Enzymatically mediated precipitation of calcium phosphate compounds: a promising approach for sustainable soil enhancement

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Publication Title
Enzymatically mediated precipitation of calcium phosphate compounds: a promising approach for sustainable soil enhancement

Abstract
Enzyme-induced soil enhancement through carbonate precipitation is a widely utilized technique, however it releases ammonium into the atmosphere during the hydrolysis reaction. This paper introduces a novel and environmentally friendly sustainable method called Enzyme Induced Calcium Phosphate Precipitation (EICPP) for soil improvement, which can address the ammonium emission problem. The EICPP method involves the application of enzymes to facilitate the hydrolysis reaction of urea, resulting in the precipitation of Calcium Phosphate Compounds (CPCs). To ensure sustainability, this method incorporates tuna fish bones, which are typically considered food waste from the industry, can be repurposed to provide valuable source of calcium and phosphorus. By utilizing this readily available and renewable resource, EICPP reduces waste generation and promotes circularity within the food industry, aligning with Sustainable Development Goals (SDGs). Various analyses, including Unconfined Compressive Strength (UCS), X-ray Powder Diffraction (XRD), Scanning Electron Microscopy (SEM), SEM with Energy Dispersive X-ray Spectroscopy (SEM-EDS) were conducted to assess the effectiveness of EICPP for binding samples and examine the characteristics and composition of the precipitates. Different calcium/urea ratios were examined to determine the optimal ratio for the best outcome. The results reveal the presence of brushite with needle-like crystals in the improved samples of Toyoura sand, demonstrating the successful implementation of EICPP for strengthening silicate soil. EICPP method offers a promising solution for soil enhancement while mitigating the ammonium emission problem associated with traditional techniques. By repurposing tuna fish bones, this approach demonstrates the potential for sustainable resource utilization and supports the achievement of SDGs.
Authors
M. Avramenko; K. Nakashima; C. Takano; S. Kawasaki

Published In

18th European Conference on Soil Mechanics and Geotechnical Engineering (ECSMGE2024)

Theme

D - Current and new construction methods

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