The feasibility of storing two electrolyzed waters (EW), acidic (AEW) and neutral (NEW), were elucidated through Escherichia coli O157:H7 and Salmonella typhii inactivation experiments. Free chlorine (FC) loss, pH and oxidation-reduction potentials were monitored for 30 days. Initial activities of fresh EWs were determined at 5 mg Cl(2)·min/L for 8 Log(10) inactivations of both strains. However, stored EWs exhibited activity declines which were associated to FC losses. All FC loss rates were first-order; AEWs underwent two phases of decays while NEWs had single decay rate constants. Two FC loss mechanisms were identified: chlorine (Cl(2)) volatilization and hypochlorous acid (HOCl) decomposition, wherein Cl(2) volatilization occurred at a faster rate. Chlorine volatilization was primarily influenced by storage condition as indicated by intensive FC losses on EWs stored in open vessels. Under the same storage conditions (open or closed), Cl(2)-rich AEW experienced higher FC losses which indicated the higher stability of HOCl-rich NEW. Overall, FC losses could be minimized if (1) samples are stored in closed vessels and (2) Cl(2) is not the main chlorine component. NEW in closed vessel is the most feasible system for EW storage; its initial activity (8 Log(10) inactivation) was preserved for up to 17 days.
Previously isolated Sphingomonas sp. D3K1 was biofilter (BF) inoculated into composite rock wool-compost packing media and biofiltration of single gas-ethylbenzene in BF1 and o-xylene in BF2-and mixed BTEX compounds in BF3 were investigated. At 62 s EBRT and feed flow rate of 0.14 m 3 /h, high removal efficiencies of 92.0 Ϯ 2.8%, 92.0 Ϯ 3.1%, and 89.2 Ϯ 1.1% were achieved in BF1, BF2, and BF3, respectively. Decreasing the EBRT to 48 s resulted in lower elimination capacities of the three biofilters, while regular nutrient addition showed an increase in the attainable elimination capacities for ethylbenzene and o-xylene of BF1 and BF2, respectively. Maximum elimination capacities of 34.3 g-ethylbenzene/m 3 /h (BF1) and 38.6 g-o-xylene/m 3 /h (BF2) were obtained at 48 s EBRT. For BF3, the maximum elimination capacity was 32.9 g-BTEX/m 3 /h at 62 s EBRT. In the case of mixed BTEX biofilter, o-xylene showed the most significant decrease in the biodegradability when nutrient was insufficient in the system. Sphingomonas sp. D3K1 was more favorable to the removal of toluene when o-xylene was less than 10 g/m 3 /h, but shifted to benzene when the loading rate of o-xylene was higher than 10 g/m 3 /h.
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