Using waste biomass to produce 3D-printed artificial biodegradable structures for coastal ecosystem restoration.

The loss of ecosystem functions and services caused by rapidly declining coastal marine ecosystems, including corals and bivalve reefs and wetlands, around the world has sparked significant interest in interdisciplinary methods to restore these ecologically and socially important ecosystems. In recent years, 3D-printed artificial biodegradable structures that mimic natural life stages or habitat have emerged as a promising method for coastal marine restoration. The effectiveness of this method relies on the availability of low-cost biodegradable printing polymers and the development of 3D-printed biomimetic structures that efficiently support the growth of plant and sessile animal species without harming the surrounding ecosystem. In this context, we present the potential and pathway for utilizing low-cost biodegradable biopolymers from waste biomass as printing materials to fabricate 3D-printed biodegradable artificial structures for restoring coastal marine ecosystems. Various waste biomass sources can be used to produce inexpensive biopolymers, particularly those with the higher mechanical rigidity required for 3D-printed artificial structures intended to restore marine ecosystems. Advancements in 3D printing methods, as well as biopolymer modifications and blending to address challenges like biopolymer solubility, rheology, chemical composition, crystallinity, plasticity, and heat stability, have enabled the fabrication of robust structures. The ability of 3D-printed structures to support species colonization and protection was found to be greatly influenced by their biopolymer type, surface topography, structure design, and complexity. Considering limited studies on biodegradability and the effect of biodegradation products on marine ecosystems, we highlight the need for investigating the biodegradability of biopolymers in marine conditions as well as the ecotoxicity of the degraded products. Finally, we present the challenges, considerations, and future perspectives for designing tunable biomimetic 3D-printed artificial biodegradable structures from waste biomass biopolymers for large-scale coastal marine restoration.

Life cycle assessment of end-of-life engineered wood.

Medium-density fibreboards (MDFs) and particleboards are engineered woods well-known for durability and structural strength. Wood shavings or discarded wooden products can be used for MDF and particleboard production. However, engineered woods are hard to manage at the end of their useful life due to the utilisation of binders or resins, which are known forms of carcinogens. Like other wood products, MDFs and particleboards can either be recovered for material recycling or energy recovery or sent to the landfill. This paper aims to identify the sustainable circular economy pathways for waste MDF and particleboard management, comparing three different scenarios: landfill, recycling, and energy recovery (incineration) via life cycle assessment methodologies (LCA). Life cycle assessment has been conducted using ReCiPe methodology of conducting life cycle assessment. The data analysis was conducted in MS Excel using @Risk v8.2 add-on function. The analysis was based on relative contribution of the impacts across the individual life cycle stages and the specific toxicity impacts were represented on a tornado chart to reflect the percentage spread of impacts across the life cycle phase. Finally, uncertainty analysis was conducted using Monte Carlo Simulation. The results showed that material recovery is preferred over energy recovery for most of the impact categories. However, energy recovery is preferred in the case of climate change and fossil fuel depletion. For both types of engineered wood products considered in this paper, end-of-life management of engineered woods has less impact than the production process. Toxicity impacts are the greatest for energy recovery compared with landfill and material recovery.

A global life cycle assessment of manganese mining processes based on EcoInvent database.

This paper presents the life cycle assessment (LCA) carried out on the manganese beneficiation and refining process. This cradle-to-gate analysis is carried out using SimaPro software version 8.5. The considered case is the manganese beneficiation and refining process, and the final product is 1 kg of refined manganese. The global average dataset is collected from the EcoInvent and AusLCI database, which are originated from literature source. The analysis methodologies considered in this study are the International Life Cycle Reference Data System (ILCD) method and Cumulative Energy Demand (CED) method. A comparative analysis is also presented which compared among ILCD, Australian Indicator, and Tool for Reduction and Assessment of Chemicals and Other Environmental Impacts (TRACI) methods to identify the best practice method for global analysis of mining processes. A detailed sensitivity analysis has been carried out considering different scenarios, to suggest possible solutions to reduce the environmental impacts associated with manganese beneficiation and refining processes. The analysis results reveal that particulate matter, climate change, categories of eutrophication, human toxicity (cancer and non-cancer effects), and acidification are some of the noteworthy impact categories. The analysis results also showed that coal consumption is significantly higher than other types of renewables and non-renewable energy consumption in manganese beneficiation and refining processes. The analysis results further reveal that using the chromium steel in manganese beneficiation process and ferromanganese consumption in the refining process has a significant effect over other materials involved in manganese beneficiation and refining operations. The obvious reason behind this result is ferromanganese utilization as an energy-intensive process, which in turn increases the environmental emissions. The analysis results also showed that, between the beneficiation and refining process, manganese refining has a much greater impact on the environment rather than the beneficiation process due to the fossil fuel and electricity consumption in refining operations.

Impacts of aluminum production: A cradle to gate investigation using life-cycle assessment.

In this study, a life-cycle assessment from the aluminum production processes is carried out by considering four major steps of aluminum production - bauxite mining from the ore, alumina production, smelting, and the ingot casting process of aluminum. The study considered the cradle to gate system to analyze and quantify the environmental impacts during aluminum production process from raw materials to the final finished product. The production input and output datasets are taken from the databases and eGrid reports and the analysis is carried out utilizing three different methods, namely the International Life-cycle Reference Data System (ILCD) method, the Tool for Reduction and Assessment of Chemicals and Other Environmental Impacts (TRACI) method, and the Cumulative Energy Demand (CED) method. The results show electricity consumption in aluminum smelting causes noteworthy environmental burdens among all the processes or materials involved. Residual fuel oil, diesel, and natural gas consumption during the alumina production is also a major contributor to environmental impacts. Sensitivity analysis is conducted to justify the variation of environmental impacts in proportion with the modes of electricity generation from different sources to be used for aluminum smelting. Further sensitivity analysis is carried out among the quantity of the fossil fuel used based on their sources for process heat generation during alumina production. According to the sensitivity analysis results, renewable energy integration or reducing the consumption of fossil fuels would be the promising alternative to reduce the environmental burdens associated with aluminum production.

Life cycle analysis of copper-gold-lead-silver-zinc beneficiation process.

Gold, silver, lead, zinc, and copper are valuable non-ferrous metals that paved the way for modern civilisation. However, the environmental impacts from their beneficiation stage was always overlooked. This paper analysed the life cycle environmental impacts from the beneficiation process of gold-silver-lead-zinc-copper combined production. The analysis is conducted by utilising the SimaPro software version 8.5. The life cycle assessment methodologies followed are the International Reference Life Cycle Data System (ILCD) method, the IMPACT 2002+ method, and the Cumulative Energy Demand Method (CED). The most significant impact categories are ecotoxicity, climate change, human toxicity, eutrophication, acidification, and ozone depletion among nearly 15 impact categories which are assessed in this study. The analysis results from the ILCD method indicate that there is a noteworthy impact on ionising radiation caused by the beneficiation process. Out of the five metals considered, gold and silver beneficiation impacts the most while lead­zinc beneficiation impacts the least. Gold beneficiation has most impacts on the category of climate change and ecosystems. Other major impact categories are ionising radiation, terrestrial eutrophication, photochemical ozone formation, human toxicity, and acidification. The IMPACT 2002+ method shows the overall impact is on ecosystem quality and human health from this combined beneficiation process, dominantly from gold­silver beneficiation. The life-cycle inventory results show that the blasting process and the amount of electricity consumption in the beneficiation process contribute to cause significant amount of environmental impacts. The comparative impact results are presented and discussed in detail in this paper. Sensitivity analyses are presented based on various electricity grid-mix scenarios and energy-mix scenarios, and the results suggest that electricity grid mix has a dominant effect over the fossil-fuel mix. This paper also highlights the potential steps which could cut down the environmental effects by integrating renewable-energy technologies.