Implementing Ozone‐BAC‐GAC in potable reuse for removal of emerging contaminants

Abstract

Removal of contaminants of emerging concern (CECs) is an important consideration in potable reuse. The effectiveness of ozonation, biologically activated carbon (BAC) filtration, and granular activated carbon (GAC) adsorption was assessed in the removal of 96 CECs. During phase 1, O3/total organice carbon (TOC) was varied between 0 and 1.5. Ozone was successful in removing CECs, achieving a total CEC concentration of 20.5 μg/L at an O3/TOC of 1.5 compared with 70 μg/L in absence of ozone. CECs such as iohexol, meprobamate, sucralose and flame retardants, tris(2‐carboxyethyl)phosphine (TCEP), tris(1‐chloro‐2‐propyl) phosphate (TCPP), and tris(1,3‐dichloro‐2‐propyl)phosphate (TDCPP) were detected in the ozone effluent even at the highest ozone dose. BAC filters did not contribute measurably to CEC removal, while the 20‐min empty bed contact time (EBCT) GAC removed 57.6% of the influent CEC concentration, even though the adsorption capacity had been exerted through previous operation. During phase 2, the average O3/TOC ratio was 0.64, and the impact of new GAC media on CEC removal was studied. EBCT was maintained at 15 min for both GAC contactors, while the used GAC (133,600 bed volume [BV]) was replaced with new media in one GAC contactor. The GAC with new media removed CECs below the limit of quantitation, up to 10,000 BV, while removal decreased to 70% after 20,000 BV, with seven CECs—sucralose, iohexol, acesulfame‐k, meprobamate, cotinine, primidone, and acetaminophen—being detected. Ozone doses for CEC removal and BV needed for adsorption of CECs on activated carbon can be determined from this study. Thus, the results from this study can help design and optimize ozone, BAC, and GAC systems used for potable reuse to target the removal of specific CECs.

Mapping the Terrain for Pathogen Persistence and Proliferation in Non-potable Reuse Distribution Systems: Interactive Effects of Biofiltration, Disinfection, and Water Age

“…For example, the California State Water Resources Control Board requires reclaimed water to be “oxidized” and “disinfected” for most agricultural reuse purposes, with an additional filtration step required for some surface reuse applications . In line with this recommendation, biologically active granular activated carbon (BAC/GAC) filtration is an economical means of reducing organic carbon prior to distribution, , while chlorine and chloramine are popular choices as secondary disinfectants for RWDSs. − …”

Surrogate-based follow-up of activated carbon adsorption preceded by ozonation for removal of bulk organics and micropollutants from landfill leachate

“…To better visualize how the EBCT affects the adsorption of COD and MPs, the number of bed volumes (BVs) of treated leachate at 80% COD breakthrough and 20% MPs breakthrough during these three column adsorption tests were determined. Since the highly adverse character of MPs, the strict discharge criteria is generally recommended for the MPs control (Vaidya et al, 2020). The 80% breakthrough of COD at different EBCT was shown in Fig.…”

Contaminant Removal in a Pilot Drinking Water Treatment Plant by Pre-oxidation Followed by Biological Activated Carbon Filtration: Spiking versus Ambient Studies

“…27 The benefits of combining ozonation and BAC filtration were also shown in a pilot-scale wastewater treatment plant for a variety of pharmaceuticals, 32 a pilot-scale drinking water plant using ozone/H 2 O 2 prior to BAC filtration, 31 and for imidacloprid, fipronil, and sulfamethoxazole in a pilotdrinking water treatment plant with ozone and BAC filtration. 41 Despite many investigations of trace organic contamination removal by ozonation or AOP with and without BAC filtration, 27,32,33 there have been few investigations of ozonation after lime-softening where elevated pH (i.e., typically between 8.5 and 9 after recarbonation) can result in ozone decomposition to •OH even without the addition of hydrogen peroxide. 42 A pilot-scale treatment system was operated for approximately 12 months (March 2021 to March 2022) where removal of a wide variety of trace organic contaminants, including geosmin, 2-MIB, 1,4-dioxane, antibiotics, and neonicotinoids, was investigated.…”

“…Despite many investigations of trace organic contamination removal by ozonation or AOP with and without BAC filtration, ,, there have been few investigations of ozonation after lime-softening where elevated pH (i.e., typically between 8.5 and 9 after recarbonation) can result in ozone decomposition to •OH even without the addition of hydrogen peroxide . A pilot-scale treatment system was operated for approximately 12 months (March 2021 to March 2022) where removal of a wide variety of trace organic contaminants, including geosmin, 2-MIB, 1,4-dioxane, antibiotics, and neonicotinoids, was investigated.…”