Application of Bioreactor Systems to
Low-Concentration Perchlorate-Contaminated Water:
PHASE 2- Pilot Scale Tests
Funded by: American Water Works Association
Research Foundation, November 15, 2000 - November 14, 2002.
Principal Investigator: Bruce Logan, Kappe
Professor of Environmental Engineering.
Contractor for Field Tests: Camp, Dresser and McKee; Steven
Price, project manager.
Contact information: Phone: 814-863-7908, Email:
of the Phase I project was to evaluate three different fixed-film
biological treatment processes at the bench scale in order to
determine their feasibility for being scaled up to treat large
quantities of perchlorate-contaminated water to drinking water
levels (<18 ug/L). These treatment systems were: a packed bed (slow
sand or GAC filter) amended with soluble substrates (acetate,
lactate, methanol, and ethanol); a hydrogen gas fed four-phase
(hydrogen gas, water, biofilm, and support media), unsaturated
trickle-type packed column; a membrane-bound biofilm reactor. Based
on bench tests, we were to estimate the costs of treating waters
using in full scale systems and to recommend one of these treatment
systems for pilot-scale testing at the Crafton-Redlands site in
All three systems successfully
removed perchlorate at rates sufficient to achieve an acceptable
level of perchlorate removal for subsequent treatment for potable
use. Our economic and engineering analysis indicated that the
least-expensive, most reliable system was an acetate-fed packed bed
reactor. The packed-bed sand reactor achieved the highest
perchlorate removal rates of the three systems. In addition, there
was a precedent for using an acetate-fed biological reactor for
drinking water treatment in the U.S., making it likely that a
reactor of this type would gain public acceptance. Nitrate has been
treated using an acetate-fed packed bed reactor for drinking water
pretreatment at a site in Coyle, Oklahoma. In addition, biological
denitrifying systems have been successfully used in Europe for
several years. The wider acceptance of biologically activated
filters in the U.S. also points to new trends in the acceptance by
water utilities to incorporate biological treatment into drinking
water treatment trains. These factors, coupled with a national trend
towards "green engineering" and sustainable technologies, suggests
that an acetate fed bioreactor is a feasible perchlorate treatment
The primary purpose of Phase 2 will
be to conduct pilot-scale testing at the Crafton-Redlands site in
Redlands, CA, of an acetate-fed, packed-bed bioreactor, referred to
here as the Penn State University Perchlorate Treatment (PSU-O4)
System. To fully evaluate scale up and operating considerations, we
will field test two acetate fed reactors, one packed with sand and
the other with plastic media.
The Crafton-Redlands groundwater source contains
necessary trace minerals for biological growth of perchlorate-reducing
bacteria. However, in addition to perchlorate, it contains as
competing electron acceptors, dissolved oxygen and nitrate-nitrogen.
Dissolved oxygen is the preferred electron acceptor and the system
is designed to biologically remove this first in the treatment
system. As flow progresses through the reactor, nitrate and
perchlorate will be simultaneous removed by the perchlorate-acclimated
culture. All three electron acceptors will be removed in the fixed
bed reactor by adding an electron donor (acetate) at sufficiently
high concentrations to ensure their complete removal. A small amount
of ammonia phosphate and ammonia-nitrogen may be needed to satisfy
bacterial nutritional requirements. Residual electron donor in the
effluent will be removed in a post treatment system (biological
The major questions, or outstanding issues, that
will be addressed during this phase of the project are:
What are the major design criteria for
facilities to reliably remove perchlorate with the tested
How much will the facility cost to construct
and operate? Costs of the various processes tested can then be
compared with each other to determine what is the best approach
to treat perchlorate-laden waters.
How much time is needed to stabilize the
How difficult will it be to operate? For
example, is it more difficult to operate and maintain process
stability than a POTW wastewater treatment facility?
What are the auxiliary needs for this
process? Do we need to treat the waste product before
discharging to a sewer or stream?
What treatment processes are needed
downstream of the bioreactor to produce water that meets
drinking water standards?
What will the primacy regulatory
agencies require to approve this process?
One student, Mr. Booki Min, is working on this
project at Penn State University with Dr. Logan.
|Mr. Booki Min (email@example.com)
has shown in the laboratory that it is possible to remove
perchlorate from a natural groundwater sample. He is now
working on settinb up and testing (at the Redlands site in
Calirfornia) a pilot scale bioreactor as a part of this
Phase 2 research project. This pilot-scale reactor project
is being conducted with the City of Redlands and the
engineering firm of Camp, Dresser and McKee.