Biotechnological Improvement of Construction Ground and Construction Materials
The biotechnological production of construction biomaterials is a sustainable process because renewable agricultural and biotechnological biomass residues are used as organic raw materials and as the components of composite biocement. In some geotechnical
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Biotechnological Improvement of Construction Ground and Construction Materials
6.1
The Stages of Biotechnological Improvement of Ground
Any microbial biotechnology of soil improvement includes following stages: 1. Preparation for the biotreatment of soil: preparation of medium, equipment, and microbial inoculum for the biotreatment of soil; preparation of soil for the treatment; cultivation and storage of inoculum. Growth of bioagent in a medium designed using stoichiometrical equation of microbial growth that includes consumption of C, H, O sources for the synthesis of biomass with the empirical formula CH1.8O0.5N0.2 and other essential elements such as N, P, S, K, Na, Mg, Ca, and Fe and microcomponents containing Cr, Co, Cu, Mn, Mo, Ni, Se, W, V, and Zn that are required in quantities of several mg/L. In some cases, organic growth factors such as vitamins, amino acids, and nucleosides are required for the growth and activity of some microbial strains. Biotreatment can be performed by indigenous microorganisms of soil, without preparation and supply of microbial inoculum (Burbank et al. 2011, 2012 a, b) but it bears a risk of the propagation in soil of pathogenic or opportunistic microorganisms. Preparation of soil or particles before biotechnological treatment can include the following steps: (1) crushing, grinding, sieving, homogenization of treated soil, solid particles, or soft clay; (2) chemical pretreatment of soil or particles with alkali, acids, salt solution, or surfactants; (3) excavation, transportation, storage and supply of soil or particles in the bioreactor in the case of the offsite biotreatment. 2. Production of biocement or biogrout. The cultivation of microorganisms is performed at suitable conditions, usually at optimal temperature, pH, osmotic pressure, and concentration of gases (oxygen, carbon dioxide, hydrogen), on a semisolid or liquid medium containing all © Springer Science+Business Media Singapore 2017 V. Ivanov and V. Stabnikov, Construction Biotechnology, Green Energy and Technology, DOI 10.1007/978-981-10-1445-1_6
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Core process
Up - stream processes
necessary substances for the growth of the strain. Microbial biomass for biotreatment is stored and used as a liquid suspension, frozen suspension, concentrated paste, dry (usually freeze-dried) biomass. The medium for microbial cultivation and the treatment medium for soil/particles can be mixed together or used separately in the form of solution, suspension, or slurry by the mixing of chemical reagents and agricultural fertilizers. Different kind of wastes or residuals such as mining and agricultural residuals, organic fraction of municipal solid wastes, sewage sludge, and reject water of municipal wastewater treatment plants can be used as a medium
Components of the medium
Water
Selection of microbial culture or strain from collection
Dissolution Inoculum from microbiological laboratory
Air Cultivation in fermentor Titrant
Bacterial suspension
Antifoam
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