Wastewater is produced by multiple sources, including chemical manufacturing, power generation, petroleum product extraction, and private residences. Specific industries can use knowledge of around the analytes present in wastewater to make decisions on reuse, treatment, or whether disposal is the most cost effective option. Prior to any discharge into ground or surface waters, the level of specific analytes must be determined to ensure that they do not exceed regulated limits. If these limits are being exceeded, treatment will be required. Ion Chromatography (IC) is the primary technique used for measuring the concentration of ions in wastewater and numerous methods have been developed that meet regulatory requirements. Learn about IC methods that enable accurate, consistent, and rapid measurement of both anions, such as chloride, sulfate, and bromate, and cations, such as sodium and magnesium.
Rapid Determination of Inorganic Ions in Wastewater by Ion Chromatography
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The world leader in serving science
Peter Bodsky
Field Marketing Manager
March 26, 2014
Rapid Determination of Inorganic Ions
in Wastewater by Ion Chromatography
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Agenda
• Wastewater sources
• Regulations and methods
• Analytes of interest in wastewater
• Challenge of wastewater analysis
• Ion Chromatography system innovations
• Inline conductivity and automated dilution
• Reagent-Free™ Ion Chromatography (RFIC™)
• High-Pressure™ Capillary IC (HPIC™)
• Conclusions
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Examples of Wastewater Sources
• Manufacturing
• Oil and gas extraction
• Petroleum refining
• Mining
• Power generation
• Household sewage
• Agriculture
4. 4
Reasons to Perform Wastewater Analysis
• Monitoring discharge
• Regulatory limits
• Nutrient Analysis
• Excessive plant growth in aqueous environments
• Known samples
• Historical analysis
• E.g., High chloride level from a treatment facility with a water inlet
near the sea/estuary
• Unknown samples
• Investigative, pollution incident, farm run-off, milk spill, or industrial
discharge plant failure
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International Wastewater Regulations
• ISO
• International Organization for Standardization
• ASTM International
• “American Society for Testing and Materials”
• DIN
• Deutsches Institut für Normung
• German Standard
• U.S. EPA
• Environmental Protection Agency
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Controlling Water Pollution in the U.S.
• National Pollutant Discharge Elimination System (NPDES)
requirements
• EPA
• Industrial or municipal facilities must obtain a permit to discharge to
surface water
• Discharge limits
• Monitoring and reporting requirements
• Ensure that surface waters stay safe for marine life, surrounding
vegetation, recreational use, and as a drinking water source
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Regulatory Method for Anions: EPA Method 300.0
• Revision 2.1 Parts A and B published in 1993
• Outlines the method for determination of inorganic anions by ion
chromatography
• Specifies use of suppressed conductivity for determination of:
• Bromide (Part A) • Ortho-Phosphate-P (Part A)
• Chloride (Part A) • Sulfate (Part A)
• Fluoride (Part A) • Bromate (Part B)
• Nitrate (Part A) • Chlorate (Part B)
• Nitrite (Part A) • Chlorite (Part B)
• Applies to:
• Drinking water
• Ground and surface water
• Wastewater (domestic and industrial)
• Raw water (unfinished drinking water)
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EPA Method 300.1
• Published in 1997
• Refinement of Method 300.0
• Greater sensitivity for ions
• Single, higher capacity Dionex IonPac AG9-HC column
• 2 mm or 4 mm i.d.
• Different injection volumes allowed depending on analytes and columns
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Regulatory Method for Cations: ASTM D6919-03
• Outlines the method for determination of cations by ion chromatography
• Specifies use of suppressed and nonsuppressed conductivity for
determination of:
• Lithium
• Sodium
• Ammonium
• Potassium
• Magnesium
• Calcium
• Applies to:
• Drinking water
• Reagent water
• Wastewaters
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Obtaining Accurate Data From Wastewater
• Manual analysis
• Post-run
• Determine concentration from chromatogram peak area
Exceed limit → dilute → re-run sample
• Pre-run
• Manual conductivity measurement
Exceed limit → dilute → run sample
• Tedious
• Dilutions prone to errors
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Increasing Accuracy With Automation
• Automated analysis
• “AutoDilution”
• Post-run analysis using ion chromatograph software to determine if too much
sample was loaded
• In-line Conductivity
• Conductivity measured prior to loading sample onto column
• Exceeding upper limit triggers loading of less sample
• Less sample injected
• Smaller sample loop
• Partial loop
• Automated sample dilution
• Loading of much lower sample amounts
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Innovations That Have Made IC Easier
• Packed Bed Suppression
• Reduced background due to mobile phase for improved signal
• Electrolytic Suppression
• Greater flexibility in mobile phase selection/strength; no chemical
regeneration
• Reagent-Free IC (RFIC)
• Electrolytic eluent generation makes gradient separations as easy as
isocratic; just add water
• Capillary IC
• 18 months continuous operation, infrequent calibration; IC on Demand
• High-pressure IC (HPIC)
• Higher flow rate, faster runs; use of 4 µm particle columns for improved
efficiency, resolution, and chromatographic flexibility
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• High purity eluents generated on line
• Accurate, precise, reproducible
• Just add water
Precise, Contamination Free Eluents
Day after Day, Analyst to Analyst, Lab to Lab
Pump
H2O
K+
Purified KOH
[KOH] Current
Flow Rate
Pt Cathode
(2H20 + 2e- 20H- + H2)
-
Reagent-Free IC with Eluent Generation (RFIC-EG)
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Capillary HPIC Advantages
• “IC on Demand”
• System is always ready for your samples
• Higher laboratory productivity
• Less labor needed for calibration
• High-pressure
• Up to 5000 psi
• Faster runs
• Lower cost of ownership
• Less eluent consumed and waste generated
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Capillary Technology – The Dionex IC Cube Module
Guard and Separation Column
Suppressor
CRD 200
Injection Valve
EG Degas
Side View of Cap
Suppressor
8.9 cm
16.5 cm
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5 25
-1.0
60
µS
Minutes
Column: Dionex IonPac AG19/AS19,
0.4 mm i.d.
Eluent Source: Dionex EGC-KOH cartridge
(Capillary)
Gradient: 10 to 25 mM KOH (0–10 min)
25 to 70 mM KOH (10–20 min)
10 mM KOH (20–25 min)
Flow Rate: 0.010 mL/min
Inj. Volume: 0.4 µL
Column Temp.: 30 °C
Detection: Suppressed conductivity,
Dionex ACES 300, recycle
mode
Sample: Treated wastewater, filtered,
0.2 µm
Peaks:
0.4 mm i.d. 4 mm i.d.*
1. Fluoride 1.76 mg/L 1.69
2. Chloride 180.00 180.00
3. Bromide 0.42 0.51
4. Nitrate 11.80 11.90
5. Sulfate 96.90 96.8
6. Phosphate 0.94 1.25
*Data from 4 mm i.d. column using appropriate run
conditions (Dionex ICS-1100 System)
1
2
3
4 5
6
10 15 200
Determination of Common Anions in Treated
Wastewater
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Conclusions
• The high ion concentrations typical of wastewater presents a
challenge to analysis
• In-line conductivity measurement and automated sample
dilution combine to ensure that what is loaded onto an IC
column is within the calibration range
• Reagent-Free IC removes the inconvenience and variability
of manual eluent preparation
• High-pressure capillary IC allows the use of faster flow rates
for quick run times, while producing very little waste