Basics of Construction Microbial Biotechnology - Biotechnologies and Biomimetics for Civil Engineering - page 24

Soil particles before biotreatment Type of biotreatment process Soil particles (dark color shows soil

particles) after biotreatment (grey
color shows biocement)

Bioaggregation of soil - increase of
soil particles size so that soil erosion
and dust emission will be reduced

Biocrusting - formation of crust on
soil so that wind and water erosions,
dust emission, and water infiltration
will be reduced

Biocoating - formation of a layer on
solid surface so that colonization or
aesthetics of surface will be
enhanced
Bioclogging - filling the pores and
channels in soil so that hydraulic
conductivity of soil will be
significantly reduced

Biocementation - binding of the soil
particles significantly increasing
strength of soil

Biodesaturation - production of
biogas bubbles in situ to reduce
saturation and liquefaction potential
of soil

Water

Water

Gas bubbles

Bioencapsulation - increase of the
strength of soft clayey soil, saturated
loose soil, quick sand, muck
(drained swampland) soil

Encapsuledc
lay
ball/cylinder

Clay ball/cylinder

Bioremediation - bioremoval from
soil or bioimmobilization of the soil
pollutant before construction

Soil
with pollutant

Fig. 2.2 The results of the construction biotechnologies

(1) upstream processes such as preparation of soil or construction material for the

treatment, preparation of the reagents, equipment and microbial inoculum for
the treatment;

(2) core process such as biotreatment of soil, construction material, or the con-

struction objects;

(3) downstream processes such as disinfection (if needed) and solid, liquid, or

gaseous wastes treatment or disposal.

All these processes should be monitored and controlled to ensure efficiency of
the processes. The example can be the biotechnology for mitigation of saturated
sand liquefaction using denitrifying and biosealing bacteria (Fig. 2.5 ).