# Presentation: 530125

## Compliance Strategies for Stage I & II DBPR4 Case Studies

**William Bellamy**
**CH2M HILL**

## DBP Compliance Case Studies

**Aurora Colorado - Chlorine dioxide**
**Casper Wyoming - Enhanced coagulation and inline ozone**
**Henderson Nevada - UV**
**Denver Colorado - Optimized chlorination / chloramination**

## Case StudyAurora Colorado

**Direct filtration plant**
**Chlorine primary disinfection**
**Chloramine residual disinfectant**

**Drivers**

**THMs can be as high as 90 ug/L**
**Disinfection with chlorine and chloramines is minimal**

## Disinfectant Evaluation - Chlorine

**Advantages**
**Current practice –**** **no change in technology required** **
**Does not form chlorite**
**Does not form bromate****	**

**Disadvantages****	**
**Relatively weak disinfectant- **not capable of providing Crypto inactivation
**Forms TTHMs and HAAs – **Aurora may not be able to meet Stage 2 of D/DBPR
**Requires construction of post-filter disinfection contact basin**
**Relatively no benefit for T&O control**
**Pre-chlorination can not be practiced.  **Loss of pre-oxidant will degrade performance of filtration process.**	**

## Disinfectant Evaluation - Chlorine Dioxide

**Advantages**
**Lowest capital cost**** **(0 to $250,000)  Minimal investment; nothing lost if ozone is implemented later.
**No construction** of new contact basin (capital cost savings of $3,000,000)
**Does not form bromate**
**Chlorite can be controlled** to < 1 mg/L (for 1-log Giardia disinfection goal).
**Does not form TTHMs and HAAs**.  would meet anticipated Stage 2 D/DBPR regs

**Disadvantages**
**Requires change in technology/operations**
- Will probably require that the existing **contact basin be covered to mitigate UV degradation**. ($400,000)
**Requires handling of sodium chlorite**, and higher attention to safety.
**Chlorite control might be required**.  Higher dosages (for possible future Cryptosporidium inactivation requirement) would produce chlorite concentrations above 1 mg/L.

## Disinfectant Evaluation - Chlorine Dioxide (cont’d)

**Advantages****	**
- Can provide **0.5-log inactivation of Cryptosporidium**
**Strong oxidant** – will help control Quincy T&O problems, and could eliminate KMNO4 and PAC system.
- Will** ****reduce manganese**** **concentrations though oxidation/filtration** **
- Application to raw water will provide** ****benefit to filtration performance**** **(pre-oxidation)**	**

**Disadvantages****	**
- Could be **more costly** (operations) than ozone for Cryptosproidium inactivation**.**
**Some negative experience with taste and odor****.  **Mainly with inefficient systems, that used free chlorine for residual disinfectant.  Chlorine oxidized chlorite and formed ClO2 in the distribution system.  (Not a problem if chloramine is used).

## Master Plan Evaluation of Disinfectant Costs

## Initial Demand and Decay Rate Determines ClO2 Dosage & CT

- 0

- 0.1

- 0.2

- 0.3

- 0.4

- 0.5

- 0.6

- 0.7

- 0.8

- 0.9

- 1

- 0

- 5

- 10

- 15

**Time (min)**

**ClO**

**2**

** ****(mg/L)**

**Initial Demand**

**ClO**

**2**

** ****Concentration Decay**

**Area Under Curve Represents **
**CT Achieved**

## Existing Contact Flocculation Basin Can Be Optimized for t10

## Chlorine dioxide contactor modifications

## Why Isn’t ClO2 More Common?

**Until recently, minimal regulatory incentive to increase disinfection**
**Poor efficiency and performance of older style generators**
**Toxicology gaps for ClO2****-**** and ClO****3****-**
- mclg for CLO2- was increased from 0.08 to 0.8 mg/L
- No mclg for CLO3-

## Aurora Conclusions

- ClO2 can meet current disinfection requirements without construction of chlorine contact basin (saves $2.8 million)
- ClO2 provides some taste and odor control

## Conclusions (cont’d)

- ClO2 can meet current disinfection requirements without chlorite control
- Implementation of ClO2 preserves capital and provides time to:
- Evaluate alternatives
- Allow regulations to solidify

## Casper Wyoming

**52 mgd plant with conventional treatment for 27 mgd and 25 mgd wells**
**Inadequate disinfection and DBPs approaching Stage I**

## Driving Factors for Casper’s Disinfection Evaluation

**GWDUI**
**Apply Disinfectant to Ground Water & Surface Water**
**Discontinue Chlorination**
**Cost Estimates**

## Existing SurfaceWater Treatment System

- FromNorthPlatteRiver

- Screens

- Floc/Sed

- Alum

- Filters

- TransferPumping

**Chlorine**

- Storage

- HighServicePumping

- To Distribution
- System

- WashwaterLagoons

- Sludge
- Lagoons

- Raw Water
- Pumping

## Upgraded Surface Water Treatment Process

- FromNorthPlatteRiver

- Screens

- Actiflo
- Clarification

- SO4
- FeCl3

- Filters

- NaOCl
- NH4Ortho-PO4

- HighServicePumping

- To Distribution
- System

- WashwaterLagoons

- Sludge
- Lagoons

- Raw Water
- Pumping

- Settled
- Water
- Pumping

**Ozone**

- OzoneContactor

## Level of Disinfection

## Surface Water Ozone Demand

## Surface Water Ozone Decay

## Ozone Contactor Alternatives

**High-Pressure In-Line Contacting**
**Low-Pressure In-Line Contacting**
**Conventional Over-Under Baffled Contactor**

## Recommended Low-Pressure In-Line Ozone Contactor

## Casper Conclusions

**Ozone will provide up to 2 log Cryptosporidium inactivation**
**THMs and HAAs will be reduced to below 10 ug/L**
**Bromate is not an issue**
**Inline ozone was the least cost alternative**

## Henderson NevadaUV Disinfection

**Direct filtration plant**
**Chlorine disinfection for 1 log Giardia and 2 log virus inactivation**

**Need to achieve 2 log Crypto inactivation**
**Future need for chloramines for THM and HAA control**

**DBP and Disinfection Drivers**

## Disinfection Objectives

**Provide Cost-Effective Disinfection**
**No Less Than 2-Log *****Cryptosporidium***** Inactivation**
**No Less Than 2-Log *****Giardia***** Inactivation**
**Provide Capability to Eliminate Use of Free Chlorine for Primary Disinfection**

## Disinfection Alternatives Evaluated

**Ozone**
**Ultraviolet Disinfection**
**Chlorine Dioxide**
**Membranes**

## Disinfectant Comparison

- _Ozone_
**Strong oxidant (+)**
**Powerful disinfectant (+)**
**Microflocculation (+)**
**Controls taste and odor (+)**
**Increases concentration of D.O. (-)**
**High cost (-)**
**Disinfection mechanism not completely defined (-)**
**Bromate formation (-) **
**Increases concentration of AOC (-)**
**Operationally complex (-)**

- _UV_
**No byproduct formation (+)**
**Effective protozoan and viral disinfectant (+)**
**Generated onsite (does not require LOX delivery) (+)**
**Lower cost (+)**
**Disinfection mechanism not completely defined (-)**
**Lamp cleaning/replacement (-)**
**No measure of disinfectant “residual” (-)**

## Calculation of UV & Ozone Disinfection Performance

- _Ozone_
**Relies on measurement of residual and hydraulic modeling to calculate CT**
**Contactor design validated with tracer testing (t****10****)**
**Monitoring  disinfectant provides continuous measure of disinfection efficiency**

- _UV_
**UV intensity sensors, flow signal, lamp age, UV transmittance and power measurement to calculate dose (I x t), and assess possible problems**
**EPA expected to publish IT values in near future (2-3 years)**

## Why Hasn’t UV Been More Prevalent for Potable Water Treatment?

## Previous Studies Used In Vitro Assays for Protozoan Inactivation 

**Cell Excystation (Viability Assay Using *****In Vitro***** Measure of Ability of Oocyst to Excystate [Open Up] Under Simulated Gut Environment)**
**Vital Dyes (*****in Vitro***** Assay Using Fluorogenic Vital Dyes That Adhere to Viable Oocysts or Non-viable Depending on Dye)**
**Study Showed UV Dose of 120 mJ/cm****2**** for       2-log *****Cryptosporidium***** Inactivation (Ransome     *****et al*****, 1993)**

## Infectivity Tests Provide  New Understanding of Protozoa Inactivation By UV

**Infectivity Assays Using Neonatal Mice (*****In Vivo*****)**
***In Vitro***** Assays Unable to Correctly Predict Infectivity**
**Infectivity Accurately Tests the Ability to Cause Disease Not Just Viability**

## Recent Research Indicates Capability of UV for Cryptosporidium Inactivation

- -5

- -4

- -3

- -2

- -1

- 0

- 0

- 50

- 100

- 150

- 200

**UV Dose, mW-sec/cm****2**

**Log (N/N****o****)**

- Excystation

- Infectivity

- After Clancy et al., 1998
- [Demonstration Scale Testing]
- Medium-Pressure UV Lamp

**Recent Research Indicates Capability of UV for***** Cryptosporidium***** Inactivation**

## Recent UV Inactivation Data for Cryptosporidium

**Clancy; 2.8 to 4.8 Log *****Crypto***** Inactivation Using 25 mJ/cm****2**
**Bolton; 3-Log *****Crypto***** Inactivation at 20 mJ/cm****2**
**Finch; 2.5 to 4.6 Log *****Crypto *****Inactivation Using 28 mJ/cm****2**
**Sobsey & Linden; 4-Log *****Crypto***** Inactivation Using 15 mJ/cm****2**

## Giardia Inactivation Capability of UV

**Previous Studies (Hoff, Karanis) Showed Doses of 100 to 180 mJ/cm****2**** Required for 2.0-Log *****Giardia***** Inactivation**
**Sobsey & Linden; 4-log *****Giardia***** Inactivation Using 15mJ/cm****2**
**Bolton; 3-log *****Giardia *****Inactivation at 20 mJ/cm****2**

## UV Regulatory Status in the U.S.

**Widely Used Since 1980’s in WW Treatment and Reclamation  (CA Title 22 Approval)**
**SWTR Included UV Doses for 2 and 3 Log Virus Inactivation in 1989/1990**
**EPA Proposes Groundwater Rule With UV As a Likely BAT in 1991**
**1998 - New *****Cryptosporidium***** Research Released**
**1999 - EPA Sponsors UV Workshop for FACA**

## Henderson’s UV Implementation Strategy

**Bench-Scale Testing**
- Conduct bench-scale collimated beam testing to establish dose-response relationship for MS-2 and/or *Bacillus* *subtilis* for Henderson’s  water
**Design and Construction**
- Evaluate/select the UV system vendor based on an evaluated bid
- Detailed design of UV system including controls and monitoring
- Installation
- Full-scale performance validation

## Henderson’s UV Implementation Strategy (cont’d)

**Validation**
- Full-scale demonstration using MS2 phage/*Bacillus* spores
- Back-calculate full-scale system dosage
**Maintenance**
- Routine cleaning/replacement of UV lamps
- Routine cleaning/calibration/replacement of UV sensors

## Henderson NV Conclusion

**UV achieved disinfection and DBP goals**
**Lowest cost option**
**Regulatory approval can coincide with design  and construction**

## Denver WaterChlorine Disinfection

**Conventional water treatment at 3 water treatment plants**
**Disinfection with chlorine followed by chloramines**

**Need to reduce THMs and HAAs**
**Planning for future disinfection and DBP regulations**

**DBP and Disinfection Drivers**

## Current Disinfection Practice

**Current Disinfection Practice**

- Chlorine

- Headworks

- Raw Water

- Rapid Mix

- Flocculation/ Sedimentation

- Filter

- Clear Water Reservoirs

- Chlorine

- Ammonia

## Project Goals

- Continue to meet current EPA disinfection requirements
- Improve safety / reliability
- Identify strategies for future compliance
- Develop implementation plan and costs

## Disinfection Regulations

- Current:   30 minutes contact
- SWTR:	0.5-log *Giardia **	**	**	**	*inactivation
- ESWTR:  0 to 3-log (0 to 99.9%) 			*Cryptosporidium **	**	**	**	*inactivation

## 
Short Term
- 0.5-log Giardia Inactivation
- TTHMs < 80 ppb, HAAs < 60 ppb
- Eliminate prechlorination
Long Term
- Cryptosporidium inactivation
-  Lower levels of DBPs

- Short Term
**- ****0.5-log *****Giardia***** Inactivation**
**- TTHMs < 80 ppb, HAAs < 60 ppb**
**- Eliminate prechlorination**
- Long Term
***- ******Cryptosporidium***** inactivation**
**-  Lower levels of DBPs**

**Disinfection Objectives**

## Short Term Planning

## Long-Term Planning

**Meets**
**Criteria**

**Long-Term Planning**

**Evaluate**
** ****Performance**
**of Chlorine**
**Chloramine**

**Chlorine**

**Ozone**
**or UV**

**Conduct**
**Ozone / UV**
**Studies**

**Crypto**
**Inactivation**

**> 1.0 Log ****Crypto?**

**Meets**
**DBPR**

**Yes**

**Yes**

**No**

**Yes**

**No**

**No**

**Yes**

**No**

**Implement****Chlorination**
**Strategy**

**Chlorine   **

**Chlorine   **
**Chloramine**

**Chlorine   **
**Chloramine**

## Long Term Disinfectants Costs (0.5-Log Cryptosporidium)

## Short-Term Implementation Elements

- Construct well-baffled chlorine contact basins
- Install emergency gas scrubbers
- Update chlorination equipment and controls
- Provide process monitoring and control for disinfection

## Computational Fluid Dynamic Model T = 25 min.

## Implementation Schedule

**Implementation Schedule**

**Design/Construct Chlorination System Improvements**
**Pilot Testing - Ozone**
**Pilot Testing - Chlorine/Chloramine**
**ESWTR Requirements Identified**
**Design/Construct Long-Term        Disinfection Improvements**

- 1997  1998  1999  2000  2001  2002  2003

## Denver Water Conclusions

- Post Filtration chlorine will meet disinfection and DBP requirements
- Study ozone and UV
- Wait for regulatory development
- Initiate revised disinfection based on regulatory requirements and study results

## DBP Compliance Now and Into the Future

**Each case is site specific when balancing disinfection needs and DBP**
**Chlorine, ozone, chlorine dioxide, and UV are all possibilities**
**A thorough analysis and cost estimate is essential to a good decision**