Removing carbonaceous pollution

The growth of a bacterial mass, M, develops according to the availability of a nutrient substrate, L, in several characteristic periods  

In aerobic purification as currently under discussion, the changes in bacterial mass versus the initial supply of nutrient L (here represented by the BOD in the medium) can be illustrated as shown in Fig. 34b. Since bacterial activity varies with the age of the bacteria, the three loads often considered in sizing activated sludge can be approximately located on the diagram. These three loads are the high and medium loads and extended aeration (see 3,2,1) where very advanced age makes the sludge mineralize and reduces its production. 

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Finally, Chapters 24—27 deal with the environmental apphcations of carbons as adsorbents for the removal of pollutants from aqueous solutions. These four chapters are highly complementary. Thus, Chapter 24, which addresses the problems associated with the removal of inorganic species, finds its alter ego in Chapter 25, which deals with the adsorption of organic solutes from dilute aqueous solutions. Both chapters provide insights into the fundamental reasons for the performance exhibited by a carbonaceous adsorbent. The global topic of water purification using carbons as adsorbents is addressed in Chapter 26, which... 

Finally, the abatement of NO pollution by using sorbing catalytic materials [59,60] must also be cited. Several solid sorbents for NO removal (metal oxides, spinels, perovskites, double-layered cuprates, zeolites, carbonaceous materials, heteropolyacids and supported heteropolyacids) have been tested. The results are interesting, but not competitive to actual technologies. To mention that the use of sorbing materials allows... 

A biological step is always necessary to remove the carbonaceous fraction from the influent wastewater suspended biomass treatments are the most common. These entail long SRTs (>25-30 d), and compartmentalization of the biological reactor is necessary for the removal of recalcitrant compounds. Furthermore, as many micro-pollutants tend to adsorb/absorb to the biomass flocks, efficient solid/ liquid separation can greatly improve their removal from wastewater and, at the same time, guarantee consistently good effluent quality. MBRs have been suggested for this purpose by many authors [9, 58, 80, 93], some of whom found that ultrafiltration (UF) membranes are more efficient than MF membranes [9, 93]. 

When activated carbons and carbon fibers were the carbonaceous materials used most extensively and their applications were limited mainly to adsorption with the requirement to remove pollutants to the levels of micrograms or parts per million, the surface chemistry of carbons was not even taken into account. It was a common belief that if adsorbents were used in excess, their purifying action was sufficient. This approach can be considered as history. Nowadays, when the environmental regulations are stricter and stricter and when sophisticated... 

Formaldehyde is one of the main pollutants in the atmosphere. In indoor air, formaldehyde mainly comes from decorating materials, paint, furniture glue, and chemical fiber carpets, and the concentration of formaldehyde is always relative low (<20 ppm). Even if the concentration of the formaldehyde is low, it can cause symptoms such as headache, nausea, coryza, pharyngitis, emphysema, lung cancer, and even death, so it is necessary to take effective measures for its removal. Adsorption by carbonaceous adsorbents is the most widely used method to purify the polluted air. Carbon nanostructure such a carbon nanofiber and fiber especially in activated form can be good adsorbents for formaldehyde [65]... 

For molecular filtration, Chen et al. [80] fabricated carbonaceous nanoflbrous (CNF) membranes functionalized by beta-cyclodextrins (CNF- -CD membrane). The membrane showed a remarkable capability to function as an ideal molecular Alter through complexation of phenolphthalein molecules with the CD molecules grafted on the CNFs. As a typical dye pollutant, fuchsin acid could also be effectively removed from the solution through such a membrane. Engineering the surface of this CNF membrane may be used for other applications such as chiral separation and drug delivery. 

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