Sustainability Archive » Water Treatment

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.

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.

Solar Drying of Biosolids – Recent Experiences in Large Installations

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

The conversion of raw sewage sludge into valuable biosolids for beneficial reuse requires a
suitable pre-treatment process. However, traditional technologies are causing high investment
costs, operation costs, and energy demand; or are not fully meeting the demands of the market.
As recent experiences from the world’s largest solar drying and solar-assisted drying plants in
Palma de Mallorca, Spain and Oldenburg, Germany show, solar drying is an effective alternative
for large facilities. Drying costs and energy consumption are less than half, maintenance is low,
and operation is simple and safe at these facilities when compared to traditional thermal dryers.
Also, carbon dioxide (CO2) emissions are reduced by a factor of seven when compared to
conventional dryers. By using waste heat from other processes, the area requirement can be
reduced by a factor of three to five. The final product is suitable as fuel for Waste-to-Energy
(WTE) plants, coal power plants, or cement kilns. It can also be used as a Class-A fertilizer for
agricultural use, or land application.

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.

“Say it Loud, Say it Clear”: Effective Communication Under Duress

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

Difficult times require an extra effort when it comes to communication. With all of the talk
about layoffs, budget cuts and salary reductions, utilities face an uphill battle against the internal
“rumor mill”, declining morale during the current economic downturn, and external pressures to
do more with less. A well-developed communication strategy is one key to sustaining
performance in the face of these challenges.
The Water Distribution and Transmission Division of the Miami-Dade Water and Sewer
Department is meeting these challenges “head-on” with an aggressive communication program
that has been developed and refined over a number of years. This presentation will highlight that
program from the perspectives of the Division Chief, managers and supervisors, and employees.
Extensive interviews at various levels of the organization identified key communication
strategies and tactics that are helping this agency maintain a high level of performance through
the most significant economic crisis the US has faced since the Great Depression. These
strategies and tactics will be discussed in detail and results will be presented as a “business case”
for optimizing communication during challenging times.
Focus of Study and Results:
This presentation will include discussion in communication topic areas including:
1. General overview of communication strategies and tactics
2. Types, frequencies, and styles for effective communication
3. Directional communication – up, down, and across the organization
4. Formal and informal communication methods and tools
5. Strengths and weaknesses of various communication approaches
6. Value and results from effective communication programs

Recycled Water Corrosivity Control: The Additional Advantage of Disinfection with Sodium Hypochlorite

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

Recycled water corrosivity control is an important consideration in the design and operation of
wastewater treatment plants and recycled water distribution systems. Even mild corrosivity can
have significant long-term impacts on equipment and pipelines. Corrosivity control involves
adjustments to water chemistry (pH, alkalinity, hardness, etc.), but how adjustments are
implemented can vary based on existing treatment processes. For the Michelson Water
Recycling Plant, corrosivity control was achieved by modifying an existing process rather than
adding a new one. This paper discusses the investigation and evaluation of several treatment
alternatives for corrosivity control. The study resulted in replacing chlorine gas disinfection with
sodium hypochlorite disinfection, which offered the additional advantage of addressing
operational, regulatory, and safety concerns associated with the use and storage of gaseous
chlorine. The study highlights the connection between disinfection and corrosivity, an important
consideration for other agencies starting water recycling programs to meet increasing water
demand.

Using Whey as a Supplemental Carbon Source under Real Time Control Conditions

justin — Fri, 20 May 2011 16:47:04 +0000

The COD:TKN ratio in the influent wastewater to the J.D Phillips Water Reclamation Facility
(WRF) in Colorado Springs is too low to allow sufficient denitrification to meet the discharge
limit for pH. To reduce the reliance on adding caustic to the effluent to raise the effluent pH,
Colorado Springs Utility (CSU), began a search of local industries to find a source of local
supplemental carbon to increase denitrification, and hence alkalinity recovery. Simultaneously, a
local dairy approached CSU requesting relief from significant monthly excess BOD and TSS
surcharges. The dairy manufactures cottage cheese, producing acid whey as a waste. A full scale
pilot test was initiated at the WRF to investigate the opportunity to use whey as a supplemental
carbon source to enhance denitrification. During this test, it was discovered that fermented whey
provided superior results to unfermented whey.
The costs of implementing and operating advanced aeration control systems have to be justified
by the reduction in energy consumption and/or improvements of the effluent quality. Control
measures should also not introduce operational problems like foaming or bulking or higher green
house gas emissions (mainly N2O). In addition to the effluent pH issues, as with all utilities, CSU
is faced with reducing operating costs as much as possible. The effluent ammonia limit for the
WRF varies on a monthly basis, which raised the question – “With the use of on-line analyzers,
could the activated sludge process be operated to produce an effluent just below the permit limit
to save aeration power?” A desktop analysis using BioWin™ and the BioWin™ Controller was
performed to predict which of feed-forward or feed-back control would provide the best control.
On-line ammonia and nitrate probes were installed at various locations and programmed into the
aeration blower and mixed liquor recycle pump control systems to determine if aeration blower
airflow and whey feed rates could be optimized. This paper will summarize the results achieved
through the full scale pilot test, list future activities at the WRF and briefly discuss the outcome
of the pretreatment permit negotiations with the dairy.

GREASE CO-DIGESTION AT DALLAS WATER UTILITIES SHOWS MAJOR ECONOMIC BENEFITS

justin — Fri, 20 May 2011 16:47:04 +0000

Dallas Water Utilities (DWU) has identified multiple projects within their wastewater treatment
plants (WWTPs) to support the Green Dallas Initiative for energy conservation and
sustainability. In 2010, a new co-generation facility at the Southside Wastewater Treatment Plant
(SWWTP) will be brought on-line. This facility will utilize digester gas for electricity
production. As part of the Green Dallas Initiative, and to optimize the co-generation facility, the
feasibility of adding high strength wastes to the anaerobic digesters at SWWTP to increase the
digester gas production was evaluated.

Utility Operations under Financially and Politically Constrained Conditions

justin — Fri, 20 May 2011 16:24:36 +0000

With the world economy struggling under a severe recession water utilities are
experiencing difficulties in continuing their business operations. They also face political
challenge since they are directly responsible to the communities they serve and at the
same time their customers are also their constituency. During such politically and
financially constrained times, utility operators have been forced to look into new ways to
cut costs and improve efficiency. Our experience shows that water utilities can become
more efficient via implementation of various strategies such as business process redesign
and implementation of lean six sigma techniques. Utilizing the above mentioned
strategies enabled Gwinnett County, GA’s Department of Water Resources (DWR) to
improve its process flow and eliminate waste, decrease personnel required for process
execution, reduce on-hand inventory and ordering costs, and to completely eliminate
Total Potential Stock-out Situations.

MAKING ENERGY FROM BIOSOLIDS, FATS, OILS AND GREASE

justin — Fri, 20 May 2011 16:24:36 +0000

The F. Wayne Hill Water Resources Center (FWHWRC), owned and operated by the Gwinnett
County, GA, Department of Water Resources (DWR), is an advanced wastewater treatment plant
which currently discharges into the Chattahoochee River and Lake Lanier. The FWHWRC
maximum month design flow is 60 million gallons per day (mgd) and currently about 30 mgd of
wastewater is received.
In light of rising energy costs and declining revenues reflective of the continuing, severe
economic downturn that began in 2007, the Gwinnett County DWR began an initiative to make
the best possible use of resources under DWR control, including renewable energy resources.
DWR retained CH2M HILL to identify and evaluate opportunities to improve resource
utilization and reduce energy costs at the FWHWRC. The results of the evaluations, procedures
for capturing stimulus funding, and technologies employed are discussed in this paper.
The energy types considered for the FWHWRC were biogas derived from anaerobic digestion,
solar, wind, and low-head hydropower. A screening analysis concluded that biogas combustion
to produce power and heat was the optimum alternative.
Next, a Business Case Evaluation (BCE) was conducted to determine if the construction and
operation of a gas-to-energy facility would be economically feasible. The BCE considered
several different scenarios for generating power from biogas, including biogas production with
and without addition of fats, oil & grease (FOG) and high strength waste (HSW) to the existing,
anaerobic sludge digesters.
The BCE concluded that a gas to energy facility based on an internal combustion engine (ICE)
was feasible. The proposed system, in addition to continuously generating electrical energy for
use at the FWHWRC, would be capable of producing sufficient heat to keep the anaerobic
digesters operating in the mesophilic temperature range of 95-100 degrees Fahrenheit (F). By
capturing the heat produced by the ICE, in addition to generating power, the system would have
a total energy-recovery efficiency approaching 80%.
The BCE recommended a gas to energy facility of approximately 2 megawatts (MW) in capacity
at the FWHWRC. The biogas requirement at a nominal 600 British Thermal Units (BTU) per
cubic foot (ft3) for an ICE of this capacity is approximately 520 standard cubic feet per minute
(scfm). However, as the FWHWRC is at only about 50% of its total design capacity, the
currently available biogas is considerably less than 520 scfm, and a purchased natural gas fuel
blend would be required to obtain full power generation and heat recovery benefits. To minimize purchase of natural gas, maximize biogas, and as a result improve the return on
investment in the cogeneration system, DWR next investigated addition of FOG and high
strength waste (HSW) to the anaerobic digesters to supplement the solids feed. The project was
made even more attractive by DWR’s successful pursuit of funding under the American
Recovery and Reinvestment Act (ARRA), as administered by the Georgia Environmental
Facility Administration (GEFA), and from the U.S. Department of Energy (DOE).
A schematic design of the system with specifications was prepared for competitive selection of a
design-build contractor. The design-build contract was awarded in October 2009. The contract
value is $5.19 million and includes the installation of a 2.1 MW engine generator along with
digester gas cleaning and drying equipment. The gas-to-energy facility is expected to reach
substantial completion by the end of 2010 with contractual completion in May 2011.
A second RFP for the design and construction of a FOG and HSW receiving facility was
advertised in February 2010. The design-build contract was awarded in June 2010 at a contract
value of $3.16 million. Its completion and startup will closely follow the completion and startup
of gas cogeneration facilities.
Once operational, the FOG/HSW handling and cogeneration facilities will have the potential to
save over one million dollars annually in power costs and generate more revenue in FOG and
HSW disposal fees. When operating at its rated capacity, the resulting power production will
offset the amount of fossil fuel used to generate over 17,000 MW-hours of electrical power
annually.