Sustainability Archive

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The design strategy included upgrading critical processes and replacing inefficient outdated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.

The Not-So-Silent Risk of Improper Controls – Water Hammer

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

Whether large or small pumps, there comes a debate when multiple drive motors are used to
cover a broad range ofoutput flow requirements: use one Variable Frequency Drive (VFD) plus
a number of softstarts, some small and some large pumps with or without VFD’s, one or more
VFD’s on a group ofpumps, and all combinations in between. Equipment rotation and
maintenance, starts per hour, starts per day, minimum flows, maximum demands, etc., all are
considerations and decisions to be made. Many of these combinations invoke unintended
hydraulic consequences. The focus ofthis paper is the benefits of synchronous, closed transition
hand-off between VFD’s and utility powered devices in multi-motor applications. Using off-theshelf,
standard, available equipment that can synchronize drive output with across-the-line loads,
the best of numerous options can be had while reducing power costs, protecting personnel and
equipment, and achieving process control.

Improving Utility O&M and Capital Decisions by Incorporating the Concepts of Asset Condition, Criticality and Risk

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

Toho Water Authority (TWA) provides water, wastewater and reclaimed water service to
approximately 85,000 customers in Kissimmee Florida. For the past three years the Utility has
been implementing an asset management program for their over $700 million dollars worth of
water, wastewater, and reclaimed water assets. During this program TWA has made significant
investments in asset management information systems including INFOR EAM Computer
Maintenance Management System (CMMS) and an ESRI Geographic Information System (GIS)
database. These two systems now contain the comprehensive asset inventory for the utility. A
built-in interface between the programs allows the CMMS and GIS to integrate and share
information.
Once the software implementation and inventory was complete, TWA wanted to obtain
additional physical, financial, and asset management attributes for their assets to support the
overall asset management program, which includes evaluating asset risk, measuring utility
performance and effectively planning for future renewal and replacement needs. The CMMS
software was configured to store the attribute data in January of 2008 after conducting interactive
workshops with staff to define the attributes. In August of 2008 a pilot project was implemented
to define the process to consistently collect and calculate the asset data including condition,
consequence of failure, risk, and replacement cost for all vertical assets in the utility. The pilot
area contained one water plant, one wastewater plant and 47 lift stations that fed the wastewater
plant. This paper will describe the methodology that was established to obtain and calculate the
data, the results of the data analysis, and uses for the data to further their asset management
program and overall decision making.

Evaluation of Onsite Sodium Hypochlorite Generation at the Blue Plains Advanced Wastewater Treatment Plant

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

Due to potential risks associated with transportation and handling of liquid chlorine, the District
of Columbia Water and Sewer Authority (DC Water), switched to the use of liquid sodium
hypochlorite as the disinfecting agent at the Blue Plains Advanced Wastewater Treatment Plant
(AWTP). The escalating cost of bulk purchased sodium hypochlorite prompted DC Water to
commission a study to evaluate disinfection alternatives that: 1) are compatible with existing
treatment processes; 2) meet all plant effluent disinfection requirements; and 3) reduce life cycle
costs of disinfection.
The study involved a detailed technical, economic and non-economic evaluation of the feasibility
of constructing and operating an onsite sodium hypochlorite generation facility in lieu of bulk
purchase. Economic analyses included capital and O&M costs, life cycle costs over a 30-year
time horizon, and sensitivity of price of bulk sodium hypochlorite and salt, electric power cost,
debt service on life cycle costs.

Decentralized Membrane Bioreactors for Water Reuse in Paulding County, Georgia

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

Before the recession, Metro Atlanta and its surrounding counties were one of the fastest growing
regions in the United States. In order to reduce the impact of treatment plant discharges on its
limited water supply and to offset water demands on potable water systems, they were
increasingly looking at water conservation and water reuse. Paulding County was one of those
fast-growing counties, consistently ranked between the 12th and 15th fastest growing counties in
the United States. Wastewater treatment facilities are among the most critical to support the
County’s rapid population increase. With tighter effluent limits on the way and a halt on surface
water discharge permits, the County had to look at alternative uses for the treated wastewater.
Several technologies were evaluated, and based on this evaluation, MBR technology became the
apparent leader. This paper provides an overview of the selection process, the procurement
process, and the performance of four MBR systems currently operating in Paulding County.

Cost Savings and Performance Improvement of Large System Iron Salt Use for Integrated Sulfide Control and Chemically Enhanced Primary Treatment by Using Peroxide Regenerated Iron Technology

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

San Diego’s Point Loma WWTP is a 160 MGD (240 MGD permitted), 100% advanced primary
treatment plant that has historically used iron salts for collection system sulfide control and
chemically enhanced primary treatment. Beginning in 2006, a PRI-SC® (Peroxide Regenerated
Iron – Sulfide Control) program was implemented by adding H2O2 at the intermediate pump
station PS2 (in place of the FeCl3), and again to the plant influent (ahead of FeCl3 addition for
CEPT). The application of PRI-SC® in the Point Loma system was designed to provide at least
$685/day in cost savings, to be achieved through reduced ferric chloride use at PS2 and Point
Loma, while improving sulfide control and CEPT performance. Since integrating the PRI-SC®
program full-time in 2008, SDMWD is realizing savings of approximately $4,700 per day
(~$1.72 million/yr) compared to the 2007 baseline iron salts program. At the same time, both
sulfide control and CEPT performance has improved. The cost savings were helped by the
hedging aspect of the PRI-SC® program – iron salt price volatility in 2008 and 2009 was
upwards of 45%. The PRI program has reduced the total iron salt use from the 2007 baseline rate
of 32.5 dry tons per day to approximately 19.3 dry tons per day in 2009, with the core savings
coming from an overall reduction in ferric chloride use at PS2 and the treatment plant (Table 1).
Significantly, ferric chloride use at PS2 was eliminated and, for CEPT, reduced from 24 mg/L to
10 mg/L (16.6 to 6.8 dry tons per day) with no loss in performance. In addition, total sulfide
removal has improved over baseline levels, and average CEPT performance exceeds the permit
levels at 89% for TSS and 65% for BOD, and effluent water quality has improved (with 60% less
spent iron (as FeS) present in the ocean discharge). For the most part, digester biogas H2S levels
were maintained below the permit requirement of < 40 ppm, but required approximately twice
the baseline FeCl2 feed rate. Even so, the overall program has maintained the stated savings
benefit.

POLYMER ADDITION COMBINED WITH RAPID DECREASE IN SOLIDS RETENTION TIME IS AN EFFECTIVE NOCARDIA FOAM CONTROL METHOD

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

In this study, Nocardia foam control using a combination of polymer addition and solids
retention time (SRT) reduction was investigated at the San Jose/Santa Clara Water Pollution
Control Plant (SJ/SC WPCP). A three-week continuous polymer addition at increased dosing
rates of 0.35 mg/l, 0.5 mg/l and 0.75 mg/l reduced Nocardia foam coverage from 100% to less
than 5%. But, foam accumulation returned to 95% coverage when polymer dosing was stopped
for a week. It only took a week to eliminate Nocardia foam from the aeration tanks when 0.5
mg/l polymer addition was accompanied by SRT reduction from eleven days to four days. A
potential effluent ammonia permit violation associated with SRT reduction was avoided by
aerating the anoxic compartment of the aeration tanks and converting the step-feed biological
process to plug flow mode. Except an increase in secondary effluent solids concentrations during
plug flow operations, polymer addition to the return activated sludge (RAS) and Nocardia
wasting to the digesters via dissolved air floatation did not cause foaming in the digesters nor
was it detrimental to effluent filtration.

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.

Digital Revolution for Water/Wastewater Utility Management; From Paper to Digital Data

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

Paper-based data is a long-term fixture of the Water and Wastewater Industry including both
Municipalities and Private Operating Companies. Transcribing handwritten log sheets into multiple Excel
spreadsheets is inefficient. It is common for monthly operation and compliance reports to take days to
compile, compared to digital systems that take minutes. Implementing a digital data solution provides a
more efficient and lower cost system with centralized information and reports.
Two questions that are addressed are how to make the transition to digital data and what kind of
technology to use. Points to consider when evaluating replacing the Operators’ handwritten log sheets
with an inexpensive, hand-held device:

Initial equipment costs
Replacement costs
Required IT support
Standard or non-standard operating system or software
Security needs
Required training

Three case studies highlight the successes realized after operations replaced traditional paper log sheets with a digital system.

Project Management – Overcoming Resistance to Change

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

The purpose of this paper is to help project managers in public agencies understand the reasons
for resistance to change and provide steps to overcome or minimize the resistance. These are
challenging times for all public agencies so there is a need to be wise stewards of public
resources. An increase in efficiency may require reorganizing departments, reallocating
resources and realigning staff roles and responsibilities and managing projects differently. These
all require change and growth from all levels of employees in an organization. Reducing the
resistance to change requires strong leadership qualities combined with proper project
management skills. If these combined skills are incorporated into projects that implement
change, they will be successful and can result in significant cost savings. The Orange County
Sanitation District (OCSD) has undergone many of the aforementioned changes in the past
couple of years and continues its austerity through efficiency while completing all tasks.