Summary of EPA Fact Sheet on Peracetic Acid (PAA) for Disinfection (September 2012), we asked Grok to Review and Summarize this EPA Fact Sheet on Peracetic Acid.

"According to WaterOperator.org, wastewater systems consider moving to peracetic acid for several reasons. "

Overview of Disinfection and PAA's Role Disinfection is essential for inactivating pathogenic organisms in wastewater to prevent waterborne diseases. The fact sheet lists common microorganisms in untreated domestic wastewater, such as bacteria (e.g., E. coli, Salmonella), protozoa (e.g., Cryptosporidium, Giardia), helminths (e.g., Ascaris), and viruses (e.g., enteroviruses, hepatitis A). PAA is a strong oxidant and virucide (An agent (physical or chemical) that inactivates or destroys viruses.)  that works by oxidizing cell walls, causing leakage and depolymerization, and generating free radicals (HO₂ and OH) for protoplasmic oxidation and cell lysis. Its effectiveness depends on wastewater characteristics, concentration, contact time, and reactor setup. Key criteria for disinfectants include pathogen destruction without toxic residuals and safe handling.

Chemistry: PAA exists in equilibrium as

CH₃COOH + H₂O₂ CH₃COOOH + H₂O

Commercial formulations include stabilizers for shelf life. It dissipates quickly in water without forming harmful disinfection byproducts (DBPs), even if overdosed.

Applications in Water Treatment (Peracetic Acid (PAA))

PAA serves as an alternative to halogenated disinfectants like chlorine, which produce DBPs. Widely used in Europe, it's being tested in the U.S. for municipal wastewater disinfection, especially after enhanced primary treatment. It's applied via flow-paced pumps into secondary effluent, with good mixing via static mixers. In the U.S., it's delivered in containers up to 300 gallons. Systems are cost-effective (e.g., <$50,000 for a 50 MGD plant at 4 ppm dose) and easy to retrofit.

Advantages

• Broad-spectrum efficacy against bacteria, viruses, protozoa, and helminths.
• Rapid action: 10-fold reduction in fecal coliforms within 8-10 minutes.
• No harmful DBPs or need for neutralization (residuals <1 ppm at discharge).
• Minimal impact on pH or BOD.
• Economically competitive with sodium hypochlorite/sodium bisulfite.
• Simple retrofitting and safer than chlorine gas.
• Passed toxicity tests (e.g., for Ceriodaphnia dubia).
• No toxic, mutagenic, or carcinogenic residuals.

Disadvantages: 

While not explicitly detailed, challenges include reliance on wastewater quality (e.g., particulates reduce efficacy), need for precise dosing due to rapid decomposition, and potential sampling/dosing inconsistencies (e.g., lower-than-target concentrations in tests).

Efficacy: Effective at low doses (0.7-5 ppm) for controlling fecal coliforms and E. coli. Tests show quick reductions and full consumption before discharge (e.g., 1 ppm dose with 67-133 minutes contact time). Comparable or superior to UV and ozone in some studies after primary treatment.

Operational Considerations: Dosing is automated based on flow. Contact times range from 8-133 minutes. Monitoring includes bacterial counts, PAA residuals (via kits), BOD, and pH. Overdosing doesn't produce harmful by-products.

Case Study: Frankfort, KY - First U.S. commercial use in 2005 at a 9.9 MGD plant during ozone system upgrades. Target dose: 0.7 ppm (12% solution) with 26-minute contact. Achieved effective control of pathogens, no pH/BOD changes, residuals <1 ppm, and passed toxicity tests. Costs were competitive.

Regulatory and Environmental Aspects: PAA addresses DBP concerns from chlorine (e.g., in combined sewer overflows). It decomposes rapidly, minimizing environmental impact, with no persistence in effluents. The fact sheet (EPA 832-F-12-030) promotes PAA as an alternative but notes unverified vendor data and does not endorse specific views. References include studies on PAA efficiency and wastewater treatment.

Products

Industrial Test Systems Water Works 480065 Peracetic Acid Test Strip, 32 Seconds Test Time, 0-100 ppm Range (Pack of 50)

More Information: " What You Need To Know About Peracetic Acid (PAA) For Water Treatment"