Sustainability Archive » Plant Optimization

Energy Efficiency in Wastewater Treatment In North America: A WERF Compendium of Best Practices and Case Studies of Novel Approaches

justin — Fri, 20 May 2011 16:24:35 +0000

After manpower, energy is the highest operating cost item for most water and wastewater companies.
Over the last decade, energy consumption by the sector has considerably increased as a result of
implementation of new technologies to meet new effluent and potable water quality standards. High
energy consumption will affect the water industry worldwide and is inextricably linked to the issue of
Climate Change. Through its Optimization Challenge program, the Water Environment Research
Foundation (WERF) participated in the Global Water Research Coalition’s (GWRC) project titled Energy
Efficiency in the Water Industry: A Compendium of Best Practices and Case Studies. For this project,
WERF served the role of North America practice coordinator, developing a Compendium of best
practices in the energy efficient design and operation of water industry assets for this region of the world.

Saving Millions through Resurrecting the Decommissioned Taber WWTP using an Innovative Design-Build Approach

justin — Fri, 20 May 2011 16:02:52 +0000

The upgraded Taber Wastewater Treatment Plant (WWTP) is located in Southern Alberta and
treats the domestic wastewater from the Town of Taber (Town). The plant formerly consisted of
two (2) rotating biological contactors (RBCs) and two (2) secondary clarifiers. Due to
operational issues with the RBCs and available capacity in the industrial system, the domestic
wastewater system was decommissioned in 2000 and all of the domestic sewage was diverted to
the aerated lagoons for co-treatment with the industrial wastewater. The coarse manual bar
screen at the WWTP remained operational during the time that the WWTP was not in service.
In 2006, Stantec Consulting Ltd. (Stantec) teamed up with Lockerbie Stanley Inc. (Lockerbie)
and EPCOR Alberta Inc. (EPCOR) to upgrade and expand the decommissioned Taber WWTP by
implementing biological nutrient removal (BNR) through a Design-Build-Operate-Finance
(DBOF) delivery process. The project was completed for $ 15 million compared to the original
estimate of $ 28 million. The project presented several challenges including the reuse of
decommissioned infrastructure and extremely tight hydraulics while providing a process train
that met the future growth requirements of the Town and the Alberta Environment effluent
quality standards. The construction of the project started in November 2007 and the plant was
commissioned in early 2009. This paper outlines how the existing WWTP infrastructure has
been reused and provides information on the challenges associated with the design, construction
and commissioning of the WWTP along with recent plant performance data.

Nutrient Removal Treatment Practices Implemented at the City of Los Angeles Upstream Water Reclamation Plants

justin — Fri, 20 May 2011 16:02:52 +0000

The principal source of nitrogen compounds in the Los Angeles River is from the City of Los
Angeles upstream plants, Donald C. Tillman (DCT) and the Los Angeles-Glendale (LAG) Water
Reclamation Plants (WRP’s). These WRP’s were major contributors, with up to 75% of the total
dry weather nitrogen load during dry weather periods. In 2007, the City has completed a nitrogen
removal program to reduce the nitrogen mass discharge from its WRP’s. As part of the process, a
comprehensive research effort was undertaken involving bench, pilot and full scale testing to
identify the most effective way to upgrade and optimize the existing WRP’s. The combined
findings were then used to upgrade WRP’s to “full” BNR plants without derating, carbon and
alkalinity addition utilizing the MLE (Modified Ludzack Ettinger) process. This paper will focus
on the MLE process design and treatment practices successfully implemented at the City’s
WRP’s.

Intermittent Carbon Addition Effectively Trims Effluent Nitrate

justin — Fri, 20 May 2011 16:02:52 +0000

Ongoing construction at the Robert W. Hite Treatment Facility in Denver, CO, requires taking up to 25
percent of the secondary treatment capacity off-line for extended periods of time. Weekly average effluent
limits for nitrate require diligent management of day-to-day performance to prevent excursions and
maintain consistent denitrification. Process modeling indicated intermittent carbon limitations for
denitrification during the construction period, leading to design and installation of a temporary carbon
addition system. Acetic acid was selected as a supplemental carbon source due to intermittent demands.
Performance testing of the acetic acid addition system at the RWHTF gave treatment personnel
confidence in its operation and performance. The carbon addition system assisted in maintaining
compliance with weekly nitrate effluent limits during construction and remains in occasional use. This
paper reviews the potential limiting factors for denitrification, solutions for compliance during
construction, and general criteria for supplemental carbon addition chemical selection.

Sustainable Odor Control: What’s in your Gas

justin — Fri, 20 May 2011 16:02:52 +0000

In response to population growth adjacent to the Drake Water Reclamation Facility (DWRF), the City of Fort Collins initiated an odor study to determine the impacts from the plant and identify possible odor mitigation alternatives. Subsequently, numerous technologies were evaluated based on criteria which included sustainability, constructability, and a chemical-free operation. The City’s design-build team, consisting of the contractor, engineer, and DWRF staff representatives, collaborated and selected a compost/woodchip biofilter as the most suitable technology for use. Two sets of biofilters were installed in 2007 and 2008, respectively. Since the commissioning of the biofilters, the City has tracked its performance and found that operation parameters differed from the initial design projections. This report and presentation will describe the odor study and evaluation process, as well as the biofilter design and operation. A key focus, and of direct importance to other facilities located in dry climates, will be the operational challenges and knowledge gained by DWRF staff in maintaining and optimizing the biofilters’ performance.

Leading Asset Management Practices Help Utilities Optimize Their Asset Life Cycle Cost

justin — Fri, 20 May 2011 16:02:29 +0000

The Water Environment Research Foundation’s (WERF) ongoing research program defines
strategic asset management (SAM) practices and develops tools and techniques that help utilities
implement asset management (AM) programs. EMA and partnering organizations lead this
research, which expands WERF and WaterRF’s Sustainable Infrastructure Management Program
Learning Environment (SIMPLE) knowledge base for AM in four “tracks”: (1) Public
Communication, (2) Benchmarking/Case Studies, (3) Decision/Analysis Implementation
Guidance, and (4) Remaining Asset Life. Track 2 identifies utilities’ leading AM practices and
develops utility examples, helping other utilities learn how to implement SAM. A utilities survey
identified opportunity areas for SAM and gaps for improvement. These leading practices
(validated through site visits and a leading practices research forum conducted in June 2010) can
help utilities optimize asset life-cycle cost in: Accounting and Costing, Business Risk
Management, Organization and People, Maintenance, Secondary Data and Knowledge, and
Strategic Asset Planning and Asset Management plans.

Low Cost Solutions that Combine Process Modeling, Optimization, and Pilot Testing to Comply with LOT Nitrogen and Phosphorus Standards at Two BNR Plants

justin — Fri, 20 May 2011 16:02:27 +0000

The objective of this study was to utilize process modeling to predict effluent quality at design
flow for two biological nutrient removal (BNR) facilities, and determine what additional
improvements would be needed at each facility to meet limit of technology (LOT) nitrogen and
phosphorus standards. Then, optimization, pilot-testing, and bench-testing were conducted to
support this approach.
Process modeling using calibrated BioWin models determined that side stream treatment and
equalization, supplemental carbon addition, and increased nitrified recycle (NRCY) rates would
optimize nitrogen and phosphorus removal at both plants. Zone dissolved oxygen (DO) control
will also enhance denitrification and the effectiveness of the supplemental carbon. Both plants
are also considering the Ostara process to improve BPR.

UV Disinfection: Design Optimization Tools

justin — Fri, 20 May 2011 16:02:27 +0000

The use of UV disinfection for wastewater and water reuse applications is a well-established technology
that continues to gain popularity, but it is not without its problems. In many cases, particularly in highdose,
reuse applications, facilities are not meeting their design requirements even though design flow and
UV transmittance are properly accounted for. This can occur for a number of reasons, but three likely
culprits are an insufficient UV dose, poor channel hydraulics and/or flow distribution, solids
accumulation, and sleeve fouling. Presented herein are descriptions of intelligent design tools and
practices that can be used to optimize the design of UV disinfection systems. Use of these tools may
increase the cost of design, but can also result in long-term cost savings by optimizing the equipment size,
avoiding fines associated with excursions of permit limits.

UV Disinfection Sizing: A Method for Comparing Apples to Oranges

justin — Fri, 20 May 2011 16:02:27 +0000

As ultraviolet (UV) light technology for wastewater disinfection has evolved, various methods
have been used to size UV systems to meet discharge permit requirements for bacterial limits.
Many of these methods have resulted in inappropriately sized UV systems, leaving agencies and
design engineers with the need for an objective approach. Using third-party validated bioassays
is one option; however, there are variations in the various bioassay validation methods, which
can make a direct comparison of the delivered dose among various equipment manufacturers
difficult. One of the goals of the Colorado Springs Utilities’ (SU) Las Vegas Wastewater
Treatment Facility (LVWWTF) Alternative Disinfection design build project, was to develop an
objective and comprehensive approach to evaluate the UV design dose proposed by various UV
manufacturers. This case study presents the simplified approach developed to select an
appropriate dose based on projected plant flows, third-party validation relationships, and
observed UV transmittance (UVT).

Effective Strategic Planning at Metro Wastewater Reclamation District (MWRD) – It’s All About Alignment and Execution

justin — Fri, 20 May 2011 16:02:27 +0000

In 2007, the Metro Wastewater Reclamation District teamed with Black and Veatch and Brown
and Caldwell to implement a Capital Project Management Program to manage expenditures
approaching $100M annually. As the Program began it was successful in managing many
elements across multiple areas, but over time delays began to occur in business process
improvement work and products. In order to address these problems, a best practices-based
strategic planning process was implemented to align the Program team around the Program
vision, reprioritize improvement efforts, and improve work process interaction among the team.
The ultimate goal was to establish a repeatable continuous improvement-based planning and
execution methodology to develop the annual Program Plan. Throughout 2009 the Program team
focused on implementing high priority initiatives and continuously measured performance on
objectives. The 2010 planning effort was much more efficient as the Program team embraced
this approach and adapted the lessons learned throughout 2009.