摘要:

Ozone is used in drinking water treatment as a biocide, as an oxidant and as a pretreatment in order to improve the performance of subsequent processes. Increasing concern over the quality of drinking water has led to a number of new stringent regulations in the control of chemical and microbiological contaminants. Disinfection deals with the concept of “CT”, which is the need to maintain a certain minimum concentration for a given time. Under ideal laboratory conditions, it is 0.4 mg O3/L for 4 min. In practice, since the method for the CT determination has not been finalized by the EPA, “T” can be the minimum detention time of 90% of total flow, and “C” can be a measured ozone residual at the outlet of cells of the contactor. New standards for micropollutants in drinking water imply an optimization of the ozonation step, by improving the ozone transfer from gas to water, and the control of the detention time as well as ozone residual within the contactor.

ISSN:0191-9512    

DOI:10.1080/01919512.1994.10555754

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Phenanthrene is considered to be a hazardous pollutant and is listed as a priority pollutant by the U.S. EPA. This laboratory study was designed to investigate the degradation of phenanthrene in water solutions by ozone, by ozone in combination with hydrogen peroxide and UV-radiation and by UV-radiation only, to compare the efficiency of different oxidation processes at different values of pH = 3, 7 and 9. On the basis of kinetic curves of phenanthrene destruction, the chemical reaction rate constants were calculated. The results obtained confirmed that phenanthrene oxidation proceeds mostly with molecular ozone and the best method for reducing its concentrations is an ozonation in neutral medium. The rate of phenanthrene autoxidation is rather slow and does not depend on pH nor H2O2addition. UV-radiation alone is also unable to reduce phenanthrene concentration significantly.

ISSN:0191-9512    

DOI:10.1080/01919512.1994.10555755

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

In this work, a first step has been made in the characterization of the organic pollutants found in the residual water from the production of dicofol and tetradifon pesticides, derived from DDT and trichlorobenzene, respectively. The behavior of the effluent also was studied using degradation techniques - treatment with ozone and ozone combined with hydrogen peroxide - and the results compared by means of the pH, conductivity, TOC, COD, TOX, ecotoxicity, GC/ECD and GC/MS analysis of the samples after the treatment.

ISSN:0191-9512    

DOI:10.1080/01919512.1994.10555756

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Guidelines for the successful use of ozone as a stand-alone cooling tower water treatment method are discussed. Included are recommendations for system sizing, proper ozone residuals, mixing and distribution of the ozonated water, and potential problems and solutions. These include excessive or insufficient cycles of concentration, chemical contamination, low flow rates, high heat exchanger temperatures, and extended system turnover times. Also discussed are recommended maximum system downtimes, preferred types of towers and heat exchangers to treat with ozone, use of filtration systems, and elastomer compatibility with ozone. System monitoring and maintenance procedures are discussed along with ozonation safety considerations. With this information, two recently reported ozonation system failures are analyzed and the causes of failure are discussed.

ISSN:0191-9512    

DOI:10.1080/01919512.1994.10555757

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0191-9512    

DOI:10.1080/01919512.1994.10555758

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0191-9512    

DOI:10.1080/01919512.1994.10555759

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0191-9512    

DOI:10.1080/01919512.1994.10555753

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor