BIOAUGMENTATION CONSIDERATIONS - Bioaugmentation for Groundwater Remediation - page 153

Table 5.2. Electron Donor Delivery Methods for Biostimulation/Bioaugmentation
Injection Wells Direct Push Trenching Fracturing

Applicable delivery type Passive Passive Passive Passive

Semi-passive Active recirculation

Active recirculation

Electron donor type Liquid donors or liquid

donors with very small
scale suspended solids

Liquid donors or liquid
donors with very small
scale suspended solids

All electron donor types
can be used

All electron donor types
can be used

Geology Applicable for all geologies Applicable for

unconsolidated media
without large gravel or
cobbles

Applicable for all geologies Applicable for low

permeability media

Areal extent of treatment
zone

Achieve larger radius of
influence (ROI) with low
pressure injections than
direct-push, but
incremental ROI
improvement decreases
with volume

ROI generally small
because inefficiency of
injection points (flow rate
per unit head) unless
injections are pressurized

Limited to the trench
footprint

Large ROI

Pressurized injections
achieve larger ROI, but
vertical distribution
generally becomes erratic
due to preferential flow

Thickness of treatment
zone

Well screens can be
installed for any thickness;
however, longer screens
will not achieve good
vertical distribution in
heterogeneous systems
(nested wells can be used
to overcome this, but
capital costs are
increased)

Can be used for any
thickness (subject to depth
limitations)

Limited to the trench depth Treatment zone limited to

the fracture thickness

Multiple fractures generally
required Conventional “bottom up”

injection approach can
lead to erratic vertical
distribution due to
preferential flow in
permeable strata

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