Sustainable bio-bricks prepared with synthetic urine enabled by biomineralization reactions

New opportunities for biologically and chemically mediated adsorption and precipitation of phosphorus from wastewater

Biologically mediated adsorption and precipitation of phosphorus (P) from waste streams can restrict environmental P discharges. Here, we appraise progress in this field over the past decade. The research discipline has grown considerably in recent years. Industry 'wastes', including steel slags, continue to show promise as adsorbents with exceptionally high P retention capacities (>500 mg P g-1). Hydrotalcite, a nanomineral, offers prospects as a P removal technology with imbedded climate change mitigation capacity. Biomineral struvite formation, driven by microbial processes, offers an exciting P removal and recovery approach that can be applied to diverse wastewater types due to its feedstock-independent mechanisms, emerging immobilisation techniques and adaptability to mixed cultures. All of these factors facilitate efficient nutrient recycling and scalable application to the wastewater industry. Adsorbed and precipitated P can be applied to cropland to offset dependence on conventional fertiliser inputs. Therefore, in addition to water treatment, these biologically mediated processes also offer opportunities to support food production. Moreover, as many of the input materials covered in this review are industry byproducts and common organic materials, the removal of P from waste streams by adsorption and precipitation offers strong circularity potential that aligns with the UN's Sustainable Development Goals. We call for future work to focus on long-term full-scale trials involving community, government and industry partners.

Bioconsolidation strategies for carbonate lithologies: Effectiveness and mechanisms in calcarenite, travertine, and marble

Toxic substances are often employed in conventional stone preservation techniques, whereas biorestoration offers material compatibility along with significant benefits for cultural heritage preservation, environmental safety, and sustainability. However, the application of this innovative technique to natural rocks is not fully understood. In this study, we evaluated the efficiency of a carbonatogenic bacterial strain (Lysinbacillus fusiformis 3.20) on three natural carbonate rocks: Calcarenite (CA), Travertine (TR) and Marble (MA), having different porosities. We integrated surface analyses (Field Emission Scanning Electron Microscopy, Atomic Force Microscopy, and X-Ray Diffraction) with bulk analyses (Porosity, Ultrasonic Wave Velocity, and Dynamic Elastic Moduli) to investigate the bioconsolidation processes. The results indicated that the biomineralization treatment had no effect on MA samples, while it improved the physical and mechanical properties of both CA and TR, evidenced by the formation of new bioprecipitates. Total and effective porosity decreased, particularly in CA, while ultrasonic wave velocities (Vp and Vs) and Young's modulus increased, with Poisson's ratio remaining unchanged. Comparative observations suggest that connected, randomly distributed, and low aspect ratio pores facilitate microbial activity by enabling deeper bacterial penetration into the stone, supporting nutrient distribution and the formation of calcium carbonate precipitates. When the treatment is effective, stiffness and strength are expected to increase due to reduced effective porosity, while resistance to shear deformation remains nearly constant, as does the relationship between porosity and wave velocities.

Synergistic mechanisms of humic acid and biomineralization in cadmium remediation using Lysinibacillus fusiformis

Heavy metal pollution, particularly cadmium, poses severe environmental and health risks due to its high toxicity and mobility, necessitating effective remediation strategies. While both microbially induced carbonate precipitation (MICP) and humic acid adsorption are promising methods for heavy metal mitigation, their combined effects, particularly the influence of humic acid on the MICP process, have not been thoroughly investigated. This study explores the interaction between humic acid and MICP, revealing that humic acid significantly inhibits the MICP process by reducing urease activity, with the 10% humic acid treatment resulting in a 23.8% reduction in urease activity compared to the control. Additionally, while higher concentrations of humic acid did not significantly reduce cadmium ion concentrations, they did result in a slight increase in organically bound cadmium, indicating an interaction that could alter metal speciation in the soil. These findings provide important insights into the mechanisms by which humic acid affects MICP, offering a foundation for optimizing combined remediation approaches. Future research should aim to fine-tune the balance between MICP and humic acid to enhance the overall efficiency of cadmium remediation strategies. This study contributes to the development of more effective and sustainable methods for addressing cadmium contamination.

Self-assembled silk fibroin cross-linked with genipin supplements microbial carbonate precipitation in building material

The process of microbially induced carbonate precipitation (MICP) is known to effectively improve engineering properties of building materials and so does silk fibroin (SF). Thus, in this study, an attempt was taken to see the improvement in sand, that is, basic building material coupled with MICP and SF. Urease producing Bacillus megaterium was utilized for MICP in Nutri-Calci medium. To improve the strength of SF itself in bacterial solution, it was cross-linked with genipin at the optimized concentration of 3.12 mg/mL. The Fourier transform infrared (FTIR) spectra confirmed the crosslinking of SF with genipin in bacterial solution. In order to understand how such cross-linking can improve engineering properties, sand moulds of 50 mm3 dimension were prepared that resulted in 35% and 55% more compressive strength than the one prepared with bacterial solution with SF and bacterial solution only, respectively with higher calcite content in former one. The FTIR, SEM, x-ray powder diffraction spectrometry and x-ray photoelectron spectroscopy analyses confirmed higher biomineral precipitation in bacterial solution coupled with genipin cross-linked SF. As the process of MICP is proven to replace cement partially from concrete without negatively influence mechanical properties, SF cross-linked with genipin can provide additional significance in developing low-carbon cement-based composites.

Computational Design and Manufacturing of Sustainable Materials through First-Principles and Materiomics

Engineered materials are ubiquitous throughout society and are critical to the development of modern technology, yet many current material systems are inexorably tied to widespread deterioration of ecological processes. Next-generation material systems can address goals of environmental sustainability by providing alternatives to fossil fuel-based materials and by reducing destructive extraction processes, energy costs, and accumulation of solid waste. However, development of sustainable materials faces several key challenges including investigation, processing, and architecting of new feedstocks that are often relatively mechanically weak, complex, and difficult to characterize or standardize. In this review paper, we outline a framework for examining sustainability in material systems and discuss how recent developments in modeling, machine learning, and other computational tools can aid the discovery of novel sustainable materials. We consider these through the lens of materiomics, an approach that considers material systems holistically by incorporating perspectives of all relevant scales, beginning with first-principles approaches and extending through the macroscale to consider sustainable material design from the bottom-up. We follow with an examination of how computational methods are currently applied to select examples of sustainable material development, with particular emphasis on bioinspired and biobased materials, and conclude with perspectives on opportunities and open challenges.