Concurrent Carbon Capture and Biocementation through the Carbonic Anhydrase (CA) activity of microorganisms ‑ a review and outlook

Biocementation, i.e., the production of biomimetic cement through the metabolic activity of microorganisms, offers exciting new prospects for various civil and environmental engineering applications. This paper presents a systematic literature review on a biocementation pathway, which uses the carbonic anhydrase (CA) activity of microorganisms that sequester CO2 to produce biocement. The aim is the future development of this technique for civil and (geo-)environmental engineering applications towards CO2-neutral or negative processes. After screening 248 potentially relevant peer-reviewed journal papers published between 2002 and 2023, 38 publications studying CA-biocementation were considered in the review. Some of these studies used pure CA enzyme rather than bacteria-produced CA. Of these studies, 7 used biocementation for self-healing concrete, 6 for CO2 sequestration, 10 for geotechnical applications, and 15 for (geo-)environmental applications. A total of 34 bacterial strains were studied, and optimal conditions for their growth and enzymatic activity were identified. The review concluded that the topic is little researched; more studies are required both in the laboratory and field (particularly long-term field experiments, which are totally lacking). No studies on the numerical modelling of CA-biocementation and the required kinetic parameters were found. The paper thus consulted the more widely researched field of CO2 sequestration using the CA-pathway, to identify other microorganisms recommended for further research and reaction kinetic parameters for numerical modelling. Finally, challenges to be addressed and future research needs were discussed

Concurrent Carbon Capture and Biocementation through the Carbonic Anhydrase (CA) Activity of Microorganisms -a Review and Outlook, Environmental Processes

Biocementation, i.e., the production of biomimetic cement through the metabolic activity of microorganisms, offers exciting new prospects for various civil and environmental engineering applications. This paper presents a systematic literature review on a biocementation pathway, which uses the carbonic anhydrase (CA) activity of microorganisms that sequester CO2 to produce biocement. The aim is the future development of this technique for civil and (geo-)environmental engineering applications towards CO2-neutral or negative processes. After screening 248 potentially relevant peer-reviewed journal papers published between 2002 and 2023, 38 publications studying CA-biocementation were considered in the review. Some of these studies used pure CA enzyme rather than bacteria-produced CA. Of these studies, 7 used biocementation for self-healing concrete, 6 for CO2 sequestration, 10 for geotechnical applications, and 15 for (geo-)environmental applications. A total of 34 bacterial strains were studied, and optimal conditions for their growth and enzymatic activity were identified. The review concluded that the topic is little researched; more studies are required both in the laboratory and field (particularly long-term field experiments, which are totally lacking). No studies on the numerical modelling of CA-biocementation and the required kinetic parameters were found. The paper thus consulted the more widely researched field of CO2 sequestration using the CA-pathway, to identify other microorganisms recommended for further research and reaction kinetic parameters for numerical modelling. Finally, challenges to be addressed and future research needs were discussed

Microbially induced calcium carbonate precipitation: a widespread phenomenon in the biological world

Biodeposition of minerals is a widespread phenomenon in the biological world and is mediated by bacteria, fungi, protists, and plants. Calcium carbonate is one of those minerals that naturally precipitate as a by-product of microbial metabolic activities. Over recent years, microbially induced calcium carbonate precipitation (MICP) has been proposed as a potent solution to address many environmental and engineering issues. However, for being a viable alternative to conventional techniques as well as being financially and industrially competitive, various challenges need to be overcome. In this review, the detailed metabolic pathways, including ammonification of amino acids, dissimilatory reduction of nitrate, and urea degradation (ureolysis), along with the potent bacteria and the favorable conditions for precipitation of calcium carbonate, are explained. Moreover, this review highlights the potential environmental and engineering applications of MICP, including restoration of stones and concrete, improvement of soil properties, sand consolidation, bioremediation of contaminants, and carbon dioxide sequestration. The key research and development questions necessary for near future large-scale applications of this innovative technology are also discussed

MICROBIAL-INDUCED CALCITE PRECIPITATION" AS A POTENTIAL SUSTAINABLE TECHNIQUE FOR POLLUTED SOIL BIOREMEDIATION: A REVIEW

Industrialization and population growth have increased the emission and buildup of environmental heavy metals. These components' bioaccumulation as exposure have been related to a range of illnesses and cancer, and the mechanical and physical properties of soil are altered. The "Microbial Induced Calcite Precipitation" is an environmentally green, friend, and sustainable method. This review focused on the metal remediation technology's effects and how to make them sustainable and more environmentally friendly. Many bacteria produce urease, the bacillus is a more common type. Bacteria, with sizes ranging from 0.5 to 3.0µm, are the most common microbes found in soils. It is critical to examine the type of soil, Bacterial size, and size of pore throat. The calcium carbonate majority tends to coat the surface of soils with coarse particles in the state of the contact points in soils with particles smaller than bacterial size (heterogeneous and limited precipitation). The bacterial concentration appears to affect crystal shape, calcium carbonate formation, and the cementation effect of geomaterials. Calcite precipitation takes place most when the pH is between 7.5 and 9.5. Calcite is formed three times at 50°C, while the unconfined compressive strength is only 60% of that at 25°C. Calcium carbonate can be immobilized or formed into undissolved compounds by binding free ions to the calcium carbonate's surfaces, resulting in a form of non-toxic and chemically stable

Uranium Bioreduction and Biomineralization

Following the development of nuclear science and technology, uranium contamination has been an ever increasing concern worldwide because of its potential for migration from the waste repositories and long-term contaminated environments. Physical and chemical techniques for uranium pollution are expensive and challenging. An alternative to these technologies is microbially mediated uranium bioremediation in contaminated water and soil environments due to its reduced cost and environmental friendliness. To date, four basic mechanisms of uranium bioremediation-uranium bioreduction, biosorption, biomineralization, and bioaccumulation-have been established, of which uranium bioreduction and biomineralization have been studied extensively. The objective of this review is to provide an understanding of recent developments in these two fields in relation to relevant microorganisms, mechanisms, influential factors, and obstacles

Applications of microbial processes in geotechnical engineering

Over the last 10-15 years a new field of ‘biogeotechnics’ has emerged as geotechnical engineers seek to find ground improvement technologies which have the potential to be lower carbon, more ecologically friendly and more cost-effective than existing practices. This review summarizes the developments which have occurred in this new field, outlining in particular the microbial processes which have been shown to be most promising for altering the hydraulic and mechanical responses of soils and rocks. Much of the research effort in this new field has been focused on microbially induced carbonate precipitation via ureolysis (MICP); while a comprehensive review of MICP is presented here, the developments which have been made regarding other microbial processes, including microbially induced carbonate precipitation via denitrification and biogenic gas generation are also presented. Furthermore, this review outlines a new area of study: the potential deployment of fungi in geotechnical applications which has until now been unexplored

Erosion mitigation with biocementation: a review on applications, challenges, & future perspectives

Soil erosion is a complex natural process that occurs by either individual or combined actions of wind, hydraulic currents, waves, and rain. This study comprehensively reviews biocementation-based soil stabilisation techniques for developing erosion-resilient landforms through an ecologically conscious strategy. The different pathways for biocementation occurring in nature are discussed with a focused view on the microbially induced carbonate precipitation (MICP) technique. MICP relies on biogenic calcium carbonate (CaCO3) precipitation via the urea hydrolysis route to bind the soil grains. The kinetics and factors affecting MICP are succinctly discussed to highlight the practical challenges associated with biocementation. This study emphasises the influence of MICP on erosion resistance (aeolian and hydraulic) and geotechnical properties of soils. The critical assessment of the previous studies revealed that aeolian and hydraulic erosion can be effectively controlled with a small to moderate quantity of biogenic CaCO3 (2% to 10% of soil weight). MICP marginally influences the hydraulic conductivity of soils with a substantial improvement in compressive strength, making it desirous over traditional soil cementation agents for erosion control due to the limited intervention to natural groundwater flow. However, the scientific design and findings of the previous laboratory-scale and pilot-scale research are still inconsistent for standardising biocementation techniques to transition towards upscaling. This study presents critical insights to the researchers of the environmental, geotechnical and geoenvironmental engineering domains to design their upcoming studies to tackle the challenges required for upscaling biocementation technology

Microbial Modification of Soil for Ground Improvement

Biomediated geochemical processes in soil offer innovative and sustainable potential solutions to some geotechnical challenges. Microbial Induced Carbonate Precipitation (MICP) has been the most researched process for geotechnical problems. Most of the research that have been performed on MICP focused on investigating its effects on soil behavior at small lab-scale. Limited particle-scale (micro-scale) and field-or large laboratory-scale tests were conducted. Furthermore, challenges of upscaling MICP to real applications still exist, including heterogeneous CaCO3 distribution due to bio-clogging, soil properties (e.g. modulus and permeability) monitoring, and byproducts management, etc. The goal of the research presented in this dissertation focuses on investigating the MICP-treated soil behavior ranging from particle-scale to macro-scale, addressing some upscaling challenges, and advancing MICP towards practically-feasible field applications. The major effort of this research focuses on investigating physical properties of MICP-treated sand and MICP bio-grouted permeable pile system ranging from particle-to large laboratory-scale (e.g. micrometer to meter scale). The results from tests at different scales demonstrate that MICP improved soil mechanical behavior and enhanced the capacity of permeable pile foundation system. The research demonstrate a promising potential for field-scale foundation enhancement using MICP, which is envisioned to be the main focus of future research. In addition, a preliminary study on the effects of biofilm modification on the physical sand properties is conducted