San Francisco Public Utilities Commission
San Francisco, California
When the City and County of San Francisco (City) first began its land application program in
Solano County in 2000, it was with an eye toward a sustainable future. Significant odors and
truck traffic were generated near a newly developed retirement community, and outraged citizens
were quick to complain about the land application practices to Solano County staff. By winter of
2002, it appeared that the practice of land application in Solano County was over. The San
Francisco Public Utilities Commission (SFPUC), along with its sister agency, the East Bay
Municipal Utilities District (EBMUD), moved swiftly to begin engaging with stakeholders. The
end result was a revised local ordinance that addressed public concerns associated with noise,
traffic, and odors, but allowed continued Class B land application. Since that time, the two
agencies have continued to engage with the community by participating in routine biosolids
stakeholders meetings and meeting annually with the Solano County Board of Supervisors. In
addition, San Francisco has taken a more proactive role in managing its biosolids. Initiatives
include enrollment in the National Biosolids Partnership’s Environmental Management System
program, inspections of land application sites, increased biosolids monitoring, and participation
in biosolids stakeholder group meetings. The Solano County ordinance that allows Class B land
application was recently extended for another five years, an achievement that would likely not
have been possible without the extensive outreach efforts of San Francisco and other Bay Area
agencies.
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Posted: May 3rd, 2011 | Filed under: >1M, Waste Water Treatment | Tags: Enhanced Interaction with Stakeholders, Improved Customer Relations, Improved Plant Sustainability, Plant Optimization | No Comments »
Metropolitan Syracuse Wastewater Treatment Plant
Syracuse, New York
The 84.2 mgd Metropolitan Syracuse Wastewater Treatment Plant (Metro) has recently
undergone a major upgrade to provide advanced ammonia-nitrogen and phosphorus removal.
Seasonal limits for ammonia are 1.2 mg/L NH3 summer and 2.4 mg/L NH3 winter, and the limit
for phosphorus is a 12-month rolling average of 0.12 mg/L. Biological aerated filters (BAFs) by
Krüger were added for ammonia removal and the ballasted flocculated settling process,
ACTIFLO (also by Krüger) was added for phosphorus removal.
To address the increased biosolids produced at Metro, Environmental Engineering Associates,
LLP (EEA – a joint venture of Stearns & Wheler, LLC, O’Brien & Gere, and Blasland, Bouck &
Lee [now ARCADIS]) was retained to develop the necessary biosolids handling improvements.
The project includes:
• Replacing existing belt filter press dewatering system with high solids centrifuges
• Installing gravity belt thickeners (GBTs) to thicker WAS
• Provide sludge blend tanks to blend thickened primary sludge and thickened WAS prior to
digestion
• Provide a cogeneration system that utilizes digester gas to generate electricity and recover
heat.
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Posted: May 3rd, 2011 | Filed under: 100K-500K, Waste Water Treatment | Tags: Improved Digestion, Improved Sludge Drying, Nitrogen Removal, Phosphorus Removal, Plant Optimization, Reduced Odors | No Comments »
Denver Metro Wastewater Reclamation District
Denver, Colorado
Polarized air ionizing hardware that produces positively and negatively charged oxygen
molecules, or ions, but no ozone, will be discussed. This European technology has been
successfully applied at wastewater facilities in Europe for over twenty years. Operating systems
in the US now have a successful track record of over six years. The ionized air effectively
oxidizes most air contaminants including hydrogen sulfide, ammonia, and other organic gases. In
addition to providing odor control to the community and a safe work environment, air ionization
is shown to prevent the corrosion of electronics and equipment while saving huge amounts of
energy. Systems employing this technology have now been applied at many installations in the
United States, and performance data has been obtained from these installations.
These ionizers are modular and can be installed in ductwork on the fresh air supply side of an
existing or new ventilation system. Alternatively, small portable modules can be installed as self
contained recirculation units complete with fan.
The power savings accrues in the low power costs to operate the modules (35 watts per
module) plus the much reduced pressure drop through the air ionization system. These
plenums are part of wide open HVAC systems with ion tubes extending into the air stream, thus
creating little air flow resistance. This should be compared to traditional collect and treat
systems with tight packed media that creates very large pressure drops.
At the 150 MGD Denver Metro Wastewater Reclamation District (Metro), a 45,533 cubic
meters/hr (26,800 CFM) fresh ionized air system has been completed for the Solids Processing
Building (SPB) basement, and a 16,700 CFM (28,373 cubic meters/hr) system for the Cake
Storage Building.
The Metro air ionization system currently uses 1680 watts of power for the ion modules. This
represents a total power savings of 98 percent over, for example, a biofilter, an $883 per year
power cost and a $48,523 annual savings. Energy costs are predicted to escalate dramatically
over the next ten years.
Based on the performance data from the facilities investigated, air-ionization has been
demonstrated to be a reliable and energy saving solution for odor control. The system has a
minimal footprint and low power requirements. The system has zero water usage and no
chemical handling or storage. Both capital and operation and maintenance costs were found to be
less than other options such as wet scrubbers, activated carbon, and biological treatment.
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Posted: May 3rd, 2011 | Filed under: >1M, Waste Water Treatment | Tags: Cost Savings, Decreased Odors, Energy Savings, Environmental Impact, Plant Optimization, Plant Sustainability, Reduced Carbon Footprint, Reduced Greenhouse Gas Emissions | No Comments »
During the past 50 years, greenhouse gas (GHG) emissions have increased considerably and the
corresponding level of GHGs in the atmosphere has almost doubled. Greenhouse gases impede
the radiation of heat from the earth back into space, resulting in increased temperatures on the
earth’s surface and contributing to the greenhouse gas effect. While the majority of the
greenhouse gases are released into the atmosphere through natural processes, some of them are
generated and emitted solely through human activities. Wastewater treatment, being one of the
largest consumers of energy for cities and municipalities, is assuming increased importance as a
potential avenue for reducing the overall GHG inventories of a community. This paper focuses
on GHG emissions from biosolids processing operations at a wastewater treatment plant
(WWTP), providing a methodology for comparing the sustainability of various treatment options
in terms of environmental impact.
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Posted: May 3rd, 2011 | Filed under: Waste Water Treatment | Tags: Environmental Impact, Plant Optimization, Plant Sustainability, Reduced Carbon Footprint, Reduced Greenhouse Gas Emissions | No Comments »
Blue River Wastewater Treatment Plant
Kansas City, Missouri
The multiple hearth furnaces (MHF) at the Kansas City, MO Blue River Wastewater
Treatment Plant (WWTP) were built in 1966. The original design contemplated almost
autogenous combustion of primary sludge. However, changes in Federal and local air
pollution regulations made it necessary to reduce both total hydrocarbon and carbon
monoxide emissions. In 1992 the MHF was modified to include a “Zero-Hearth” afterburner.
By 2007 the combined effect of lower sludge solids due to adding some secondary sludge and
a radical increase in the price of natural gas was having a major impact on the operating
budget.
Twin 900 kW I.C. engines to generate power from biogas were installed in 1992. However,
by 2005 the cost of the natural gas that was blended in the biogas to maintain a consistent
heating value was negating many of the cost-reductions achieved. Therefore in 2006 it was
decided to see if it would be possible to modify the burners in the MHF to burn digester gas.
Furthermore, in order to expedite the conversion process, it was decided to investigate
approaches that could be done within the confines of maintenance staff and budget thereby
eliminating the need for the longer, more drawn out capital expenditure approach which
necessitates (1) study, (2) specifications and finally (3) bid and award.
The original burners were natural gas only. However, by adding the modification that
allowed for the firing of #2 oil, and then further modifying this equipment by removing the oil
nozzle and introducing biogas into the oil atomizing air pipe, a biogas flame that could be
seen by the existing Ultra-Violet flame detectors was achieved.
By June 2007, only 120 days since the effective Notice to Proceed, the furnace was
processing sludge with biogas supplying the majority of the auxiliary fuel. This conversion
was not without its problems and difficulties, not the least of which was the burner
manufacturer’s parts list on replacement burners that had been installed 3 years earlier
incorrectly depicting the location of the flame detector. Close cooperation and teamwork
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Posted: May 3rd, 2011 | Filed under: 500K-1M, Waste Water Treatment | Tags: Cost Savings, Energy Savings, Environmental Impact, Plant Optimization, Plant Sustainability, Reduced Carbon Footprint, Reduced Greenhouse Gas Emissions | No Comments »
Municipalities across the Midwest typically operate at greater than 80% capacity and run out of
biosolids and back-filter (lime and alum) residual storage capacity when land application
contractors (if applicable), drying beds, and storage lagoons are unable to keep up with volume
demands. Land application may not be economically or operationally available, an operations
timeline for solids removal prompts onsite dewatering, and residuals may be contaminated with
metals (e.g., Cu, Fe, Hg, Mo, Ni, Pb, Zn, etc.), oil and grease (O&G), nutrients, pathogens, or
pesticides. Several mechanical dewatering options (e.g., belt filter press, centrifuge, etc.) are
available as short-term or long-term remedies for onsite dewatering but are capital intensive for
municipalities and contractors that already operate on competitive budgets. The objective of this
study was to evaluate Geotube® containers as a residuals dewatering option for a municipal
wastewater treatment facility (WWTP) and a water filtration plant (WTP) including cost
effectiveness, ease of operation, solids retention, handling time, flow and volume rates, and
seasonality.
A southern Alabama WWTP treats approximately four million gallons of influent per day (8 to
10 million gallons of biosolids annually at 3 to 5 percent dry weight solids). It was calculated
that 1,400 linear feet (lf) of 30-ft circumference Geotube® container would be needed to
supplement onsite sand drying beds to dewater and contain this annual volume to 20 percent
solids, sufficiently dry to pass a paint filter test and haul off site to an appropriate landfill. The
resulting volume and mass of residuals at 20 percent solids would be 3,931 yd3 and 3,343 tons,
respectively.
A southeast Ohio WTP produces approximately 1.19 million gallons (5,874 yd3) of back-filter
residual per year at 1.0 percent dry weight solids. It was calculated that 96 lf of 45-ft
circumference Geotube® container would be needed to complement onsite equalization basins to
dewater and contain this annual volume to 20 percent solids, sufficiently dry to pass a paint filter
test and haul off site to an appropriate landfill. The resulting volume and mass of residuals at 20
percent solids would be 345 yd3 and 248 tons, respectively.
WaterSolve performed bench-top dewatering trials for biosolids and back-filter residual samples
collected from the WWTP’s liquids storage tank and WTP’s equalization basin, respectively.
Dewatering polymers were evaluated based on water release rate, water clarity, settling rate, and
flocculent appearance. In addition, dosing rate(s) were determined during these bench-top
dewatering experiments and recommendations provided to the facilities during this phase of the program. We recommended using Solve 9244 at a dose rate of 200 ppm (7.4 lb/dry ton) for
dewatering this WWTP’s biosolids and Solve 152 at a dose rate of 100 ppm (15.0 lb/dry ton) for
dewatering the WTP’s back-filter residuals. Water release rate and volume during pumping to a
Geotube® container were evaluated by adding 150-mL flocculated residual samples to a filter
apparatus with a GT500 Geotube® filter. Water release rate and volume were measured with a
250-mL graduated cylinder over 12 hours. Remaining solids were collected and measured for
percent dry solids by U.S. EPA Method 160.3.
Geotube® containers, with the aid of dewatering polymers, were recommended to and
implemented by the WWTP and WTP into which solids were pumped directly from an above
ground storage tank and equalization basin, respectively. After inline flocculation, the permeable
textile that forms the Geotube® container allows efficient dewatering while containing the fine
grain solids and the filtrate water returns to the head-works of the WWTP and is discharged via
sand filters from the WTP. Overall, this dewatering methodology greatly reduced the volume and
mass of residual solids and costs associated with hauling and disposal while allowing continual
operation of the facilities. For containment and dewatering of biosolids and back-filter residual,
Geotube® dewatering (including polymer and feed equipment) cost less than $0.02/gallon,
required minimal technical assistance to install and operate, retained greater than 99 percent
solids, solids dried sufficiently for hauling and disposal (18 to 40 percent cake solids), and did
not interfere with plant operations. Compared to the previous management techniques (i.e., belt
filter press, sand drying beds, or hauling to a landfill), these Geotube® projects saved both
facilities nearly $25,000 after the first year of operations.
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Posted: May 3rd, 2011 | Filed under: Waste Water Treatment, Water Treatment | Tags: Biosolids Management, Cost Effective Treatment, Cost Savings, Decreased Mass of Residual Solids, Ease of Operation, Improved Drying, Plant Optimization | No Comments »
Milton Regional Sewer Authority
Milton, Pennsylvania
Designed in the 1960’s and constructed in the mid-1970’s, the Milton Regional Sewer
Authority’s (MRSA’s) 3.420 MGD wastewater treatment plant (WWTP) is in need of a
complete facility upgrade. The upgrade will need to not only account for strict nitrogen
and phosphorus effluent requirements, but also seek out opportunities to minimize energy
dependence and operational costs through biogas production, electrical generation,
biosolids drying and sale of electricity to the Grid.
The end goal for this project is to create an energy independent, green wastewater
treatment facility. The objectives are to maximize energy recovery by exploiting all
reasonable sources; to minimize energy use throughout the facility; and to identify the
most feasible methods of energy recovery. Anaerobic treatment will be used were
applicable to meet these objectives through lower connected horsepower and biogas
production.
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Posted: May 3rd, 2011 | Filed under: <50K, Sanitary Sewer, Waste Water Treatment | Tags: Biosolids Management, Cost Savings, Energy Production, Energy Savings, Environmental Impact, Improved Plant Efficiency, Plant Optimization, Plant Sustainability, Reduced Carbon Footprint, Reduced Greenhouse Gas Emissions | No Comments »
Greenfield Water Reclamation Plant
Gilbert, Arizona
A unique partnership of Owners, Engineers and Architects, and Contractors worked together for
the successful implementation of the Greenfield Water Reclamation Plant (GWRP) to meet
increased wastewater treatment capacity and reuse water supply requirements. The project team
faced several challenges ranging from local community integration, dramatic and on-going cost
escalations, and the need for a regional biosolids management solution. The project created an
architectural design that flawlessly blended the solids treatment facility with the surrounding
upscale residential community. Balancing the capital cost constraints with the functional needs
of the facility helped to keep the project within the Owner’s budgetary constraints. An
innovative project delivery method – Construction Manager at Risk (CMAR) – allowed the three
owners, the joint venture CMAR contractor, and the multiple architectural and engineering firms
to achieve a successful balance. The project achieved a regional biosolids management solution
by linking together the Mesa Southeast Water Reclamation Plant (SEWRP), a remote treatment
facility, and the GWRP using a solids pumping facility and a solids pipeline.
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Posted: May 3rd, 2011 | Filed under: Waste Water Treatment, Water Treatment | Tags: Biosolids Management, Cost Savings, Energy Savings, Improved Customer Relations, Plant Optimization, Plant Sustainability | No Comments »
Wakarusa WRF
Lawrence, Kansas
Wastewater and biosolids treatment processes are designed to support regulatory requirements
for effluent quality and solids final use. However, it is common that future changes in the
regulatory environment or solids management area can require subsequent modifications to the
plant’s processes. While the objective of the original design is to provide for anticipated future
requirements, it can be difficult to predict when, or if, more stringent requirements will be
imposed. Since higher levels of treatment correspond to greater capital and operating costs,
treatment that exceeds anticipated needs is typically not desirable. Consequently, the goal is to
design flexible systems that meet current needs but minimize future facility obsolescence or
abandonment.
The design for the Wakarusa WRF in Lawrence, KS incorporates features that support initial
liquid stream and biosolids treatment requirements, but allows relatively easy conversions and
upgrades to meet potential tightening of effluent treatment criteria as well as changes in biosolids
final use within the lifespan of the plant. These design features avoid abandoning or replacing
equipment or facilities. This paper discusses design approaches incorporated in the Wakarusa
treatment processes that can maximize system flexibility, which, in turn, will minimize costs
associated with removal or abandonment of existing treatment processes.
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Posted: May 3rd, 2011 | Filed under: 50k-100k, Waste Water Treatment, Water Treatment | Tags: Biosolids Management, Cost Minimization, Planning for Future Compliance, Plant Optimization, Plant Sustainability, Reduced Plant Disruption | No Comments »
Letchworth Avenue Wastewater Treatment Facility
Billerica, Massachusetts
When replacing equipment that has reached the end of its life cycle, breaking with tradition and
exploring the marketplace for industry trends and cutting edge technologies can often yield
substantial results. For example, when the Town of Billerica, Massachusetts, needed to replace
its aging belt filter press; rather than replacing the equipment in kind the Town installed a rotary
sludge press for dewatering of blended primary and thickened waste activated sludge, the first
installation in Massachusetts and one of only a few in New England, at its 5.4-MGD municipal
wastewater treatment facility.
Replacing a belt filter press with a rotary sludge press is a unit process replacement with a
smaller footprint, making design, construction, and installation a logical retrofit. Where the open
belt filter press presents greater exposure to odors, health hazards, and presents a challenging
work environment for operators, the rotary sludge press is fully enclosed, providing a more
operator friendly environment.
This paper presents a review of the piloting, design, construction, startup, and operation of
Billerica’s new rotary sludge press over the first year of operation.
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Posted: May 3rd, 2011 | Filed under: <50K, Waste Water Treatment | Tags: Cost Savings, Environmental Impact, Improved Plant Efficiency, Improved Working Conditions, Increased Cake Dewatering, Increased Process Reliability, Optimized Chemical Usage, Plant Optimization, Reduced Carbon Footprint | No Comments »