1. Drinking Water Quality
August 31 & September 1, 2011
Presented By:
Mark Smith, PE, SJRA GRP Administrator
Stan Williams, PE, HDR Project Manager
2. Agenda
Water Quality – Regulations and Goals
Three Steps to Treatment Process
Selection
Post Treatment – Quality at the Tap
Selected Treatment Processes
Next Steps
Discussion – Q&A
3. Perspectives on Drinking Water Quality
Regulators define Drinking Water Quality by:
• Numeric Standards
• Treatment Techniques
• Compliance with Rule & Regulations
• Monitoring & Reporting
For Quality Definition – First Look to the
Regulations
4. Evolution of the Safe Drinking Water Act
1986 Safe Drinking Water Act (Update)
Cryptosporidium Outbreak in 1993 Resulted
in:
• New perspective on surface water treatment
• Comprehensive overhaul of industry’s approach
• Unprecedented plan for new regulations
• Opportunities for innovation in treatment
technology
5. Drinking Water Quality
Additional contaminants regulated
Existing technologies enhanced
New treatment technologies developed
New Federal Regulations
• ESWTR, D/DBP, D/DBP2, LTESWTR,
LT2ESWTR, FBRR, and many more
High Quality Water 20 years ago would
not meet today’s standards
6. Project Quality Standards Consider The
Regulations AND the Consumer
Project Standards go beyond the regs
• Alkalinity
• Hardness
• Aggressiveness (corrosiveness)
• Odor
• Taste
These Constituents Affect
Water Quality AT THE TAP
7. Project Quality Standards Consider The
Regulations AND the Consumer
Project Definition of Water Quality:
• Compliance with Regulations
• Aesthetics at the tap
Clarity
Taste & Odor
Color
• Healthy and Safe
• Compatible with existing groundwater sources
• Consistent Quality
9. Three Step Process to Selecting
Treatment Processes
Step 1 - Bench Scale Studies
Step 2 - Pilot Plant Studies
Step 3 - Finished Water Polishing
10. Structured Screening Process Establishes
Viability of Alternates
Possible ID Primary
Treatment Desktop Study Impacts
Strategy
Evaluate NO Mitigation YES
Impact Impacts?
Possible?
YES NO
Develop Mitigation Implement Testing &
NO Impacts
Manageable? Strategies Further Evaluation
YES NO
YES NO Will
YES Secondary NO All Impacts
Mitigation
Work? Impacts? Addressed?
YES
Abandon Strategy Implement Testing &
Further Evaluation
11. STEP 1 - Bench Scale Studies Selects
Processes for Further Evaluation
Review Historical Water
Quality Data
Conduct Bench Scale
Treatability Studies
Screen Potential Broken Arrow Settled Turbidity
Processes 7
6
Verdigris River Raw
Lake Conroe Water
Water
Select Processes for Step
Turb. = 10.6 NTU
5
Turbidity, NTU
Optimum Dose
4
2 - Pilot Testing 3
2
1
0
10 20 30 40 50 60
Aluminum Chlorohydrate Dosemg/L
Ferric Sulfate Dosage, (mg/l)
12. STEP 2 - Pilot Studies Test Processes
Under Real Life Conditions
Construct Pilot Plant Kruger Ceramic
Membranes
GAC
Lake
Conroe
Operate Pilot Plant Static
Mixer
Select/Rank Criteria
Pall Microza
Membranes
Membrane
Feed Tank
Static
Influent From
Lake Conroe
Evaluate Processes against criteria
Mixer
GE ZeeWeed
1000
Discharge
Tank
Discharge
Membranes
Select Process for Full Scale Development
MIEX
Contactor
Conventional
Plate Settler Filter
Filter Feed
Tank
BAF
Ozone
Feed BAF
Contactor
Tank
Bypass
Stream
From From Membrane From From Cleaning From From From BAF
From Plate From From BAF Feed From BAF
Kruger Feed Feed Tank Conventional Neutralization Conventional BW Tank BW Tank
Settlers GAC Tank Overflow Backwash
Tank Overflow Overflow Feed Tank Tank Filter Backwash Overflow Overflow
Overflow
Gravity Discharge
Collector
17. Process Process Description Criteria Rank Criteria
Train 1 Clarification + Conv. Filter 1 Community Impact
Train 1A Clarification + Conv. Filter + UV/H2O2 2 Water Quality Aesthetics
Train 1B Clarification + Conv. Filter + GAC 3 Relative Capital Cost
Train 2 PS + Ozone + BAF 4 O&M Requirements and Cost
Train 2A PS + Ozone/H2O2 + BAF 5 System Robustness
Train 3 PS + Polymeric Membranes Water Integration Compatibility/Blending
6
Train 3A PS + Polymeric Membranes + GAC Non-Proprietary Equipment
Train 3B PS + Polymeric Membranes + Organix
8 Safety and Environmental Site Impacts
Train 3C MIEX + Polymeric Membranes
Train 3D MIEX + Polymeric Membranes + GAC 9 Premium Pathogen Removal
Train 3E PS + Polymeric Membranes + UV/H2O2 10 System Simplicity
Train 4 Ceramic Membranes 11 Area Required and Site Constraints
Train 4A Ceramic Membranes + GAC
12 Regulatory Flexibility
Train 4B Ceramic Membranes + UV/H2O2 13 Ease and Cost of Expansion
18. Particle Size Relationships
Organic macromolecules
Colloids
Bacteria Viruses
Pollens Yeasts
100 mm 10 mm 1 mm 0.1 mm 0.01 mm 0. 1 nm
Red globule
hair visible to naked eye Smallest microorganisms Polio virus
Sand filter UF
Conventional MF Ultrafiltration
Filters Microfiltration
Membranes
19. Relative Sizes of Small Particles
Pencil Dot (40 µm)
Cryptosporidium
Oocysts (3 - 6 µm)
Giardia Cyst
(5 - 15 µm)
Average size opening
in a standard filter (60 µm)
Microfiltration (0.1 µm)
20. Conventional vs. Membrane Filtration
Granular / Mixed Media Membrane Media
• Irregular Pore Size Distribution • Controlled Pore Size Distribution
(50 -70 micron between grains) (0.1 micron)
• Probable Filtration • Absolute Filtration
20
21. STEP 3 – Finished Water Polishing
Water Blending Chemistry Analyses
• Sample Water from Distribution System
• Sample Pipes from Distribution System
• Compare compatibility with proposed
treatment process
Defines Required Water Chemistry
Adjustments
Finished Water Polishing Provides
Quality Water AT THE TAP
22. Understanding What’s In the Pipe Leads
to Compatible Water Chemistry
Iron scales represent a
reservoir of metals,
particulates, and biomass.
Chemistry changes in
distribution system
can release built-up
deposits
23. Finished Water Chemistry Must be
Compatible with Existing Infrastructure
Pipe Samples From Conroe
Existing water is slightly
aggressive
Minor corrosion scale
No carbonate scale build-up
Design water chemistry to
maintain existing corrosion
scale
24. Treatment Techniques for Compatibility
Sodium Hydroxide:
Samples From The Woodlands
• Increase pH & alkalinity
Calcium Hydroxide:
• Increase pH, alkalinity and
calcium
Carbon Dioxide:
• Lower pH
All treatment chemicals are approved
by NSF for use in drinking water
25. Standard Indices Provide Goals for Post
Treatment
The Langelier Saturation Index (LSI)
Ryznar Stability Index (RSI)
Calcium Carbonate Precipitation Potential
(CCPP)
Larson Index (LI)
26. Post Treatment Provides Stable,
Compatible Water to Consumers
Desired Average Conditions
Parameter
Value Current Treated
LSI >0 -0.34 0.62
RSI <7 8.27 6.97
CCPP 4 – 10 -3.99 5.48
Larson Index < 0.8 0.54 0.49
27. Selected Treatment Processes
Membrane Post Treatment
Sedimentation
Filtration & Polishing
A B C 1 2 3 D E
CHEMICAL TREATMENT PHYSICAL TREATMENT
PROCESSES PROCESSES
A Permanganate – Iron & Manganese Sedimentation – Particulate and
1
Organics Removal
B Calcium Hydroxide – pH and Alkalinity
Membrane Filtration – Particulate
C Coagulant – TOC & Sediment Removal 2
Removal
D Sodium Hydroxide – pH & Alkalinity
Activated Carbon – Organic
3
E Chlorine - Disinfectant contaminants removal
28. Next Steps to Quality at the Tap
Acquire and analyze water samples from
each receiving station – Refine post
treatment plans as necessary
Identify treatment techniques currently used
at existing utilities
Develop “Baseline Operations Report” at
existing systems
Develop Guidelines to assist utilities to
prepare for surface water
29. Summary
Federal & Texas Regulations dictate very
high drinking water quality
Project Specific Standards drive
compatibility with existing groundwater
Project focuses on “Quality at the Tap”
Extensive testing of treatment techniques
and existing conditions provides real life
results – not textbook “rules of thumb”