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Herford, Germany

Benedek G.P.,Norwegian Institute for Water Research | Ried A.,ITT Wedeco | Lopez A.,CNR Water Research Institute | Liltved H.,Norwegian Institute for Water Research | Vogelsang C.,Norwegian Institute for Water Research
Ozone: Science and Engineering | Year: 2010

In this study, we investigate factors that can affect nitrification and denitrification in a moving bed biofilm system, treating partly stabilized landfill leachate. The optimization of biological treatment by means of controlled ozonation is additionally evaluated. Results obtained with a laboratory-scale, continuous-flow biofilm system suggest that nitrogen removal can be limited by the low influent biodegradable substrate concentrations, and that autotrophic nitrification can be adversely impacted by the high alkalinity buffer and ammonium/ammonia concentration. Our results suggest an optimum ozone dosage as high as 0.5 g/L O3 can be required to effectively decrease the effluent soluble COD concentration and pH profile in the aerobic reactors, improve the biodegradable COD production from inert compounds, and induce chemical nitrification in the system. The specific cost of ozonation evaluated is 0.36-0.73 euro/m3 with 911 mg/L average effluent soluble COD measured in the biofilm system. © 2010 International Ozone Association. © 2010 International Ozone Association. Source


Metais A.,ITT Wedeco | Hostachy J.-C.,ITT Wedeco
PPI Pulp and Paper International | Year: 2011

Some of the significant benefits of industrial ozone bleaching in pulp mills are discussed. Ozone bleaching is efficiently used on hardwood and softwood pulps, on kraft, and sulphite pulps dedicated to all kinds of final applications. Investors always focus on the return on investment (ROI) and all TCF ozone users have realized that bleaching costs are reduced by 20-32% when introducing an ozone stage in an ECF bleaching line, including in the case of TCF bleaching. The high bleaching efficiency of ozone also allows a significant reduction in the consumption of expensive bleaching chemicals. These chemicals include chlorine dioxide in ECF bleaching and hydrogen peroxide in TCF bleaching, along with sodium hydroxide in ECF bleaching and TCF bleaching. Ozone users have also observed that bleaching with an ozone stage gives a wide range of opportunities without affecting the pulp strength properties in comparison with conventional ECF sequences. Source


Metais A.,ITT Wedeco | Hostachy J.-C.,ITT Wedeco
Paper Technology | Year: 2011

First industrial production of ozone bleached pulp started almost 20 years ago in connection with increasing environmental pressure and the Total Chlorine Free (TCF) wave. Like many other new technologies, ozone bleaching did not immediately reach its optimal efficiency from a technical viewpoint, but had to face several issues during its early years. By improving mixing technology, better understanding ozone chemistry on pulp components and tuning the whole process, the socalled ECF-Light bleaching sequences - including an ozone stage - made it possible to deliver a pulp quality similar or better than is produced by conventional ECF bleaching. Today the choice of ozone may still be motivated by ecological requirements but it is mostly justified by the economical savings resulting from chemical reduction. Actually, both targets are reached simultaneously when implementing an ozone bleaching stage, whilst pulp quality is either maintained or improved. Using results from several industrial sites, this article describes process improvements in ozone bleaching since 1992 and shows why ozone should now be considered as the keystone of modern pulp bleaching processes. Source


Metai A.,ITT Wedeco | Germer E.,Saint Petersburg State Forest Technical Academy | Hostachy J.-C.,ITT Wedeco
International Pulp Bleaching Conference 2011, IPBC 2011 | Year: 2011

The first industrial production of ozone bleached pulp started almost 20 years ago in connection with increasing environmental pressure and the Total Chlorine Free (TCF) wave. Like many other new technologies, ozone bleaching did not immediately reach its optimal efficiency from a technical viewpoint, but had to face several issues during its early years. By improving mixing technology, better understanding ozone chemistry on pulp components and tuning the whole process, the so-called ECF-Light bleaching sequences - including an ozone stage - made it possible to deliver a pulp quality similar or better than conventional ECF bleaching would do. Today the choice of ozone may still be motivated by ecological requirements but it is mostly justified by the economical savings resulting from chemicals costs cut-off. Actually, both targets are reached simultaneously when implementing an ozone bleaching stage. Through several industrial results, this work describes process improvements in ozone bleaching since 1992 and points out why should ozone now be considered as a keystone of modem pulp bleaching processes. Source

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