Production and Removal of Assimilable Organic Carbon Under Pilot-Plant Conditions Through the Use of Ozone and PEROXONE

Case Study: Ozonation and distribution system biostability

“…Considering process data only (i.e., raw water and plant effluent), the AOC concentration after O 3 increased by more than 200%, which agrees with previous work performed by Paode et al (1997), Hacker et al (1994), and Volk et al (1993), among others. Thus, as expected, the AOC concentration of the treated water significantly increased (Wilcoxon p-value < 0.0001) from ozonation, probably because of the partial oxidation of larger organic carbon compounds to carboxylic acids facilitated by O 3 oxidation (Volk et al, 1997;Hacker et al, 1994;Roche et al, 1994;Volk et al, 1993).…”

“…O 3 reacts directly on aromatics, unsaturated organic compounds (e.g., double bonds: C = C, C = O, C = S, = N-H), and amino compounds (-NH 2 ), leading to the formation of saturated polycarbonaceous compounds and methyl ketones, diacids, dialdehydes, aldehydes, and acids (Volk et al, 1997). This leads to a decrease in DOC (because of oxidation to carbon dioxide [CO 2 ]) and ultraviolet (UV) 254 (carbon-carbon double bonds are known to absorb UV light at 254 nm) and an increase in AOC and BDOC (Volk et al, 1997;Najm & Krasner, 1995;Hacker et al, 1994;Roche et al, 1994;Volk et al, 1993). The previously noted studies reported an approximate increase in BDOC of 20-30% and an approximate threefold increase in AOC after ozonation.…”

Biological filtration for BOM and particle removal: a critical review

“…In a study conducted by Huck et al 14 involving two‐stage biofiltration, total EBCTs ≤25 min were necessary to consistently achieve effluent AOC levels <20 μg/L C. Data presented by Hacker et al 36 suggested higher AOC removals (90 percent) at higher filter influent concentrations (~550 μg/L C), compared with AOC removals averaging 80 percent at lower influent levels (~300 μg/L C). Similar findings, i.e., higher percentage removals of BOM at higher influent concentrations, were obtained in modeling work for BDOC removal 75 .…”

“…Cl 2 (~2 m g/ L). Oth ers h ave observed relatively good BOM rem ovals in an th racite-san d 36 an d GAC-san d 33 filters, despite backwash in g with ch lorin ated water. With regard to th e effect of Cl 2 in th e backwash water of biofilters, th e du ration of th e backwash in g procedu re-i.e., th e period of Cl 2 exposu re (sim ilar to th e con tact-tim e con cept for disin fection )-is likely a relevan t factor, as is th e Cl 2 con cen tration in th e backwash water.…”

“…Thus, the increase in BOM upon ozonation generally considerably enhances biological activity in filters following ozonation 32 . Often, biofiltration following ozonation can reduce BOM concentrations to approximately preozonation levels, 15 , 33 – 36 although this depends on the specifics of the biofilters and water quality parameters, and the composition of BOM may be different after biofiltration. Currently identified organic ozonation by‐products include aldehydes, carboxylic acids, aldo acids, and keto acids, 27 , 37 – 40 which are all relatively easily biodegradable, and good removals, i.e., >75 percent, are normally observed in biofilters 35 , 41 – 43 …”