Kong, Eric

Eric Kong is a process engineer with Freese and Nichols, Inc. in San Antonio, Texas with design and construction experience in water production and...

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About Kong, Eric

Eric Kong is a process engineer with Freese and Nichols, Inc. in San Antonio, Texas with design and construction experience in water production and water resource recovery facilities. His experience includes membrane and water quality studies, disinfection & corrosion analysis, and process design for water production and reclamation facilities.

Kong, Eric

Titles from this speaker

Strategies for Gaining Pathogen Removal Credits using Reverse Osmosis Membranes

Abstract

Past studies have demonstrated that reverse osmosis (RO) membranes can be highly effective in rejecting pathogens such as Cryptosporidium oocysts, Giardia cysts, and viruses. Nonetheless, most regulatory agencies have defaulted to a null log removal value (LRV) when using RO membranes. This disparity between regulatory acknowledgement and implementation is largely due to the challenge of developing a practical Direct Integrity Testing (DIT) method. Undervaluing the pathogen control efficacy from RO membranes necessitates additional treatment processes, e.g., chemical disinfection or physical separation, to meet pathogen LRV goals for potable reuse applications. This lack of acknowledgement leads to increased capital costs and redundant operational complexity. The United States Environmental Protection Agency (USEPA) Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) and USEPA Membrane Filtration Guidance Manual (MFGM) provides a framework in determining pathogen credit for Cryptosporidium, but it is then left at the discretion of State agencies to award credit for other pathogens such as viruses. Although RO technology transcends state boundaries, the current regulatory path to obtain accreditation in potable reuse applications is on a state-by-state basis. For example, the California State Water Resources Control Board granted the RO process of the Orange County Groundwater Replenishment System with a 2-log LRV for pathogens while Texas has not established any treatment credit. Methodology & Results Our study investigates the use of surrogates as an integrity testing method using the Wichita Falls brackish surface water treatment plant as a test site. Through parallel testing using a virus surrogate, i.e., MS2 bacteriophage, our results provide a better understanding of the variability in pathogen removal efficiency for RO membranes. Our testing utilized background concentrations of sulfate and strontium in the range of 800-1000 mg/L and 3000-5000 ug/L, respectively, with MS2 doses of 105 - 106 PFU/mL to compare rejection performance. Testing was performed on a variety of membrane conditions, including membranes that have been in continuous full-scale operations for +9 years, newly purchased membranes, and intentionally impaired and oxidized membranes. Multiple sample locations were analyzed, including samples from individual pressure vessels, combined permeate, and total concentrate. Lastly, samples were measured over the course of a 20-to-40-minute duration to identify effects of attenuation or accumulation that may occur with surrogates. To date, this is the only full-scale study of its kind and provides comprehensive data from a variety of practical conditions, such as varying membrane condition, multiple sample locations on a full-scale RO system, and measurements taken over a practical timescale. Study Implications Although prior studies with a similar scope have been implemented, our study has two novel elements that will expand industry and regulatory knowledge on this subject. First, our study utilizes a full-scale system to demonstrate practical RO performance and second, our analysis is performed on a variety of operating conditions. This data can be an integral tool for public and regulatory agencies to award pathogen LRVs for RO membranes while also providing guidance for systems to monitor and maintain their RO system's pathogen rejection performance. Our presentation will address the following objectives that can be valuable for reuse applications. 1.Learn whether ions are suitable surrogates in identifying virus-sized breaches or defects in RO membranes, including limitations and recommended practices of the proposed method. 2.Review statistical correlations between removal efficiencies of surrogates and other conventional water quality parameters, e.g., total organic carbon (TOC) or conductivity, and determine whether they can be used for indirect integrity monitoring. 3.Review the effects of membrane condition that impact DIT testing accuracy.

Our full-scale study investigates whether ionic indicators can be used to develop a membrane integrity testing method for RO membranes. This presentation presents testing results using MS2 bacteriophage, sulfate, and strontium on a 2.0 MGD RO system and we hope these results can help establish guidelines to grant pathogen removal credits for membranes, specifically in potable reuse applications.

SpeakerKong, Eric

Presentation time

09:30:00

09:45:00

Session time

08:30:00

10:00:00

SessionEnhancing Water Safety: MBR & RO Technologies for Achieving LRV Credits

Session number315

Session locationRoom 349

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

Author(s)

Kong, Eric, Nix, Daniel, Southard, Mark, Adams, Hunter, Sloan, David, Kumar, Manish, Ikehata, Keisuke, Arroyo, Jorge

Author(s)E. Kong1, D. Nix2, M. Southard2, H. Adams2, D. Sloan3, M. Kumar4, K. Ikehata4, J. Arroyo5

Author affiliation(s)1Freese and Nichols, TX 2City of Wichita Falls, TX, 3, OH, 4, TX, 5Freese and Nichols, Inc., TX

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159504

Volume / Issue

Content sourceWEFTEC

Word count11

Base text size -

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