electron beam treatment for potable water reuse: removal of … · 2017. 4. 27. · perfluorinated...
TRANSCRIPT
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
Electron Beam Treatment for Potable Water
Reuse: Removal of Bromate and
Perfluorooctanoic Acid
B. Batchelor, S.D. Pillai, L. Wang and V.S. Botlaguduru
National Center for Electron Beam ResearchAn IAEA Collaborating Center for Electron Beam Technology
Texas A&M University, USA
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
Water is a Precious Commodity
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
Abbreviated Contaminant List of Concern in Texas’ Reclaimed
Water (TWDB, 2015)
Chemical Contaminants Microbial Contaminants
Disinfection by products (bromoform, bromate, chloroform, trihalomethanes)
Cryptosporidium oocysts
Household products and food additives (Bisphenol A, Perflurooctanoic acid, Perfluorooctane sulfonate)
Giardia cysts
Estrogenic compounds (17β-estradiol) Enteric viruses, Norovirus
Total coliforms, E.coli
Bacterial pathogens
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
➢ What and Why Bromate?
❖ Formation
Bromate is a disinfection by-product, primarily formed
when ozonating bromide-containing waters
a) Molecular ozone mechanism
b) Hydroxide radical mechanism
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
➢ What and Why Bromate?
❖ Health Impact & Regulation
a) Renal cell cancer
b) Classified as a substance possibly carcinogenic to
humans by International Agency for Research on Cancer (IARC)
c) Maximum contaminant level: 10 μg/L
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
Experimental System
• Synthetic waste water to simulate reclaimed water– Revere osmosis water
– pH 7.3
– 50 mg CaCO3/L alkalinity
– 50 µg/L Dissolved organic carbon (from fulvic acid)
• Fulvic acid chosen since mol weight < 1000 Daltons used as surrogate for NOM
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
Experimental System
• Samples prepared under anaerobic system
• Sample volumes ~ 30 mL
• Sealed bags to maintain anaerobic conditions
• Analytical technique
– BrO3- and Br- and F- measured using ion
chromatography
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
Effect of Nitrate on Bromate Removal
20 mg/L
10 mg/L
5 mg/L
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
Scavenging Model for Effect of Nitrate on Bromate Dose
Constant
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
Effect of Alkalinity on Bromate Dose Constant
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
Effect of pH on Bromate Dose Constant
pH 5.0
pH 7.3pH 9.0
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
Effect of Dissolved Oxygen on Bromate Removal
Without dissolved oxygen
With dissolved oxygen
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
Perfluorinated Chemicals (PFCs)
• Perfluorooctanoic acid -PFOA: C7F15CO2-
• Perfluorooctane sulfonate – PFOS C8F17SO3-
Widely used in consumer products (carpets and
fabrics)
Widely used in fire fighting foams
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
PFOS & PFOA
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
Perfluorinated Chemicals (PFCs)
• Extremely mobile in aquifers
• Contaminating drinking water wells
• PFOA and PFOS are extremely stable
– C-F bond ~ 9-116 kcal/mole)
• PFOA and PFOS have entered the food chain
– Breast milk, blood, umbilical cord blood, wildlife
• US EPA health advisory threshold : 70 ng/L
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
Remediation Technologies Attempted
• In situ chemical oxidation
• Bio-augmentation using vault proteins
• PFC-coagulant
• Photochemical approaches
• Electro microfiltration
• Sonochemical decomposition
• Cobalt-60 irradiation
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
Effect of Nitrate on PFOA Defluorination
20 mg/L
0 mg/L
NO3- (mg/L) Defluorination(%)
0 34
5 70
10 76
20 93
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
Effect of Alkalinity on PFOA Defluorination
100 mg/L
0 mg/L
Alk (mg/L) Defluorination(%)
0 54
25 72
50 76
100 95
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
Effect of Fulvic Acid on PFOA Defluorination
FA(μg /L) Defluorination(%)
0 100
25 89
50 77
100 72
0 μg/L
100 μg/L
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
Effect of Dissolved Oxygen on PFOA Defluorination
With dissolved oxygen
Without dissolved oygen
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
eBeam eliminates toxicity of wastewater
effluent based on V.fischeri test
-35
-30
-25
-20
-15
-10
-5
0
5
10
0 10 15
% Li
ght l
oss (
-) or
gai
n (+
)
Dose (kGy)
Toxicity of eBeam processed effluents
Exploiting eBeam Technologies for Cleaning, Healing, Feeding, and Shaping this World and Beyond…
Take-Home Messages for eBeam-based Degradation
of Chemical Contaminants
# 1 Electron beam (eBeam) irradiation has been tested to remove bromate and peflurooctanoic acid (PFOA) in synthetic wastewater effluent simulating potable water reuse
# 2 A simple model has been developed for bromate degradation, and a pseudo one-component model has been developed for PFOA defluorination
# 3 eBeam treatment is a viable option to treat reclaimed water if dissolved oxygen levels are controlled and nitrate levels can be modulated
# 4 Transportable eBeam systems are needed to address contaminated groundwater situations