Waste gas treatment

It was quite recently reported that La can be electrodeposited from chloroaluminate ionic liquids [25]. Whereas only AlLa alloys can be obtained from the pure liquid, the addition of excess LiCl and small quantities of thionyl chloride (SOCI2) to a LaCl3-sat-urated melt allows the deposition of elemental La, but the electrodissolution seems to be somewhat Idnetically hindered. This result could perhaps be interesting for coating purposes, as elemental La can normally only be deposited in high-temperature molten salts, which require much more difficult experimental or technical conditions. Furthermore, La and Ce electrodeposition would be important, as their oxides have interesting catalytic activity as, for instance, oxidation catalysts. A controlled deposition of thin metal layers followed by selective oxidation could perhaps produce cat-alytically active thin layers interesting for fuel cells or waste gas treatment. 

Clean air is an important prerequisite for sustainable development and is a basic requirement for human health and welfare. In addition, air pollutants contribute to atmospheric problems such as acidification and global climate change, which have impacts on crop productivity, forest growth, biodiversity, buildings, and cultural monuments. The benefits from the progress made in the areas of waste gas treatment and environmental legislation are partially offset by industrialization, an increase in the number of private cars in use, and overpopulation. 

Considerable information about pollutants, emission sources, and treatment techniques has been given in the reference document on best available techniques (BATs) in common waste-water and waste gas treatment released by the European Commission in 2003 (EC, 2003). 

Waste-treatment techniques are classified by the type of contaminant. The main techniques concerning waste gas treatment are the following. 

European Commission, Integrated Pollution Prevention and Control, Reference Document on Best Available Techniques in Common Waste Water and Waste Gas Treatment/Management Systems in the Chemical Sector (February 2003)... 

Fig. 7.3. Analogies between adsorptive, membrane and reverse-flow reactors for flue gas denitrification and oxidative catalytic waste gas treatment.

Since the advent of three way catalysts (TWCs) for vehicle waste gas treatment in the 1980s, the demand for pollutant removing has been on the rise. The TWCs remove the pollutants by converting the nitrogen oxides. 

Reij MW, Keurentjes JTF, Hartmans S. Membrane bioreactors for waste gas treatment. J Biotechnol 59 1998 155-116. 

A number of environmental problems are strongly related to the emission of sulfur compounds, such as SO2, in the atmosphere. SO2 emission is mainly due to combustion of fossil fuels containing H2S or organic S-compounds. In the atmosphere, SO2 is oxidized forming sulfuric acid resulting in acid rain. Fortunately, the emission of SO2 has decreased considerably since the 1970s due to selection of low sulfur-content fuels, waste gas treatment and specialized combustion processes. 

To summarize, MBR have been successfully utilized for both wastewater and waste gas treatment. Membranes play a variety of roles. They are used for separating and recycling... 

Heat treatment furnaces are known to be continuous sources of well known non-air components. Emission levels are closely related to energy consumption, burner design and maintenance. Emission collection is trivial in annealing furnaces. The capture of the emissions in the different furnaces does not differ considerably, and emissions are expelled via the waste gas pipe. In general, no further waste gas treatment is applied. 

Table 5.1 Membrane bioreactors for biological waste gas treatment in historical order [57],...

Kumar, A., Dewulf, J., and Van Langenhove, H. (2008), Membrane-based biological waste gas treatment, Chemical Engineering Journal, 136(2-3) 82-91. 

Hartmans, S., Leenen, E. and Voskuilen, G. 1992. Membrane bioreactor with porous hydrophobic membranes for waste-gas treatment. Studies in Environmental Science, 51,103-106. 

Reij, M. W., De Gooijer, K. D., DeBont, J. A. M. and Hartmans, S. 1995. Membrane bioreactor with a porous hydrophobic membrane as a gas-Uquid contactor for waste gas treatment. Biotechnology and Bioengineering, 45,107-115. 

Dewulf, J., Van Langenhove, H., and Dirckx, J., Energy analysis in the assessment of the sustainability of waste gas treatment systems, Sci. Total Environ., 273 41-52, 2001a. 

Common Waste Water and Waste Gas Treatment/Management Systems in the Chemical Sector CWW... 

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