Sargasso Seaweed as Lignocellulosic Material for Particleboards: Technical Viability and Life Cycle Assessment

“…The LCA was carried out with GaBi 6 software, using secondary databases, with Eucalyptus production and the MDP panel production inputs and output taken from the "SICV Brasil" LCA database [https://sicv.acv.ibict.br/] (accessed on 6 February 2024). The processing for sargassum was taken from Bueno et al [45] and the other Ecoinvent 3.7.1 processes. Allocation was avoided for all production stages, except for the sugarcane bagasse, where the current Ecoinvent 3.7.1 process already presents its mass allocation impacts.…”