Comparison of O3 + GAC, O3 + H2O2 + GAC, and GAC unit operation on natural organic matter and taste and odor causing compounds removal using a pilot plant study

Abstract

Removal of natural organic matter (NOM) and taste and odor problems in drinking water are a sensitive issue in municipal water treatment plants. This study investigated the effectiveness of ozone (O3) + granular activated carbon (GAC), O3 + hydroperoxide (H2O2) + GAC, and GAC processes using a pilot scale plant to remove NOM and geosmin (50–1,000 ng/L), and 2-methylisoborneol (2-MIB: 50–300 ng/L). In the O3 + GAC process, NOM-related parameters showed an average of 52% dissolved organic carbon (DOC) removal from 2 mg/L DOC influent, 99.3% haloacetic acids (HAAs) removal from 0.097 mg/L HAAs influent, and 100% removal from 0.05 mg/L bromide influent. Taste and odor removal rates were 94–100% for geosmin and 87–100% for 2-MIB. The O3 + H2O2 + GAC process removed an average of 55% DOC, 99.7% HAAs, 100% bromate, 94–100% geosmin, and 93–100% 2-MIB. The GAC process removed 46% DOC, 98.3% HAAs, 100% bromate, 83–100% geosmin, and 81–100% 2-MIB. Based on a comparison of the efficiencies and an economic analysis, the O3 + H2O2 + GAC process was determined to be the optimal system for removing NOM and taste and odor compounds.

Ozone/peroxide advanced oxidation in combination with biofiltration for taste and odour control and organics removal

“…addition (Park et al, 2015;Wang et al, 2015). However, much of the existing information regarding H2O2/O3 optimization has been based on the bench-scale studies (Chang et al, 2002;Li et al, 2012;Mizuno et al, 2011;Parinet et al, 2010).…”

“…Direct O3 reaction is selective and occurs with electron-rich moieties mainly double bonds, aromatic phenols and amine functional groups, whereas hydroxyl radical oxidation is nonselective and has fast reaction rates with organics (Acero and von Gunten, 2001). As, advanced oxidation processes (AOPs) are based on enhanced formation of OH, peroxide (H2O2) addition can be cost efficient way for converting an ozone treatment into an AOP based treatment (Park et al, 2015). In this process, OH are generated by complex radical chain reaction, which consumes two O3 and one H2O2 to produce two OH (Hoigné and Bader, 1979).…”

“…resulted in increased rate of O3 depletion  Increase in alkalinity resulted in increased rate of OH depletion Initial geosmin and MIB concentration = 100 ng/L O3 efficiency can be improved with the addition of H2O2 to produce hydroxyl radicals (OH) with fast reaction rates for geosmin and MIB (KOH ~10 9 M -1 s -1 ) (Lee and von Gunten, 2016;Peter and von Gunten, 2007). Previous pilot studies have reported increases of 10-15% in geosmin and MIB removals upon H2O2 addition Park et al, 2015;Wang et al, 2015).…”

“…In addition, selection of O3 dose also play an important role in oxidizing these compounds. Use of H2O2/O3 AOP have shown to improve geosmin and MIB removal efficiencies by 10-15% (Park et al, 2015;Li et al, 2010a;Mizuno et al, 2011). For maximum removals, optimal H2O2/O3 ratio for each water matrix should be tested (Acero et al, 2001).…”

“…Application of O3 prior to biofiltration has been shown to be effective for the removal of geosmin, MIB, and DBP precursors (Klausen and Grønborg, 2010;Park et al, 2015;Sánchez-Polo et al, 2006;Yan et al, 2010). An investigation of O3-biofiltration treatment at full-scale by Nerenberg et al (2000) reported MIB removals of 36-54% by ozonation (1.3 mg/L O3) followed by 26-46% removal across biofiltration (17 min EBCT).…”