Ozonation and biodegradation

Assess results Several methods can be applied to minimize the ozone consumption in combined processes of ozonation and biodegradation. For example, the different operational behavior of batch and continuous-flow systems, with the resulting differences in oxidation products, etc. has to be considered, as well as the fact that multi-stage systems for each treatment process may be of advantage over single stage systems. 

Allen, B. Wu, J. Doan, H. Inactivation of fungi associated with barley grain by gaseous ozone. J. Environ. Sci. Health 2003, B5.S (5), 617-630. Nam, K. Kukor, J.J. Combined ozonation and biodegradation for remediation of mixtures of polycyclic aromatic hydrocarbons in soil. Biodegradation 2000, 11, 1-9. 

Ozone caimot be employed for the disinfection of distributed water because of its short lifetime. Unless removed from the treatment plant, the presence of low molecular weight, oxygenated, and biodegradable organics that ozone produces can promote biological growth. 

For color removal, ozonization has achieved the greatest practical importance as seen by the plethora of articles and patents on this method (147—163). Ozonization in combination with treatments such as coagulation, flocculation, carbon adsorption, uv irradiation, gamma radiation, and biodegradation significantly and successfully remove dye wastes and reduce costs (156,164—170). 

Many wastewater flows in industry can not be treated by standard aerobic or anaerobic treatment methods due to the presence of relatively low concentration of toxic pollutants. Ozone can be used as a pretreatment step for the selective oxidation of these toxic pollutants. Due to the high costs of ozone it is important to minimise the loss of ozone due to reaction of ozone with non-toxic easily biodegradable compounds, ozone decay and discharge of ozone with the effluent from the ozone reactor. By means of a mathematical model, set up for a plug flow reactor and a continuos flow stirred tank reactor, it is possible to calculate more quantitatively the efficiency of the ozone use, independent of reaction kinetics, mass transfer rates of ozone and reactor type. The model predicts that the oxidation process is most efficiently realised by application of a plug flow reactor instead of a continuous flow stirred tank reactor. 

Kuo, W.S. Effects of photolytic ozonation on biodegradability and toxicity of industrial wastewater. Environ. Sci. Health 1999, A34 4), 919-933. 

In many full-scale applications the variable costs for energy and oxygen are regarded as economically decisive. Ozone and cost savings have often been achieved by the application of combined ozonation/biodegradation systems. Today, in most cases, ozonation of waste... 

Ozone is applied in three-phase systems where a selective ozone reaction, oxidation of residual compounds and/or enhancement of biodegradability is required. It can be used to treat drinking water and waste water, as well as gaseous or solid wastes. Especially in drinking water treatment full-scale applications are common, e. g. for particle removal and disinfection, while in waste water treatment sludge ozonation and the use of catalyst in AOP have been applied occasionally. Current research areas for three-phase ozonation include soil treatment and oxidative regeneration of adsorbers. Ozonation in water-solvent systems is seldom studied on the lab-scale and seems favorable only in special cases. In general, potential still exists for new developments and improvements in ozone applications for gas/watcr/solvent and gas/waler/solid systems. 

A typical plot of the change in DOC concentration and biodegradable fraction as a function of the specific ozone dose shows a continuous increase in the biodegradable fraction until a certain maximum is reached. Further ozonation decreases the biodegradable fraction (Figure 6-2). This is an optimization problem the compounds must be made bioavailable, but mineralization in the chemical stage must be minimized. 

Figure 6-2 Typical change in DOC remaining after ozonation (1) and biodegradable (2) as a function of the specific ozone dose / for the ozonation of model pollutant M and subsequent biodegradation of its oxidation products in a batch system.

Jones B M, Saakaji R H, Daughton C G (1985) Effects of Ozonation and Ultraviolet Irradiation on Biodegradability of Oil Shale Wastewater Organic Solutes, Water Research 19 1421-1428. 

KornmUller A, Wiesmann U (1999) Continuous ozonation of polycyclic aromatic hydrocarbons in oil/ water-emulsions and biodegradation of oxidation products, Water, Science Technology 40 107— 114. 

Murphy, Jr, Ultraviolet-Ozone and Ultraviolet-Oxidant Treatment of Pink Water , ARCLO-TR-78057, US Army ARRADCOM, Dover (1978) 38) J.D. Hoffsommer et al, Biodegradability of TNT A Three-Year Pilot Plant Study , NSWC/WOL-TR-77-136, Naval Surface Weap Cent, Silver Spring (1978) 39) D.F. Carpenter... 

Kuo [198] studied the effect of O3/UV on the toxicity and biodegradability of an industrial pesticide wastewater. He observed increases of BOD/ COD ratio up to a value of 0.4 with more than 50% reduction in toxicity (measured as EC50) when using 400 g m-3 h-1 of ozone and 3 mW cm 2 of UV light intensity. The author also recommended the use of the integrated 03/UV-aerobic biodegradation system for scale-up purposes. 

Takahashi M, Nakai T, Satoh Y, Katoh Y. Ozonolysis of humic acid and its effect on decoloration and biodegradability. Ozone Sci Eng 1995 17 511— 526. 

Adams CD, Scanlan PA, Secrit ND. Oxidation and biodegradability enhancement of 1,4-dioxane using hydrogen peroxide and ozone. Environ Sci Technol 1994 28 1812-1818. 

CavaUi, L., Gellera, A. and Landone, A. (1993) LAS removal and biodegradation in a wastewater treatment plant. Environ. Toxicol. Chem. 12, 1777-1788 Chu, W. and Ching, M. H. (2003) Modeling the ozonation of 2,4-dichlorophoxyacetic acid through a kinetic approach. Water. Res. 37,39 16... 

Beltran FJ, Garcia-Araya JF, Alvarez P (1997) Impact Of Chemical Oxidation On Biological Treatment Of A Primary Municipal Wastewater. 1. Effects On COD And Biodegradability, Ozone Sci. Eng. 19 495-512. 

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