TACWA September Meeting CHALLENGES IN MEETING THE TEXAS BACTERIAL LIMITS WITH UV ALONG THE COAST AND BAYS. Gennady Boksiner, P.E. September 30, 2011

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1 TACWA September Meeting CHALLENGES IN MEETING THE TEXAS BACTERIAL LIMITS WITH UV ALONG THE COAST AND BAYS Gennady Boksiner, P.E. September 30, 2011

2 Bacterial Groups Intestinal bacteria of humans and other mammals Pathogenic intestinal bacteria Ideal Indicator Organism: Be present only with fecal contamination Exhibit similar survival characteristics as pathogen Not reproduce outside the host animal Be readily monitored (speed, simplicity, cost) Universe of All Bacteria

3 Bacterial Groups Intestinal bacteria of humans and other mammals Coliform group: Gram negative Non spore forming rods Ferment lactose at 35 C IMVC reactions Pathogenic intestinal bacteria Drawback: Many genera of coliforms; most are not intestinal bacteria.

4 Bacterial Groups Intestinal bacteria of humans and other mammals Escherichia coli Klebsiella spp. Fecal Coliforms: Gram negative Non spore forming rods Ferment lactose at 44.5 C IMVC reactions Coliform group Drawback: Mostly, but not exclusively, intestinal bacteria.

5 Bacterial Groups E.coli: Can be differentiated from other FC s by special media (MUG) Drawback: Can t distinguish between human & non human sources.

6 Bacterial Groups Fecal Streptococci: Gram negative chains of spheres Aerotolerant anaerobes Occur in large numbers Easily measured & quantified Drawback: Not all fecal streptococci are intestinal insects!

7 Bacterial Groups Enterococci: Two species (EPA) Can be pathogenic outside the gut Formerly in Streptococcus: E. faecalis E. faecium Enterolert test Drawback: Excludes some fecal streps & includes some non fecal.

8 Regulations Background TCEQ Water Quality Standards Prior to 2000 Standards Limits Chlorine and Alternative Disinfection Systems Fecal Coliform Standard 200/100mL geometric mean Fecal Coliform Standard 400/100mL single samples Alternative Disinfection Systems also require: Engineering report TCEQ assigned effluent limitations as necessary to verify disinfection is adequate (TAC 30 Ch (g)(3))

9 Regulations Background 2000 TCEQ Regulatory Updates Freshwater E. coli Limit: TAC 30 Ch (h)(1)(a) To demonstrate disinfection, Escherichia coli (E. coli) must be the indicator bacteria measured for discharges to fresh water. Contact Recreation 126/100mL geometric mean 394/100mL single sample maximum Noncontact Recreation 605/100mL geometric mean Saltwater Enterococci Limit: TAC 30 Ch (h)(1)(b) To demonstrate disinfection, Enterococci must be the indicator bacteria measured for discharges to salt water. Contact Recreation 35/100mL geometric mean 89/100mL single sample maximum Noncontact Recreation 168/100mL geometric mean Fecal coliform can also continue to be used as a surrogate indicator in the effluent limits for wastewater discharges for both freshwater and saltwater. (TAC 30 Ch (b)(1)(c))

10 Regulations Background 2009 TCEQ Regulatory Updates Characterization of Water Bodies: Primary Contact Secondary Contact 1 Secondary Contact 2 (freshwater only) Noncontact

11 Regulations Background 2009 TCEQ Regulatory Updates Freshwater E. coli Limit: Primary Contact Recreation 126/100mL geometric mean 394/100mL single sample maximum Secondary Contact Recreation 1 630/100mL geometric mean Secondary Contact Recreation /100mL geometric mean Noncontact Recreation 2060/100mL geometric mean Saltwater Enterococci Limit: Primary Contact Recreation 35/100mL geometric mean 104/100mL single sample max Secondary Contact Recreation 1 175/100mL geometric mean Noncontact Recreation 350/100mL geometric mean

12 Disinfection Technologies Chlorine (chlorine gas and sodium hypochlorite) and UV account for 96% of all disinfection methods in wastewater treatment in the United States (WEF Study, 2003). UV market share has been increasing 1% per year on average over the last 25 years Over 25% of NA wastewater treatment plants now disinfect with UV light 1982 first UV system introduced in the United States Courtesy of TROJANUV

13 Ultraviolet Irradiation 390 nm 750 nm Visible Spectrum UV Spectrum 10 nm Germicidal Range 220 nm 320 nm Most Effective Range 250 nm 265 nm 400 nm

14 Ultraviolet Irradiation Generation of Ultraviolet Radiation Mercury vapor charged by an electric arc inside the lamp Ionized mercury vapor emits UV radiation

15 Ultraviolet Irradiation Inactivation Mechanism Ruptures the microorganisms cell walls at high doses Alters microorganisms DNA when absorbed at lower doses Causes formation of double bonds between certain DNA bases Double bonds prevent microorganisms from reproducing

16 Ultraviolet Irradiation Equipment Classification Low Pressure vs. Medium Pressure Open Channel vs. Closed Pipe Horizontal vs. Vertical

17 Ultraviolet Irradiation Equipment Classification Low pressure: Internal Mercury vapor pressure 0.2 psi Monochromatic emission at 254 nm Output power: 35 W to 100 W = low intensity 100 W to 500 W = high intensity

18 Ultraviolet Irradiation Equipment Classification Medium pressure: Internal Mercury vapor pressure 20 psi Emission range = 185 nm to 400 nm Output power: 3,000 W

19 Ultraviolet Irradiation Equipment Classification Open channel: Gravity flow Typical for wastewater treatment plants Closed pipe: Pressure flow Requires less space Typical for water treatment plants IDI/Ozonia Aquaray H2O 36 Trojan UVSwift Trojan UV3000 PLUS IDI/Ozonia Aquaray 3x

20 Ultraviolet Irradiation Equipment Classification Horizontal: Lower headloss Longer exposure time Vertical: More turbulent (good) Electrical connections above water Less sensitive to water depth variations Vertical UV Horizontal UV

21 Ultraviolet Irradiation The amount of UV required to destroy or inactivate microorganisms is measured as dosage, defined by: D = I x t Where: D = UV dose in mj/cm 2 or mws/cm 2 Dose Response Curve: I = UV intensity in mw/cm 2 t = exposure time in seconds

22 Ultraviolet Irradiation UV system efficiency is a factor of: System configuration Lamp age Sleeve cleanliness Glass blocks radiation below 330 nm Quartz glass sleeves allow transmission of UV radiation Wastewater quality TSS shading or shielding (20 mg/l) UV transmittance (55%) Microbiology Different UV doses are required for the effective inactivation of different organisms Selection of a test microorganism is important Complete penetration Particle shading Incomplete penetration UV light scatter UV lamp Region of limited cellular damage E. Coli Enterococcus

23 Enterococci and UV New limits are more stringent! Assume Fecal Coliform = Enterococci: 9 mj/cm 2 UV Dose required to meet 200 CFU/100 ml 19 mj/cm 2 UV Dose required to meet 35 CFU/100 ml

24 Enterococci and UV Fecal Coliform E. Coli Enterococci??? Fecal Coliform and E. Coli have similar deactivation characteristics Courtesy of Aquionics Inc.

25 Enterococci and UV Fecal Coliform E. Coli Enterococci 15.5 mj/cm 2 UV Dose required to meet 100 CFU/100 ml Enterococci 12 mj/cm 2 UV Dose required to meet 100 CFU/100 ml Fecal Fecal E. Coli Enterococci 20% 25% higher dose required for 1 log reduction of Enterococci than 1 log reduction of Fecal Courtesy of TROJANUV

26 Enterococci and UV Fecal Coliform E. Coli Enterococci TSS shielding of Enterococci: Enterococci will experience smaller reduction under increased TSS conditions than Fecal Coliform or E. Coli UV UV UV 0.2% 4% 15.8% Primary Treatment 80% Secondary Treatment- Fixed Film Treatment (i.e.rbc) Secondary Treatment- Suspended Growth Treatment (i.e. MLSS) Tertiary Treatment (i.e. Sand Filtration) Courtesy of TROJANUV

27 Enterococci and UV Options to Move Forward: Add/improve filtration Increase operating intensity Add lamps New/Additional Modules or Banks Expand Existing Modules or Banks System retrofit Aqua Aerobic Systems, Inc., AquaDisk

28 Enterococci and UV QUESTIONS?