Vaidya, Ramola

Ramola Vaidya is a Water/Wastewater Process Engineer with HDR in the Vienna, VA office. She has been working with HDR for over four years on water,...

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About Vaidya, Ramola

Ramola Vaidya is a Water/Wastewater Process Engineer with HDR in the Vienna, VA office. She has been working with HDR for over four years on water, wastewater and reuse water treatment process, design, research and pilot projects. Prior to HDR she worked for four years at Hampton Roads Sanitation District on their managed aquifer recharge project, SWIFT. She has Masters and PhD degrees in Civil and Environmental Engineering from Virginia Tech.

Vaidya, Ramola

Titles from this speaker

Description: Advancing Indirect Potable Reuse in Anne Arundel County Maryland by Validating...

Advancing Indirect Potable Reuse in Anne Arundel County Maryland by Validating Carbon-based Treatment Process for MAR

Abstract

With a view to meeting stringent nutrient goals and provide sustainable water solutions, Anne Arundel County in Maryland is evaluating indirect potable reuse through their Our wAAter Program. Managed aquifer recharge is being evaluated by treating secondary or tertiary effluent from the Water Reclamation Facility (WRF), by advanced treatment technologies. The finished water from this advanced treatment train will be injected in the aquifer. Results from initial sampling conducted at Patuxent WRF favored a carbon-based treatment train consisting of flocculation/sedimentation followed by ozone, biofiltration, granular activated carbon adsorption and UV disinfection. Data collected from this pilot will help in validating carbon-based treatment train and help with full-scale implementation.

Drivers such as stringent nutrient regulations and sustainable water solutions have made it imperative for some utilities on the East Coast to investigate and implement water reuse. This presentation will provide guidance on implementing a carbon-based advanced water treatment approach for indirect potable reuse. Water quality results from a WRF sampling plan, strategies for selecting an appropriate treatment train, and lessons learned from pilot startup and operation will be shared.

SpeakerVaidya, Ramola

Presentation time

15:30:00

16:00:00

Session time

15:30:00

17:00:00

SessionOzonation: Water Reuse on a New Level

Session locationRoom S402a - Level 4

TopicAdvanced Level, Disinfection and Public Health, Microconstituents and Contaminants of Emerging Concern (Non-PFAS), Potable Reuse, Water Reuse and Reclamation

Author(s)

Vaidya, Ramola

Author(s)R. Vaidya 1; C. Alito 3 ; G. Heiner 2; G. Heiner 2;

Author affiliation(s)HDR 1; HDR 3 ; Anne Arundel County, MD 2; HDR 2;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159043

Volume / Issue

Content sourceWEFTEC

Word count17

Description: Can Biologically-activated Carbon be Used for Removal of 1,4-Dioxane and Other Trace...

Can Biologically-activated Carbon be Used for Removal of 1,4-Dioxane and Other Trace Contaminants In an Indirect Potable Reuse System?

Abstract

1,4-dioxane is commonly used as a solvent stabilizer for 1,1,1 trichloroethane and is readily soluble in water with a low Henry’s law constant. It is poorly removed by conventional air stripping and adsorption techniques and is generally thought to be resistant to biodegradation. Certain bacteria, such as Rhodococcus sp., Pseudonocardia sp. and Mycobacterium sp. have been shown to biodegrade 1,4-dioxane by monooxygenase enzymes in presence of co-substrates such as propane, butane and tetrahydrofuran (THF) (Vainberg et al. 2006; Mahendra et al. 2007). The goal of this project was to evaluate the feasibility of using biologically activated carbon (BAC) filtration used for indirect potable reuse biodegradation of 1,4-dioxane. 1,4-dioxane can be removed by hydroxyl radicals in an advanced oxidation (AOP) process, such as ozone hydrogen peroxide or UV peroxide (Stefan and Bolton, 1998). However, biodegradation in a BAC filter would be cost efficient and mitigate production of disinfection byproducts produced by the above AOPs.

SpeakerVaidya, Ramola

Presentation time

09:10:00

09:30:00

Session time

08:30:00

10:10:00

SessionAvoid the Brine: Achieving Potable Reuse Without RO

Session number328

TopicMicroconstituents, Water Reuse and Reclamation, Water Supply and Management

Author(s)

C.B. BottR. VaidyaG. Salazar-BenitesC. WilsonA. Pruden

Author(s)C.B. Bott2; R. Vaidya1; G. Salazar-Benites2; C. Wilson2; A. Pruden1;

Author affiliation(s)Civil and Environmental Engineering Department, Virginia Tech1; Hampton Roads Sanitation District2

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2020

DOI10.2175/193864718825157842

Volume / Issue

Content sourceWEFTEC

Word count20

Description: Is It Possible To Remove PFAS From Biosolids? A Review of Different PFAS Removal...

Is It Possible To Remove PFAS From Biosolids? A Review of Different PFAS Removal Technologies

Abstract

Introduction
Emerging contaminants per- and polyfluoro alkyl substances (PFAS) have been labeled as forever chemicals due to their ubiquitous detection in nature and hard to degrade characteristics. Although EPA has established health advisory levels (70 ppt for PFOA plus PFOS) in drinking water, there hasn't been any federal or statewide regulations for treated wastewater or biosolids. Only Maine has imposed regulations for three PFAS compounds in biosolids (Sheets and Ledoux, 2021).
Problem
Long chain PFAS compounds have been banned but the PFAS replacement compounds have the capability of degrading into long chain PFAS precursors. The carbon fluorine bond in PFAS is one of the strongest bonds and does not breakdown easily. Thus, conventional wastewater treatment technologies are not capable of removing PFAS. This results in PFAS leaching into agricultural soils and entering crops after land application (Ebrahimi et al., 2021). The prevalence of these compounds in addition to their adverse health effects have raised concerns and necessitated the search of PFAS removal technologies (Ahrens, 2011; Gorrochategui et al., 2014).
Wastewater secondary sludge and biosolids have shown to be routes for PFAS emission to the environment. Class A and class B biosolids have both been used for land application and can help to enrich soils and prove to be a great source of fertilizer. PFAS precursors from biosolids have shown to be transformed into PFAS compounds even after 6 months of land application (WRF, 2021). Treatment techniques for removal of PFAS in biosolids have been evolving but the results are not publicly available and have not been compared to each other. The objectives of this research were to compare different PFAS removal technologies in biosolids in terms of their development and implementation, and further summarize the lessons learnt from different case studies employing these technologies.
Methods
Technologies for removing PFAS have been piloted and researched but are not widely implemented and need further understanding. This presentation will provide a deeper dive into the various technologies being developed along with considerations for each technology. The research team identified six technologies for PFAS destruction/removal from biosolids and reviewed case studies for each technology. These technologies are summarized in Table 1. The different technology readiness levels defined by EPA were used to evaluate the status of each technology in terms of development and testing (Watkins, 2021).
Results and Discussion
Table 2 describes the current status of each technology with a few examples of pilot or full-scale facilities. The key points for each technology are as follows: - Incineration has strong evidence demonstrating that it can destroy PFAS (Winchell et al., 2020; Loganathan et al., 2007), however the high temperatures of greater than 1000oC needed for PFAS destruction (Kucharzyk et al., 2017) might not be attained in conventional incinerators. A few lab-scale studies showed no detectable levels of perfluoroocatanoic acid (PFOA) after thermal destruction of fluorotelomer-based polymers (Yamada et al., 2005; Taylor et al., 2014). The biggest concern around this technology includes the possibility of PFAS being released into the atmosphere and transformation into other fluorinated byproducts (EPA, 2020). - Very few studies by technology manufacturers have documented PFAS removal by pyrolysis (Bioforcetech, 2020). Complete destruction of all PFAS compounds and precursors is yet to be verified. EPA is currently analyzing PFAS content in biochar produced by full-scale pyrolysis facilities (EPA, 2021). - Similar to pyrolysis, gasification has the potential for PFAS destruction based on a pilot-scale study (Aries Clean Energy, 2020). However, transformation of PFAS compounds and detection in gas phase has not been conducted. - SCWO has been developed only in the past couple of years by researchers at Duke University. Initial research shows potential for PFAS destruction in landfill leachate (Jama et al., 2020) but more research is needed to validate its ability to eliminate PFAS in biosolids. - Vitrification facilities operate at temperatures greater than conventional incinerators resulting in combustion of recalcitrant compounds and thus has potential for PFAS destruction (CDM Smith, 2020). A full-scale vitrification facility was operated in Illinois for 3 years but had to be decommissioned due to cost and performance issues. PFAS removal by this technology has not yet been established. - Hydrothermal liquefaction bench-scale studies showed greater degradation of carboxylated PFAS compounds over sulfonic compounds but original PFAS compounds were still present (Yu et al., 2020). This technology needs further modification and development before being implemented for biosolids PFAS removal.
Significance and Conclusions
Figure 1 shows the readiness levels for each technology. Out of the six technologies reviewed, incineration, pyrolysis and gasification have been studied in greater detail due to their widespread use and show potential for PFAS reduction. Other technologies are still being developed and have no full-scale implementations. Case studies for each of these technologies will be studied in detail in the final manuscript and will include lessons learnt from each bench or pilot-scale and full-scale installations. These case studies for PFAS removal from biosolids can improve existing knowledge and database for WRRFs trying to remove PFAS. In depth understanding of each technology, advantages, disadvantages and difficulties in implementing each technology can be crucial for future treatment optimization and modifications.

Recently PFAS in biosolids has been getting considerable attention due to leaching of PFAS in agricultural soils and crops after land application coupled with upcoming PFAS regulations. Currently PFAS removal technologies in biosolids are still being researched and developed, with few showing potential for PFAS destruction in full-scale applications. This paper will provide better understanding of PFAS removal in biosolids by comparing different biosolids thermal treatment technologies.

SpeakerVaidya, Ramola

Presentation time

13:35:00

13:50:00

Session time

13:30:00

15:00:00

TopicIntermediate Level, Biosolids and Residuals, PFAS

Author(s)

Vaidya, Ramola

Author(s)Ramola Vaidya1; Mamatha Hopanna2; Sebastian Smoot3

Author affiliation(s)HDR, Vienna, VA1; HDR, Fulton, MD2; HDR, Fulton, MD3

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2022

DOI10.2175/193864718825158608

Volume / Issue

Content sourceWEFTEC

Word count16

PFAS Removal in AWT: Using RSSCT to Accelerate GAC Design

Abstract

Introduction Emerging contaminants like per- and polyfluoroalkyl substances (PFAS) have gained attention in the past 5 years due to anticipated health concerns and a rapidly changing regulatory climate. The draft EPA regulations propose MCLs of 4 ppt for PFOA and PFOS, and a hazard index of 1 for PFHxS, HFPO-DA, PFNA, and PFBS. Additionally, the upcoming fifth Unregulated Contaminant Monitoring Rule (UCMR5) is focused on sampling for 29 different PFAS with greatly improved analytical methods. It is expected that >20% of all drinking water utilities will have reportable levels of PFOA and PFOS, based on past data sets. The estimated national capital costs for drinking water utilities to adequately remove these compounds are anticipated to exceed $200M net, with similar life cycle/replacement costs incurring on an annual basis. All these factors have made it essential to act now for preventing PFAS exposure and finding effective ways to treat PFAS in water. Drinking water utilities have been stressed to rapidly install reliable and cost-effective PFAS treatment technologies. In many cases, customer demands have pressured utilities to identify and implement these solutions as quickly as possible. Problem Granular activated carbon (GAC) can be highly effective for removal of total organic carbon (TOC) and PFAS. With water-stressed communities across the U.S. shifting towards non-traditional supplies, such as potable reuse and impaired groundwaters, and the growing national concern around PFAS and other emerging contaminants, the water industry is looking for reliable, rapid implementation strategies for proven technology solutions, like GAC. Currently, data from Rapid Small Scale Column Testing (RSSCT), is used for predicting full-scale GAC performance by scaling up the adsorption data. RSSCT can enable bench testing different GAC media in a short amount of time and provide fast results using less resources (media, water and labor). This method is faster and cheaper than pilot or demonstration-scale systems. However, RSSCT only provides qualitative insights on performance and lacks the sensitivity to characterize the impacts of media size, pretreatment, and moderate source water quality fluctuations. The main objectives of this study were: (1) To determine the best GAC media for PFAS and TOC removal, (2) To determine bed volumes needed for PFAS and TOC breakthrough, (3) To calculate GAC media changeout frequency, (4) To develop a tool for predicting GAC breakthrough for full-scale GAC design Methods The bench and pilot-scale work were conducted at Anne Arundel County, MD's advanced water treatment (AWT) pilot. This AWT pilot is being used for validating a carbon-based treatment approach for managed aquifer recharge. Figure 1 shows the process flow diagram of the carbon-based pilot treatment train. This AWT pilot was installed at the Patuxent WRF in September 2022 and consists of coagulation, flocculation, sedimentation, ozone, biologically activated carbon filtration (BAF), GAC adsorption, and UV disinfection. The GAC treatment acts as a final barrier for removing contaminants that are not removed in the upstream treatment processes. RSSCT was conducted using small glass columns of varying diameters (7, 10 and 15 mm) filled with GAC media from two different vendors Calgon (Filtrasorb(R) 400) and Evoqua (UltraCarb(R) 1240LD10). The media was grounded and packed in these glass columns. Two different empty bed contact times (EBCT) were tested, 6.5 and 12 min. BAF effluent from the pilot study was used for RSSCT. PFAS and TOC samples were collected at 5,000, 10,000, 20,000, 30,000 and 40,000 bed volumes. This setup allowed to see the impact of various media types, media sizes and EBCT on the PFAS removal and breakthrough. Results and Discussion Pilot-scale data showed that only short-chain unregulated PFAS such as PFPeA, PFHxA and PFBA are being detected in GAC effluent after 6,000 BV as shown in Figure 1 and 2. The long-chain PFAS such as PFOA and PFOS that might be regulated by EPA were removed by GAC below detection even after 12,000 bed volume (BV) at an EBCT of 30 min. At 12,000 BV, TOC removal was 60%, with an effluent TOC level of 1 mg/L. Figure 3 shows the RSSCT PFAS and TOC data for one column. Short-chain PFAS such as PFPeA and PFHxA similar to the pilot study were detected in RSSCT. This data showed that GAC sites were exhausted by TOC and removal plateaued around 15,000 BV. Significance and Conclusion This data is important for GAC media changeout which can be a cost-intensive process due to cost of GAC media. This data can help in deciding if media changeout is dominated by TOC limits for potable reuse or by PFAS regulations. Next steps involve comparing RSSCT PFAS breakthrough data with full-scale GAC PFAS data. This will allow to understand the discrepancies in predicting PFAS breakthrough for RSSCT. Using this comparison, a predictive tool can be developed for full-scale GAC design. Using RSSCT scale up models, we can predict the bed volumes needed for breakthrough of PFAS and CECs to help design full-scale GAC treatment. Developing modified RSSCT scale up models for different contaminants can ensure consistent and reliable data for the industry. Optimizing GAC performance using real time RSSCT tools can revolutionize the way GAC treatment is implemented in the One Water industry.

Recent PFAS regulations have made it imperative for all utilities to implement solutions for treating PFAS not only in drinking water but also wastewater and water reuse. This presentation will provide guidance on designing a full-scale GAC treatment for treating PFAS using Rapid Small Scale Column Testing (RSSCT). Using RSSCT can help predict PFAS breakthrough and help optimize overall GAC treatment.

SpeakerVaidya, Ramola

Presentation time

16:00:00

16:30:00

Session time

15:30:00

17:00:00

SessionRevolutionizing PFAS Treatment: Harnessing the Power of Media Technologies

Session number230

Session locationRoom 338

TopicIntermediate Level, Microconstituents and Contaminants of Emerging Concern (Non-PFAS), PFAS, Research and Innovation

Author(s)

Vaidya, Ramola, Alito, Christina, Lauderdale, Chance

Author(s)R. Vaidya1, C. Alito1, C. Lauderdale2

Author affiliation(s)1HDR, VA, 2, VA

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159494

Volume / Issue

Content sourceWEFTEC

Word count11

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Vaidya, Ramola

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