CU-Boulder technology could make treatment and reuse
of fracking wastewater cheaper and simpler
Feb. 24, 2015
Casey Forrestal/Zhiyong Jason Ren
Treating an estimated 21 billion barrels per year of wastewater from oil
and gas operations in the U.S. is an expensive and time-intensive process.
But CU-Boulder technology could change that. University engineers
have invented a simpler, cheaper process that can simultaneously remove
both salts and organic contaminants from wastewater, all while producing
additional energy, says Casey Forrestal, a CU-Boulder postdoctoral researcher
in environmental and sustainability engineering.
CUT 1 “What we do is, we use this fuel cell system that converts stored
chemical energy which gets converted into electrical energy using microorganisms and then that energy is then used to desalinate salt water – insitu - meaning inside the reactor.” (:22)
The new treatment technology, called ‘microbial capacitive
desalination,’ uses microbes to feed on energy-rich hydrocarbons found in the
wastewater. As they feed the microbes release energy that is used to create
positively and negatively charged electrodes in the battery-like cell, says
Forrestal.
CUT 2 “The way that the microbes work is they need to eat and breathe.
Instead of breathing air just like we do, they actually breathe to an electrode - to a solid surface that takes those electrons. (:16) And then this specialized
fuel cell operates also in the same manner where it’s eating this food, the
waste product, and then generating this electricity and we use oxygen from
the air to complete the circuit to generate this electrical power.” (:33)
Forrestal says the generated power is then used to remove the salts
from the wastewater.
CUT 3 “It’s actually a two-step process where the microorganisms are actually
generating the electricity and then we use the secondary process called
‘capacitive deionization’ inside the reactor to remove the salts. (:14) So the
microbes, per say, are not actually removing the salts, but they are generating
the energy required to remove the salts.” (:22)
The result is water clean enough to meet discharge standards and only
another step way from being clean enough for agriculture use or even
drinking water, says Forrestal.
CUT 4 “The water is not potable at that point coming out of the reactor but
because we’re generating external electricity we can actually use secondary
processes to treat the water to any level we need. It could be potable or for
agricultural purposes.” (:16)
If the water can be treated inexpensively enough, oil companies could
reuse the water instead of injecting it into deep wells -- an expensive,
environmentally sensitive and controversial practice -- says co-researcher
Zhiyong Jason Ren, a CU-Boulder associate professor of environmental and
sustainability engineering.
CUT 5 “The water is precious resource for everybody, including them, so they
want to reuse the water as much as they can so they don’t need to buy fresh
water every time and they don’t want to lose water permanently to deep
wells. (:14) If we can help them reuse the water that saves them money.” (:17)
Forrestal says the CU-Boulder research team came up with this
simplified treatment system after investigating similar technologies.
CUT 6 “People have been thinking about this issue for a long time and
working on a lot of different technologies. What we did was we tried to come
up with a way in which we could integrate some existing technologies into a
single system that could then perform the desired function. (:18) We felt like
we had a real interesting niche in that we generate the electricity ourselves
and we can desalinate it.” (:26)
To try and turn the technology into a commercial reality, Ren and
Forrestal have co-founded a startup company called BioElectric Inc.
To determine if the technology offers a viable solution for oil and gas
companies, the pair first has to show they can scale up the work they’ve been
doing in the lab to a size that would be useful in the field.
The cost to scale up the technology also needs to be competitive with
what oil and gas companies are paying now to buy water to use for fracking,
Forrestal said.
-CU-