George Tchobanoglous, University of California, Davis - Speaker at the marcus evans Water & Wastewater Management Summit, held in Summerlin, NV, May 3-4, 2012, delivered his presentation on Wastewater Treatment Trends in the 21st Century

1. WASTEWATER TREATMENT TRENDS Topics
IN THE 21ST CENTURY
Part-1 Some Global Trends
Part-2 Uncontrollable Events and
Unintended Consequences
Water & Wastewater
Management Summit
Part-3 Future Challenges and
Las Vegas, NV Opportunities
May 3, 2012
George Tchobanoglous
Department of Civil and Environmental Engineering
University of California, Davis
Part-1 Some Global Trends that will Impact of Urbanization on Plant Siting
Impact Wastewater Treatment
• Population Demographics
Impact of urban spread
Urbanization along coastal areas
• Climate Change (
g (wetter/dryer)
y )
Sea level rise
Impact of storm events on WWTPs
• Aging infrastructure
Impact of Coastal Population Demographics
Hyperion WWTP, Los Angeles, CA Urbanization Along Coastal Areas
• By 2030, 60 percent of world’s population
will near a coastal region
• Withdrawing water from inland areas,
transporting it to urban population centers,
treating it using using it once and
it, once,
discharging it to the coastal waters is
unsustainable.
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2. Impact of Sea Level Rise on
Impact of
Sea Level
Stormwater Collection System
Rise on
Stormwater
Collection
System
Courtesy City of San Francisco Courtesy City of San Francisco
Climate Change: Impact of Intense
Rainfall on Operation of WWTP Aging Infrastructure Challenges
• Aging wastewater infrastructure, typical age
75 years, in large cities over 100 years old
with excessive exfiltration
• Flowrates have decreased over the past
decade and will continue to decrease
1. Increased corrosion
2. Most conventional gravity sewer design
equations no longer suitable
3. Increased mass concentration loading factors
have impacted wastewater treatment facilities
Part-2 Impact of Uncontrolled Events Impact of Sea Level Rise on
Wastewater Management Infrastructure
and Unintended Consequences
• Uncontrollable events
Natural disasters
Climate change
Chemical costs
• Unintended consequences
Treatment plant siting
Water conservation
Treatment plant hydraulics
Energy usage
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3. Impact of Conservation and Drought:
Solids Deposition, H2S Formation, and At $0.03/kWh Energy Efficiency was not an Issue.
Downstream Corrosion due to Reduced Flows Example: Excessive Headloss (Energy Loss)
at Primary Sedimentation Tank Weir
Part-3 Future Challenges and Opportunities
• Paradigm shift in view of water
• Alternative collection systems
• Food waste management
• Energy and nutrient recovery
• Recycling through direct potable
reuse
• Integrated wastewater management
New View of Wastewater: A Paradigm Shift Modified Collection System For Reduced
Flow Rates (e.g., Conservation)
WASTEWATER is a RENEWABLE
and RECOVERABLE SOURCE OF
ENERGY (heat and chemical),
RESOURCES,
RESOURCES and WATER
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4. Wastewater and Food Waste Management Options
Energy Content of Wastewater
Heat energy
Specific heat of water = 4.1816 J/g •°C at 20°C
Chemical oxygen demand (COD)
C5H7NO2 + 5O2 5CO2 + NH3 + 2H2O
(113) 5(32)
Chemical energy (Channiwala,1992)
HHV (MJ/kg) = 34.91 C + 117.83 H - 10.34 O
- 1.51 N + 10.05 S - 2.11A
Required and Available Energy for
Wastewater Treatment, Exclusive of Heat Energy
Energy Content of Wastewater
• Energy required for secondary wastewater
Constituent Unit Value treatment
1,200 to 2,400 MJ/1000 m3
Wastewater, heat basis MJ/10°C•103 m3 41,900
Energy available in wastewater for treatment
Wastewater,
Wastewater COD basis MJ/kg COD 12 - 15
(assume COD = 5 0 g/m3)
5.0
15 - 15.9 Q = [500kg COD/1000 m3) (1000 m3) (13 MJ/ kg COD)
Primary sludge, dry MJ/kg TSS
Secondary biosolids, dry MJ/kg TSS 12.4 - 13.5 6,000 MJ/1000 m3
• Energy available in wastewater is 2 to 4 times
the amount required for treatment
Alternative Technologies for
Primary Treatment and Energy Recovery
Heat Recovery from Wastewater
SOURCE : City of Vancouver, Sustainability website retrieved from
http://vancouver.ca/sustainability/neuTechnology.htm
FALSE CREEK ENERGY CENTER
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5. Alternative Wastewater Treatment Multiple Reclaimed Water Qualities
Without Biological Treatment for DWM Systems
Energy and product recovery
Solids
processing
Enhanced Wastewater Management and Use of Existing Collection System For
Water Reuse Through Urine Separation Source Separated Resource Streams
Maximum recovery of nutrients
Removal of trace organics (EDCs, etc.)
Enhanced treatment with respect to residual
nutrients and trace organics with less treatment
complexity
Reduced energy requirements
Use of soil for advanced treatment of residual trace
organics and unknown pathogens
Enhanced protection of the environment
Nutrients and Trace Organics in Domestic Examples of Urine Separation Fixtures
Wastewater: A Case for Urine Separation
Greywater
100
Greywater Greywater
Feces
80
Feces
Feces
Composition, %
60 Relative
Greywater distribution
unknown,
Urine preliminary
40 > 70%
Urine Feces
in urine and
Urine
urine
20
0
Nitrogen Phosphorus Potassium Volume Trace organics
Wastewater constituent
Source: Jönsson et al.(2000) Recycling Source Separated Human Urine.
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6. Potential Impacts of Urine Separation Nutrient Separation, Storage, and Recovery
On Biological Wastewater Treatment From Individual Residence
With US, After primary, Cell yield,
Constituent mg/L
mg/L mg/L
BOD5 ~450 292 190
COD ~1050 525 -
TSS ~500
500 150 -
NH4-N 3 ~3
Req. N for
Organic N 13 ~9 cell growth
23.5
TKN 16 ~12
P (biogenic) 3.3 2.3 Req. P
P (other) 2.6 1.8 4.7
Urine Utilization in Indoor Wetland System Passive Water, Nutrient, and Energy
Near Os, Norway Recovery System
Factors Limiting Nonpotable and
Indirect Potable Reuse Recycling Through
Direct Potable Reuse
Agricultural Irrigation
• Large distance between reclaimed water and
agricultural demand
• Need to provide winter storage
Landscape Irrigation
• Dispersed nature of landscape irrigation
• Cost of parallel distribution system
Indirect Potable Reuse
• Most communities lack suitable hydrology for
groundwater recharge
• Availability of nearby suitable surface storage
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7. Microfiltration, Cartridge Filters, Reverse Osmosis, and
Typical Flow Diagram Now Used for the Advanced Treatment (UV), OCWD
Production of Purified Water
Adapted from OCWD
Planned Indirect and Direct Potable Reuse Driving Forces for Direct Potable Reuse
• De facto indirect potable reuse is largely unregulated
OCWD
Groundwater Buffer • Infrastructure requirements limit reuse opportunities
• Population growth, demographics, and global
warming will result in unsustainable situation
• Lack of an environmental buffer
• Existing and new technologies can and will meet the
water quality challenge
• The value of water will increase significantly in the
future
Upper Occoquan,
San Diego, CA (Proposed) • Stringent environmental regulations
Surface Water Buffer
De Facto Indirect Potable Reuse Integrated Wastewater Management With
Decentralized, Satellite, Centralized Facilities
Courtesy City of San Diego
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8. Intercepted In-Building
Self-Contained Water Recycle System
Satellite
Systems for
Reclamation
and Reuse
Reclaimed water is used for
toilet flushing, landscape irrigation,
and cooling water
Offsetting Potable Water Demand for Irrigation
Review of Opportunities and Challenges
(System has been in Operation for 25 Years, Upland, CA)
• Energy and nutrients in wastewater under
utilized
• New models needed for retrofitting collection
systems
• New technologies will revolutionize WWTP
• Direct potable reuse solves multiple problems
with existing wastewater systems and future
demographics
• New integrated infrastructure needed for
enhanced water reuse
Courtesy D. Ripley
The Future
Replacement or repair of infrastructure
with the same thinking and technology
used to create it, will perpetuate the THANK YOU
problems now experienced and create FOR LISTENING
new problems
problems.
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