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Hampton Roads Sanitation District is a regional sewer authority
in Virginia with 13 regional wastewater treatment plants.
Their service area, which has a population of 1.6 million,
includes 17 cities and counties—virtually the entire
Tidewater Region, from Virginia Beach to just east of Richmond.
HRSD has the capacity to treat up to 230 million gallons of
wastewater per day.
Within the district, the York River Treatment Plant is adjacent
to a large oil refinery currently owned by Giant Industries
Inc., a mid-sized refiner located just across a tidal creek
from the York River Treatment Plant. The refinery had contacted
HRSD about using its treated secondary wastewater effluent
as a water source for certain industrial applications. Engineers
involved in the project spent a number of years researching
alternatives and negotiating a contract. The current water
reclamation project was put online in 2002, and has been operating
successfully for three years.
The project already has received several awards, including
the Water Reuse Association’s 2003 “Outstanding
Project of the Year,” and the American Council of Engineering
Companies of North Carolina’s 2004 “Honors Award
for Engineering Excellence.”
“We’ve been very successful with this pilot project,”
says Bruce Husselbee, P.E., a civil engineer who was HRSD’s
project manager for the reclamation initiative. “We were
able to meet our schedule for the project, be online by our
deadline of July of 2002, and meet our cost goals. The water
quality has been better than that which was needed by the
refinery.”
The Giant Industries refinery uses the water for a number
of process and service applications. It is also experimenting
with using it for cooling water. “They have been so satisfied
with the results that they are now looking at using reclaimed
water for this additional application,” says Husselbee,
who was recently promoted to director of engineering for HRSD.
“If Giant Industries decides to proceed with the new
process application, it would expand their demand for water
from the half million gallons per day that they now use to
approximately one million gallons per day.”
The York River Water Reclamation Project is the first of
its kind in the Commonwealth of Virginia. Although there are
other indirect water reuse projects, this was the first permitted
industrial water reuse project.
North Carolina, Florida, and California have had water reuse
plants that have been running for many years now. “These
states have taken things much further than we have,”
Husselbee says. “This is primarily because of the cost
of their water and their inability to discharge their wastewater
treatment plant effluent to acceptable outfall locations.”
When work started on the reclamation facility, those involved
realized they were working under a tight schedule. “One
of our main goals was to complete this plant by July of 2002,”
Husselbee says. “We also wanted to make sure that as
a municipal organization we recovered all of our costs. We
negotiated a contract with the refinery prior to having the
facility built. We were a little anxious because we knew conceptually
what we were going to do, but we had to agree to a rate prior
to building the facilities and operating them. Because it
had never been done before, our cost estimates were very rough.
There wasn’t a database that we could use as a basis.”
The initial work on the fee structure has proven to be well
worth the effort, however, and provides a means for Giant
Industries to reduce its cost for process water by 50% while
allowing HRSD to completely cover its costs for production
of reclaimed water.
The primary goal of the project was to produce a high-quality
process water to replace expensive potable water for a variety
of process-related operations at the refinery. Those involved
with the project wanted to be certain that the water quality
met the requirements set by the refinery in the initial agreement,
including concentrations of such parameters as biolochemical
oxygen demand (BOD—a measure of organic matter present
in the water), total suspended solids (TSS), ammonia, turbidity,
and fecal coliform bacteria. “To date we have actually
met and exceeded expectations on all parameters,” Husselbee
says. “The refinery is now looking to use more of our
reclaimed water.”
Giant Industries currently uses the water it obtains from
the York River Treatment Plant for service applications such
as cooling, firewater, odor scrubbers, and various internal
process streams. Giant is also experimenting with using the
water in its boilers. In this application, the reclaimed water
would replace potable water now being used for cooling hot
water generated in the oil refining process.
The refinery first contacted HRSD about eight years ago as
the costs for potable water continued to rise. They wanted
to control costs and to ensure that they had enough water
for their needs. HRSD currently charges the refinery $1.50
per 1,000 gallons for reclaimed water. The refinery was paying
$3.50 per one thousand gallons for potable water when the
project began.
The total cost of the project—including construction,
engineering, administration and legal fees—was $3 million.
HRSD funded the project using a 20-year, low-interest loan
from the Virginia Water Facilities Revolving Fund. Giant Industries
compensates HRSD based on the volume of reclaimed water used
by the refinery. The fee paid covers both capital debt repayment
and on-going operations and maintenance costs.
The Commonwealth of Virginia’s regulators had to approve
the project prior to commencement of the design as well as
construction. George Kennedy, one of the environmental scientists
in HRSD’s water quality department, was the chief champion
of the project. Kennedy negotiated with the oil refinery,
performed conceptual work, and handled many other aspects
of the project. HRSD’s treatment department also has
been critical to the success of the project. They were actively
involved in planning and construction, and now operate and
maintain the reclamation facility. Richard Baumler, P.E.,
chief of North Shore Treatment, oversaw the treatment end
of things.
HRSD pumps primary effluent from its conventional activated
sludge plant to the new reclaimed water “side-stream
process,” consisting of a sequencing batch reactor (SBR),
and a cloth disk filtration process prior to disinfection
with sodium hypochlorite. The finished water is of high quality
and can be used directly by the refinery to replace potable
water for odor-scrubber and cooling-tower make-up. The reclaimed
water is pumped from the York River Treatment Plant through
an 8-inch transmission main that was directionally drilled
under Back Creek and into a 2-million-gallon storage tank
located on the refinery property.
During the three years the plant has been in operation, it
has only been down twice. On those occasions the plant was
down for less than a few hours. “We have been able to
consistently provide high quality water to the refinery,”
says Husselbee.
Actual construction costs exceeded the preliminary estimates,
primarily because the project had to be constructed in phases
using two different contractors to meet the schedule for production
of reclaimed water. The original design concept was changed
to allow HRSD to feed either primary effluent or disinfected
secondary effluent to the reclaimed water side-stream treatment
process. This provides additional flexibility for stable operation,
but increased the cost of construction. The annual operation
and maintenance costs of the facility are 50% of the original
estimates due primarily to lower labor and maintenance requirements.
The current average daily production capacity of the new facility
is 500,000 gallons of water per day, and Giant Industries
has used 417 million gallons of reclaimed water to date.
“The Commonwealth of Virginia is now in the process
of drafting water reuse regulations—though they haven’t
yet been adopted—for future projects such as ours,”
says Husselbee. “They have been very much in favor of
our project, as is evidenced by their low-interest loan, which
was used for construction. We are also using our York River
Water Reclamation Project as a demonstration for businesses
and industries throughout Hampton Roads. By proving the potential,
we hope to encourage others to pursue water reuse projects.”
According to Kennedy, HRSD is hoping that this will lead
to a variety of initiatives at multiple treatment plants.
“We are discussing several possible reuse projects with
US Navy facilities in our service area,” says Kennedy.
“Irrigation is another use under consideration. A major
power plant is also contemplating the use of about 1 million
gallons per day of reclaimed water in a planned stack-scrubber
system. That project would accomplish two environmental objectives
by using treated wastewater to clean the air.”
HRSD is actively seeking other projects that, like the York
River initiative, can be accomplished at no cost to its ratepayers.
“Our organization is very interested in the concept of
water reuse and the resulting environmental benefits,”
Kennedy says. “Water reclamation not only conserves potable
water, it also reduces nutrient discharges to waterways.”
Water reuse, he contends, is a way to provide for reasonable
growth while also protecting water quality in the Chesapeake
Bay. HRSD’s ultimate goal is to recycle all of the wastewater
they treat at all of their plants. Though Kennedy admits they
may never achieve that, it is a long-term goal nonetheless.
From an environmental standpoint there are two big advantages
of the York River Water Reclamation Project. The first is
that the water piped to the refinery is water that isn’t
being discharged to the York River, which reduces nutrient
loads in the Chesapeake Bay watershed. Secondly, providing
water to the refinery reduces the demand for potable water,
and frees that valuable resource for other customers. This,
in effect, increases the capacity of the region’s potable
water purveyors to meet the needs of growing communities.
Firm Works on Design-Engineering
McKim & Creed, the engineering and surveying firm headquartered
in Wilmington, NC, that worked on the project, is involved
with many reclaimed water treatment facilities. It started
working on reclaimed water projects in its Florida offices
more than 10 years ago. With an exploding population in Florida
and a shortage of potable water, that state has had to find
other water sources for lower-grade uses, such as irrigation
and cooling towers. From the standpoint of discharge, and
reusing the water, the limiting factor is the amount of nutrients
that can be discharged to the surface water. By taking this
water and putting it to a beneficial reuse somewhere else,
it takes it out of the streams. That means fewer pounds of
nutrients being added to the environment and the creation
of more future capacity.
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| Area where HRSD employees monitor the flow of reclaimed water. |
The HRSD project was somewhat different from most projects
the firm does in that it was the first industrial reuse project
in Virginia. At the time it was started, there weren’t
even any reclaimed water reuse regulations in place. Preliminary
guidelines were being drawn up. There was nothing hard and
fast to go from. “What made this project interesting
was the fact that we had to form a partnership with not only
the utility and the industry,” says Kevin Eberle, P.E.,
project manager with McKim & Creed, “but we also
had to have the state regulators on board to make sure that
the end-product could set the stage for anything that comes
out afterwards. It was interesting trying to come up with
a reasonable set of criteria that everybody could live with.”
The partnership decided early on that HRSD would not need
to provide the stringent level of treatment that is required
for reuse in some states. Giant Industries proposed to use
the reclaimed water primarily for make-up to their odor-scrubbing
process, to remove exhaust gases from the refining process,
and for fire protection. “On the other hand, because
the reclaimed water was to be used exclusively for industrial
reuse, contaminants such as ammonia had to be removed to extremely
low levels to prevent corrosion to existing process units
and piping,” Eberle says. “Yellow metals in particular
are susceptible to ammonia corrosion.” In addition, it
was necessary to maintain minimum chlorine residual in the
reclaimed water delivery system to prevent growth of bacteria
in the system that could damage cooling towers. “Thus
the treatment issue in this case was driven more by what the
industrial requirements were for the odor-control scrubbers
at the oil refinery than by regulatory.”
The Key Component: SBR
McKim & Creed ended up designing a sequential batch reactor
(SBR) sidestream treatment process to remove ammonia from
the wastewater via biological nitrification. It looked at
a chemical process to do the same thing, with extensive bench
testing, but rejected it because it ended up with dissolved
solids in the solution that formed scale on the scrubbers.
“In the end, the biological solution made the most sense,”
Eberle says. “An activated sludge process, designed so
that it would grow nitrifying bacteria, is what we finally
went with. We basically cultured specific bacteria to accomplish
biological nitrification.”
The SBR incorporates the ability to biologically select specific
bacteria by sustaining specific conditions that favor growth
and development of the desired species. The first cycle in
the SBR therefore incorporates a period of low dissolved oxygen
concentration to discourage the growth of filamentous bacteria
and other heterotrophic aerobic bacteria that normally out-compete
the nitrifying bacteria. The nitrifying bacteria are then
retained in the system longer by increasing the sludge age.
In addition to chemical and biological solutions, the engineering
firm, as part of their preliminary evaluation, also evaluated
the possibility of retrofitting the existing treatment plant
processes to achieve full biological nitrification. Although
converting to a step-feed aeration process was considered
to be a viable alternative from a technical standpoint, it
would have cost significantly more in annual O&M. Retrofitting
the entire 12-million-gallon-per-day plant for full biological
nitrification could not be justified, since initially HRSD
could only provide 0.5 MGD. In the end it turned out to be
more economical to simply build a small side-stream process
on the same site and just treat to a little higher quality
level. “In effect, we had a treatment plant within a
treatment plant,” says Eberle. “We’re taking
part of the wastewater and we treat it together through the
primary clarification process, which removes coarse solids,
before splitting off a side-stream—one half million gallons
per day—and feed an SBR that we built onsite. The SBR
is a conventional activated sludge process designed to biologically
oxidize wastewater organic matter and accomplish biological
nitrification to convert ammonia to nitrate.”
Although SBR technology is well proven, the system HRSD built
was specifically designed for this application based upon
the effluent requirements. Most municipal waste processing
systems are not required to fully nitrify ammonia from the
system. “Typically, nitrate is not a problem for most
industrial odor control and cooling tower equipment”
says Eberle.
The cloth disk filter used to polish the finished reclaimed
water utilizes the latest technology. Eberle compares this
felt disk structure to a bicycle tire with spokes. Wrapped
around the outside is a polyester filter-fabric material.
This AquaDisk filter is manufactured by Aqua-Aerobic Systems
Inc.
Aqua-Aerobic’s Role in the Project
HRSD selected Aqua-Aerobics based on a prequalification process
followed by competitive bids for equipment. The company had
to sign a performance guarantee to ensure it could achieve
the effluent quality required for the reuse application, including
an effluent turbidity of less than 5 NTU, ammonia less than
2 mg/l, total phosphorus less than 2 mg/l, TSS less than 10
mg/l, and a COD of less than 40 mg/l.
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| HRSD's York River Treatment Plant and Giant Industries' Yorktown refinery. |
Once selected in November 2001, Aqua-Aerobics began working
directly with McKim & Creed to ensure the design was fully
compatible with all the Aqua Aerobics–supplied equipment.
The design was completed in January 2002, competitively bid
by General Contractors in March, and the system was started
up and producing complying reclaimed water in July 2002.
This job was unique for Aqua-Aerobics, because it was set
up for boiler and feed-water applications. It also found the
project something new in that this was a “side-stream”
project, where only a fraction of the flow that is needed
is taken as opposed to the whole flow. “Since this project
was a high-profile reuse application, we were excited to be
involved in the project for that reason as well,” says
Paul Klebs, senior applications engineer at Aqua-Aerobics.
“We actually profile this plant as part of our seminar
program, showing photos and discussing it when we are talking
about reuse.”
Aqua-Aerobics has been in business since 1969. It has offered
SBRs since 1987 and have offered its cloth media technology
since 1992. The company has roughly 800 sequencing batch reactor
installations and 500 cloth media installations. Many of the
projects the company supplies its line of filters to are located
in Florida, California, and—more recently—New York.
This same technology is being used across the US, especially
in drought-stricken areas and places where there is high demand
for reuse. “The need is ever-growing and we are applying
the same combinations of technology in a lot of different
places,” Klebs says. “The economics of the Virginia
project are such that it was quite economical for this industry
to use this reuse water to the tune of paying less than half
of what they would have been paying, as well as benefiting
the district by having Giant Industries pay for the construction
and operation of this York River Water Reclamation Facility.
Other opportunities like this are available around the country.
It is just a question of getting the right people to talk
to each other.”
PETER HILDEBRANDT writes extensively on engineering and
scientific subjects.
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- September/October 2005
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