Industrial and commercial uses of bacteria for waste water treatment and soil remediation.

1. BENEFICIAL BIOFILMS
From: http://www.cs.montana.edu/ross/personal/intro-biofilms-s3.htm
In natural environments
As we have already pointed out, biofilms are all around us, on us, and in us. Obviously,
then, not all biofilms are harmful. Many play an important role in the ecology of the earth
and the sustainability of life in general. The report, "Global Environmental Change:
Microbial Contributions, Microbial Solutions," points out: ". . .the basic chemistry of
Earth's surface is determined by biological activity, especially that of the many trillions
of microbes in soil and water. Microbes make up the majority of the living biomass on
Earth and, as such, have major roles in the recycling of elements vital to life." Imagine
that! "Microbes make up the majority of the living biomass on Earth," and, as we are
learning, those microbes often live in biofilm colonies on surfaces.
For example, it is known that bacteria are early colonizers (in a biofilm) of initially clean
surfaces submerged in water. Scientists have been able to document a predictable pattern
of the way in which biofilms form on a clean surface under water. Whether the surface in
question is a boat hull floating on top of the water, or a new deep sea vent at the bottom
of the ocean, microbes are already present in the those environments and are capable of
rapid attachment to and community development as a biofilm on those surfaces (the boat
hull or the deep sea vent).
It is important to recognize that microorganisms, such as bacteria, that colonize in
biofilms have evolved along with other organisms, including human beings. While some
bacteria produce effects that are bad for other organisms, most bacteria are harmless or
even beneficial. When it comes to bacteria, higher organisms (like us) are just another
environment to colonize. So here's a thought: humans, who are often thought to be the
colonizers of the world, are themselves the target of colonial powers, in the form of the
many microorganisms that sneak into and inhabit our body!
Water and wastewater treatment
One of the best examples of successful, beneficial application biofilms to solve a huge
problem is in the cleaning of wastewater. Think of it this way. We know that
microorganisms are the main agents that cause decay in dead plants and animals. Decay
happens (partly) as the microorganisms feed on the tissue of the dead organism. Since
that is true, perhaps one could engineer a system that uses the proper microorganisms (in
the form of a biofilm) to process wastewater and sewage: if the contaminated water were
passed through such a biofilm, perhaps the microorganisms in the biofilm would eat (and
thus remove) the harmful organic material from the water.
Good idea! Indeed, even before biofilms were recognized and became the subject of
intense research, engineers were taking advantage of natural biofilm environmental
activity (without knowing about biofilms) in developing water-cleaning systems.

2. Biofilms have been used successfully
in water and wastewater treatment for
well over a century. English engineers
developed the first sand filter treatment
methods for both water and wastewater
treatment in the 1860s. In such
filtration systems the the filter medium
(i.e., sand) presents surfaces to which
microbes that feed on the organic
material in the water being treated can
attach. The result? The formation of a
beneficial biofilm that eats the "bad"
stuff in the water, effectively filtering
it. Of course, we don't want the
microorganisms in the biofilm to get into the filtered water, or for chunks of biofilm to
detach from the colony and make it through the system. Ideally, the biofilm stays
attached to the filtration system and can be cleaned when the system is flushed.
Interestingly, scientists and water treatment engineers have discovered that drinking
water and wastewater that have been processed with a biofilm system in a treatment plant
are more "biologically stable" than water filtered by other types of treatment systems.
This just means that there is likely to be less microorganism contamination in water that
has passed through a biofilm-based filter than there is in water that has passed through
some alternative treatment system. This implies that biofilm treated water typically has
lower disinfectant demand (e.g., use of chlorine) and disinfection by-product formation
(e.g., that unsavory taste and smell of chlorine) potential than water treated in other ways
if the water prior to treatment is high in the kind of nutrients the biofilm craves (which in
this case is organic carbon).
People are finicky. We want our drinking water to be crystal clear, have no odd odor,
and to taste, well, like pure water. Water that is safe to drink because of being treated
with chlorine can still have an odd color, smell bad, and taste worse. So, drinking water
utilities go to great lengths to provide us with the kind of drinking water we want (using
ozone in the primary treatment phase is one approach that is used). In any such system, a
biofilm treatment phase may well be one approach that will help yield the desired result.
Remediation of contaminated soil and groundwater
One of the less obvious beneficial applications of biofilms is in cleaning up oil and
gasoline spills. That's right, certain bacteria will eat oil and gasoline. Remember that oil
was produced over many years by decaying vegetation, so it is an organic compound.
We wouldn't recommend that you suck up any spilled oil or gasoline, but the fact that
some of the naturally occurring bacteria in soil love the stuff leads to a new idea:

3. bioremediation. This is a term that refers to the engineering of a biofilm that can be
introduced into the area of an oil or gasoline spill to help clean up the mess, and all with
natural, non-harmful means.
Indeed, bioremediation using
biofilms has emerged as a technology
of choice for cleaning up
groundwater and soil at many sites
contaminated with hazardous wastes.
Bioremediation results in
• the reduction of both
contaminant concentration
and mass for many subsurface
contaminants (e.g., petroleum
hydrocarbons and chlorinated
organics) and/or
• a beneficial speciation change in the bacteria in the biofilm that allow them to
tackle other contaminants, such as heavy metals (such as mercury)
In other words, bioremdiation is a great idea! How to actually make it work requires an
understanding of biofilm processes and engineering systems for introducing a biofilm
into the contaminated ground and providing the necessary environment below the surface
of the ground to encourage the biofilm to do its job (illustrated in the diagram above).
For students interested in this topic, the study of biofilms and engineering (e.g.,
environmental engineering or chemical engineering). Just keep on truckin', and you will
get there.
Microbial leaching
As you probably know, mining for precious metals of various kinds (gold, silver, copper
and so forth) is a messy job. The desired metal is not generally found in nice, big, pure
chunks. The largest gold nugget ever found was reputed to weigh about 70 Kilograms.
But most gold, as with all other precious metals, is generally hard to see with the naked
eye, mixed in the ground with dirt, rocks, and other ground debris--the ore from which
the gold must be extracted (note that the ore in a good copper mine, for instance, will
typically consist of less than 1% copper). The extraction process, when done with
chemicals, is called "leaching." For years, the leaching of copper, for example, was done
with acid. Not good, very not good for the environment. In fact, most leaching
technologies have resulted in toxic leftovers.

4. Well, guess what? Today approximately 10 to 20 percent of copper mined in the United
States is extracted from low grade ore with the assistance of biofilms. And mining
companies are making a considerable investment to extend this process to the extraction
of other precious metals.
How is a biofilm engineered to accomplish this job? Again, one must find a bacteria with
a particular appetite--one that would eat the ore, say, that encased copper particles, thus
releasing the copper to be recovered. This idea has led to the most common biofilm
supported leaching process, called "heap leaching." Low grade ore is placed in a "heap,"
and sprayed with a mildly acidified water solution that encourages the growth of a
particular bacteria that eats away at the ore, releasing water soluble cupric ion (copper)
that can then be recovered from the water.
Other biofilm technologies with promise
...coming soon.
Microbial fuel cells
Biofilm "traps”
Microbial "canaries"
From: http://www.cs.montana.edu/ross/personal/intro-biofilms-s3.htm