Steve Reiber, Ph.D. HDR Engineering Seattle, WA Past History/Future Challenges Water Treatment...

Steve Reiber, Ph.D. • HDR Engineering • Seattle, WA

Past History/Future ChallengesWater Treatment

Legionella

Evolutionary Change in Water treatment – The History of a Developing Market

Early water treatment engineers describe the first

dirt molecule.

Take-Away Points

• Despite predictions to the contrary, the cost of new technology (especially membranes) will not increase the cost of water treatment.

• When quality is factored in, the cost of water treatment will actually decline.

• Conventional sand filtration will be phased out in favor of low-pressure membranes. (This represents a 10 BGD market.)

Disinfection: The Most Important Treatment Step

• Gate Houses and Chlorination Plant at Boonton Reservoir (Jersey City),circa 1908

DyNasand Filter

Actiflow

Deep Bed Mono-Media

Slow Sand Filtration

(Germany 1820)

Rapid Sand Filtration

(Chicago 1900)

River Bed Filtration

(Roman Times)

Evolution of Water Filtration Technology

Rapid sand filters are no longer the most cost-effective polishing step.

Cellulosic Membranes (1980)

• New water supplies are inferior.

• Fear of waterborne disease.

• SDWA regulations

• Expensive infrastructure replacement

Numerous factors are influencing these changes.

Market Drivers

The Water-Consuming Public is Aware (and Wary)

Well-publicized “events”

Bottled water sales increase dramatically

Waterborne Disease Outbreaks Cause Irreparable Damage to Public & to PWSs

Year State/Territory Cause of Disease No. of People Affected

1985 Massachusetts Giardia lamblia (protozoan) 703 illnesses

1987 Georgia Cryptosporidium parvum (protozoan) 13,000 illnesses

1987 Puerto Rico Shigella sonnei (bacterium) 1,800 illnesses

1989 Missouri E. coli 0157 (bacterium) 243 illnesses / 4 deaths

1991 Puerto Rico Unknown 9,847 illnesses

1993 Missouri Salmonella typhimurium (bacterium) 650 illnesses / 7 deaths

1993 Wisconsin Cryptosporidium parvum (protozoan) 400,000 illnesses 50+ deaths

1998 Texas Cryptosporidium parvum (protozoan) 1,400 illnesses

1999 New York E. coli 0157 (bacterium) 150 illnesses / 1 death

2000 Ontario E. coli 0157 (bacterium) 1,000 illnesses / 7 deaths

Source: HDR’s Handbook of Public Water Systems

Public Health IssuesPathogenic bacteria, viruses and protozoa in water and wastewater represent potential risks to public health.

(Giardia) (Cryptosporidium)

Viruses

(Hepatitis, Polio)

Bacteria

(E.coli)

Protozoa

Historical mortality from waterborne diseases exceeds the current mortality rates

of all diseases combined.Typhoid Fever Mortality in Chicago (1860-1950)Typhoid Fever Mortality in Chicago (1860-1950)U.S. Leading Causes of Death (1990)U.S. Leading Causes of Death (1990)

Viruses: smallest (0.02-0.3 µm diameter); simplest:

nucleic acid + protein coat (+ lipoprotein envelope)

Bacteria: 0.5-2.0 µm diameter; prokaryotes; cellular; simple internal org.; binary fission.

Protozoa: most >2 µm - 2 mm; eucaryotic; uni-cellular;

non-photosynthetic; flexible cell memb.; no cell wall; wide range of sizes and shapes; hardy cysts and oocysts;

flagellates (Giardia sp.), amoebae, ciliates, sporozoans (Cryptosporidium sp.) and microsporidia.

C. parvum oocyst

~5 um

Classes of Microorganisms:The Microbial World

What is a low-pressure membrane?

Membranes can remove anything that is smaller than the pores.

Giardia

Cryptosporidium

A Short History of Membrane TechnologiesMembrane treatment is not new.

Cellulosic membranes have been in use for four decades.

What is new is that membrane systems are now affordable!

Membrane TreatmentWhat is driving the technology?

• Competitive costs

• Complete microbial barrier

• Improved organics removal

• Small space requirements

• Reduced solids

• Automation

Improved materials are the key to cost-effective performance.More recent polymeric materials are more robust than cellulosic materials.

Teflon

Polypropylene (PP)

Polyvinylidenefluoride (PVDF)

Polysulphone (PSf)

Chemical and

Mechanical

Resistance

They foul more easily, but can be regularly and vigorously cleaned.

Growth in drinking water low-pressure systems is

exponential.

Combined

Microfilter

Nanofiltration

Ultrafilter

Capital costs for membrane technology continues to drop.

*Per gal/d of Installed Capacity

*

Membrane Architecture is Evolving

Encased systems trap solids, are difficult to backwash and cannot be used with high concentrations of coagulants or adsorbants, but offer high flux rates!

Open systems are easier to backwash, but generally have lower flux rates!

Hollow Fiber Encased Membranes

Submerged MembranesZenon’s ZeeWeed Process

Integration with Other Processes

• TOC & DBPs (Coagulant/PAC/GAC)

• Taste & Odor (Aeration/PAC/GAC/ClO2)

• Soluble Fe & Mn (Oxidants)

• Arsenic (Ferric coagulants)

Size Exclusion Device

Cellulosic Systems

Immersed membrane

Treated water

InflowCoagulant

Sorbant

PVDF and Fluoropolymer systems

Residuals

Solids Contact Separation System

Particle Removal vs. Dissolved Organics Removal

Evolution

Membrane processes are not trouble free!

Cellulose acetate (CA)

Poly(m-phenylene isophtalamide) (Normex)

Polyacrylonitrile (PAN)

Polyethersulphone (PES)

Polysulphone (PSf)

Teflon

Polyvinylidenefluoride (PVDF)

Polypropylene (PP)

Polycarbonate (PC)

Hydrophilic

Fouling Resistant

Hydrophobic

Fouling Susceptible

Hydrophobicity

Support Substrate

Membrane

Fouling by organic material is the most serious threat to membrane operations.

The dense NOM gel-like layer reduces capacity and fouls an unprotected membrane.

Fouling at 20 hours; 79% flux reduction

Membranes do fail. However, failure is never catastrophic – less serious than microbial penetration of rapid sand filter beds.

• Membranes fail incrementally – one fiber at a time.

• Statistically, individual fiber breaks are insignificant to the overall microbial water quality.

What Will Not Change!

• Urban-Industrial society depends on a safe and abundant supply of water. It is the most important public health function - bar none!!!

• Water Wars are not imminent.

Price

Cap

acit

y

SupplyDemandNon-Non-

Commodity Commodity Pricing of Pricing of Water!!Water!!

Water Industry/Distribution System Issues

The American Water Industry is Not Being Privatized!

Municipal advocacy supplants privatization efforts

Merchant water will be limited to speculative markets.

Distribution Water Quality is Improving

98

99

100

1990 1992 1994 1996 1998 2000 2002 2004 2006

Almost 100% of national samples tested met health-based and aesthetic standards for drinking water

The number of tests failing water quality standards has fallen by 60% since 1992

Com

plia

nce

Perc

ent

The Cost Efficiency of Public Water Purveyors is Increasing

0

1

2

3

4

1.00

Misc. Cost

Capital Cost

Operating Cost

1990 1995 2000 2005

$ / 1

000

Gal

.

Public drinking water is a remarkable bargain

Efficiencies derive primarily from manpower and technology

It is still inexpensive despite more stringent regulations and dwindling supplies

Inflation-Adjusted Homeowner Costs

0

1

2

3

1 2

1990 2000

Cost as a % of Household Income

Waterborne Disease Outbreaks are Decreasing. Distribution System Contribution is Increasing

1971 – 1974

1975 – 1978

• Most distribution failures are related to cross-connection and back siphonage.

• Magnitude of outbreaks – 180 illnesses per event.

1979 – 1982

1983 – 1986Source: Lee and Blackburn, 2004

1987 – 1990

1991 – 1994

1995 – 1998

1999 – 2000

2001 – 2002

Disease and Distribution System Evidence shows that current endemic levels of Evidence shows that current endemic levels of

gastrointestinal diseases are associated with gastrointestinal diseases are associated with the consumption of tap waterthe consumption of tap water

The typical disease symptoms are generally The typical disease symptoms are generally mild, short term, and clear spontaneouslymild, short term, and clear spontaneously

The organisms causingThe organisms causingthese diseases arethese diseases arecultured in the distributioncultured in the distributionsystem (not the raw water)system (not the raw water)

Challenge – Many 20th century iron distribution mains are approaching the end of their service lives.

Projected annual replacement needs for transmission lines and distribution mains. Source: EPA 2002)

• Average post-WWII pipe service life ≈ 75 years.• 19th century cast iron pipe service life ≈ 120 years• Drinking water infrastructure spending to reach $6 billion per year by 2010.

Challenge - The Bottled Water Industry Continues to Grow

Year GPCAnnual % Change

2000 17.3

2001 18.8 9.7

2002 20.9 10.7

2003 22.4 7.3

2004 24.0 7.4

2005 25.7 7.1Fairly, or not, the continued success of bottled water creates the perception of a growing deficiency (“lack of purity”) in our public water system.

7%

11%

35%

12%

35%

7% Taste

11% Other

35% Worried about tap water safety

35% Substitute for other beverages

12% Worried about tap water safety

and substitute for other beverages

Why People Drink Bottled WaterBottled Water MarketU.S. Per Capita Consumption