This report is about five treatment plants sharing how they conserve energy by converting wastewater into bio methane and others. learn how to produce electricity out of waste!

1. Case Studies in
Residual Use and Energy
Conservation
at Wastewater Treatment
Plants
Interagency Energy and Environmental Research Report
Presented By:
MS. YVONNIE D. MANERA
U.S. Environmental Protection Agency Office
of Wastewater Management Washington, DC
U.S. Department of Energy Efficiency,
Conservation and Renewable Energy
Washington, DC

2. Outline
Introduction
I. County Sanitation Districts of Orange County
II. City of Los Angeles Hyperion Wastewater Treatment Plant
III. Sunnyvale Water Pollution Control Plant
IV. Sanford Big Buffalo Creek WWTP, North Carolina
V. Seattle Metro Renton Water Reclamation Plant
Other Promising Technologies
Factors that Contribute to Success
The Influence of Financial Factors
Conclusions

3. Introduction
• Founded this study for the U.S DOE
 Environmental Protection Agency (EPA)
 National Renewable Energy Laboratory (NREL)
• For the purpose of:
 to document energy conservation activities and their effects on
operation costs
 regulatory compliance
 process optimization

4. Background
• Wastewater treatment
processes with the highest
energy usage but also exhibit
the greatest potential for
energy savings.
activated sludge
dewatering and conditioning
biosolids incineration
aerobic digestion
advanced wastewater treatment
aeration ponds

5. Basics of Biogas Generation and Use
 Biogas is the type of gas that is
produced in an anaerobic digester.
 produced from raw materials such as:
 agricultural waste
 Manure
 municipal waste
 Plants
 Sewage
 green waste or food waste

6. How does Biogas Produce?

7. • Biogas In-plant uses are:
heating boilers in process heating operations
space heating and cooling
engine-driven machinery
Engine generators for electricity generation
solids incinerators
generation of electricity by steam turbines and fuel cells
*Biosolids: nutrient-rich organic materials resulting from the treatment of domestic sewage in a treatment facility

8. I. County
Sanitation
Districts of
Orange County

9.  Uses of biogas
 heat the digesters
 fuel engines that run pumps and blowers
• In 1989, CSDOC codified formal energy conservation plans in the "2020
Vision Plan.“
 The 2020 Vision Plan
energy conservation activities
lighting
building heating and cooling
generation of electricity onsite
Biogas: gaseous fuel, especially methane, produced by the fermentation of organic matter.

10. • CSDOC PLANT 1

11. CSDOC PLANT 2

14. Financial Benefits
• facility reduced electrical power purchases by:
 biogas fueling of engines,
 process changes,
 lighting energy conservation,
 peak load shifting,
 reduction of loadings to the secondary process.

15. • With Central Gen on-line are able to fully use the biogas produced, the
calculated savings in 1993-94 are substantial.
• The plant staff estimates savings totaling 12,630 kilowatts, worth about
$8,850,000
• The $65 million cost for Central Gen and all associated projects will be
recovered in about seven years because of the savings achieved by this
project

16. II. City of Los Angeles Hyperion
Wastewater Treatment Plant
The Hyperion Treatment Plant from the air.

18. The Hyperion Energy Recover System (HERS) came on-line in 1987. HERS
generates energy from biosolids using two distinct methods:
1. Biogas from anaerobic digestion fuels three gas turbines.
produce 4,500 kW of electricity (each).
2. Biosolids from the digesters are dehydrated
 powder is burned in a fluid bed gasification multi-stage combustion chamber.
Ash from this combustion process is currently used in an offsite cement manufacturing
process.
total average electrical production is 20 megawatts.

19. • The facility currently uses about
600,000 cubic feet per day of
natural gas to supplement biogas
production.

20. Location of Hyperion Treatment Plant
Coordinates
33° 55′ 31.44″ N, 118° 25′ 47.28″ W
33.9254, -118.4298

24. III. Sunnyvale Water
Pollution Control Plant

25. Facility Description
The plant was equipped with
• two 55-ft diameter anaerobic
digesters
• two biosolids drying lagoons
Biogas produced by the anaerobic
digestion Use to wastewater pump
pre-aeration blower
power generation facility

26. • 7.5 MGD primary plant was
designed to service a population
of 10,000
• to provide separate treatment
for a seasonal cannery load of
4.0 MGD

27. • Location of the Sunnyvale Water Pollution Control
Plant
1444 Borregas Ave, Sunnyvale, CA 94089, United States

28. History
1956 The Sunnyvale Water Pollution Control Plant (WPCP), in California incorporated
use of biogas in its original plant construction
1960 Sunnyvale's population increased by 500 percent to 60,000 People
1965 Plant expansions
1968 • increased the treatment plant's capacity to 15 MGD
• third 55ft-diameter anaerobic digester
• 440-acre oxidation pond with a four-pump circulation pumping station
• remote three-engine-generator facility to provide power for the pumps
(use either natural or biogas as fuel)
• Addition of a third biosolids lagoon
1972 • The City increased the plant capacity
• constructed a fourth 70-ft diameter anaerobic digester

29. 1978 • due to substantial upgrading of effluent discharge
regulations—including the ammonia removal requirements
• Additional treatment:
• add fixed growth reactors (FGRs)
• air flotation units (AFTs)
• dual media filters
• Breakpoint chlorination and dechlorination
equipment
1980 • increased treatment capacity to 22.5 MGD when the
population exceeded 100,000 with a final upgrade to 30.0
MGD

30. Description of the Technologies
• A design goal for the Sunnyvale wastewater treatment plant was to make
maximum use of biogas.

31. Waste Heat Recovery
Use of waste heat:
digestion
chlorination systems
space heating for various buildings at the treatment plant
waste heat is recovered in three systems:
(1) pump-engine heat recovery,
(2) generator-engine heat recovery
(3) stack heat recovery
• Heat from all sources is converted into hot water for use throughout the plant.

32. Operation and Maintenance
• influent pumps were designed to pump
 min. flow (dry weather)= 1.0 MGD
peak flow (storm)=50 MGD

33. • During installation in 1956, the pump
engines used dual suction-type
carburetors.
• Biogas system
Engine fuel use biogas when
pressure built up to 4 inches
Natural gas fuel is use when the
pressure in the biogas system fell
two inches below
1) it combines gasoline and air creating a highly
combustible mixture, 2) it regulates the ratio of air and
fuel, and 3) it controls the engine's speed

34. Landfill Gas Production
• The Sunnyvale WPCP is located next to the municipal landfill (closed).
• Landfill gas (LFG) is produced by bacterial decomposition of the organic
portion of refuse in the absence of oxygen.

35. • The proposed energy conservation project will collect LFG and use it
together with biogas from the WPCP anaerobic digesters to fuel engines
and generators that supply the WPCP with electricity.
• The City projects savings in reduced purchases of electricity to be
$826,400 in Year 94-95.

36. • The total cost of the LFG project is estimated at $4.47 million.
• The project has received a grant from the California Energy
Commission for $500,000.
• At the $ 826,400 annual savings in electrical costs, project
payback is anticipated in approximately six years.

37. IV. Sanford Big Buffalo
Creek WWTP , North
Carolina

38. Facility Description
• The Big Buffalo Creek (BBC) WWTP provides wastewater
treatment for a population of approximately 17,000 people.
• average influent flow
3.52 MGD
• peak flow
6.8 MGD
• major rainfall
12 MGD

39. History of the Energy Conservation Program
late 1970 several U.S. oil companies VioIated price controls
years of 1983
to 1986
NCDECD and Energy Division used part of the grant to conduct
on-site energy audits of 15 wastewater treatment plants and three water
treatment plants.
NCDECD-North Carolina Department of Economic and Community Development
The audit found that the plant components which consumed the major
power were:
• extended aeration (70%),
• influent pumping (1 7%),
• aerobic digestion (5%),
• sludge pumping (3%),
• small miscellaneous uses (5%).

40. Location of BBC WWTP

41. Description of the Technologies
Process control system consists of an
Andover controller unit which
communicates with a laptop
computer.
controls the aeration basin aerators
according to DO, high flow and low
flow
A photo of Andover Control

42. • During low flows, if the process is stable, the process control
system continues to operate from the DO input.
• monitors the tertiary fiIter for flow rate to determine optimal
timing for backwashing.

43. An Allen Bradley controller was added
to the influent pump station.
an automatic "Beck" valve was
installed to maintain a constant head,
of approximately ten feet, in the
influent pump wet well.
A photo of Allen Bradley Controller

44. During the facility upgrade
Gasters Creek Pump
Station pumps
replaced with high efficiency, higher capacity
centrifugal Pump
The Little Buffalo Creek
Pump Station
replaced with high efficiency submersible pump
RAS screw pumps replaced with centrifugal pumps
The screw pump belt
drives
replaced with direct drive units to conserve energy
mercury vapor yard
Lighting
replaced with energy efficient sodium vapor lighting,
and installed energy efficient windows in the
operations Building

45. Process Modifications
The aeration basin were designed to treat 10 MGD
average flow is 4.56 MGD
Use of a single aeration basin allowed operators to match
the flow volume with the design.

46. Financial Benefits
• Actual payback time for the process control system was less than the 1 year
originally estimated.
• before energy conservation the two-year average monthly electrical cost
during 1982-83 was $8,755 at $ 0.044 per kilowatt hour).
• Monthly electrical costs averaging $4,200 over the period July 1993 to April
1994 reflect the effects of energy Conservation measures on electrical costs at
the BBC plant.

47. V. Seattle Metro
Renton
Water
Reclamation
Plant
Renton wastewater treatment plant
built by Metro, 2000

48. Outline Seattle Metro Renton Water Reclamation Plant
Facility Description
 Energy Recovery from Biogas
 The Metro Therm Program
Benefits of the Energy Conservation Program

49. Facility Description
• South Plant, located in Renton, is part of King County's regional
wastewater treatment system.
• does not use its biogas onsite for heating and/or cooling.
• to sell the gas for offsite use and replace its potential in-plant use
with electrically operated heat pumps that remove heat from
effluent.
• feasible depend on the low prices for electricity in the Seattle area

50. Timeline
1965 Completed to built as a secondary treatment plant
1986 a new effluent discharge pipeline and outfall was completed to
eliminate discharges to the Green/Duwamish River and carry
treated wastewater 12 miles to a deep-water outfall in Puget
1997 Plant began producing reclaimed water.
2001 expanded to its current capacity of 115 million gallons per day of
average wet weather flow and 325 MGD during peak storms

51.  The Renton plant treats about 108 MGD of
wastewater.
 Plant processes consist of:
primary settling,
Aeration
secondary settling
chlorination
Dechlorination
 Biosolids are treated in dissolved air flotation
thickeners, followed by anaerobic digestion and
belt filtration

52. • Location of the WWTP

53. Energy Recovery from Biogas
four anaerobic digesters generate 1.2 million f³/d of
biogas
They scrubs the biogas to remove carbon dioxide, and
sells the resulting 99 percent pure methane to the local
gas utility.
receives $1,100/day for the scrubbed gas

54. The Metro Therm Program
• MetroTherm is designed to provide treated wastewater
effluent for heating and cooling of buildings (WWTP)
1982 the State of Washington began a "District Heating and Cooling" (DHC) program
to encourage communities to develop centralized hot water production to serve
various energy needs
1994 Provided grants and assistance and will continue to provide support to Metro
with a $25,000 grant and $25,000 in services

55. Facilities can use effluent in three modes:
• heating and cooling,
• cooling only,
• heating only
 A heat pump or heat exchanger and a compatible heating or
cooling system is necessary to use the effluent

56. Benefits of the Energy Conservation Program:
Regulatory Compliance
• Metro's energy conservation activities have positive environmental
benefits.
• By not burning biogas onsite, Metro avoids creating air emissions from
such a process.
• In addition, companies use heat exchangers rather than natural gas for
heating purposes, additional reduced emissions would be expected.

57. Factors that Contribute
to success

58. Factors that contribute to success
CSDOC Hyperion Sanford's BBC WWTP
• Advanced primary treatment
• Secondary treatment
• Loading based limits for
industrial users
• identified the importance of
management and staff
training, interest, and
technical expertise to
successfully carry out energy
conservation
• identified staff
expertise as most
important to the
success
• trained plant operators
and instrumentation
staff whose primary
responsibilities are in
wastewater treatment.
• extended aeration basins
• process control system
• identified the importance of
management and staff
training, interest, and technical
expertise to successfully carry
out energy Conservation
• cites the value of a
comprehensive energy audit
as an essential tool for cost-
effective energy conservation.

59. The Influence of
Financial Factors

60. BIOSOLIDS: Onsite Use versus Offsite Reuse
• 1) If the cost of electricity purchased from the public power
company were to increase by 45 percent or more, the onsite
option becomes more economical.
• 2) If the cost to dispose of biosolids offsite were to at least
double, it becomes more cost effective to process the biosolids
onsite.
• 3. Hyperion staff show that the addition of steam dryers lowers
the cost of onsite biosolids processing to $109 per dry ton,
compared to $132 for offsite management

61. BIOGAS: Onsite Use versus Offsite Sale
Onsite use:
• to generate electricity
• to provide heat for digesters and buildings.

62. Conclusion

63.  Energy recovery from biogas is universally cost effective and has
gained widespread acceptance.
 Recovery and use of biogas accomplish energy conservation and
pollution prevention goals, and also cost savings.
 Wastewater treatment plants located near municipal landfills, and
could develop the landfill gas as an additional energy source