Status and Role of Water Reuse

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Status 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

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Uses of Reclaimed Water

• Agricultural irrigation
• Landscape irrigation
• Nonpotable urban uses
• Industrial uses
• Impoundments

• Commercial uses
• Environmental uses
• Groundwater recharge
• Indirect potable reuse
• Miscellaneous uses

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Nonpotable Reuse
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Indirect Potable Reuse
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Direct Potable Reuse
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Incidental or Unplanned Indirect Potable Reuse
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Drivers 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

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Drivers 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

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Water 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

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Public 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

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Opposition to Reuse- Summary of Various Studies -
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Water Reuse in Selected Regions
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Current 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

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Treatment 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

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Examples 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

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Groundwater Recharge/Potable Reuse - Surface
Spreading -
Recharge Basin
Production Well
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Groundwater Recharge/Potable Reuse - Injection -
Injection Wells
Production Well
Ocean
Saline Water
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Microbial Pathogens in Wastewater

• Bacteria Parasites
  Viruses
• Protozoa
• Helminths

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Occurrence 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

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Disease 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

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The Bottom Line(For nonpotable uses)
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Chemical 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

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EDCs, 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

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Reclaimed 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

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Removal Through Wastewater Treatment
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Water 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

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Regulations 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
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Water 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.)

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Reclaimed Water Standards for Irrigation of Food
Crops Eaten Raw (Examples)
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California Water Recycling Criteria- Summary for
nonpotable uses -
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Draft California Regulations for Groundwater
Recharge into Potable Aquifers
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Agricultural IrrigationSalinas Valley
Reclamation Project(Monterey, California)
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Salinas 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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Irrigation 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

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Supplemental Well
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Grower turnout
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Costs

• 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

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Salinas Valley Reclamation Project- Microbial
Water Quality -
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Indirect Potable ReuseOrange County Water
District(California)
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Joint 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
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GWR 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
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Where 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

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Project 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

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Benefits 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

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Trends 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

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James Crook, Ph.D., P.E. Environmental
Engineering Consultant E-mail jimcrook_at_msn.com