Human and industrial activities produce and discharge wastes containing heavy metals into the water resources making them polluted, threatening human health and the ecosystem. Biosorption, the process of passive cation binding by dead or living biomass, represents a potentially cost-effective way of eliminating toxic heavy metals from industrial wastewater. The abilities of microorganisms to remove metal ions in solution have been extensively studied; in particular, live and dead fungi have been recognized as a promising class of low-cost adsorbents for the removal of heavy metal ions. The biosorption behavior of fungal biomass is getting attention due to its several advantages; hence, it needs to be explored further to take its maximum advantage on wastewater treatment. This review discusses the live and dead fungi characteristics of sorption, factors influencing heavy metal removal, and the biosorption capacities for heavy metal ions removal and also discusses the biosorption mechanisms.

Because of the alarming rate of human population growth, technological improvement should be needed to save the environment from pollution. The practice of business as usual on material production is not creating a circular economy. The circular economy refers to an economic model whose objective is to produce goods and services sustainably, by limiting the consumption and waste of resources (raw materials, water, and energy). Fungal-based composites are the recently implemented technology that fulfills the concept of the circular economy. It is made with the complex of fungi mycelium and organic substrates by using fungal mycelium as natural adhesive materials. The quality of the composite depends on both types of fungi and substrate. To ensure the physicochemical property of the fabricated composite, mycelium morphology, bimolecular content, density, compressive strength, thermal stability, and hydrophobicity were determined. This composite is proven to be used for different applications such as packaging, architectural designs, walls, and insulation. It also has unique features in terms of low cost, low emission, and recyclable.

As the global population rises, resource depletion and environmental pollution also aggravate. To meet the needs of the population, different products have been manufactured. However, most industrially manufactured products are not eco-friendly, costly, and locally unavailable. To solve these problems, using and enhancing locally available biomaterials are the key option. Three substrates sawdust, bagasse, and coffee husk and the fungus Pleurotus ostreatus were used. Mycelium was fully colonized by 9, 14, and 27 days on potato dextrose agar (PDA), sorghum grain, and substrate, respectively. The mycelium growth on coffee husk showed the fastest growth rate whereas that of the sawdust was slowest. The fully colonized substrates were molded for 7, 14, and 21 days by plastic mold to maintain their regular 3D structure. The result shows that the block made with sawdust at 21 molding period has higher compressive strength and density of 750 kPa and 343.44 Kg/m3, respectively, followed by bagasse and coffee husk. These variations were due to the mycelium density difference between the substrates. Physicochemical and mechanical characteristics such as mycelium morphology, bimolecular and elemental analysis of substrates, density, water absorption, and compressive strength of the block were analyzed. This technology has the potential to replace conventional construction and packaging materials used for indoor applications such as insulation, partition walls, and other design and architectural applications. It also benefits in terms of its low cost, green synthesis approach, nontoxicity, low environmental emission, recyclability, and local availability.

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Building practices began with human civilization. Cement is the most commonly used building construction material throughout the world. These traditional building materials have their own environmental impact during production, transportation, and construction, but also have limitations on building quality and cost. Biological construction materials are currently emerging technology to combat emissions from the construction sector. Different civil and biotechnology researchers have turned to microorganisms for the production of bio construction materials that are environmentally friendly, socially acceptable, and economically feasible but can also produce high strength. Scanning electron microscope (SEM) and X-Ray diffraction (XRD) are the most characterization methods used to observe and ensure the production of calcite precipitate as bacterial concrete. As compared to conventional concrete, bacterial concrete was greater by 35.15% in compressive strength, 24.32% in average tensile strength, and 17.24% in average flexural strength, and it was 4 times lower in water absorption and 8 times lower in acid resistivity than conventional concrete. Genetic engineering has great potential to further enhance the mechanical strength of bacterial concrete for use in crack repairs in existing buildings.

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