End of pipe technology

Up to now, most of the investigations dealing with the simultaneous removal of NO and N2O utilizing end-of-pipe technologies did not provide a maximum 

5 mbar CsHg. (Reproduced with permission from Ref. [9].) 

Particular attention was paid to Fe-zeolite using ammonia as a reducing agent A comparative study carried out by Guzman-Vargas et al. [46] revealed that this transformation is feasible when isolated Fe species are stabilized. The host zeolite structure and the nuclearity of iron oxocation were found to influence the catalytic properties. By way of illustration, MeUan-Cabrera et al. [47] show a remarkable stability of exchange iron species stabilized as Fe-hydr(oxo) complexes in ferrierite framework, much better than Fe/ZSM5, under realistic conditions. 

These latter observations suggest alternative solutions still involving a sequential approach, since most of the attempts to optimize a catalyst capable to convert simultaneously NO and N2O below 200 °C failed. Hence, end-of-pipe technologies cannot be reasonably envisioned except if it is coupled upstream with a catalytic system capable to decompose N2O. 

Many attempts at the lab scale were devoted to the catalytic abatement of N2O, and the technology is now available at the industrial scale even if some problems persist related to the catalyst stability at high temperature inside the ammonia burner. In the particular case of nitric acid plant, the simultaneous removal of low concentration of N2O and NO, is still of interest, since no technology is viable especially end-of-pipe systems for which the low temperatures of the exhaust gas do not allow the simultaneous conversion of N2O and NO. The implementation of a process running at medium temperatures is technologically 

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For either plant type, incineration, or fuel type, these factors must be empirically determined and controlled. Because dioxins as effluents are concerned, it is possible to reduce I-TE values from about 50 ng/m to about 1 ng/m. Additional secondary measures (filter techniques) are therefore necessary for obtaining the lower limit value of 0.1 ng/m. Secondary measures are special filter techniques for pollutants formed in nongreen processes, also called end-of-pipe technology. The main part of technical incineration plants consists of filter devices, mostly coke as adsorbent is used, which must be decontaminated later by itself by burning in hazardous-waste incinerators. The inhibition technology, discussed later, is related on principles of primary (green) measures for a clean incineration method. 

To facilitate an overview and to consider the specific differences of textile fibers during pretreatment, dyeing, and finishing, the sections have been focused on the most important types of fibers wool, cotton, and synthetic fibers. Mixtures of fibers can be seen as systems combining problems of the single fiber types. In Section 8.3 end-of-pipe technologies have been summarized. 

Treatment of the total wastewater this technique will be discussed in Section 8.3, End-of-pipe Technologies. The general scheme of such treatments is shown in Figure 11. 

The application of end-of-pipe technologies as general procedures for the treatment of wastewater has changed from simple procedures to sophisticated concepts, applying a consecutive set of methods that has been adapted to the particular situation of a textile plant [72]. As already discussed in the previous sections, the separation of concentrated wastes and the treatment of small volumes of concentrates are much more efficient compared to a global treatment of mixed wastes. 

As a result, a high COD is found in the effluents and end-of-pipe technologies that form sludge have to face a high amount of precipitate. 

Diesel soot emissions can be reduced by two different end-of-pipe technologies ... 

End-of-pipe technology is not attractive - both technically and economically. 

By using improved fuel injection and engine control techniques, the concentration of soot particles in the exhaust gas was reduced (less gray filter paper), but the number of soot particles was increased and their average size was reduced, which made the diesel engine emissions even more harmful. So, everyone was back to square one - and the unfavored end-of-pipe technology for the reduction of diesel soot emissions came back to life again ... 

Environmental concerns are here to stay. They can be viewed as a threat requiring ever increasing expenditure on end of pipe technologies to meet ever-increasing legislation or they can be viewed as an opportunity to introduce cleaner processes, which are more efficient and cost effective. 

Environmental protection in the chemical industry is divided into product related and production related areas. Environmental protection related to products covers the development and production of environmentally friendly products (e.g., paints, herbi-cides/pesticides, washing powder) and treatment of product wastes from processing and consumption (Chap. 4). Environmental protection related to production covers the concept of the production-integrated environmental protection and additive environmental protection. Additiv environmental protection is the German term for end-of-pipe technology. This further subdivision can be examined in Figure 4 [18]. 

Capital investment into end-of-pipe technologies does not satisfy the precautionary measures preferred by environmental policy... 

Residues and wastes can arise in more than one environmental area of production. Concepts for residue management must therefore extend over many such areas. Disposal of residues as wastes, considered alone, even if carried out in an appropriate, environmentally compatible form, has the disadvantage that the waste problem is dealt with at the end of the production chain there may also be ecological and economic drawbacks associated with this arrangement. These end-of-pipe technologies are generally more expensive than upstream measures. 

It is remarkable that basically all sub-global air pollution problems (dust and smoke, sulfur and nitrogen pollution) in connection with fossil fuel combustion have been (or can be) solved by end-of-pipe technologies. Hence, the last and apparently insoluble problem remains CO2 emissions and the subsequent increase in the greenhouse effect. CCS technology is another end-of-pipe approach and far from any sustainable chemistry. But it seems the only practical way to start the abatement of CO2 emissions. 

Environmental spending the definition of what is environmental cost is not always evident. Pollution abatement costs and other "end-of-pipe" technologies as well as legal compliance costs can certainly be counted as environmental... 

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