Indianapolis Department of Public Works
Indianapolis, Indiana
The City of Indianapolis Department of Public Works (DPW) constructed eleven real-time
controls (RTC) in the operation of the collection system between 1995 and 2004 to reduce
combined sewer overflows (CSO). These eleven RTC facilities are part of the Early Action
Projects (EAP) to reduce CSO frequency and volume. In 2009, DPW completed a hydraulic
performance evaluation of each RTC facility using a computer hydraulic model simulation of
RTC operations, and successfully quantified their environmental benefits in CSO volume
reduction. This evaluation helped DPW to demonstrate the feasibility of utilizing RTC in the
collection system to reduce CSOs. This evaluation of the RTC facilities provided a basis for
DPW to further investigate additional CSO control projects that can utilize RTC. This technical
paper provides a case study on quantifying the environmental benefits of RTC in a large sewer
collection system.
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Posted: May 20th, 2011 | Filed under: 500K-1M, Sanitary Sewer, Stormwater, Waste Water Treatment | Tags: Enhanced Operational Efficiency, Environmental Improvement, Improved Plant Reliability, Reduced Combined Sewer Overflows | No Comments »
Dallas Water Utilities (DWU)
Dallas, Texas
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.
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Posted: May 20th, 2011 | Filed under: 100K-500K, Stormwater, Waste Water Treatment, Water Treatment | Tags: Cost Savings, Electricity Production, Environmental Impact, Improved Plant Sustainability, Increased Digester Gas, Reduced Carbon Footprint, Reduced Greenhouse Gas Emissions | No Comments »
Milwaukee Metropolitan Sewerage District (MMSD)
Milwaukee, Wisconsin
Significant opportunities exist to increase renewable energy production using existing municipal
anaerobic digesters. Many wastes can be added to co-digest more carbon and produce more
methane. The objectives of this study were to identify and compare potential co-digestates,
determine synergistic, antagonistic and neutral co-digestion outcomes, quantify performance of
co-digestion for selected wastes and estimate economic benefits. Over 80 wastes were identified
from 54 facilities within 160 km of an existing municipal digester. The most promising wastes
(26 wastes) were characterized by biochemical methane potential (BMP) and other testing. A
simple economic comparison identified the greatest benefits for seven co-digestates.
Performance was investigated using bench-scale digesters receiving synthetic primary sludge
with and without co-digestates. Methane production rates in co-digesters were as much as 180%
greater than anticipated from the additional chemical oxygen demand (COD). Therefore,
significant synergism was observed. The VS destruction efficiencies were 49 and 33% higher
when co-digestates were present. Co-digestion is one method to increase renewable energy
production via anaerobic digestion.
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Posted: May 20th, 2011 | Filed under: >1M, Sanitary Sewer, Stormwater, Waste Water Treatment | Tags: Cost Savings, Environmental Impact, Improved Plant Performance, Improved Plant Sustainability, Increased Biogas Production, Reduced Carbon Footprint, Reduced Greenhouse Gas Emissions | No Comments »
Gwinnett County Department of Water Resources
Lawrenceville, Georgia
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.
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Posted: May 20th, 2011 | Filed under: 500K-1M, Stormwater, Waste Water Treatment, Water Treatment | Tags: Business Process Redesign, Cost Savings, Improved Plant Efficiency, Improved Process Flow | No Comments »
Gwinnett County Department of Water Resources
Lawrenceville, Georgia
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.
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Posted: May 20th, 2011 | Filed under: 500K-1M, Stormwater, Waste Water Treatment, Water Treatment | Tags: Cost Savings, Energy Savings, Environmental Impact, Heat Production, Improved Energy Production, Improved Plant Sustainability, Reduced Carbon Footprint, Reduced Greenhouse Gas Emissions | No Comments »
Sacramento Area Sewer District
Sacramento, California
The Sacramento Area Sewer District (District) is in the final stages of implementing a new
Supervisory Control and Data Acquisition (SCADA) system for their 103 pump stations. While
implementing this new SCADA system, the District faced many challenges and obstacles, such
as developing the SCADA system requirements, designing the networking system, testing station
communication, and cutover to the new SCADA system. Implementing a new SCADA system
has provided the District with valuable experience that can be shared with other sewer agencies
that may also be in the process of replacing their SCADA system.
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Posted: May 20th, 2011 | Filed under: >1M, Sanitary Sewer, Stormwater | Tags: Improved Plant Efficiency, Improved Plant Performance, Improved Plant Reliability, Reduced Communication Failure | No Comments »
Pump stations are an integral part of wastewater collection and treatment systems. Their
applications can be quite varied: lift stations in the collection network pump raw sewage up to a
level where gravity can take over; pumping systems within the treatment plant move effluent
through various treatment stages or deliver it from the plant to agricultural users and others.
While wastewater pumps have a common function––moving fluid where gravity can’t––the
design of any individual pump station can depend on many factors.
Choosing the right pump station design for the application is a matter of balancing personal
preference with the requirements of the job, the necessity for energy efficiency and the need for
pump station reliability. This presentation examines three very different pumping system
designs, and weighs the advantages and disadvantages of each in the context of real-world
applications.
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Posted: May 20th, 2011 | Filed under: Stormwater, Waste Water Treatment | Tags: Efficient Lift Station Design, Energy Efficiency, Improved Plant Performance, Improved Plant Reliability, Improved Wastewater Pumping | No Comments »
The current NPDES permit of an industrial aerospace complex located on Ventura
County, California requires to provide treatment to any stormwater overflows originated
at the complex typically during storm events. These overflows occur when the individual
capacities of a series of storage ponds located at different points of the site are exceeded.
A stormwater treatment system (STS) is required to avoid exceedances of certain
constituents of concern (COCs), especially certain heavy metals (iron, manganese,
copper, mercury, lead) and organics (dioxins and volatile organic compounds – VOCs),
that may washout from the soil during storm events. Coarse filtration (sand and
multimedia filters) was the basis of the STS, but did not achieve the required removal of
COCs to meet the permit. Additional analyses were required to increase filtration
effectiveness. Fractionation of the solids present in the water revealed the presence of
large fractions of silts and clays, which are too small to be removed by coarse filtration.
These small solids also had a significant fraction of the total COCs attached to them,
which prompted the exceedances of the permit limits. This analysis highlighted the need
for coagulation chemicals to clump these small particles together and form flocs that may
be further removed by coarse filtration while meeting permit limits. This analysis also
allowed to better characterize the raw water from different storage ponds and select the
location with the best water quality to feed the STS.
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Posted: May 20th, 2011 | Filed under: Stormwater, Waste Water Treatment | Tags: Improved Filtration Effectiveness, Improved Plant Reliability, Meet Regulatory Constraints | No Comments »
Stormwater discharges from an industrial aerospace complex located in Ventura County,
California require substantial treatment in order to meet the stringent NPDES permit
limits. Overflows are generated during heavy rain events when onsite storage pond
capacities are exceeded. Multiple treatment configurations have been tested to remove the
constituents of concern (COCs) below the permit limits. Past experiences have indicated
that chemical treatment with rapid clarification consistently produced water quality close
to the permit limits. Therefore, additional treatment is required to fully meet the treatment
goals. Ultrafiltration (UF) membranes were tested for this effect during a pilot study
conducted to determine performance of a submerged membrane unit. Effluent from the
rapid clarification unit (i.e., Kruger’s ACTIFLO) was further treated with multimedia
filters and used as influent to the membrane pilot. The submerged UF membrane was
able to remove approximately 99% of the influent turbidity. Ultimately, the submerged
UF membrane proved to be a viable treatment alternative that consistently removed
COCs below their NPDES permit limits, which in this particular case are even more
stringent than drinking water limits for certain COCs.
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Posted: May 20th, 2011 | Filed under: Stormwater, Waste Water Treatment | Tags: Improved Filtration Effectiveness, Improved Plant Reliability, Improved Total Suspended Solids Removal, Meet Regulatory Constraints, Turbidity Control | No Comments »
Montgomery County Water Services
Dayton, Ohio
Montgomery County Water Services (MCWS) is a regional water and sewer provider
with 11 water booster stations, 36 sewage lift stations, three equalization basins, and two
regional WWTPs (20 MGD and 13 MGD). MCWS provides an average 26 MGD
drinking water to 250,000 people. All drinking water is purchased from the City of
Dayton, OH. MCWS staff is comprised of 242 persons.
Responding to operational alarms and work requests at remote water and sanitary pump
stations often requires sending two people—one mechanic and one electrician. This often
creates unnecessary overtime as the corrective action usually requires either mechanical
or electrical repair—not both. In 2007, we began to study how to maintain core operation
and maintenance (O&M) responsibilities, save labor costs, provide improved mechanical
and electrical maintenance support using existing staff, and to develop better-skilled
maintenance employees. The ability to improve maintenance skills within the two
WWTPs was also examined.
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Posted: May 20th, 2011 | Filed under: 100K-500K, Stormwater, Waste Water Treatment, Water Treatment | Tags: Improved Employee Morale, Improved Maintenance, Improved Plant Reliability, Increased Equipment Service Life, Lobor Cost Savings, O&M Savings | No Comments »