Water Reuse


Water_Reuse Chapters_1_7.pdf - Consortium of Institutes for ...

Water Reuse

Bruce Lesikar

Texas Cooperative Extension

University Curriculum Development

for Decentralized Wastewater


NDWRCDP Disclaimer

This work was supported by the National Decentralized Water

Resources Capacity Development Project (NDWRCDP) with

funding provided by the U.S. Environmental Protection Agency

through a Cooperative Agreement (EPA No. CR827881-01

01-0) 0)

with Washington University in St. Louis. These materials have

not been reviewed by the U.S. Environmental Protection

Agency. These materials have been reviewed by

representatives of the NDWRCDP. The contents

of these materials do not necessarily reflect the views and

policies of the NDWRCDP, Washington University, or the U.S.

Environmental Protection Agency, nor does the mention of trade

names or commercial products constitute their endorsement or

recommendation for use.

CIDWT/University Disclaimer

These materials are the collective effort of individuals from

academic, regulatory, and private sectors of the

onsite/decentralized wastewater industry. These materials have

been peer-reviewed reviewed and represent the current state of

knowledge/science in this field. They were developed through a

series of writing and review meetings with the goal of formulating

a consensus on the materials presented. These materials do not

necessarily reflect the views and policies of University of

Arkansas, and/or the Consortium of Institutes for Decentralized

Wastewater Treatment (CIDWT). The mention of trade names or

commercial products does not constitute an endorsement or

recommendation for use from these individuals or entities, nor

does it constitute criticism for similar ones not mentioned.


Lesikar, B.J., B. Lee and D. Waller 2005. Water

Reuse - PowerPoint Presentation. in (M.A.

Gross and N.E. Deal, eds.) University

Curriculum Development for Decentralized

Wastewater Management. National

Decentralized Water Resources Capacity

Development Project. University of Arkansas,

Fayetteville, AR.

Reclaimed Water IS a Resource

Water is necessary to sustain life

• Human consumption

• Food production

• Many daily tasks

‣Current supplies are not sufficient given

increased demand

Reuse water has the capacity to augment

current potable water supplies for various


‣Higher demand = Less available supplies

Hydrologic Cycle

‣ Natural system of water recycling

Water moves back and forth between the

Earth and the atmosphere

‣ Evapotranspiration takes water into the

atmosphere; precipitation returns water to

the Earth’s surface

‣ On-site system catches water after use

and allows the water to be used again

before release

Hydrologic Cycle

Earth’s Water Resources

Salt Water (97%)

Frozen Fresh Water


Other 3%

Ground and

Surface Waters


Frozen Fresh Water


Ground and Surface

Waters (1%)

Salt Water


Water Demand in the U.S.

‣ U.S. water demands in 1995

• Source: USGS Survey - Estimated Use of Water in

the United States in 1995 (1998).

• Average 402 billion gallons per day withdrawn

• 90% (362 billion gallons per day) was for

agricultural/industrial purposes

• 33.3% (134 billion gallons per day) was for irrigation

• 10% (40 billion gallons per day) was for household:

75 to 80 gallons per person per day

Water Reuse Stabilizes Demand






Total Water Withdrawals, 1000 mgd









Reclaimed Wastewater, 1000 mgd





1950 1955 1960 1965 1970 1975 1980 1985 1990 1995



Total Water Withdrawal

Reclaimed Wastewater

Typical Water Reuse Cycle

Another View of the Cycle

Chapter 2

Applications for

Reclaimed Water

Applications for

Reclaimed Water

‣ Greywater * Recovery

‣ Greywater * Recycle

‣ Greywater * Reuse


is water captured from sinks, showers, baths,

clothes washing machines, laundry tubs and dishwashers,

but NOT from toilets or urinals.


‣ Various sources of contamination


• Microorganisms

• Biological

• Chemical

• Dissolved salts – sodium, nitrogen, phosphates,


• Chemicals – oils, fats, milk, soap, detergents

• Physical

• Soil

• Food

• Lint

Greywater Recovery

‣ Greywater Reuse

• May be treated or untreated

• Diverted or collected, treated, stored, and reused

‣ Use Sudsaver *

* a setting on some washing machines that retains water

from the rinse cycle and uses that water in the following

wash cycle.

‣ Direct

Greywater Reuse

• Divert water

• Filter before use for irrigation

• No kitchen water used

• No storage of untreated water

‣ Collect, treat, store, and use

• Treatment processes vary

• With disinfection, may be used for surface


Greywater Diversion Devices

‣ Greywater has a potential of

pathogens and therefore is generally

kept below ground surface

‣ Direct application to soil

‣ Kitchen wastewater - excluded

‣ No storage

‣ Must pass Coarse screen

Greywater Diversion Example

Using Sudsaver

‣ Sudsaver – a setting on some clothes

washing machines that holds used rinse

water and reuses it for the next washing


‣ Saves ~20 gallons of water per cycle

‣ Caution for usage

Typical Sudsaver

Greywater Recycle

‣ In-facility Use

• Use greywater for toilet and urinal flushing

• Two levels

• Individual buildings

• Cluster water reuse system

‣ Total Recycle/Non-Discharging/Closed Loop

• No water enters or leaves the system

• Drawback: potential accumulation of contaminants

due to repeated passage of water through the


In-Facility Use

‣ Used for toilet and urinal flushing

‣ Common in highly populated areas

‣ Two (2) types

• Individual building

• Cluster systems

Individual Building System

‣ Collect wastewater from sinks


‣ Each building has its own reclamation


‣ Each building has dual plumbing


Cluster System

‣ Treat wastewater from block(s)

‣ Transfer treated (reclaimed)

wastewater back to buildings for


‣ Blocks and buildings have dual

plumbing system

Cluster System

Irvine Ranch Water District, CA

Total Recycle/

Non-Discharging/Closed Loop

‣ Use wastewater for beneficial purposes without

discharging – closed loop wastewater reuse

• This type of reuse is generally not allowed in the US

‣ Accumulation of certain constituents due to

repeated passage of water through the system

may be a problem

‣ Denver Potable Water Demonstration Project

• Feasibility study incorporating the highest form of

advanced technology under management by highly

skilled people

Denver Potable Water

Demonstration Project

‣ 1985 – 1992

‣ 0.1 MGD treated wastewater to produce

drinking water

‣ Multiple barrier approach

Water met or exceeded drinking water


‣ No adverse health effects detected

Potential Reclaimed Water Uses

‣ Irrigation

Water Features

‣ Parks

‣ Artificial Snow-Making

‣ Groundwater Recharge

‣ Preventing Salt Water Intrusion

‣ Aquifer Storage and Recovery (ASR)

‣ Foundation Stabilization

‣ Fire Protection


‣ Agricultural

‣ Landscape

‣ Golf Courses

• Highest Risk for public health (Asano,(

et al.)

‣ Sport Fields

Agricultural Irrigation

‣ A well established practice

‣ U.S. EPA illustrated the guidelines in

Manual - Guidelines for Water Reuse

(EPA/625/R-92/004, 1992)

Application of Reclaimed Water for

Crop Production

‣ Protected from any possible diseases

‣ Specific regulations

Landscape (Turf) Irrigation

‣ Applications

‣ Two (2) types

• Irrigation of restricted areas 1

• Irrigation of open access areas 2

Water quality standards

‣ St. Petersburg,Florida

‣ Hawaii

1. Areas where the public has limited access or exposure to

reclaimed water (e.g., freeway landscapes)

2. Areas where the public has full access (e.g., golf courses,

playgrounds, parks, schoolyards, residential landscapes)

Golf Courses

‣ A popular application of reclaimed water

‣ In Florida, 419 golf courses had been

reported to use 110 MGD of reclaimed

water in 2001

‣ Many states in U.S. have this application

Sport Fields

‣ Irrigate sport fields by reclaimed water

‣ Reclaimed water must be highest quality

to protect the public

‣ In Hawaii, subsurface irrigation system

(drip system) is used

Sprinkler system

Drip System

Important Water Quality

Parameters for Irrigation Water

‣ Salinity

‣ Specific Ion Toxicity

‣ Long-Term Decreased Water

Infiltration Rates

‣ Nutrients


‣ Electrical Conductivity (EC)

• decisiemens per meter (dS/m(


mmho/m or mgTDS/L

‣ TDS (mg/L) = EC x 640

‣ Adverse effects on plant growth

• Increases osmotic pressure

Specific Ion Toxicity

‣ High concentration of specific ions

affects plant growth

‣ Ions: sodium, chloride and boron

‣ Boron - most prevalent

‣ In arid regions – high

evapotranspiration accelerates the


Decreased Water Infiltration Rates

‣ Sodium deteriorates soil physical


• Formation of crusts

Water logging

• Reduced soil permeability

‣ Sodium adsorption ratio (SAR) and

Adjusted SAR (adj(

R Na ) help to predict the

impact of sodium on soil especially for

surface irrigation systems

SAR and Adjusted SAR







+ Mg











+ Mg




‣ N, P, K, Zn, B and S act as beneficial plant

nutrients in correct doses

‣ High content of nutrients may reduce crop


‣ Nitrogen - most excessive nutrient

‣ Measure to balance nutrients

Water Features

‣ Use for aesthetic purposes

‣ Examples: decorative pools,

fountains, ponds, etc.

‣ Variable

water quality



‣ Use reclaimed water to create green

spaces in arid areas

‣ Reclaimed water quality requirements

depend on human access to the property

‣ Japanese Garden in Los Angels

metropolitan area

Japanese Garden

in Los Angles Area, CA

Created Park in

Los Angeles County, CA

Artificial Snow-Making

‣ Making snow in winter

‣ High quality required

‣ Snow melt feeds

surface water and

becomes irrigation

water in summer

The Snow Valley Ski Resort, CA

from Water Environment & Technology, Feb. 1993

Groundwater Recharge

‣ Purposes

• Retard saltwater intrusion

• Provide further treatment

• Augment aquifers

• Provide storage

• Control or prevent ground subsidence

Recharge Methods

‣ Surface Spreading

‣ Direct injection

Surface Spreading

‣ Replenishing groundwater by spreading

reclaimed water over ground

Water enters the ground and percolates

through the soil

‣ Rapid Infiltration Basins (RIBs(

RIBs) ) are the

fastest way to move water into soil


‣ Greywater spread across ground

‣ Additional treatment provided by


‣ Factors for treatment requirements

Percolation Field in Orange County, CA

Rapid Infiltration Basins (RIBs(


‣ Infiltrating reclaimed water

‣ Requires highly permeable soils

‣ The soil for RIBs can be the


- sandy loam, loamy sand, fine


‣ Basins must be rotated

RIB Site in Orange County, FL

Direct Injection

‣ Practiced where surface spreading

is NOT possible

‣ Injecting reclaimed water into a

confined aquifer

‣ Creating Salinity Barrier System

‣ Highest quality of reclaimed water

Problems with Groundwater


‣ Large surface land requirement for


‣ High cost to inject reclaimed water

‣ Possible contamination of groundwater

‣ Large affected area

Water right issues

Saltwater Intrusion

‣ Zone of brackish water between salt

and fresh water along coastlines due

to withdrawal of fresh water from


‣ Saltwater may be drawn into

freshwater supplies to replace

overdrawn freshwater supplies

‣ Occurs in many coastal communities

Saltwater Intrusion

Salinity Barrier System

‣ Establishing a fresh water barrier by

injecting reclaimed water back into

the aquifer

‣ Safe distance away from potable

water wells

‣ Specific regulations

Water quality required: highest

Aquifer Storage and Recovery


‣ Inject reclaimed water into a

subsurface formation

‣ Store water for later use

‣ Eliminate large surface water storage

requirement and associated

environmental and economic


Considerations associated with


Water quality changing during


‣ Contamination of existing


‣ Treatment and disinfection upon

water recovery

‣ State of Florida

Foundation Stabilization

‣ Use reclaimed water

for construction


• Foundation compaction

• Dust control

• Mixing of concrete

‣ Reclaimed water

quality issues

Fire Fighting & Protection

‣ Use for fire fighting and protection

‣ Creating greenbelt to prevent forest


‣ Main issues:

• Reclaimed water storage

Water transportation cost

Fire Fighting

‣ Structural fire fighting – requires

the highest water quality

‣ Nonstructural fire fighting – lower

water quality requirements

Fire Protection

‣ Hydrants, sprinkler system ONLY in

commercial and industrial buildings

‣ Sprinkler system in residential

buildings - requires the highest water



‣ Layer of vegetation surrounding a property

that acts as a fire barrier

‣ Reclaimed water is used to maintain the

vegetation, especially in arid areas

‣ Between five and ten feet thick


‣ Storage tanks generally located uphill of

the site

‣ Must have enough capacity for all

demands, including fire protection

‣ Must account for operational and seasonal

storage and disposal

‣ Open reservoir or closed tank

‣ Problems with each type of tank need to

be considered

Problems with Open


‣ Odors – hydrogen sulfide

‣ Temperature stratification

‣ Loss of chlorine residual and DO

‣ Excessive growth of algae

‣ High level of turbidity and color

‣ Regrowth of microorganisms

Water quality deterioration

Open Reservoir

Problems with Closed Tanks

‣ Release odors – hydrogen sulfide

‣ Stagnation

‣ Loss of chlorine residual

‣ Regrowth of microorganisms

Closed Tank for Reclaimed Water

End of Slide Show

Greywater Reuse

‣ Greywater sources?

‣ Contamination of Greywater and its


- How contaminated?

- Reuse methods

Greywater Reuse Methods

‣ Reusing on site.

‣ Methods

- Greywater diversion devices

-Domestic greywater treatment


Domestic Greywater Treatment


‣ Treating greywater

‣ Kitchen wastewater – included

‣ a variety of wastewater treatment

systems can be used

‣ Implementation of disinfection.

Greywater Treatment & Reuse

Common measures to solve

‣ Aeration


‣ Injecting chemicals

‣ Recirculation by mixers

Chapter 3

Water Reuse Design


Design Considerations

‣ System reliability and redundancy

‣ Site loading

‣ Performance of reclamation plants

‣ Safe design procedures

System Reliability and


‣ Performance of reclamation plant

• Need consistently high quality water,

regardless of the circumstances

‣ Regulations for water reclamation

plant – requires specific design

practices and equipment

Site Loading

‣ Considerations for irrigation

(especially agricultural)

• Hydraulic loading

• Organic loading

• Nutrient loading

• Salinity

Hydraulic Loading

‣ Limits on systems that use land

application to treat water for disposal

‣ Hydraulic loading is the limiting factor

‣ Generally set by site conditions

‣ Example: Nebraska sets maximum at

4 inches/week

Organic Loading

‣ High organics in water clog soil with a

biological mat

• Prevents oxygen transfer

• Creates anaerobic conditions

‣ Organic loading is a main design factor in

land treatment system for raw wastewater

‣ Organic loading is generally not a design

factor for irrigation with reclaimed water

Nutrient Loading

‣ Reclaimed water provides necessary

nutrients to crops

‣ Major nutrients

• Nitrogen

• Phosphorus

‣ Excessive nitrogen at the end of the

growing cycle may damage crops

Nitrogen in Reclaimed Water

‣ Nitrogen is often an excessive


‣ Methemoglobinemia (“Blue Baby”

Syndrome) caused by nitrate

‣ Must NOT exceed 10 mg nitrate-

nitrogen/L (Florida state standard)


‣ Affecting soil structure, texture and

plant growth

‣ Adjusted Sodium Adsorption Ratio

(R adj )

‣ State of Idaho Requires less than 2

mmho/cm Electrical Conductivity

Chapter 4



‣ Record Keeping

‣ Signage

‣ Cross-connection control

Record Keeping

‣ Recording all operational data

‣ Data recorded

• Analyses

• Records of operational problems

• Unit processes and equipment breakdowns

• Diversions to emergency storage or disposal

• Corrective or preventive actions taken


‣ Inform public that reclaimed water is being


‣ Locations of signage

• Use areas

• Valves

• Storage facilities

• Outlets

‣ Signs generally colored purple

‣ Example wording on sign: “DO NOT


Typical Signage

Typical Signage

Typical Signage

Cross-Connection Connection Control

‣ No cross-connection connection allowed between

reclaimed water and potable water

‣ Practices to prevent cross-connection


• Back flow prevention devices

• Air gap separation

• No reclaimed water use in residential

building unless residents are denied


Chapter 5



‣ Capable operator present in plant

‣ Monitoring reclaimed water quality

Certified Operator

‣ Certification of water/wastewater

treatment operators

‣ Certified operator presence


Sampling and Testing

‣ Sampling frequencies and analyses

determined by the type of reuse

‣ Requirements vary from state to state

• Arizona – daily sampling for fecal coliforms for

unrestricted urban reuse

• California, Florida and Washington require on-

line turbidity monitoring

Chapter 6

Public Health


Inorganic & Organic

Constituents in Wastewater

‣ Conventional/Common Constituents

‣ Nonconventional

‣ Emerging

Public Health Considerations

‣ Protection of the public in reclaimed

water use. See


• Website about endocrine disruptors

‣ Inactivation of infectious agents

‣ Removal of endocrine disrupters

Emerging Organics

‣ Synthetic chemicals

‣ May disrupt the hormonal systems of

humans and wildlife

‣ Four (4) types

• Veterinary and human antibiotics

• Human prescription and nonprescription


• Industrial and household waste products

• Sex and steroidal hormones

Pathogenic Organisms

‣ Types

• Bacteria

• Parasites

• Viruses

‣ Viruses are of most concern

‣ Complete list available in:

Manual - Guidelines for Water Reuse

EPA/625/R-92/004 (1992)

Infective Dose

‣ Dosed number of microorganisms

starting immunological response by a


‣ Number of microorganisms required

to show signs of a disease could be

higher than the infective dose

‣ Susceptibility is highly dependent on

the individual

• Higher for infants, elderly people and

malnourished people

Inactivation of Pathogens

‣ Pathogens must be destroyed during

the reclamation process

‣ Typical disinfectants

• Chlorine

• Ozone

• Ultraviolet (UV)


‣ The most typical disinfectant

‣ Efficiency depends on various


‣ The order of resistance:

Parasite ova > Virus > Bacteria

‣ Can maintain a residual

Chlorine Contact Chamber

Requirements for Chlorine


‣ Low organic materials and ammonia


‣ Low Total Suspended Solids (TSS)


Disinfection Byproducts (DBPs(


‣ Produced by Chlorination

‣ Typical DBPs

• Trihalomethanes (THMs(


• Haloacetic Acids (HAAs(


‣ Probable human carcinogens


Ozone (O 3 )

‣ A powerful oxidant

‣ Must be generated on-site

‣ Requires electricity and complex


‣ No DPBs and ozone residues

Ultraviolet (UV)

‣ Wave length 254 nm

‣ Mechanism of UV disinfection

‣ No DBPs and no residues

‣ Destruction of Endocrine Disrupters

‣ Gaining popularity

Interferences with Ultraviolet Light


• Blocks UV rays

‣ Dirty Tubes


• Requires frequent cleaning

‣ UV Light Intensity

• Voltage drops decrease effectiveness

‣ Flow Rate

• High flow rates decrease time of exposure for



Chapter 7

Public Education

Public Education

‣ Wastewater reuse issues

Water source requirements

• Environmental impact and cost

• Saving water sources

‣ Early involvement of the public

‣ Redundancy and extensive

monitoring program presence


‣ Reclamation (water reclamation)

Reuse (water/wastewater Reuse )

‣ Color coding

‣ Reclaimed Water

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