Sustainable valorization of macroalgae residual biomass, optimization of pyrolysis parameters and life cycle assessment.

The major challenges for the current climate change issue are an increase in global energy demand, a limited supply of fossil fuels, and increasing carbon footprints from fossil fuels, which have necessitated the exploration of sustainable alternatives to fossil fuels. Biorefineries offer a promising path to sustainable fuel production, converting biomass into biofuels using diverse technologies. Aquatic biomass, such as macroalgae in this context, represents an abundant and renewable biomass resource that can be cultivated from water bodies without competing with traditional agricultural land. Despite this, the potential of macroalgae for biofuel production remains largely untapped, with very limited studies addressing their viability and efficiency. This study investigates the efficient conversion of unexplored macroalgae biomass through a biorefinery process that involves lipid extraction to produce biodiesel, along with the production of biochar and bio-oil from the pyrolysis of residual biomass. To improve the effectiveness and overall performance of the pyrolysis system, Response Surface Methodology (RSM) was utilized through a Box-Behnken design to systematically investigate how alterations in temperature, reaction time, and catalyst concentration influence the production of bio-oil and biochar to maximize their yields. The results showed the highest bio-oil yield achieved to be 36 %, while the highest biochar yield reached 45 %. The integration of Life Cycle Assessment (LCA) in the study helps to assess carbon emission and environmental burdens and identify potential areas for optimization, such as resource efficiency, waste management, and energy utilization. The LCA results contribute to the identification of potential environmental hotspots and guide the development of strategies to optimize the overall sustainability of the biofuel production process. The LCA results indicate that the solvent (chloroform) used in transesterification contributes significantly to greenhouse gas emissions and climate change impacts. Therefore, it is crucial to explore alternative, safe solvents that can mitigate the environmental impacts of transesterification.

Efficient utilization of tire chip reinforced sand under footings subjected to purely inclined loads-an experimental and life cycle investigation.

The proper disposal of large stockpiles of tire wastes has become a major challenge today. Through this study, an attempt was made to effectively utilize the large chunk of tire wastes as a reinforcement for improving the bearing capacity of shallow foundations subjected to purely inclined loads. The study was accomplished in two phases. In the first phase, the tests were conducted on reinforced beds by varying the quantity of tire chips, the thickness of the reinforced zone, the inclination of loading, and the equivalent relative density of the reinforced zone. The bearing capacity ratio (BCR) was used as a factor to quantify the gains. It was observed that the optimum quantity and thickness of the reinforced zone were 20% by weight and 1B, respectively, where B is the width of the footing. Improvements were found significant at both loose and dense equivalent relative densities. The BCR values under inclined loads were higher than in central vertical loading conditions indicating that the technique is more useful in the latter. The study also compares the environmental impacts generated from tire chip and geogrid foundations in terms of various midpoint and endpoint impact categories using cradle-to-gate LCA. Midpoint environmental impacts have been shown in climate change, freshwater ecotoxicity, fossil depletion, ozone depletion, and water depletion, and endpoint impacts are represented in terms of damage to ecosystem quality, damage to human health, and damage to resources. The study found that foundation prepared with waste tire chips is less polluting to the environment compared to geogrid foundation. In addition to this, landfill of waste tires will be reduced by this technology which will further help in the reduction of the total environmental impact of the system. Henceforth, by adopting the current technology into construction practices, the large stockpiles of discarded tires can be disposed of in a sustainable way.