Sustainability Archive » <50K

NEW PLANT IMPROVEMENTS RESULT IN SUBSTANTIAL O&M COST SAVINGS

justin — Fri, 20 May 2011 16:47:36 +0000

The Hangtown Creek Water Reclamation Facility (HCWRF) is located in the Sierra Nevada
foothills of Northern California. The treatment plant capacity is 101 L/s (2.3 mgd) average dry
weather flow. Substantial improvements were required to comply with new waste discharge
requirements (including nutrient removal, year-round tertiary treatment, reduction of disinfection
byproducts, and effluent cooling) and a cease and desist order, sludge treatment regulations, to
address safety issues. A substantial increase in annual operation and maintenance (O&M) cost
was probable with the addition of the upgraded treatment processes and need to meet more
stringent effluent limits.
The design strategy included upgrading critical processes and replacing inefficient outdated
technology to improve treatment plant efficiency while mitigating increases in overall operation
O&M cost. Since the City service area is of limited size and the number of connections is not
growing, controlling O&M costs was a major concern of the City.

Converting Residuals To Reuse: Taking Aeration Out Of Oxidation

justin — Fri, 20 May 2011 16:47:35 +0000

Aeration accounts for up to 60% of the total energy required for a typical activated sludge wastewater plant. A new process was developed that decreases aeration demand during secondary wastewater treatment. This process, called BIOBROx, blends oxidant-laden residuals with screened municipal wastewater followed by treatment in a fixed-bed (FXB) bioreactor. Pilot testing showed that the BIOBROx process was effective at removing perchlorate and nitrate from membrane residuals. Considerable biochemical oxygen demand (BOD) and suspended solids were also removed across the process. A 3.8-mgd BIOBROx demonstration facility is now operating at the Magna Water District. The BIOBROx train treats 1/3 to 1/2 of Magna’s total wastewater flow, uses no aeration, has an empty-bed contact time of 10 minutes, and has a footprint that is one-twentieth the size of the conventional secondary processes. Preliminary data show effluent that even under these conditions, BOD5 and TSS levels in the effluent from the BIOBROx process are similar to those in Magna’s conventional secondary treatment effluent.

CSO Control, Treatment and Disinfection at Saco Wastewater Treatment Plant using Advanced Vortex Technologies

justin — Fri, 20 May 2011 16:47:34 +0000

The use of novel CSO control, treatment and disinfection systems based on advanced vortex technologies
including Vortex Flow Controls (VFC) and Hydrodynamic Vortex Separator (HDVS) that enable,
Screening, Grit Removal, Sedimentation and Disinfection to be accomplished in one vessel is described.
The application of the technologies at the Saco Wastewater Treatment Plant involves a new generation of
HDVS and vortex flow controls that regulate wet-weather flows to control maximum flows to the existing
wastewater treatment plant to avoid hydraulic overloading and the diversion of excess combined sewage
flows to the new CSO treatment facility.
The wet-weather treatment facility utilizes an advanced HDVS that incorporates a non-powered, selfactivating
and self-cleansing CSO floatables screening system; with the captured pollutants comprising
sewer debris and solids including sediments, settleable organic solids and floatables, being returned to the
headworks at the treatment plant and the clarified, screened and disinfected overflow being discharged to
the receiving environment (Saco River), after de-chlorination.
The ability to perform several essential unit processes (i.e. Screening, Grit Removal, Sedimentation and
Disinfection) all in one vessel resulted in significant savings in the overall project scheme costs on
account of the more compact design of the advanced HDVS system coupled with the elimination of
additional tanks and vessels that would have been required with the conventional approach. Analytical
results from post-construction compliance monitoring have confirmed the efficacy of the advanced vortex
technologies.

Improving Nutrient Removal While Reducing Carbon Footprint at Three Swiss WWTPs Thanks to Advanced Control

justin — Fri, 20 May 2011 16:47:05 +0000

Aeration consumes about 60% of the total energy of a WWTP and therefore makes up for a
major part of its carbon footprint. Introducing advanced process control can help plants to reduce
their carbon footprint and at the same time improve effluent quality through making available
unused capacity for denitrification, if the ammonia concentration is below a certain set-point.
Measuring and control concepts are a cost-saving alternative to the extension of reactor volume.
However, they also involve the risk of violation of the effluent limits due to measuring errors,
unsuitable control concepts or inadequate implementation of the measuring and control system.
Dynamic simulation is a suitable tool to analyze the plant and to design tailored measuring and
control systems.
During this work, extensive data collection, modeling and full-scale implementation of aeration
control algorithms were carried out at three conventional activated sludge plants with fixed predenitrification
and nitrification reactor zones. Full-scale energy savings in the range of 16-20 %
could be achieved together with an increase of total nitrogen removal of 40%.

Removal of Emerging Contaminants to Obtain Aquifer Recharge Credits in Broward County: Compliance with the Future Regulatory Provisions

justin — Fri, 20 May 2011 16:02:53 +0000

The Town of Davie, FL, is evaluating the feasibility of an upgrade its System II Wastewater
Treatment Plant (WWTP) with tertiary treatment to promote indirect potable reuse and obtain
aquifer recharge credit in Broward County. Florida Department of Environmental Protection
(FDEP) requires the evaluation and piloting of any advanced treatment technologies that plan to
engage direct recharge to the Biscayne Aquifer. Chapter 62-610, Part V, F.A.C mandates the
evaluation of such technologies via a pilot study to show the compliance of the reclaimed water
with groundwater recharge standards.
AECOM is currently conducting an advanced treatment pilot study for the Town consisting of
Ultrafiltration (UF), Reverse Osmosis (RO) and Ultraviolet Light/Hydrogen Peroxide (UV/H2O2)
processes. This study is intended to evaluate the feasibility of this process for compliance with
the FDEP and Broward County Environmental Protection Department (BCEPD) regulations for
direct recharge to the Biscayne Aquifer.

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.

Lake Concord Stormwater Park – A Water Quality BMP Showcase

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

The Lake Concord Stormwater Park project is located in the urban core of the city of
Casselberry. Part of Casselberry’s “City Center” concept, the park is a combination of urban
community redevelopment and stormwater/water quality retrofits with an educational
component. The park showcases multiple stormwater best management practices (BMPs),
including detention, exfiltration, baffle boxes, pervious pavement, bioretention, environmental
swales, stormwater reuse, native and water efficient plantings, and wetland restoration through
shoreline and littoral revegetation. Educational signage within the park describes each BMP
employed, and also provides visitors with information on broad watershed/water quality issues
and practical BMPs they can use in their own backyards. Because the park is a redevelopment
project within a highly urbanized area, its design and construction posed several challenges and
resulted in several lessons learned that can be applied to redevelopment.

Green Roof Technology as a Stormwater Best Management Practice

justin — Fri, 20 May 2011 15:57:43 +0000

Many older cities have antiquated sewer systems that are unable to accommodate increasing
amounts of impervious surface runoff from urban expansion. Excess stormwater runoff often
causes systems to become overwhelmed resulting in untreated raw sewage spills into lakes,
streams, and rivers.
Installation of green roofs addresses this problem by using plants to cover the roofs of buildings;
providing runoff control as well as lowering the amount of radiant heat absorbed by the roof.
Green layered roofing systems absorb water that otherwise would have become runoff and
entered the sewer system, reduce runoff flow rates, delay peak flows and, possibly, improve the
water quality of runoff. Quantitative information is presented on the long term performance of
two different green roof technologies in terms of initial runoff retardation, maximum peak flow
retardation, and quantity of flow as compared to companion control roofs located in the
Pittsburgh, Pennsylvania area.

Remarkable Turnarounds in Good Times and Bad: Engaged Workforce Leads a Change from Good to Great!

justin — Fri, 20 May 2011 15:57:23 +0000

Through a process of management changes, employee engagement and adopting a performance
culture, a small utility transformed itself from near financial ruin to a utility known nationwide as
one of the best small companies to work for in America. By following the simple steps outlined
in this article, Utilities across the country can follow this model to build their own winning
workplace.

OVERCOMING CHALLENGES ASSOCIATED WITH IMPLEMENTING ODOR CONTROL IMPROVEMENTS – A CASE STUDY

justin — Tue, 03 May 2011 20:15:18 +0000

The 1.8 MGD (ADWF) Sausalito-Marin City Sanitary District (SMCSD) wastewater treatment
plant is situated on a small (approximately 2.5-acre), constrained site on the San Francisco Bay.
The plant has numerous odor sources that impact nearby residents and cause odor complaints.
Spray masking agents installed in 2003 and liquid phase treatment systems have been marginally
effective in controlling offsite odors. Customer surveys determined that odor control from the 50
year-old treatment plant was an important community goal and SMCSD Board of Directors
authorized funding and implementation of state of the art odor control measures.
An odor study was completed in 2004 that identified the major odor sources at the plant and
made recommendations for odor control improvements. The SMCSD initiated an odor control
improvements project immediately thereafter for addressing and controlling plant fugitive odor
emissions. The initial concept design phase selected biotechnology as the preferred odor control
technology based primarily on performance, safety, and ease of operation.
During the detailed design phase several significant challenges surfaced, including the extremely
limited footprint available at the site for new odor control facilities. This challenge was met by
selecting small footprint bioscrubbers that would be installed on the roof of an existing control
building. This decision triggered a seismic analysis of the existing control building (constructed
in 1981), since local seismic criteria had since changed significantly since it was constructed.
Structural roof improvements were implemented, coupled with the selection of multiple lightweight
bioscrubbers (to spread the load). Roof weight limitation, equipment comparative
performance assessment, and schedule issues drove the project to procure the bioscrubbers via a
sole-source arrangement. Ongoing plant improvements that were impacting detailed odor control
design had to be carefully coordinated.
Two major design changes produced a significant cost savings for the project. First, a decision
was made to reduce the primary clarifier cover to a launder-only cover. This accomplished a
desire of plant staff to minimize confined spaces (for ease of maintenance and renewal and
replacement efforts). In addition, there was an expected benefit that planned ferric chloride
addition to plant influent would have on both primary clarifier performance and reduction of
hydrogen sulfide (H2S) related odors. Second, the design team reversed the fixed film reactor air
flow (air flow was changed to a vertical downward direction)_in order to delete the requirement
for a fixed film reactor cover from the project (the downward flow pattern was expected to
reduce fugitive emissions from the open top). These cover cost savings alone were realized at
over $300,000 for the overall $1.5 million dollar project.
During the construction phase of this project additional challenges surfaced, including an
accelerated deteriorating vehicle access causeway that required the contractor to adjust
construction work approaches. In addition, due to limitations related to access at the plant, an
ocean barge and crane was used via San Francisco Bay to hoist the bioscrubber equipment onto
the roof of the existing control building. Finally, more stringent plant effluent permit
requirements imposed by the local water board required that treated plant effluent, designed to be
utilized for bioscrubber irrigation, be chlorinated to greater than 5 parts per million (ppm) Cl-, a
level exceeding that recommended by the bioscrubber manufacturer. This required that a
separate non-chlorinated pumped irrigation system (secondary effluent) be implemented as both
an irrigation and nutrient source.
The various challenges encountered during implementation of the odor control improvements at
the SMCSD were met with ingenuity, creativity and perseverance by both plant staff and the
engineering consultant. This allowed the project to move forward, meeting both schedule and
budget constraints, and accomplish the project goal of mitigating offsite odors while building
community trust and demonstrating that SMCSD is acting as a good neighbor.