Environmental Engineering Reference
In-Depth Information
design includes protocols for treatment-specif-
ic, representative sampling, control, and moni-
toring: these should take into account abiotic
and biotic pollutant fate processes in all relevant
process compartments. A number of well-estab-
lished and novel chemical and molecular bio-
logical monitoring techniques and parameters
are available (Schneegurt and Kulp
1998
).
Bioremediation research is generally con-
ducted at one of the three scales: laboratory,
pilot scale, or field trial. To help ensure that
results achieved at the first two scales can be
translated to the field, the research program
should be conceived as a continuum, with inves-
tigators working at each scale involved through-
out the research conceptualization and planning
process. The aim is to translate research find-
ings from the laboratory into viable technolo-
gies for remediation in the field mechanisms of
bioremediation that include bioaugmentation in
which microbes and nutrients are added to the
contaminated site or biostimulation in which
nutrients and enzymes are added to supplement
the intrinsic microbes. In the injection method,
bacteria and nutrients are injected directly into
the contaminated aquifer, or nutrients and en-
zymes, often referred to as “fertilizer,” that
stimulate the activity of the bacteria that are
added. In soil remediation, usually nutrients
and enzymes are added to stimulate the natural
soil bacteria, though sometimes both nutrients
and bacteria are added. When the treatment is
stopped, the bacteria die. This technique works
best on petroleum contamination.
ratory scale completely mixed continuous flow
activated sludge system to treat settled chrome
tannery wastewater and to develop biokinetic
parameters for the same. Occasionally, a large
amount of phenol gets into the wastewater treat-
ment plant in the phenol discharging industries,
creating shock loading conditions on activated
sludge systems. The immobilization of microbial
cells on solid supports, is an important biotechno-
logical approach introduced only recently in bio-
remediation studies. Treatment of industrial cells
has also been attempted successfully. Bioreactors
using immobilized cells have several advantages
over conventional effluent treatment technolo-
gies. Various bioreactors have been designed for
the application of microbial consortium for the
treatment of tannery effluent. Upflow anaerobic
sludge blanket (UASB) reactors were used to
treat tannery waste water containing high sul-
fate concentration, competition between sulfate-
reducing (SRB) and methane-producing (MPB)
bacteria. Bench scale continuous flow activated
sludge reactors were used to study the removal of
PCP mixed with municipal wastewater.
Ex situ solid phase techniques consist of soil
treatment units, compost piles, and engineered
biopiles. Soil treatment units consist of soil con-
tained and tilled (to supply oxygen) with appli-
cation of water, nutrients, and possibly micro-
bial inoculate to the soil. Compost piles consist
of soil supplemented with composting material
(i.e., wood chips, straw, manure, rice hulls, etc.)
to improve its physical handling properties and
its water- and air-holding capacities.
Flavobacterium
cells are immobilized on poly-
urethane and the degradation activity of cells in
semicontinuous batch reactor is studied. The abil-
ity of
Arthrobacter
cells to degrade PCP in min-
eral salt medium was evaluated for immobilized,
nonimmobilized and coimmobilized cells. The
immobilized cells were encapsulated in alginate.
A microbial consortium able to degrade PCP in
contaminated soil was used in a fed batch biore-
actor. The microorganism in the biofilm employs
natural biological processes to efficiently degrade
complex chemical process and can remediate
high volume of waste more cheaply than other
available cleanup procedures (Figs.
1.2
and
1.3
).
1.6
Types of Bioremediation
1.6.1
Ex situ Bioremediation
Bioreactors—Place of Action
of Microbes
The most promising areas for technology de-
velopment efforts as well as the critical issues
have been identified, which must be addressed in
moving from laboratory scale testing to the de-
velopment of commercially viable technologies.
Experiments are conducted by operating a labo-
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