|
Membrane bioreactor (MBR) technology is being used for municipal
and industrial wastewater treatment in many locations across
the country and around the world. This emerging technology
shows particular promise due to its reduced footprint, simplified
process train, and consistently high effluent quality. Thus,
MBR is a treatment option that offers several advantages over
conventional systems.
Advances in this technology continue to occur while more
knowledge is gained concerning key factors that assure successful
installations and optimization of processes. However, the
cutting-edge nature of this technology, varying levels of
experience among manufacturers, and the manufacturers’
equipment differences create an uneven playing field that
can cause problems when using the conventional design-bid-build
(DBB) approach to procurement.
An agency attempting to take full advantage of this MBR technology
will benefit by asking a series of questions.
Inherent Problems
What problems are inherent in using the conventional DBB approach
for procuring an MBR facility? Many of the problems encountered
with the DBB procurement process are linked to (1) a lack
of equipment knowledge, (2) manufacturers’ equipment
differences, (3) limited operational experience, and (4) the
failure of DBB to address operations and maintenance (O&M)
costs.
MBR is a competitive field and manufacturers are seeking
to gain a marketplace advantage by applying proprietary knowledge
developed through years of research and applications. Unfortunately,
due to the openness of the DBB approach, a manufacturer is
less willing to share this information with the design engineer
because this would leak valuable information to his competitors
and reduce his competitive advantage. Additionally, there
is no guarantee that the manufacturer would benefit from a
sale. In the end, this lack of knowledge can result in substandard
installations or incompatible treatment process components,
causing the system buyer and user to suffer with inefficiencies
and less than optimal treatment facilities.
The DBB process ignores differences in manufacturer’s
equipment by making the MBR a generic “black box.”
These differences can create a situation in which the manufacturer’s
equipment interfaces differently with other processes and
process equipment. The specific ancillary processes/process
equipment that works best for one MBR manufacturer’s
equipment may differ from the specific ancillary processes/process
equipment that works best for another.
For example, the optimal screening mechanism for MBR Manufacturer
A features 1-mm openings, whereas the optimal screening mechanism
for MBR Manufacturer B features 3-mm openings. Therefore,
using a conventional DBB approach, in which screening equipment
is limited by design specifications, may result in one MBR
manufacturer being unwittingly favored over another. Importantly,
a more suitable overall treatment train could have been developed
had the differences in MBR equipment been taken advantage
of.
The DBB approach does nothing to ensure competent and reliable
long-term operation after construction is complete. Given
the cutting-edge nature of this technology, there are a limited
number of operators with experience operating these advanced
technology facilities. The lack of expertise can lead to O&M
errors, potentially resulting in process failures. This issue
might be overcome by outsourcing the O&M function. However,
that would require more administrative action, possibly another
bid/interview process, beyond the bid that was already undertaken
to construct the facilities.
A conventional DBB approach creates competition among bidders
with the goal of ensuring cost-effective construction of facilities.
This approach, however, does nothing to address the long-term
O&M costs that will be associated with the facilities
in the future, nor does it allow the examination of life-cycle
costs in determining which MBR equipment to choose.
There are several characteristics of MBR technology that
make O&M costs a major consideration in the life-cycle
costing of a facility: expected life of the membranes, extent
of process automation and operator involvement, and energy
use. By ignoring these factors, the system purchaser may be
saddled with a process that requires huge infusions of capital
(e.g. membrane replacement) to maintain effective and reliable
operations that could dramatically increase the life-cycle
costs of the facility.
So, approaching the procurement from a conventional DBB standpoint
leaves the agency purchasing the MBR with a system that is
potentially
- substandard and inefficient;
- not the most suitable for the application;
- difficult to staff with adequate O&M personnel; and
- expensive to operate and maintain.
What Alternatives Are Available?
A different project delivery approach is the design-build-operate
(DBO) method. From the purchaser’s point of view, this
approach involves
- outlining project performance requirements and expectations;
- developing a set of contract documents that reflects
those requirements;
- assigning the risk of performance, construction and operating
costs to the DBO entity;
- pre-qualifying DBO entities;
- evaluating and selecting the best DBO proposal; and
- monitoring facility construction, startup, and performance
of the process, and the charges from the DBO entity.
How Will DBO Address the Difficulties Identified?
The DBO approach solves the problem of limited sharing of
technical knowledge. Both the engineer and manufacturer are
working together as a team to develop a design that optimizes
the MBR equipment to its full potential. The manufacturer’s
knowledge can be applied under this DBO team-oriented arrangement
to maximize the team’s chances of success.
The difficulties associated with differences in equipment
are resolved in the DBO approach. Each design is tailored
to optimize the MBR process being featured. In the DBO approach,
the MBR “black box” is not forced into a design
that may or may not take advantage of its full potential.
Since the DBO process integrates design, construction, and
anticipated operation from the very beginning, the approach
allows the manufacturer the opportunity to surround equipment
with processes that best complement its function.
By its nature, the DBO process places the role of O&M
squarely on the shoulders of those most familiar with the
equipment and its nuances, dramatically increasing the opportunity
for successful long-term operation. Given the evolution of
the technology involved in MBR, the association of the manufacturer
with the O&M of the equipment becomes even more important
than with a more conventional technology.
The potential for outsourcing of the operations function
was discussed earlier, in conjunction with the DBB approach.
However, outsourcing brings with it the difficulty of procuring
economical O&M services once a plant has been designed
and constructed by a third party. The DBO approach avoids
this problem by locking in operations as part of the initial
DBO package.
Optimizing long-term O&M and life-cycle costs is directly
addressed in the DBO process. As part of determining the most
suitable MBR process, all of the construction and O&M
costs are included in the DBO proposal packages submitted
by the integrated teams. This information allows the calculation
of a project life-cycle cost based on guaranteed capital,
O&M and repair and replacement costs. Therefore, the purchaser
will avoid the potential costs of premature membrane replacement,
in addition to staff and legal time involved with determining
fault for the early membrane failure.
Are There Other Advantages to the DBO Process?
Two additional advantages of the DBO approach include the
reduction in the project implementation schedule and construction
cost savings. The advantages are not specific to the MBR process,
but are inherent in many more complex, long-term projects.
By eliminating several stages of the normal agency design
review process, significant schedule efficiencies can be realized
by using the DBO approach, in favor of the conventional DBB
process. Also, due to the integrated involvement of the contractor
and equipment manufacturer in the design, it is likely that
construction will be completed more rapidly. Furthermore,
because of the manufacturer’s involvement, problems during
the startup period will be minimized and the facility will
be ready sooner for operation. As a result, using the DBO
approach instead of the conventional approach reduces the
time—from design to startup—by three to four months.
Construction cost savings are also realized by using a DBO
procurement approach as opposed to the DBB process. The complete,
100% bid-level design of MBR facilities is not necessary under
the DBO process, as the design and contractor work on the
same integrated team. Further, by placing the design engineer,
contractor, and equipment manufacturers on the same team,
opportunities for efficient, economical construction are greatly
elevated. The contractor benefits by sharing its experience
in economical construction with the engineer, who can then
create a design that takes advantage of this knowledge without
the need for troublesome and delaying change orders. In addition,
the equipment manufacturer assists in optimizing the design
by maximizing the advantages of equipment to the fullest.
Summary
The DBO approach to MBR procurement not only avoids disadvantages
of the DBB process, but makes the best use of experience and
technology, as well as schedule and cost efficiencies that
can provide dramatic project benefits. It creates a situation
in which the water entity wins by virtue of a low-cost reliable
system, the manufacturer wins by being provided the best opportunity
to feature his equipment and, ultimately, the consumers win
through lower rates and a protected environment.
JOHN CHRISTOPHER, P.E., is with management
consulting and engineering firm R.W. Beck Inc. in its San
Diego, CA, office. KYLE RHORER is
a principal with R.W. Beck Inc. in its Sacramento, CA, office.
OW
- November/December 2005
|
