deSilva, Viraj

Dr. Viraj deSilva is a Senior Treatment Process Leader at Freese and Nichols, specializing in PFAS management. He currently chairs the Emerging Contaminants Community at WEF and previously led the PFAS Task Force. He was also recently appointed as Chair for AWWAs Emerging Contaminants Issues Committee. Viraj has received AWWA Best Paper Awards for Managing and Treating PFAS in Membrane Concentrates (2021) and Potable Reuse and PFAS (2022). He also serves on the Technical Advisory Group for research projects at five universities.

Titles from this speaker

Description: Development of PFAS Pretreatment Programs: Challenges Faced by Landfills and...

Development of PFAS Pretreatment Programs: Challenges Faced by Landfills and Industrial Customers in the United States

Abstract

Many industries discharge to municipal WWTPs rather than discharge directly to surface waters or groundwater. Municipal WWTPs are not known to have historically used materials containing significant quantities of PFAS; however, many receive wastewater from local industries via their Industrial Pretreatment Program (IPP). Some of those IPP permit holders, may have used PFAS-containing materials. Because PFAS are resistant to degradation and conventional treatment, they could have passed through most industrial pretreatment systems and made their way to the local WWTP, where they would be just as resistant to degradation and treatment and released to local receiving water via the WWTP's discharge. Similarly, WWTPs receiving landfill leachate could have unknowingly received PFAS. The presence of PFAS in some types of industrial wastewater and in landfill leachate was not known until relatively recently, so the process of WWTPs receiving and passing through PFAS could have been occurring for many years. Many states have required all municipal wastewater utilities with an IPP to identify potential industrial users that may be potential sources of PFAS, collect data on PFAS in their discharges, report the findings to the state, and develop plans to reduce the concentration of two PFAS compounds, PFOS and PFOA, in their effluent to meet state water quality standards. Minnesota's PFAS Initiatives with the updated IIP Program Minnesota's PFAS Blueprint, released in February 2021, provides more information about PFAS toxicity and their occurrence in Minnesota. In addition, it lays out the state's approach to managing and addressing PFAS. Across the topics covered by the PFAS Blueprint, themes emerge among the needed actions. These include: 1. Pollution prevention, 2. Investigation of PFAS discharges, 3. Environmental monitoring, 4. Toxicity research, 5. Regulatory development
Goals and objectives for PFAS monitoring
The goals of the monitoring plan are: 1. Gather Minnesota-specific information in order to craft effective policies around PFAS and their incorporation into MPCA programs; 2. Identify areas of particular concern (due to PFAS concentrations or routes of exposure) that need quick action; and 3. Gather data that galvanizes support for PFAS source reduction and pollution prevention.
How frequently will monitoring occur? Levels of PFAS in various media can change depending on the time of year, the weather, the activities occurring at industrial facilities, and other variables. PFAS monitoring and reporting requests will generally be aligned with existing monitoring and reporting that facilities already conduct for other pollutants. Aligning PFAS monitoring with other required monitoring and reporting will be efficient for both MPCA and permittees. The monitoring data will be used to support the three main goals articulated above.
Michigan's IPP PFAS Initiative To address the potential that municipal WWTPs could be passing through elevated levels of PFAS through their treatment systems to lakes, streams, and groundwater, EGLE launched the IPP PFAS Initiative in February 2018. The IPP PFAS Initiative required all municipal WWTPs with required IPPs (95 statewide) to find out if they were passing through PFOS and/or PFOA to surface waters or groundwater and, if found, to reduce and eliminate any sources. Under the Initiative, WWTPs were required to: - Identify industrial users to their system that were potential sources of PFAS. - Sample probable sources and their WWTP discharge (effluent) if sources were above screening criteria (12 ppt PFOS). - Require source reduction at confirmed sources. This is being accomplished through pollutant minimization plans, equipment/tank change out/clean outs, product replacement, and installation of pretreatment to remove PFAS, specifically PFOS, prior to discharge. - Monitor compliance of confirmed sources and ensure that they meet local IPP PFAS requirements. - Submit required reports and monitoring results as required by the WRD. Table 1 shows Sources of PFOS to WWTPs in Michigan. Landfill leachate Landfill leachate poses further consideration, as constituent concentrations of the various emerging contaminants range from low ng/L levels to tens of thousands of times that level. PFAS data on landfill leachate, WWTP influent, effluent, and biosolids within Michigan were analyzed to identify chemical signatures in landfill leachates and WWTP influent, effluent, and biosolids/sludges. Landfill leachates show diverse PFAS chemical signatures dominated by C-4s, C6s and C8s. Numerous transformations of undetected polyfluorinated precursors in the influent during the wastewater treatment process to more terminal perfluorinated compounds that are detectable in the effluent yield PFAS concentrations in the effluent that are 2-10 times greater than in the influent. A summary chart of average concentrations of the 5 Regulated PFAS at VT landfills is illustrated in Figure 1.
Summary
If your utility has an industrial pretreatment program, it may be a good idea to develop a PFAS strategy and share the concerns with your industrial users. As a first step, before sampling is required, it would be beneficial to have industrial users review their existing processes and raw products to determine whether there is a likelihood of PFAS present. Maintaining a collaborative relationship between your utility and your industrial users will help to identify ways to minimize, reduce, and eliminate PFAS from the industrial stream with product substitution and/or additional operational controls. To completely treat PFAS some of the innovative destruction technologies will be reviewed including:
- Modified bentonite adsorbents -
Foam Fractionation - Supercritical Water Oxidation -
Low-Temperature Plasma
These technologies are in their infancy and have shown significant promise. However, there still are concerns about residuals management, complete destruction, or sequestering short-chain PFAS. Additional evaluation on treatment processes is also needed to address concerns about treatment results where PFAS precursors become regulated PFAS constituents.

Municipal WWTPs that receive industrial wastewater also could be receiving water contaminated with PFAS, which pose potential public health risks and resist degradation and treatment. Though chemical makers in the U.S. stopped making PFAS, they persist in industrial discharges, are released by airports and military bases using PFAS-containing firefighting foams and can leach from landfills. Given the lack of federal regulations, utilities and industrial customers should work together to protect

SpeakerdeSilva, Viraj

Presentation time

11:00:00

11:25:00

Session time

10:30:00

12:00:00

TopicIntermediate Level, Industrial Issues and Treatment Technologies, Municipal Wastewater Treatment Design, PFAS, Sustainability and Climate Change

Author(s)

deSilva, Viraj

Author(s)Viraj deSilva1

Author affiliation(s)Freese and Nichols, Tampa, FL1

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2022

DOI10.2175/193864718825158560

Volume / Issue

Content sourceWEFTEC

Word count17

Description: How Different Water Utilities Around the US are responding to PFAS contamination in...

How Different Water Utilities Around the US are responding to PFAS contamination in Rivers

Abstract

Introduction
Per-polyfluroalkyl substances, or PFAS, are man-made chemicals that can be found in numerous watersheds throughout the country. PFAS have earned the term forever chemicals because they do not naturally breakdown in the environment. PFAS are commonly used in many industrial processes to make up common everyday household items. Due to these industrial processes, many PFAS have ended up in watersheds and waterways that are the drinking water sources for many communities across the country. Rivers can become polluted through many different sources; this is especially true for PFAS pollution. One-way rivers become polluted is through a nonpoint source in which the pollutant can come from run off or seeps into the ground and eventually ends up in rivers nearby. Another example is through the application of biosolids that could contain PFAS. The EPA passed new PFAS MCLs on April 10, 2024, which would require the water utilities around the country to comply with these MCLs by 2029. Before the EPA set this standard, different communities were already testing for PFAS and making the treated water PFAS free. This was heavily incentivized due to the negative effects the communities were seeing among the residents that rely on and consume polluted water.

#PFAS Dataset
This study analyzed five different rivers across the United States; each of these rivers are a source of drinking water for the surrounding population and levels of PFAS have been detected in them. The rivers that will be talked about in this presentation are: the Cape Fear River in North Carolina, the Conasauga River in Georgia, the Mississippi River in Iowa, the Tennessee River in Alabama and the Ohio River which covers multiple different states. The data comes from the publicly available UCMR5 data, as well as the latest data from the water quality reports published by each of the different municipalities that are looked at.

#Timeline of Pollution
The history of these rivers is a long one, often times these became polluted due to different companies and industries discharging PFAS to surface water in the area. This can be from landfill leachate or from wastewater treatment plants that take industrial waste and then unknowingly discharge PFAS into rivers. Another common example of how rivers can get polluted is through different industries and facilities in the area that produce PFAS compounds as a product or by-product of their process and discharge that waste directly into rivers upstream of water treatment plants. Common examples of the different industries would be companies like 3M, DuPont or Chemours, which is an off shoot of DuPont, and other different companies as well.

#A historical review of each river was conducted to fully understand how the PFAS pollution came to be. Each river is different in its history as well as location, this could affect different parts of the river, different communities; this means that different communities will see different results when it comes to treatment and PFAS pollution removal.

#PFAS Removal Technologies
A review of each of the different treatment technologies was conducted. This summarizes the different solutions each different municipalities took for their respective water treatment plants. The technologies that were reviewed were Granular Activated Carbon (GAC), Reverse Osmosis (RO) and Membrane and Micro filtration. Although there are more technologies available for PFAS removal, the ones that are highlighted in this presentation will be covered in depth, regarding the cost associated with implementation at the respective treatment plants as well as the associated MGD and date the technology was put into operation. This is to better qualify the cost of treating for PFAS in drinking water to help outline the growth of costs over the years.

#Conclusion
PFAS pollution is a widespread issue that affects all corners of the country. PFAS pollution is primarily due to different industrial companies who discharges PFAS directly into our drinking water sources. These industries were able to discharge directly into rivers partially because there were no federal restrictions on how much PFAS could be discharged into the environment. For many it wasn't until recently that PFAS started to become a hot topic of discussion and testing, and lawsuits arose that brought the attention of the public to these companies and industries. Now that the new PFAS regulations are in place, these communities will need to provide PFAS treatment solutions to show that their levels can get below the EPA MCLs by the year 2029. Different technologies will work best for different municipalities, which is why comparing all the available technologies and data from other water drinking plants from the area is important when making decisions for each individual water source and water system. This presentation will help water utilities during the PFAS remediation plan implementation, by showing what is being done around the country.

This paper was presented at WEFTEC 2025, held September 27-October 1, 2025 in Chicago, Illinois.

Presentation time

08:30:00

09:00:00

Session time

08:30:00

10:00:00

SessionTackling PFAS: From Discharges to Watershed Mitigation Strategies

Session locationMcCormick Place, Chicago, Illinois, USA

TopicContaminants of Emerging Concern & Trace Organics

Author(s)

Matamoros, Aleyda, deSilva, Viraj

Author(s)A. Matamoros1, V. deSilva1

Author affiliation(s)Freese & Nichols, Inc1

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2025

DOI10.2175/193864718825159897

Volume / Issue

Content sourceWEFTEC

Word count15

India's Original Direct Potable Reuse Project

Abstract

Modern-day Mumbai has seen large population growth driven by commercial activities. The current population of Mumbai is approximately 14.08 million. BrihanMumbai Municipal Corporation (BMC) is the municipal authority responsible for supplying water within the municipal limits. Mumbai's existing water supply sources are shown in Table 1. Due to growing demand, a scarcity of water supply is anticipated. The projected water demand for years 2031 and 2041 is approximately 5,320 and 6,424 MLD, respectively, as shown in Figure 1. BMC has been planning to meet the ever-growing demand for potable water by looking into various options. Initiatives undertaken by BMC include:

*Source Augmentation: Create new sources or augment existing sources to draw more water.

*Demand-side Management: Metering, telescopic rates, pre-paid water

*Supply-side Management: Water distribution management, non-revenue water (NRW) reduction Because the above initiatives are long-term, used water (domestic wastewater) treatment and reuse has become an option in minimizing the demand-supply gap. At Colaba WWTF, BMC is developing this pilot project to produce potable grade water. In the conventional wastewater treatment plant, the treated wastewater is discharged into water bodies. For indirect potable or direct potable reuse, the high-quality treated used water (wastewater) is further treated by advanced processes and is passed through a natural or engineered buffer to ensure additional safeguards before its distribution/consumption as shown in Figure 2. Colaba Advanced Tertiary Treatment Plant (ATTP) The Colaba WWTF in South Mumbai is a 37 MLD capacity municipal sewage treatment plant consisting of a sequential batch reactor (SBR) process that is followed by disk filtration as a tertiary treatment. The proposed Colaba ATTP will take the tertiary treated water from the outlet of the disk filter and further treat it to make potable water for potential supply to the nearby 'A ward' area of Mumbai. The primary objective of this first-of-its-kind project in India is to establish a 12 MLD full-scale advanced tertiary treatment plant (ATTP) as well as a 0.1 MLD pilot ATTP facility mounted inside a trailer. The 0.1 MLD pilot facility could be moved to various other wastewater treatment plant locations in Mumbai to ensure the same or slightly modified treatment process can be adopted for developing potable water at these locations. The Colaba ATTP aims to generate water that will be of equal or higher quality than the quality of water that BMC currently supplies. Table 2 provides details of Mumbai's present water quality results. The direct potable reuse (DPR) project will have a treatment process based on worldwide (see Figure 3) practices and will consist of ozone, GAC/BAC, ultrafiltration, reverse osmosis, ultraviolet disinfection with or without advance oxidation process (AOP), and a remineralization facility with chlorine for distribution residual management. The entire process in the proposed ATTP is being considered to get a multiple barrier approach in mitigating risks associated with physical, chemical and biological contaminants while producing water of drinkable quality. Proposed Treatment At present, an extensive sampling exercise is being carried out to assess the quality of wastewater that will be taken further for the advance treatment process. The results of the initial analysis and the historical data are presented in Table 3. Based on the analysis and global trends in the ATTP processes, a tentative treatment process train customized for the local conditions and allied constraints has been developed and is provided in Figures 4 and 5. The process for the 0.1 MLD pilot plant is being developed so sequences can be altered to determine the most optimum treatment process train. The data generated during the operation of the 0.1 MLD prototype will be useful for fine-tuning the process and developing an effective public outreach program. Public Outreach Public outreach is essential for the success of the ATTP concept. The project team has planned an extensive Information Education and Communication (IEC) program to be disseminated over the next several years. The IEC program will be based on the proven guidelines that include, but are not limited to:

*Build on lessons learned from existing potable reuse projects

*Start outreach early and engage the public throughout the lifetime of the project

*Engage the media

*Increase awareness of the value of potable reuse and build confidence in the quality of ATWT

*Create messages that are consistent and communicated to the entire community, including different audiences

*Build relationships with influential community members

*Create transparency in all aspects of the project, including costs, water quality, and safety

*Prepare for tough questions and address misinformation Summary To evaluate the efficacy of treatment trains within an ATTP, the following must be considered:

*Water meets published guidelines or health advisory levels

*A large dynamic range of constituents

*Diversity of constituents that cause health concerns

*Constituents with different properties that affect their removal by various unit processes

*Real-time online monitoring for maintaining standards and getting real data

This paper was presented at the WEFTEC 2024 conference in New Orleans, LA October 5-9.

SpeakerdeSilva, Viraj

Presentation time

13:45:00

14:00:00

Session time

13:30:00

15:00:00

SessionInternational Experience: Safeguarding Our Shared Water Resources

Session number415

Session locationRoom 346

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

Author(s)

deSilva, Viraj, Kelkar, Uday

Author(s)V. deSilva1, U.G. Kelkar2

Author affiliation(s)1Freese and Nichols, FL, 2NJS Engineers India Pvt Ltd., MH

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159482

Volume / Issue

Content sourceWEFTEC

Word count7

PFAS, The Challenge for Water/Wastewater Utilities

Abstract

The management of PFAS has been a topic of discussion among the water/wastewater industry for the last few years, which has led to the development of the EPA's interim guidance for PFAS management. Our current understanding of both the extent of PFAS contamination nationwide in drinking water supplies and the concentrations that produce adverse health effects in the human body are in their early stages. What is certain is that PFAS will become an issue of growing concern over the next several years, if not decades, with the advancement of contamination site and health testing. Recently drafted EPA interim guidance and its key focus areas. The current on-going USEPA's PFAS Action Plan intend to develop MCLs for PFOA and PFOS in drinking water and to take steps to classify PFAS as hazardous substances. These actions have the potential to affect wastewater utilities in two keyways: (1) By requiring higher levels of treatment to protect downstream public water supplies and/or expanded source water protection measures; and (2) By limiting disposal options for PFAS contaminated waste or biosolids. States are also developing their own standards for PFAS in surface waters. The standards could be drivers for new permit limits and/or additional monitoring requirements for WWTPs. In turn, these requirements could result in costly investments in new treatment technologies to achieve a higher level of PFAS removal. Following States have already developed MCLs ahead of EPAs action plan: -New York established MCLs for PFOA and PFOS of 10 ppt individually -New Jersey adopted MCLs for drinking water for PFOS (13 ppt), PFOA (14 ppt), PFNA (13 ppt), and groundwater quality standards for PFNA (13 ppt), PFOA (14 ppt), and PFOS (13 ppt) -Michigan adopted groundwater cleanup standards for PFNA (6 ppt), PFOA (8 ppt), and PFOS (16 ppt), and MCLs in drinking water for PFNA (6ppt), PFOA (8ppt), PFOS (16ppt), PFHxS (51ppt), GenX (370ppt), PFBS (420ppt), and PFHxA (400,000ppt) -New Hampshire adopted drinking water MCLs for PFOA (12 ppt), PFOS (15 ppt), PFHxS (18 ppt), and PFNA (11ppt) -Vermont adopted a drinking water MCL for PFHxS, PFHpA, PFNA, PFOS, and PFOA of 4ppt individually and 20 ppt combined. -Massachusetts adopted drinking water MCLs for PFOS (3.3 ppt), PFOA (3.3 ppt), PFNA (3.3 ppt), PFHpA (3.3 ppt), PFDA (3.3 ppt) and not to exceed 20 ppt combined. During this presentation the following topic areas will be also covered: 1.Removal mechanisms of the PFAS treatment technologies focused on destruction, concentrating, and sequestration 2.'Off-the-shelf' and innovative treatment technologies 3.PFAS minimization as a primary management strategy and the fate and transport of PFAS when these substances are used Although most municipal wastewater utilities have not yet had to deal with PFAS issues, a proactive approach, starting with an initial PFAS risk evaluation is recommended. This initial risk evaluation is intended to provide municipal decision-makers with some idea of where their PFAS risks lie, as well as give them recommendations for next steps to inform proactive planning for PFAS response.

This paper was presented at the WEF/AWWA Utility Management Conference, February 21-24, 2022.

SpeakerdeSilva, Viraj

Presentation time

10:30:00

12:00:00

Session time

10:30:00

12:00:00

SessionEnvironmental and Regulatory Issues

Session number4

Session locationHyatt Regency Grand Cypress, Orlando, Florida

TopicAsset Management, Infrastructure, PFAS, Regulatory Requirements, Strategic Plan, Water Quality