Bioclogging and Biogrouts

Abstract

Grouting is a process to fill the soil voids with fluid grout, which is used to control water flow in soil. Such common grouts as solutions or suspensions of sodium silicate, ultrafine cement, acrylates, acrylamides, and polyurethanes have such disadvantages as high viscosity and low depth of penetration in soil, high cost, and toxicity. Bioclogging or biogrouting is either using formation of microbial biopolymers or microbially induced precipitates of inorganic compounds in situ for water flow control. Biogrouting includes formation of impermeable layer of algal and cyanobacterial biomass; production of slime in soil by aerobic and facultative anaerobic heterotrophic bacteria, production of undissolved sulfides of metals by sulfate-reducing bacteria; formation of undissolved carbonates of metals by ammonifying bacteria and urease-producing bacteria; production of ferrous solution by iron-reducing bacteria, and precipitation of undissolved ferrous and ferric salts and hydroxides in soil by iron-oxidizing bacteria; self-decay of calcium bicarbonate with formation of calcium carbonate clogging. Bioclogging can be applied to diminish piping of the slopes and dams, prevention of soil erosion, construction of the channels, sealing of the aquaculture ponds, reservoirs, landfills, tunneling space before and after excavation in sandy soil or sedimentary rocks, and sealing of the sedimentary and fractured rocks.