Porat, Iris

Dr. Iris Porat has 23 years of experience in microbiological research in industrial, government and academic environments. Dr. Porat has served as a Principal Scientist at Kemira for the past 10 years. Her work focuses on antimicrobial biocide effectiveness in municipal wastewater treatment and the pulp & paper applications. Currently, she is the lead researcher within an interdisciplinary group focused on introducing a new wastewater disinfection technology to the North American market. The technology, KemConnect DEX is based on performic acid and it has been available in Europe for the last 15 years. Iris earned Bachelor of Science and Master of Science degrees in Life Sciences, holds a Master of Business Administration, and a Ph.D. in Biochemistry and Molecular Biology from Ben-Gurion University in Israel.

Titles from this speaker

Performic Acid Disinfection at Capital Region Water: Including Stormwater Events

Abstract

The Capital Region Water (CRW) Advanced Wastewater Treatment Facility (AWTF) sits along the banks of the Susquehanna River in Harrisburg, the capital of Pennsylvania. The facility treats 21 MGD, with a service population of 125,000. CRW is one of the largest potential point sources of water contamination in the Chesapeake Bay watershed. The city's collection system includes approximately 60% combined sewers, many built in the 19th century. Wet weather can push peak flows to 80 MGD. The CRW process includes grit removal, primary clarifiers, biological treatment, post-anoxic tanks, final clarifiers, and disinfection contact tanks (Fig 1). Recent capital investments at the AWTF have focused on nutrient removal and energy recovery; however, the disinfection process is nearly identical to the one installed at initial commissioning in 1959. Currently, chlorinators dissolve gaseous chlorine into an aqueous solution, which is then added to treated effluent. Increased chlorine costs, the risk of storing large volumes onsite, and concern regarding chlorine's disinfection byproducts (DBPs) challenge the future use of chlorine at CRW. Implementing increased wet weather capacity also increases the demand on the disinfection process. For these reasons, CRW is evaluating alternative disinfection technologies. PFA is a wastewater disinfection technology that has been in use in Europe for over a decade. Currently, PFA is used in nine European countries for disinfection at 18 municipal wastewater treatment plants (WWTPs) and at 20 paper manufacturing facilities. Studies were performed prior to PFA implementation at Paris and Biarritz (France), and Venice (Italy). These case studies, addressing efficacy and European discharge requirements, were published in 2021 (7). PFA is a peracid made from hydrogen peroxide and formic acid; it is similar to peracetic acid (PAA). Compared to PAA, PFA has a shorter carbon chain that makes it unstable for storage, so PFA must be made onsite. PFA reacts rapidly with a higher redox potential compared to most disinfectants (9). Post disinfection, residual PFA degrades into carbon dioxide and water. Studies have shown that PFA has a low potential for toxic DBPs formation (2, 8). To comply with regulations for selling PFA in North America (NA), lab scale efficacy tests were performed. Good results were obtained using doses from 0.25 to 1.0 mg/L with contact times of 5 to 20 minutes (3, 4). Later PFA efficacy was tested at pilot scale in QC, Canada and OR, USA using secondary WW. PFA reduced required indicator bacteria below their permit limits with doses of 1.0 -1.5 mg/L using 15 - 30 minute retention times (5, 6). No toxic effects were documented in these studies (4, 6). The purpose of this research is: (1) Evaluate if PFA reduces fecal coliform (FC) below CRW's permit limit in secondary WW, (2) Evaluate disinfection during stormwater events, (3) Compare methods for FC enumeration Initial lab studies showed good efficacy for PFA at 0.5 mg/L (Fig 2). The pilot design system was similar to a previous pilot run (6). The pilot located at CRW (Fig 3) included the PFA generator, contact basins, precursor chemicals, and automatic samplers (Fig 4). The online probes included pH, TSS, and residual PFA. The pilot flow rate was 34 gpm of WW, and the effluent was collected from port #6 with a retention time of 34 minutes. To mimic storm events, the pilot at CRW included the testing of blended mixtures of secondary and primary WW (Fig 5). FC was maintained below the required limit using (Fig 6): (1) 0.5 mg/L PFA with 100% secondary WW, (2) 1.5 mg/L PFA with 90% secondary and 10% primary WW, (3) 2.3 mg/L PFA with 80% secondary and 20% primary WW. The effect of WW blended with PFA doses is shown in Fig 7. A higher proportion of primary WW increases the demand for PFA. PFA didn't affect other parameters tested in composite samples (Table 1). Two methods for FC enumeration, IDEXX Colilert-18 and IDEXX Tecta system, were used during the pilot. Tecta was tested to simplify FC enumeration during the pilot. This is a semi-automatic system where a sample is tested, without dilution, and an email report is sent upon test completion. The instrument follows FC growth by identification of the beta-galactosidase activity signal. Tecta system is an EPA approved method for drinking water but not currently approved for WW. Comparable results between the Tecta system and the Colilert method have been published for FC enumeration (1). During the pilot at CRW, samples were collected and tested using both methods. Comparable results were obtained (Fig 8) after IDEXX technical support provided additional calibration of the Tecta unit. In conclusion, the pilot study demonstrated that very low doses of PFA disinfected and met CRW FC limits. Low doses have a positive impact on disinfection costs. Compliant disinfection was achievable with a mixture of primary and secondary WW using elevated doses of PFA. This simulates stormwater events when primary and secondary WW are mixed. The IDEXX Tecta system produced comparable results to the IDEXX Colilert-18 in this study and it decreased the time, cost and complexity of the FC testing process. The result of this study and the known environmentally preferable characteristics of PFA support its use as an alternate disinfectant. These benefits are most important during storm events when higher levels of organics react with chlorine increasing DBPs.

During the Capital Region Advanced Treatment Facility expansion and upgrade of the chlorine-based disinfection process, performic acid was tested as a viable alternative. A low dose of PFA reduced fecal coliform below permitted limits in secondary wastewater. Simulated storm event showed that fixed doses of PFA met FC requirements when blending 1050% primary with secondary. Then, a proportional-integral-derivative controller maintained a 0.2-0.3 mg/L residual PFA dose and FC below limits.

SpeakerPorat, Iris

Presentation time

09:00:00

09:30:00

Session time

08:30:00

10:00:00

SessionPeracids Challenge Traditional Disinfectants

Session number503

Session locationRoom 338

TopicDisinfection and Public Health, Intermediate Level, Research and Innovation

Author(s)

Porat, Iris, Stammegna, Marco, Hill, Christopher, Skold, Ingrid, Hansen, Jennifer, Hoke, Raymond, Hart, Brian, Rosentel, Jess

Author(s)I. Porat1, M.W. Stammegna2, J. Rosentel3, C. Hill4, I. Skold1, J. Hansen5, R. E Hoke6, B.A. Hart3

Author affiliation(s)1Kemira Water Solutions Inc., GA, 2Kemira Water Solutions, OH, 3Capital Region Water, PA, 4Kemira Water Solutions, GA, 5Kemira Water Solutions Inc., 6Capital Region water, PA

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159501

Volume / Issue

Content sourceWEFTEC

Word count11

Performic Acid Disinfection for a Sustainable Future

Abstract

KemConnect DEX, a new North American disinfection technology, employs performic acid (PFA) chemistry. PFA has a strong oxidation potential, higher than chlorine compounds and peracetic acid but lower than ozone. PFA reacts quickly and degrades to CO2 and water in a short time. PFA is made onsite for municipal treatment plant (WWTP) applications using the DEX unit. The presented research shows PFA efficacy tests on samples from US WWTPs. Results demonstrate that low PFA concentrations, 0.25-0.5 mg/L dose, reduced E. coli to below required counts, and PFA degrades to below toxic levels in a short time. The current study presents novel acute toxicity data of PFA using Pimephales promelas, Daphnia magna, and Ceriodaphnia dubia. KemConnect DEX is a superior solution for disinfection since it reduces regulated bacteria to below-required numbers. At the same time, it also degrades to below toxic levels, eliminating the need for quenching of residual disinfectant.

KemConnect DEX is a new North American technology that uses performic acid (PFA) to disinfect municipal wastewater. PFA is a strong oxidizer that reacts quickly and degrades to CO2 and water in a short time. The paper presents PFA efficacy results, where low PFA doses (0.25-0.5 mg/L) reduced regulated bacteria to below permit requirements. The PFA then quickly degraded to below toxic levels eliminating the need for quenching of residual PFA. This paper includes PFA acute toxicity data against strains of water fleas and fathead minnows.

SpeakerPorat, Iris

Presentation time

16:20:00

16:40:00

Session time

16:00:00

17:30:00

SessionPeracid Post-up: What's New in Alternative Chemical Disinfection with PAA and PFA?

Session number112

TopicDisinfection and Public Health, Municipal Wastewater Treatment Design, Policy and Regulation, Sustainability and Climate Change

Author(s)

Iris Porat

Author(s)I. Porat1; C. Hill1; J.M. McDonald1; W. Hall2;

Author affiliation(s)Kemira Chemicals, Inc. Atlanta, GA1Hall and Associates, DC2Hall & Associates4

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2021

DOI10.2175/193864718825158016

Volume / Issue

Content sourceWEFTEC

Word count8

Description: Performic Acid (PFA) Disinfection Pilot Program and Options for PFA Methods of...

Performic Acid (PFA) Disinfection Pilot Program and Options for PFA Methods of Analysis

Abstract

BACKGROUND
The disinfection of municipal wastewater (WW) is essential to ensure discharge quality and minimize potential human health risks. Effective treatment is particularly essential when discharges are near recreational water. Chlorine-based disinfectants are the most common disinfectants due to their low costs, but they produce harmful by-products. In this pilot study, an alternative disinfectant is evaluated, performic acid (PFA), and methods for the manual and online detection of PFA. Kemira KemConnectâ„¢ DEX is an advanced technology designed to meet future sustainability requirements for disinfection. KemConnect DEX is a treatment process that combines hydrogen peroxide and formic acid onsite to form PFA. Peracetic acid (PAA), like PFA, is another peracid that has been used in WW disinfection for 40 years. PAA has a longer carbon chain that makes it stable to be stored onsite as a liquid product. In comparison, PFA, which has been used in Europe safely and effectively for over a decade, has a greater reactivity and is, therefore, made on-site using the DEX unit. The DEX unit includes a built-in reaction vessel, dosing pumps, process control box, safety flushing system, cooling/heating, and an uninterruptible power supply (Figure 1). Disinfection occurs within minutes, and any residual PFA degrades into CO2 and H2O within an hour and has low potential for disinfection by-product formation (Karpova et al., 2013). A full-scale implementation of KemConnect DEX at an Italian wastewater treatment plant (WWTP) showed that PFA is an effective disinfectant, ensuring the reduction of bacteria to below established limits (Regazzo et al., 2013). Kemira is seeking product registrations to sell PFA in North America. As part of the registration process, efficacy tests were conducted using PFA on WW from two Canadian WWTPs. The data showed greater than a 3-log reduction for indicator bacteria using a 1 mg/L PFA dose and 5 minutes contact-time on secondary effluent (Porat et al., 2019). PFA efficacy was tested on samples from three WWTPs in the US. Results demonstrated that low PFA concentrations (0.25-0.5 mg/L) reduced E. coli to below required counts, and PFA degrades to below toxic levels in a short time (Porat et al., 2021). In addition, PFA toxicity data against Pimephales promelas and Ceriodaphnia dubia, model organisms for toxicity in the US, showed higher toxicity for C. dubia. The PFA LC10 value for C. dubia tested in WW was 0.30 mg/L. This could become the PFA discharge limit value when no dilution is available (Porat et al., 2021).
OBJECTIVES
It is expected that US and Canadian regulatory authorities will require PFA residual monitoring to ensure dosing meets microbial reduction targets and to confirm that water quality limits are being achieved. PFA measurement methods should be rugged, accurate, fast, and operator-friendly to monitor residual PFA levels efficiently and effectively. This study aims to validate methods for detecting PFA, manual or online applications, and to test an online PFA detection method in a KemConnect DEX pilot.
METHODOLOGY and RESULTS
PAA (CH3COOOH) is chemically similar to PFA (HCOOOH). Currently, PAA is more widely used than PFA, and commercial methods exist to analyze PAA. The Reflectoquant PAA test with the RQflexÂ® 20 (Merck KGaA, Darmstadt, Germany) is designed to determine PAA concentrations. The detection range for the PAA test is 1 to 22.5 mg/L PAA. Due to the difference in the molecular weights of PFA and PAA, a factor of 0.82 is used to convert the PAA value into PFA concentration. To validate the Reflectoquant method for PFA, fresh PFA solution was prepared, and the concentration was determined first by the two-step titration method (Gehr et al., 2009). PFA measurement was linear (r2=0.98) throughout the detection range (0.8 â€“ 18.5 mg/l); the accuracy (recovery 85 â€“ 116 %) and repeatability (RSD <9.2%) were within acceptable parameters. A PAA method using N-N-diethylâ€“p-phenylenediamine (DPD) method is now published (4500-PAA PERACETIC ACID). A Joint Task Group has been established to validate this method for PFA measurement. Results of our testing include calibration curves for PFA and PAA that showed slopes with a ratio of 0.82 (3.2/3.9), in agreement with the molecular weight conversion factor mentioned above. Also, accuracy (recovery 102%), repeatability (RSD <4.6%), and method detection limit (MDL=0.03 mg/L PFA) were comparable to Standard Methods PAA single operator data signaling that the DPD method is applicable for PFA. Two online devices (Device 1 and Device 2) provided a good correlation with the manual method CHEMetrics K-7913 kit (Figure 2). Both online devices were set up in the lab, and both devices were fed from the same tank containing secondary effluent with PFA. KemConnect DEX technology with online Device 1 was tested in a pilot run at a Canadian WWTP, where their WW was previously tested (Porat et al. 2019, Figure 3). The WW to be treated came from the clarifiers and was sent to a contact tank using a centrifugal pump. The treated water then passed by overflowing into a retention tank (tote) before being returned to the beginning of the plant's treatment process. The DEX unit was installed inside a container (Figure 3), and it generated 10.4Â±0.7% PFA. The WW was treated with 1.1 mg/L PFA for 15 minutes retention time in the contact tank. After treatment, the residual PFA in the WW was monitored by the online Device 1, connected to the KemConnect system. Kemira's KemConnect system provides live online results to customers. During the pilot, the system generated daily reports (Figure 4). Under current conditions, the fecal coliform was maintained (7 out of 9 times tested) below the required limit (200 CFU/100 mL), and the residual PFA was below 0.52 mg/L PFA (PFA LC50 for Daphnia magna, Porat et al. 2021). In addition, no significant difference between PFA treated and untreated WW were found during the pilot run when tested for pH, COD, TSS, alkalinity, ammonia.
CONCLUSIONS
Two manual methods are applicable for the detection of PFA. CHEMetrics K-7913 kit for lower concentrations and Reflectoquant PAA test if the concentrations are higher. The KemConnect DEX system provides disinfection by reducing bacteria to below-required limits, then the active disinfectant, PFA, degrades to below toxic limits. The KemConnect DEX system offers online monitoring of PFA production and residual PFA.
REGULATORY NOTE
The pesticide technology described herein, is not available for sale or distribution in the United States or Canada until the applicable registration is approved by the respective agency.

Kemira KemConnect DEX is a sustainable disinfectant technology based on performic acid (PFA). This paper presents a pilot study and methods for the manual and online detection of PFA. Two peracetic acid (PAA) test kits were validated for the detection and measurement of PFA. The KemConnect DEX system offers onsite PFA generation with online monitoring of residual PFA. PFA was shown to achieve efficacy requirements and to degrade below toxic thresholds using the validated testing methodologies.

SpeakerPorat, Iris

Presentation time

11:30:00

11:55:00

Session time

10:30:00

12:00:00

TopicIntermediate Level, Disinfection and Public Health, Municipal Wastewater Treatment Design, Research and Innovation, Water Reuse and Reclamation

Author(s)

Porat, Iris

Author(s)Iris Porat1; Jaakko Ekman4; Chris Hill2; Jenny Hansen2; Marco Stammegna2; Catherine Brosseau3; Francois Marchand3; Sylvain Beaudry3; Bill Kornicker5; Joanne Carpenter5

Author affiliation(s)Kemira Chemicals Inc., Atlanta, GA1; Kemira Water Solutions Inc., Atlanta, GA2; Kemira Water Solutions Canada Inc., Quebec, Canada3; Kemira OYJ, Espoo, Finland4; CHEMetrics, Inc., Midland, VA5

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2022

DOI10.2175/193864718825158575

Volume / Issue

Content sourceWEFTEC

Word count14

Description: Performic Acid Testing for Evaluation of Disinfection Efficacy and Toxicity in WWTP...

Performic Acid Testing for Evaluation of Disinfection Efficacy and Toxicity in WWTP Secondary Effluent at Both Laboratory and Onsite Pilot Demonstration

Abstract

PFA has been used in Europe for nearly 20 years as a disinfectant for wastewater because of its environmentally sustainable characteristics. The goals for this study were to determine the required conditions for PFA efficacy to achieve permitted limits for bacteria and toxicity at the Gresham WWTP; to evaluate the log inactivation of PFA for indicator organisms; and to compare the efficacy of PFA to chlorine. Comparing PFA to hypochlorite, lab testing demonstrated that PFA required 5.6 times less dose to reduce E. coli to below the WWTP permit limit using a 15-minute contact-time. The pilot results showed a CT (dose * contact-time) of 20 - 40 mg * minute/L to provide effective disinfection (with a 2-3 log reduction). PFA doses up to 4 mg/L with a contact-time of 15 minutes showed no toxic effects. This evaluation proved PFA to be a good disinfectant alternative for the North American market.

Performic Acid (PFA) testing on secondary effluent from Gresham's WWTP is presented. Bench-scale testing first identified initial disinfectant dose/contact time scenarios. Chemical-based disinfection effectiveness is dependent on water quality characteristics, contact time, contactor hydraulics, and kinetics of inactivation; onsite pilot testing was then conducted to further investigate these conditions. Lessons learned are documented to guide potential implementation of this technology.

SpeakerNoesen, Matthew

Presentation time

16:00:00

16:30:00

Session time

15:30:00

17:00:00

SessionAdvancements and Optimization with Chlorine, Peracetic Acid, and Performic Acid Disinfection

Session locationRoom S405 - Level 4

TopicDisinfection and Public Health, Intermediate Level, Municipal Wastewater Treatment Design, Research and Innovation

Author(s)

Noesen, Matthew