Application of the process of ozonization in technologic practice is not frequent due to high investment and operational costs. The effort to reduce the consumption of ozone led to research of various modifications of the ozonization process or combinations thereof with other processes.
The ozone oxidation removes the contaminants which are not effectively removed by conventional methods of treatment of waste water. The macromolecules are split into smaller segments, and in this process, a large volume of oxygen is built in the reaction products. At the same time, toxicity of water, if any, may be eliminated, which enables removal of the products of ozonization by the subsequent biologic activation. The ozonization may help to transform the biologically resistant CHSK to BSK, meaning that the combination with biologic processes of treatment is advantageous.
In order to apply ozonization, several experiments were carried out. During biologic treatment of waste water, the efficiency of removal of organic contamination and the efficiency of removal of ammonia contamination were surveyed.
The possibility to use the ozone for increasing the biologic reducibility of resistant substances in the waste water was verified. Also changes in the concentration of organic contamination relating to CHSK indicators and the pH value in the waste water were followed. The most efficient removal of CHSK was achieved at the duration of ozonization between 11.5 and 12.5 hours. The concentration of BSK5 was raised depending on the duration of ozonization. The highest value of BSK5 was measured at the duration of ozonization 11.5 hours.
Another intention was to investigate the possibility of biologic treatment of seepage water after ozonization, or to review its inhibiting or toxic effect on the continuing treatment processes. For such purpose, kinetic tests were carried out in a semi-continual model.
By combination of biologic pre-treatment in continual activation with time segregation, ozonization, and subsequent biologic treatment in semi-continual model of activation, the total efficiency of removing CHSK in respect of the initial value in the raw seepage water was approximately 70 to 85 %. The measured value of the specific velocities of removing the ammonia nitrate and denitrification are in the scope of the data published for municipal waste water.
The possibility to use ozone for increasing the biologic reducibility of resistant substances in seepage water from a real dumping of solid waste was reviewed. The efficiency of removing CHSK by ozonization was about 60 to 70 %. In the biologically pre-treated seepage water, the ozone oxidation helped to increase the share of the biologically reducable CHSK by approximately 55 %.
The results of kinetic tests confirmed the possibility of subsequent biologic treatment of seepage water after ozonization.
In: Water Management Journal, Year 45, No. 7-8/2002, p. 19
Information & Contact
Ing. Angelika Gulyasova,
Doc. Ing. Jan Derco, PhD.,
Slovak Technical University,
Environmental Department,
Faculty of Chemical and Food Technology
(FCHPT STU),
Radlinskeho 9
812 19 Bratislava 1
Tel.: 00421 2 6029 1111-3, 00421 2 5932 5111
Fax: 00421 2 6542 0415, 00421 2 5249 3198
