The coronavirus disease 2019 pandemic has posed severe threats to humans and the geoenvironment. The findings of severe acute respiratory syndrome coronavirus 2 (Sars-CoV-2) traces in waste water and the practice of disinfecting outdoor spaces in several cities in the world, which can result into the entry of disinfectants and their by-products into storm drainage systems and their subsequent discharge into rivers and coastal waters, raise the issue of environmental, ecological and public health effects. The aims of the current paper are to investigate the potential of water and waste water to operate as transmission routes for Sars-CoV-2 and the risks of this to public health and the geoenvironment. Additionally, several developing countries are characterised by low water-related disaster resilience and low household water security, with measures for protection of water resources and technologies for clean water and sanitation being substandard or not in place. To mitigate the impact of the pandemic in such cases, practical recommendations are provided herein. The paper calls for the enhancement of research into the migration mechanisms of viruses in various media, as well as in the formation of trihalomethanes and other disinfectant by-products in the geoenvironment, in order to develop robust solutions to combat the effects of the current and future pandemics.

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For a long time in the practice of geotechnical engineering, soil has been viewed as an inert material, comprising only inorganic phases. However, microorganisms including bacteria, archaea and eukaryotes are ubiquitous in soil and have the capacity and capability to alter bio‐geochemical processes in the local soil environment. The cumulative changes could consequently modify the physical, mechanical, conductive and chemical properties of the bulk soil matrix. In recent years, the topic of bio‐mediated geotechnics has gained momentum in the scientific literature. It involves the manipulation of various bio‐geochemical soil processes to improve soil engineering performance. In particular, the process of microbial‐induced calcium carbonate precipitation (MICP) has received the most attention for its superior performance for soil improvement. The present work aims to shape a comprehensive understanding of recent developments in bio‐mediated geotechnics, with a focus on MICP. Referring to around one hundred studies published over the past five years, this review focuses on popular and alternative MICP processes, innovative raw materials and additives for MICP, emerging tools and testing methodologies for characterizing MICP at multi‐scale, and applications in emerging and/or unconventional geotechnical fields.

Microbially Induced Calcite Precipitation (MICP) is a sustainable method of stabilizing (i.e., 2 cementing) loose sandy deposits and/or to create an impervious barrier within the soil mass. 3 MICP can occur through various biochemical pathways, among which 'Urea Hydrolysis (UH)' is considered to be the most efficient method of biochemically inducing calcite 5 precipitation. To date, the geotechnical engineering community investigating MICP has 6 tended to focus on the hydro-mechanical behaviour of the end product, i.e. MICP cemented 7 sands; however, many biochemical factors that affect reaction-rate kinetics and MICP 8 outcome have been understudied or neglected. This study investigated the kinetics of UH and 9 compared different sources of urease enzyme: those microbially cultivated in the laboratory 10 (i.e., Sporosarcina pasteurii) and those extracted from plants (i.e., Jack bean meal), to 11 investigate the influence of urea concentration, buffer capacity, and cell harvesting method on 12 UH. Through this study, an attempt has been made to arrive at an optimal concentration of 13 urea, under the influence of the above mentioned parameters along with the buffering action 14 of the soil, on urea hydrolysis. These results have implications towards optimising MICP and, 15 in particular, for upscaling these methods to in-situ applications.

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Soil has a great role in construction of any structure. In order to improve the behaviour of the soil, various ground improvement methods are available. Methods like chemical stabilisation, cement stabilisation has been adopted for stabilising cohesionless soils in the construction industry. The inherent drawbacks of these methods are not new to the industry. In the absence of a popular method which can act as an alternative to this, it has been widely used. Soil has microorganisms which are capable of developing strength in the soil, with modification of the existing environment. This is microbial geotechnology. Microbial geotechnology promises to provide a solution for the existing problems along with addressing the environmental issues related to other methods like chemical stabilisation. Work in the aspects of strength improvement has been going on in the world. Unlike conventional methods, the durability of Microbially Induced Calcite Precipitation (MICP) treated soils is of great concern and this paper makes an attempt to study the durability aspects of the MICP treated soils. This paper presents behaviour of MICP soils with respect to strength under different environmental conditions. The strength and durability of poorly graded sand (SP), silty sand (SM) and clayey sand (SC) soils were treated with MICP studied and compared in this paper.

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The incessant growth in urbanization, and the population explosion associated with it, has resulted in an increased discharge in sewage disposal lagoons and has led to their overloading. This results in the improper functioning of these lagoons, which greatly affects the treatment of sludge and wastewater. The influents, which carry along with them a huge load of substance, referred to as socioeconomically generated sediments (SeGSs), substantially reduce the capacity of the lagoons and the retention time of the sewage water and sludge. This situation poses a major challenge to municipal engineers and town planners, and to overcome it, either periodic or once-per-lifetime desiltation of these lagoons is warranted. However, in present-day megacities, there are several concerns associated with the desiltation process, viz., selection of the most economical and efficient technique, the availability of dumping ground(s), and transportation of the SeGSs to these dumping grounds. This is where utilization of SeGSs as a manmade resource could be a good initiative towards sustainable development. However, this endeavor entails a holistic understanding of the SeGSs by conducting detailed investigations to characterize them based on their physical, chemical, morphological, and microbial attributes before postulating a strategy for their sustainable utilization. With this in view, extensive sampling of the SeGSs from sewage disposal lagoons located in the western part of India was conducted followed by their very comprehensive characterization. Details of the methodologies adopted for this exercise were presented in this manuscript, and recommendations were made to utilize SeGSs for sustainable development in the most efficient manner.