BIOFILMS IN GEOTECHNICAL AND GEO-ENVIRONMENTAL PROCESSES
Regulatory bodies, in many countries, require part of the lining system, for such facilities, to comprise of a compacted clay layer with a hydraulic conductivity of 1x10¯9m/s or less. Suitable material can be expensive, or indeed impossible, to obtain in some areas. There are many examples of biofilms and biopolymers increasing the viscosity of fluids or causing reductions in the hydraulic conductivity of porous media. In many of these cases, the phenomenon is cited as detrimental to the operation of the system in which it occurred. "Biofouling" is often reported in heat exchangers, cooling towers, filtration media, pipes and ship hulls. In these cases, the biofilms may reduce conductivity, reduce flow or increase drag. There are also many widely used beneficial uses of biofilms and biopolymers. Biopolymers are used in the food and cosmetic industries as emulsifiers or thickening agents. Biopolymers have also been used in the oil well drilling industry to clog porous media to improve resource recovery. For many pathogenic bacteria, biofilm dispersal plays an important role in the transmission of bacteria from environmental reservoirs to human hosts, in horizontal and vertical cross-host transmission, and in the exacerbation and spread of infection within a host. Also, the bacterial cells form by biofilms effectively improved the geomechanical properties of sand. Continues growing bacteria cells improved the sand properties owing to microbially induced precipitation and related pore volume changes, whereas dead and resting cells generally caused smaller increases in friction angle and bearing strength. Consideration of soil as a living ecosystem offers the potential for innovative and sustainable solutions to geotechnical problems. Recent studies have sought to investigate the potential for biofilms and biopolymers to improve the hydraulic conductivity of material for use as liners in waste containment facilities. Geotechnical applications currently being explored include cementation of sands to enhance bearing capacity and liquefaction resistance, sequestration of carbon, soil erosion control, groundwater flow control, and remediation of soil and groundwater impacted by metals and radionuclides. It is proposed that by adding relatively small quantities of bio-substances to marginal material, a low permeability can be achieved. The researcher reviewed some of the published research to date. Other reported properties of biofilms and biopolymers indicate further promising potential. Some of the potential geotechnical and geo-environmental applications of these bio-substances are broached as well as some of the drawbacks to be overcome.
Authors : Dadiri, M.B. and Abubakar, H.F.
Category : Open Access Volume (Issue) : 8(1) Date Uploaded : 6th August 2022
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4th May 2019
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