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.
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Posted: May 20th, 2011 | Filed under: Uncategorized | Tags: Energy Efficiency, Equipment Protection, Lower Capital Cost, Personnel Protection, Reduced Power Costs, Smaller Carbon Footprint | No Comments »
Washington State Parks and Recreation Commission
Olympia, Washington
As part of an ongoing initiative to decrease pollution in Puget Sound, Washington State Parks and
Recreation Commission (WSPRC) identified for replacement lower performing wastewater
treatment systems at five parks. In the interest of producing high quality effluent, particularly with
respect to nitrogen, while minimizing footprint on historic property and maximizing remote
operations potential, WSPRC decided on membrane bioreactor (MBR) technology to replace
existing systems. WSPRC selected a consulting firm to draft a procurement document which
standardized MBR systems across all parks which resulted in an Invitation for Bids (IFB) to select
a single MBR supplier. Flow and load capacity requirements for each park were not developed,
rather, only two MBR system sizes were defined, and representative influent criteria were applied.
This paper provides a brief overview of the procurement process, identifies successes and
challenges associated with this process, and assesses the performance of one MBR at Ft. Flagler
State Park.
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Posted: May 20th, 2011 | Filed under: Uncategorized | Tags: Environmental Impact, Improved Effluent, Increased Nitrogen Removal, Plant Sustainability, Reduced Carbon Footprint, Reduced Greenhouse Gas Emissions | No Comments »
Solid Waste Authority of Palm Beach County
Palm Beach County, Florida
The Solid Waste Authority of Palm Beach County, Florida, operates an in-vessel composting
facility that processes 30 dry tons/day of dewatered biosolids combined with shredded yard
waste. The facility consists of 36 aerated agitated bays in three buildings supplied by
International Processes Systems (Now Siemens Water Technology). All exhaust air from the
buildings is treated in three 60,000 cfm biofilter cells. New biofilter cells were commissioned in
December 2002. Design and construction included some innovative features including: use of
locally available limestone for the support plenum, use of locally available finely ground bark
mulch in the media, a pre-humidification system with air-atomizing nozzles, clean-outs for every
perforated lateral, and a fast-track design-build method of delivery.
After start-up the well water used for humidification caused rapid scaling of the laterals, due to
the high mineral content and high evaporation efficiency. Pre-humidification was discontinued
while a water softening and deionization system was under consideration. Since then the filters
have been operated only with surface irrigation. The most recent rounds of performance testing
have indicated that surface irrigation, combined with rainfall, were sufficient to maintain optimal
moisture content throughout the full depth of media. Without pre-humidification, the irrigation
distribution pattern is critical.
The filters have been periodically tested for odor and ammonia removal, most recently in 2006
and scheduled again for 2007. The filter media in the different cells have been in continuous use
for 2.6 to 3.1 years. Typical inlet conditions were:
Temperature: dry-bulb range 96-105 deg. F. wet-bulb range 86-92 deg F.
Ammonia: 22 – 40 ppm
Hydrogen sulfide and methyl mercaptan: neglible or non-detect
Odor concentration: 1,500 – 2,400 D/T, using the prEN 13725 olfactometry standard.
The biofilters have consistently removed 100 % of ammonia and 93 – 98 % of odor with outlet
odor concentrations in the range of 66 to 86 D/T. Thus, the biofilter is showing highly effective
performance, despite the high temperature and moisture deficit in the inlet air. As a result, the
composting facility is no longer a significant source of off-site odors.
Ammonia is an alkaline gas and there little acid gas present. The media has a pH in the range of
4.8 – 6.8. The acidic pH indicates that alkalinity is being consumed as a result of nitrification. A
nitrogen mass balance indicated that the biofilters are operating in steady state rather than
accumulating nitrogen, and that nitrogen leaves the biofilters by way of leachate and
denitrification. Denitrification was demonstrated by the detection of nitrous oxide. Nitrous oxide
is of increasing interest due to its effect as a greenhouse gases.
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Posted: May 3rd, 2011 | Filed under: Uncategorized | Tags: Biofiltration, Reduced Air Pollutants, Reduced Greenhouse Gas Emissions, Reduced Odors | 1 Comment »
In this paper, the results of the process of designing, installing and commissioning the
full-scale biofilter systems will be discussed. All of the biofilter system utilized an
inorganic synthetic media. The objective of this paper is to emphasize major pitfalls in
specifying full-scale biofilter systems, wherein the impact of inlet concentration on
treatment efficiency is often ignored, and simultaneous treatment requirements of exit
odor levels as well as treatment efficiencies for hydrogen sulfide and each of the major
reduced sulfur compounds are required to be met by the full-scale system. The major
differences between the performances of a biofilter, thermal oxidizer and chemical
treatment systems will be discussed, with special emphasis on correctly specifying
biofilter systems to meet the goals of odor control at a wastewater treatment plant.
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Posted: May 3rd, 2011 | Filed under: Uncategorized | Tags: Improved Installation and Operation for Biofiltration, Increased Efficiency, Reduced Air Pollutants, Reduced Odors | No Comments »
A roadmap to reduce biosolids cake odors was developed under the WERF Phase 3 Project 03-
CTS-9T entitled “Biosolids Processing Modifications for Cake Odor Reduction” encompasses
nine research agenda items developed from the results of Phase 2, which was completed under
WERF Project No. 00-HHE-5T (Adams et al, 2003). Phase 3 has been a 3-year project dedicated
to testing hypotheses in the laboratory as well as on pilot-scale and full-scale bases, to determine
the causes and biosolids odors and find ways to remediate them. The Phase 3 project has
concluded and the Final Report was published in late 2007.
Laboratory and full-scale investigations conducted in Phase 3 that helped develop a biosolids
cake odor reductions roadmap included:
1. The role of cations in odor production from anaerobically-digested biosolids
2. The effect of anaerobic digestion parameters such as mixing, detention time, temperature,
and phasing on cake odor production.
3. Effects of dewatering processes and their control parameters on cake odors
4. Effects of chemical addition on cake odors
Demonstration of promising research findings at full-scale biosolids digestion and dewatering
facilities were undertaken in Phase 3. The main goal of this last phase of the project was to
develop a biosolids cake odor reduction roadmap. This roadmap matches wastewater or
biosolids facilities that need to reduce biosolids odors with specific technology solutions,
potential changes in operational practices, and/or chemicals, or biological agents additions. Each
biosolids processing facility or wastewater treatment plant (WWTP) will need to determine their
own biosolids cake odor reduction goal, which is typically determined by either
reducing/eliminating surrounding site or application location odor complaints or set using odor
dispersion modeling to demonstrate that the odor threshold goal is met at the sites property line.
The roadmap provides several approaches to meet any level of biosolids cake odor reduction
needed to meet reduction goals. Typically a combination of roadmap approaches, such as
technology, operational, and/or chemical strategies are needed to meet higher cake odor
reduction requirements. Whereas, for smaller cake odor reduction needs, only one or several
roadmap approaches are needed. All roadmap approaches are independently viable and have
shown cake odor reductions. Several WWTPs are currently looking at the roadmap concept to
meet needed biosolids cake odor reduction needs. WERF is considering adding another phase to
this project to roll-out and fine-tune the roadmap concept at a WWTP. To date, parts of the
roadmap have been used by WWTP to meet their biosolids cake odor reduction needs.
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Posted: May 3rd, 2011 | Filed under: Uncategorized | Tags: Improved Customer Relations, Improved Plant Operations, Reduced Biosolids Cake Odors | No Comments »
Odor control equipment is important to the wastewater industry throughout the world. It allows
wastewater plants and collection systems to operate with minimal impact on the surrounding
regions. One very prominent technology is engineered dry-scrubbing media. This media
consists of various base materials formed into spherical media through the processes of
agglomeration and impregnation. The base materials include adsorbents such as activated
alumina, activated carbon, and sodium bicarbonate. The liquid impregnants include potassium
permanganate, sodium permanganate, and potassium hydroxide. These materials combine to
form an engineered media having physical and chemical properties that allow contact with and
removal of odorous gases.
This paper focuses on reducing capital cost by increasing the velocity of air through an odor
control system. In the past, odor control systems performed well at face velocities of 60-100 feet
per minute (fpm) across a media bed. Experience and performance tests on installed systems
confirm this. In the examples sited here, systems have achieved acceptable life times as well as
efficiencies greater than 99.5%.
The efficacy of an air velocity increase depends on the following parameters: gas mass transfer
zone, media pressure drop, capital cost reduction, and energy consumption. These factors point
toward 125 fpm as the optimum velocity-increase point. The scrubber is also capable of
operating at 150 fpm with higher energy consumption. Wastewater plants can use these results
to evaluate scrubber options and meet budgetary constraints.
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Posted: May 3rd, 2011 | Filed under: Uncategorized | Tags: Decreased Energy Consumption, Engineered Odor Control Media, Improved Odor Control, Improved Plant Efficiency, Increased Cost Savings | No Comments »
New York City Department of Environmental Protection
New York City, New York
Upcoming construction work related to facilities upgrades will require a shut down of the Gowanus Flushing Tunnel for approximately 26 months. During this time, DO levels in the Canal are expected to drop to unsatisfactory levels. To address this problem, an interim system was developed to maintain satisfactory DO levels throughout Gowanus Canal at all times during a typical year. This centralized oxygenation system would withdraw Canal water at a rate of approximately 0.43 m3/s, oxygenate it to between 16 mg/L and 40 mg/L (as necessary to maintain desired ambient oxygen levels), and then discharge it via a diffuser system featuring 51 nozzles: one at the head end to support DO levels there, and 50 spaced 12 to 15 m apart between Sackett Street and the 4th Street turning basin—a reach of the upper Canal with minimal boat traffic and water depths of at least 1.2 m at mean low tide. The diffuser system is expected to achieve mixing across the width of the Canal without disturbing bottom sediments as long as the discharge ports can be placed at least 0.6 m below the surface and 0.6 m above the bottom at MLW. In a typical year, the system would need to operate from April through November. With the system discharging about 1,500 kg/d of oxygen (discharge concentration about 40 mg/L), the results show that DO levels of 3.0 mg/L would be maintained throughout the length of the Canal continuously throughout a typical year. Reducing the discharge to 40 percent of that level (600 kg/d of oxygen, or a discharge concentration of 16 mg/L) is projected to maintain satisfactory DO levels throughout most of the year and minimum DO levels of at least 1 mg/L throughout the Canal at all times. Source: WEFTEC 2009 Proceedings
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Posted: August 27th, 2010 | Filed under: Uncategorized | Tags: Improved Water Quality, Maintaining Satisfactory DO Levels | No Comments »
Blue Plains AWTP
Washington, D.C.
Carbon footprinting was used to evaluate several biosolids processing alternatives
considered for the Blue Plains Advanced Water Treatment Plant AWTP biosolids
management plan update. These alternatives include a combination of a thermal
hydrolysis process followed by anaerobic digestion; anaerobic digestion followed by
thermal drying; and lime stabilization of dewatered solids. Energy and mass balance was
conducted for the different alternatives where biogas was used for energy recovery in a
combined heat and power facility to produce electricity and necessary heat for the
thermal hydrolysis and thermal drying processes. CO2 emission factors for the different
processing were obtained from published literature and were used to estimate CO2
emission. The analysis showed that the Blue Plains facility has the potential of producing
about 11 MW of electricity, at an annual equivalent savings of $9.6 M, from biogas when
processing annualized solids production through anaerobic digestion.
Carbon footprinting benefits from land application of biosolids and dried pellets were
considered in this analysis. Results showed that of the various digestion options, thermal
hydrolysis offered the most benefit in terms of reduced CO2 emissions. This benefit was
further enhanced when the offsets associated with land application of the Class A
biosolids produced by this process were considered.
Beneficial reuse of class B, lime stabilized biosolids, also offsets CO2 emissions,
however the benefit is reduced somewhat by CO2 emissions associated with lime
production. When the dried pellets are used as a fuel source offsetting use of fossil fuel,
the carbon footprinting for processing combining thermal hydrolysis and thermal drying
are the most beneficial.
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Posted: August 24th, 2010 | Filed under: Uncategorized | Tags: Biosolids Management, Cost Savings, Environmental Impact, Reduced Carbon Footprint, Reduced Greenhouse Gas Emissions, Thermal Hydrolysis | No Comments »
Blue Plains AWWTP
Incorporating thermal-hydrolysis pretreatment in conjunction with mesophillic anaerobic digestion as the backbone of a long-term biosolids treatment plan to produce Class A biosolids. DC WASA began the process of identifying an alternative approach to lime stabilization. Selection criteria for the new process included a compact footprint, cost effectiveness, ease of operation by local staff, production of a Class A product, minimization of odor potential, elimination of indicator organism reactivation or regrowth in addition to maximizing energy recovery from biogas. A broad number of alternatives were evaluated and discarded, with thermal hydrolysis and thermal drying as the two remaining alternatives. After evaluating both remaining alternatives, including hybrid of both and sub-alternatives to reduce project cost and eliminate the risk from using only one alternative, thermal hydrolysis in conjunction with mesophillic anaerobic digestion was ultimately chosen as the two processes that best meet the needs of the Authority. This paper summarizes the decision making process for selecting thermal hydrolysis along with the conceptual design for the thermal hydrolysis process. Source: WEFTEC Proceedings 2009
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Posted: June 25th, 2010 | Filed under: Uncategorized | No Comments »