Various WWTP's
Switzerland
Aeration consumes about 60% of the total energy of a WWTP and therefore makes up for a
major part of its carbon footprint. Introducing advanced process control can help plants to reduce
their carbon footprint and at the same time improve effluent quality through making available
unused capacity for denitrification, if the ammonia concentration is below a certain set-point.
Measuring and control concepts are a cost-saving alternative to the extension of reactor volume.
However, they also involve the risk of violation of the effluent limits due to measuring errors,
unsuitable control concepts or inadequate implementation of the measuring and control system.
Dynamic simulation is a suitable tool to analyze the plant and to design tailored measuring and
control systems.
During this work, extensive data collection, modeling and full-scale implementation of aeration
control algorithms were carried out at three conventional activated sludge plants with fixed predenitrification
and nitrification reactor zones. Full-scale energy savings in the range of 16-20 %
could be achieved together with an increase of total nitrogen removal of 40%.
Metric Used:
Posted: May 20th, 2011 | Filed under: <50K, 100K-500K, 500K-1M, Waste Water Treatment | Tags: Ammonia Control, Cost Savings, Energy Savings, Environmental Impact, Plant Sustainability, Reduced Aeration, Reduced Carbon Footprint, Reduced Greenhouse Gas Emissions | No Comments »
Two clean technologies, namely, “Anaerobic hydrogen production” and “Microbial fuel cells
(MFC)”, hold great potential for producing energy from wastewater, which can provide economic
and environmental benefits. Although 1 mole of glucose can theoretically produce 12 moles of
hydrogen, the experimental hydrogen yields obtained are only 0.9-2.0 moles [1, 2]. The liquid
fermentation products in the anaerobic treated wastewater cause the high chemical oxygen demand
(COD) in the effluent. It is desired to further treat these liquid products using MFCs to improve
effluent quality and harvest energy. By converting the chemical energy stored in wastewater to
electricity, MFCs can substantially reduce the operational cost in wastewater treatment plants [3].
Due to the limitation of current technologies, the operation of hydrogen bioproduction and MFC
individually in wastewater treatment is not suitable. Although hydrogen production is a good energy
resource, the COD removal efficiency remains low. On the other hand, MFC could achieve high
COD removal efficiency, but the power densities are low. In this study, the HPB and SCMFC were,
for the first time, operated in series to increase overall energy recovery from wastewater and enhance
COD removal efficiency for potential reclamation.
Metric Used:
Posted: May 20th, 2011 | Filed under: Waste Water Treatment | Tags: Cost Savings, Energy Savings, Enhanced COD Removal Efficiency, Environmental Impact, Plant Sustainability, Reduced Carbon Footprint | No Comments »
J.D Phillips Water Reclamation Facility
Colorado Springs, Colorado
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.
Metric Used:
Posted: May 20th, 2011 | Filed under: 100K-500K, Waste Water Treatment, Water Treatment | Tags: Cost Savings, Enhanced Denitrification, Enhanced Nitrogen Removal, Enhanced Phosphorus Removal, Increased Effluent pH, Increased Treatment Reliability, Supplemental Carbon | 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.
Metric Used:
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 »
Annacis Island Wastewater Treatment Plant
Vancouver, British Columbia (Canada)
Annacis Island Wastewater Treatment Plant which is operated by Metro Vancouver, is leading
the way in working within a carbon based regulatory environment. British Columbia has
instituted carbon reduction legislation province wide, a leader in North America. As a result
public entities, such as Metro Vancouver, must be carbon neutral by 2012. In response the utility
is holistically investigating different approaches to achieve the required GHG reductions. One
approach now being actively pursued is the implementation of co-digestion at Annacis Island.
Having developed a the scope for a full co-digestion program at the plant, a pilot facility was
constructed to provide further process controls as well as a start at reducing emissions by codigesting
material at the plant. This project also provided Metro Vancouver a basis of handling
its own sludges from other wastewater treatment plants on an emergency or planned basis by
dual tasking the receiving facility to receive both sludges and co-digestion substrates.
Metric Used:
Posted: May 20th, 2011 | Filed under: 500K-1M, Waste Water Treatment | Tags: Cost Savings, Energy Production, Environmental Impact, Improved Plant Performance, Improved Plant Sustainability, 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.
Metric Used:
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.
Metric Used:
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.
Metric Used:
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 »
Various WWTP's
Various States
After manpower, energy is the highest operating cost item for most water and wastewater companies.
Over the last decade, energy consumption by the sector has considerably increased as a result of
implementation of new technologies to meet new effluent and potable water quality standards. High
energy consumption will affect the water industry worldwide and is inextricably linked to the issue of
Climate Change. Through its Optimization Challenge program, the Water Environment Research
Foundation (WERF) participated in the Global Water Research Coalition’s (GWRC) project titled Energy
Efficiency in the Water Industry: A Compendium of Best Practices and Case Studies. For this project,
WERF served the role of North America practice coordinator, developing a Compendium of best
practices in the energy efficient design and operation of water industry assets for this region of the world.
Metric Used:
Posted: May 20th, 2011 | Filed under: Stormwater, Waste Water Treatment, Water Treatment | Tags: Compendium of Best Practices, Cost Savings, Energry Efficiency, Energy Recovery Technologies, Energy Savings, Environmental Impact, Plant Optimization | No Comments »
Various WWTP's
Various States
Public agencies are increasingly pressured to become more sustainable. Wastewater plants are
significant consumers of energy and correspondingly produce significant quantities of
greenhouse gas (GHG). Reductions in energy and GHG are challenges for wastewater facilities
as flows and loads increase and discharge requirements become more restrictive. The results
highlight some methods to reduce energy and GHG, including the concept of becoming energy
neutral. Energy (as represented by electrical energy or fuels) equate directly to GHG production.
A significant portion of the fuel source for most utilities in the United States is from
anthropogenic sources such as coal, oil, or electric. To achieve energy neutral facilities, the
wastewater plant must implement energy conservation and shift to biogenically derived energy
sources, such as biogas, or alternative energy sources, such as wind. This paper and presentation
describe how wastewater treatment plants can significantly reduce energy to the point of
becoming energy neutral.
Metric Used:
Posted: May 20th, 2011 | Filed under: Stormwater, Waste Water Treatment, Water Treatment | Tags: Best Practices, Cost Savings, Energy Efficiency, Energy Savings, Environmental Impact, Improved Biogas Production, Plant Sustainability, Reduced Carbon Footprint, Reduced Greenhouse Gas Emissions | No Comments »