Ozone application in water sources: effects of operational parameters and water quality variables on ozone residual profiles and decay rates

Abstract

-Systematic ozonation tests were conducted by means of a mobile pilot plant. Water source 1 was a low turbidity stream with very low solids content and very low turbidity, apparent color and alkalinity. Water source 2 was reservoir water with higher turbidity, solids content and alkalinity than source 1. The ozone plant was a counter-current contactor composed of four columns in series. Variations in contact time, in the feed gas concentration (in terms of percent by weight of ozone) and in splitting of the total applied ozone dosage between columns 1 and 2 were tested. Concentration -time (CT) products were calculated and decay coefficients K were estimated from experimental data. The relative importance of water quality and certain operational parameters with regard to CT products and ozone decay was assessed. Total CT values seemed to increase with: (a) total applied ozone dosage, (b) percent by weight of ozone in the feed gas to the bubble contactor, (c) increasing contact time and (d) higher water quality, with regard to turbidity, apparent color, total organic carbon and particle counts. As the total applied ozone dosage was increased, the more important the contact time and ozone dosage configuration became for the total CT value. The apparent first order ozone decay rate constant (K) decreased with increasing total applied ozone dosage. The contact time appeared to exert a much stronger influence on total CT values than on K values, particularly so as the total applied ozone dosage was increased.

Ozonized Water in Microbial Control: Analysis of the Stability, In Vitro Biocidal Potential, and Cytotoxicity

“…A Spectroquant ® Ozone Test kit 100607 (Merck, Darmstadt, Germany) was used to confirm the concentrations determined by the standardized method. Considering the previous data on the stability of O 3 in ultrapure water, which was previously considered the best type of water for increased O 3 stability [26,32], changes were applied in its physicochemical parameters. Samples of ultrapure water with these different physicochemical characteristics are displayed in Table S1, and the changes are related to the temperature and pH.…”

“…The air is bubbled directly into the water through an air outlet. After this ozonation process, it is necessary to perform the quantification and determination of the dissolved O 3 concentration [25][26][27].…”

“…O 3 dissolved in water (or ozonized water) can be defined as water obtained after an O 3 infusion by the ozonation process. During this process, the only chemical reactions that can occur are those between O 3 and inorganic matter, organic matter, or biological materials that are available, emphasizing that there is no reaction with the pure water itself [25,26]. Some parameters of evaluation and maintenance of the stability of ozonized water are important for this process of production and use, such as the pH and temperature, these being among other important factors for the half-life of the gas dissolved in water [26,28].…”

Direct application of ozone in aquaculture systems

“…Summerfelt & Hochheimer ; Summerfelt et al . ; Lage Filho ). Briefly, the highly reactive nature of ozone means that it decomposes to free radicals and other ozone‐derived chemical species, leaving ‘residual’ dissolved ozone.…”

“…The rate of ozone decay increases with time after deployment, whilst higher flow rates (differing hydraulic retention time) or low initial dosages and high water pH may reduce ozone concentration (previously reviewed by Lage Filho ; Gonçalves & Gagnon ; Rahmadi & Kim ). Sharrer and Summerfelt () also suggested that bacteria embedded within particulate matter, or that formed bacterial aggregates, provided shielding from oxidation.…”