Title: Status and Role of Water Reuse
1Status and Role of Water Reuse
- James Crook, Ph.D., P.E.
- Environmental Engineering Consultant
- Boston, Massachusetts
- International Conference on Water Policy 2009
- 2226 June 2009
- Prague, Czech Republic
2Uses of Reclaimed Water
- Agricultural irrigation
- Landscape irrigation
- Nonpotable urban uses
- Industrial uses
- Impoundments
- Commercial uses
- Environmental uses
- Groundwater recharge
- Indirect potable reuse
- Miscellaneous uses
3Nonpotable Reuse
4Indirect Potable Reuse
5Direct Potable Reuse
6Incidental or Unplanned Indirect Potable Reuse
7Drivers for Reuse
- Principal driver is water stress (need for water)
- Scarcity of renewable freshwater resources due
to - Population increases
- Industrial development
- Droughts
- Global climate changes
8Drivers for Reuse
- Other drivers include
- Conservation of potable supply
- Environmental enhancement
- Pollution abatement
- Reliability of supply
- High cost of alternative sources of water
- Regulatory policies/regulations
9Water Reuse Benefits/Savings
- Reduction of freshwater use
- Water treatment cost savings
- Extends current freshwater supply
- Delays/eliminates development of new water
sources - Reduction of wastewater discharge to surface
waters - Environmental benefits
- Extends discharge capacity
- Often least-cost water supply alternative
- Provides a reliable water supply
10Public Acceptance of Water Reuse
- Public generally strongly supports nonpotable
uses - Uses involving no or minimal contact with
reclaimed water (e.g., irrigation) are favored - Acceptance related to knowledge of reuse
- Lower level of acceptance for potable reuse
- Surveys indicate about 50 of people opposed
- Some projects have been rejected due to public or
political opposition - Major reason for opposition almost always related
to health concerns - Hidden issues, e.g., may enhance population growth
11Opposition to Reuse- Summary of Various Studies -
12Water Reuse in Selected Regions
13Current Status in U.S.
- More than 1,500 water reuse facilities in U.S.
- Only about 6 of municipal wastewater is reused
- Estimated that more than 11 x 106 m3/d of
municipal wastewater are reclaimed - 4 states account for about 90 of reclaimed water
use - Arizona
- California
- Florida
- Texas
14Treatment Technology
- Nonpotable reuse
- Varies from primary to tertiary (secondary,
filtration, disinfection) - Mechanical processes predominate in
industrialized countries (conventional biological
treatment, media filtration, BNR, disinfection,
etc.) - Trend is membranes, MBRs, and UV disinfection
- Pond systems predominate in developing countries
- Potable reuse
- AWT typical (e.g., secondary treatment, MF, RO or
GAC, and advanced oxidation with H2O2 and UV ) - Soil aquifer treatment (after tertiary treatment)
common for recharge
15Examples of Potable Reuse Projects
- 1962 CSDLAC (California) groundwater recharge
- 1968 Windhoek (Namibia) direct potable reuse
- 1976 OCWD WF-21 (California) seawater barrier
- 1978 UOSA (Virginia) surface water
augmentation - 1985 El Paso (Texas) groundwater recharge
- 1995 WBMWD (California) seawater barrier
- 2000 Scottsdale (Arizona) groundwater
recharge - 2002 Torreele, Belgium groundwater recharge
- 2003 ESW, Langford, UK surface water
augmentation - 2003 Singapore surface water augmentation
- 2005 Alamitos Barrier (California) seawater
barrier - 2005 IEUA (California) groundwater recharge
- 2008 OCWD GWR System (California) seawater
barrier and groundwater recharge
16Groundwater Recharge/Potable Reuse - Surface
Spreading -
Recharge Basin
Production Well
17Groundwater Recharge/Potable Reuse - Injection -
Injection Wells
Production Well
Ocean
Saline Water
18Microbial Pathogens in Wastewater
- Bacteria Parasites
Viruses - Protozoa
- Helminths
19Occurrence of Pathogens in Raw Wastewater
- Occurrence and concentration fluctuate widely
- Factors include
- Sources contributing to the wastewater, e.g.,
medical wastes - Existence of disease carriers in the population
- Ability of infectious agents to survive outside
their hosts under a variety of environmental
conditions - Viruses generally more resistant to environmental
stresses than bacteria - Parasitic cysts and oocysts generally maintain
their viability longer in the open environment
than either bacteria or viruses
20Disease Incidence Related to Water Reuse
- High infectious disease rates (e.g., typhoid
fever, cholera, ascaris, hookworm, tapeworm) in
regions using untreated or poorly-treated
wastewater for crop irrigation - Middle East
- Far East (e.g., India, Pakistan)
- Latin America
- Some allegations of gastrointestinal illnesses in
industrialized countries resulting from cross
connections - Most not confirmed or medically documented
21The Bottom Line(For nonpotable uses)
22Chemical Constituents- Nonpotable Uses -
- Paucity of research data on health risks for some
organic constituents, but - Only incidental/inadvertent ingestion of
reclaimed water - Constituents generally in µg/L or ng/L range
- Many organics have short half-lives and are
biodegradable in the environment - Studies indicate large organic molecules dont
enter edible portions of food crops from
irrigation - Potential health hazard if reclaimed water
percolates to potable groundwater supplies
23EDCs, PhACs, and PCPs
- Many are ubiquitous in
- municipal secondary and
- tertiary wastewater effluents
- at µg/L or ng/L levels
- Some, EDCs in particular,
- have been shown to
- adversely affect aquatic
- animals
- Little definitive data on
- human health effects at
- levels found in wastewaters
- Many dont have drinking
- water limits
-
- Cartoon courtesy of Shane Snyder
24Reclaimed Water Treatment
- Removal of PhACs and EDCs by secondary treatment
highly variable - Tertiary treatment and soil aquifer treatment
reduce many but not all PhACs and EDCs to low
levels - AWT processes, such as RO and/or advanced
oxidation (H2O2 UV), effectively reduce most
PhACs and EDCs to extremely low levels - Most below detection limits
25Removal Through Wastewater Treatment
26Water Reuse Criteria/Guidelines
- Vary widely around the world
- Particularly between developing and
industrialized countries - Most use fecal coliforms or E. coli as the
indicator organism - Some include both treatment process and reclaimed
water quality requirements - WHO guidelines favored in developing countries
- California-type criteria favored in several
industrialized countries
27Regulations and Guidelines Vary Depending on Type
of Reuse
- Indirect potable reuse
- Agricultural Reuse on Food Crops
- Unrestricted Recreational Reuse
- Unrestricted Urban Irrigation Reuse
- Restricted Urban Irrigation Reuse
- Restricted Recreational Reuse
- Industrial Reuse
- Environmental Reuse
- Agricultural Reuse on Non-food Crops
More Stringent Regulations
Less Stringent Regulations
28Water Reuse Criteria
- Generally include
- Water quality requirements
- Treatment process requirements
- Treatment reliability requirements
- Monitoring requirements
- Operational requirements
- Cross-connection control provisions
- Use area controls (signs, color-coded pipes,
setback distances, etc.)
29Reclaimed Water Standards for Irrigation of Food
Crops Eaten Raw (Examples)
30California Water Recycling Criteria- Summary for
nonpotable uses -
31Draft California Regulations for Groundwater
Recharge into Potable Aquifers
32Agricultural IrrigationSalinas Valley
Reclamation Project(Monterey, California)
33Salinas Valley Reclamation Project- Operational
in 1998 -
- Treatment plant capacity 114 x 103 m3/d
- Current flow 76 x 103 m3/d
- Treatment
- Secondary
- Rapid mix of Coagulant and polymer added
- Flocculation
- Dual media gravity filtration
- Disinfection using gaseous chlorine
- Diurnal flow equalization storage
- Crops irrigated artichokes, broccoli,
cauliflower, lettuce, celery, and strawberries
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36Irrigation Distribution System
- Distributes reclaimed water to 222 parcels of
farmland - Irrigate 4,800 ha of food crops
- Distribution pipelines 74 km
- Diameter 0.2 to 1.3 m
- 22 supplemental wells for peak demand
- 111 flow-metered turnouts
- Pressure and flow metering stations
- Centralized control system
- 3 booster pump stations
- Cathodic protection for ferrous metal piping
37Supplemental Well
38Grower turnout
39Costs
- Capital costs
- Treatment facilities 30 million (US dollars)
- Distribution system 37 million
- OM costs/year
- Treatment facilities 3.9 million
- Distribution system 1.5 million
- Repayment of loans/year 1.8 million
- Cost to treat and deliver water 0.23/m3
- Excludes secondary treatment costs
- Includes debt service and OM costs
40Salinas Valley Reclamation Project- Microbial
Water Quality -
41Indirect Potable ReuseOrange County Water
District(California)
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43Joint Partnership
- Orange County Sanitation District (OCSD)
- Wastewater Collection, Source Control, Treatment
and Disposal - Orange County Water District (OCWD)
- Manages and protects the Groundwater Basin, AWT
OCSD
OCWD
Source Control
Primary Treatment
Secondary Treatment
Advanced Water Purification
Sewage
Reuse
44GWR System Flow Diagram
EnhancedSource Control
265 x 103 m3/d
265 x 103 m3/d
Reverse Osmosis (RO)
Ultraviolet Light (AOP)
322 x 103 m3/d
Microfiltration (MF)
SecondaryTreatment
Product Water
OCSD Secondary Effluent
Ground-water Recharge (injection spreading)
with hydrogen peroxide
Backwash OCSD Plant 1
Brine OCSD Outfall
45Where Does GWR System Water Go?
- Water is returned to groundwater basin
- 132 x 103 m3/d is sent to injection wells for
seawater intrusion barrier - 132 x 103 m3/d is sent to recharge basins in
Anaheim
46Project Funding and Timing
- Capital cost approximately 481 million
- Split equally between OCWD and OCSD
- Operating cost approximately 30 million/year
- Produces 97 x 106 m3/yr of water
- Costs comparable to imported water
- 92 million in state/federal grants and an 86
million subsidy for OM from Metropolitan Water
District - Unit cost of water 0.47/m3
- Without outside funding cost of water would be
0.65/m3 - Operational since January 2008
47Benefits of GWR System
- Higher quality than other water sources in Orange
County - Reduces salinity build up
- Provide additional groundwater supply
- Uses 40 less energy than imported water
- Reliable, drought-proof source
- Protects basin from seawater intrusion
- Decreases wastewater discharge to ocean
- Defers need for a new ocean outfall
- Provides needed water for Orange County
48Trends in Water Reuse
- Integrated resource planning
- Dual systems
- Decentralized systems
- Indirect potable reuse
- UV for disinfection
- Membrane processes
- Regulation development
- Public perception studies
- Increased interest in direct potable reuse
49James Crook, Ph.D., P.E. Environmental
Engineering Consultant E-mail jimcrook_at_msn.com