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Controlling Trace Organic Contaminants Using Alternative, Non-FAT Technology for Indirect Potable Water Reuse

Project: 13-10
Type: Scientific Investigation
Scope of Work

Program: Tailored Collaboration
Total Investment: $1,460,987 (Cash: $99,787, In-Kind Cash and Service: $1,361,200)

Principal Investigator: Benjamin Stanford, Ph.D., Hazen and Sawyer

Background

Rising wastewater effluent discharge standards have led to more advanced wastewater treatment and growing demand has taxed existing water supplies, making planned indirect potable reuse a feasible scenario for more utilities. A majority of planned potable reuse schemes currently in operation or planned to be employed in the U.S. make use of AOPs and RO, the FAT technology, to ensure maximum removal of known and unknown contaminants. This study will consist of pilot-scale evaluations of combinations of a) ion exchange, AOP and biological activated carbon (BAC) treatments (City of Hollywood, FL) and b) alternative biologically-active media (Las Vegas, NV).

Goals and Objectives

The project will investigate the advanced treatment of wastewater for indirect potable reuse (IPR) using ion exchange (IX), advanced oxidation processes (AOPs) and biofiltration as an alternative to the fully available treatment (FAT) technology of reverse osmosis (RO) and UV AOPs. Pilot plants will be operated to evaluate and validate the formation and removal of nitrosamines and the removal of other trace organic chemicals (TOrCs) by these processes.

Research Approach

Task 1: Literature Review. The project team has already completed extensive literature reviews and studies on the subject of TOrC removal and formation by IX, AOP and biotreatment processes in IPR systems. Through research conducted by the Project Team in WateReuse projects 03-014, 08-05, 09-10, 08-08 and 11-08 and involvement in the Water Research Foundation’s Nitrosamine Focus Area Committee, there is already a significant amount of information and data that has been collected by the project team that can be used to support the development of a literature review specific to the objectives of this project. Thus, time will be devoted throughout the project to track and document the latest developments in this field.

Task 2: Pilot-Scale Demonstration (City of Hollywood, Florida). IX, AOP and BAC biofiltration processes will be operated to treat the secondary effluent produced at SRWWTP. The post-secondary treatment processes will be evaluated for potable reuse purposes. Already SRWWTP plans to monitor 102 primary drinking water contaminants plus 14 secondary contaminants. 23 Florida-specific regulated groundwater contaminants will also be monitored along with a suite of unregulated contaminants. For the project proposed here, the following DBPs and TOrCs will be additionally evaluated that will not otherwise be monitored: NDMA, total nitrosamine assay, a suite of perfluoroalkyl chemicals, estrogenicity and toxicity assays and a suite of low-level (RL<1 ng/L) indicator TOrCs (i.e., pharmaceuticals, personal care products, endocrine disrupting compounds). The indicator TOrCs represent chemicals that are frequently detected in treated wastewater and have various sorption, oxidation and bioamenable characteristics to assess IX, oxidation or biotreatment performances. The low-level reporting limits assure that a sufficient detection ratio is achievable and performance removals can be quantified. Organic matter characterization, including TOC, UV254, fluorescence, dissolved organic nitrogen, state-of-the-art size exclusion chromatography and a new nitrosamine precursor assay, will be performed to assess the impact of treatment on these bulk surrogate parameters and develop potential correlations between the removal of TOrCs and reduction or changes in bulk parameter measurements. For example, the team has proven that the removal of UV254 is an effective surrogate parameter for the removal of TOrC during ozonation of treated wastewaters (Wert et al. 2009b, Dickenson et al. 2009, Gerrity et al. 2012).

Task 3: Pilot-Scale Biofilter Media Investigations (Las Vegas, Nevada). Biofiltration columns will be operated to treat tertiary filtered effluent that has undergone full-scale ozone treatment at the CCWRD’s Main Facility in Las Vegas, Nevada. Biofiltration columns containing readily available Jaeger Tri-Pack hollow plastic media, floating beads, biochar, sand, anthracite, fresh commercial BAC and exhausted BAC that has been used in treatment for several years will be evaluated in parallel. The biologically-active sand, anthracite and BAC columns will provide benchmarks that can be compared against.

NDMA and indictor TOrCs will be measured before and after biofiltration to determine their removals. The removal of unknown AOP byproducts will be evaluated by measuring baseline non-specific toxicity (using the V. fischeri bioassay) before and after ozonation and biofiltration. General water quality parameters, such as TOC, BOD, turbidity and ammonia and other ozonation byproducts, such as ketoacids, aldehydes and carboxylic acids, will also be monitored. The pilot scale investigation will proceed in two phases: Acclimation and Demonstration Phases.

Task 4: Cost Comparison of Alternative Non-FAT and FAT-RO/AOP Technologies. A full cost analysis will be performed by Hazen and Sawyer. The cost of the non-FAT technologies employed in this study will be compared with cost analyses of FAT technologies employed at other reuse sites. Additionally, the nitrosamine and other TOrC treatment performance of the pilot plant studies will be compared with previously reported performances of FAT systems. These cost and effectiveness comparisons will be considered to determine if IX, AOP and/or biofiltration processes are viable alternatives to FAT systems for planned indirect potable reuse.

Task 5: Final Report. The procedures performed and the results obtained will be reported and analyzed in the form of a WateReuse Research Foundation Report.

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