The Importance of Anion and Organic Acid Determinations in Fracking Wastewater by Ion Chromatography

Significance of the Topic

Monitoring anions and organic acids in hydraulic fracturing wastewater is essential to safeguard groundwater and surface water from contamination. Compounds such as chloride, bromide, sulfate, formate and acetate can influence fracturing fluid performance and pose health risks through formation of toxic disinfection by-products.

Objectives and Study Overview

This study evaluates ion chromatography methods for accurate quantification of inorganic anions and organic acids in fracking flowback waters. It addresses regulatory demands, environmental concerns and process optimization in hydraulic fracturing operations.

Methodology

Analytical procedures employ suppressed conductivity ion chromatography with the following steps:

• Sample preparation: filtration (0.2 µm) and appropriate dilution (up to 100-fold) to accommodate high salt matrices.
• Strong anion-exchange separation of chloride, bromide and sulfate using an AS18 column with potassium hydroxide eluent.
• Detection of short-chain organic acids (formate, acetate) under the same chromatographic conditions.
• Ion exclusion chromatography on an ICE-AS6 column with heptafluorobutyric acid eluent to resolve longer-chain organic acids in saline samples.

Instrumentation

• Dionex ICS-2100, ICS-5000+, ICS-1600 and ICS-1100 ion chromatography systems
• Dionex IonPac AG18/AS18 (4×250 mm) and ICE-AS6 columns
• Dionex EGC III KOH eluent generation cartridge
• Anion Self-Regenerating Suppressor (ASRS 300) and Anion MicroMembrane Suppressor (AMMS ICE)

Main Results and Discussion

Key findings include:

• Baseline separation of chloride, bromide and sulfate in fracking flowback allowed quantification at concentrations up to tens of thousands of mg/L.
• Formate and acetate were quantified at sub-mg/L levels, reflecting both additive use and microbial activity.
• Long-chain organic acids (tartaric, citric, malic, glycolic, lactic, succinic) were resolved in high-salt matrices, avoiding interference from chloride peaks.
• Microbial sulfate reduction was linked to hydrogen sulfide formation and corrosion potential in stored waters.

Benefits and Practical Applications

Ion chromatography delivers:

• High sensitivity and selectivity for multi-analyte detection in complex industrial effluents.
• Rapid, robust methods for routine environmental monitoring and laboratory quality control.
• Compliance support for regulatory limits on bromate, chlorite and other regulated species in drinking water.

Future Trends and Possibilities

Emerging developments include:

• Coupling ion chromatography with mass spectrometry for enhanced identification and lower detection limits.
• Portable IC systems for on-site, real-time monitoring at fracturing sites.
• Automated sample handling and multi-analyte workflows to increase throughput.
• Advanced suppressor and column chemistries for faster separations and improved resolution.

Conclusion

Ion chromatography represents a versatile, reliable approach for comprehensive analysis of anions and organic acids in hydraulic fracturing wastewater. The methods support environmental protection, operational efficiency and regulatory compliance.

Reference

1. Thermo Scientific. Fracking Wastewater Anion and Organic Acid Determinations by Ion Chromatography, 2013.
2. Jack R. Anions and Metals Analysis in Hydraulic Fracturing Waters from Marcellus Shale Drilling Operations, Chem. Eng. News Webinar, July 26, 2012.
3. Thermo Scientific. Dual IC Configurations for Complex Sample Analysis, 2013.
4. U.S. EPA. Method 300.1: Determination of Inorganic Anions in Drinking Water by Ion Chromatography, 2007.
5. U.S. EPA. Study of the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources, Section 5.3.1, 2011.
6. Thermo Scientific. Anion and Cation Analysis in Drinking Water by IC, Application Bulletin AB70453 E.
7. Nelson S., Yonge D., Barber M. J. Environ. Eng., 2009, 135(7), 505–510.
8. Novotny E., Stefan H. Water Air Soil Pollut., 2010, 211(1-4), 261–271.