Abstract
The UV-ozone (UV-O3) process is not widely applied in wastewater and potable water treatment partly for the relatively high cost since complicated UV radiation and ozone generating systems are utilized. The UV-microozone (UV-microO3), a new advanced process that can solve the abovementioned problems, was introduced in this study. The effects of air flux, air pressure, and air humidity on generation and concentration of O3in UV-microO3reactor were investigated. The utilization of this UV-microO3reactor in microcystins (MCs) degradation was also carried out. Experimental results indicated that the optimum air flux in the reactor equipped with 37 mm diameter quartz tube was determined to be 18∼25 L/h for efficient O3generation. The air pressure and humidity in UV-microO3reactor should be low enough in order to get optimum O3output. Moreover, microcystin-RR, YR, and LR (MC-RR, MC-YR, and MC-LR) could be degraded effectively by UV-microO3process. The degradation of different MCs was characterized by first-order reaction kinetics. The pseudofirst-order kinetic constants for MC-RR, MC-YR, and MC-LR degradation were 0.0093, 0.0215, and 0.0286 min−1, respectively. Glucose had no influence on MC degradation through UV-microO3. The UV-microO3process is hence recommended as a suitable advanced treatment method for dissolved MCs degradation.
Highlights
As a combination of ozonation and photochemical excitation, the ultraviolet-ozone of hydroxyl radical (∙(UV-O3) process is based on the effect OH) generated from UV radiation and ozone photolysis to improve the oxidation capability [1, 2]
Microcystins (MCs) are hepatotoxins containing cyclic heptapeptides produced by cyanobacteria
Researchers have found more than 80 isomers, in which microcystin-RR, YR, and LR (MC-LR, MC-RR, and MC-YR) are the most important isomers [13]
Summary
As a combination of ozonation and photochemical excitation, the ultraviolet-ozone of hydroxyl radical (∙(UV-O3) process is based on the effect OH) generated from UV radiation and ozone photolysis to improve the oxidation capability [1, 2]. The utilization of complicated UV radiation and O3 generating systems, together with the high energy consumption, leads to relatively high cost which limits the wide application of this process [8]. To solve this problem, a new advanced process, UV-microO3, was developed [9]. The study conducted by Zhao et al [10] showed that the ∙OH radical exposure in UV-microO3 process was significantly higher than that in UV-air system, and UV-microO3 process could remove aniline more efficiently. Ozone generation in UV-microO3 process is not mentioned in these above studies, and researches on organic contaminants removal by UV-microO3 process are still limited.
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