Membrane Bioreactor (mbr) as an Advanced Wastewater Treatment Technology
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| Streptococcus faecalis as Salmonella spp. and Coliphages [134]. However, how
to cope with wastewater when different types of viruses coexist and how to dispose the virus-bearing excess sludge must be studied further. 6 Removal of Trace Organic Compounds by a Membrane Bioreactor WWTPs treating wastewater from municipalities and industries have been shown as major sources of many environmental pollutants. These pollutants usually originate from synthetic chemicals that have been used widely for industrial, agricultural, and household purposes. Compounds like pharma- ceutically active compounds (PhACs), industrial chemicals, and pesticides are produced worldwide on a 100 000 t scale. After their usage for the in- tended purpose, a large fraction of these substances will be discharged into the wastewater unchanged or in the form of degradation products that are of- ten hardly eliminable in conventional WWTPs. Depending on the efficiency of the treatment and chemical nature of a compound, they reach WWTP ef- fluents and surface waters in certain concentration. In the worst case, they are present in drinking water, in spite of expensive treatment steps. Although the exact effect of consistent exposure to trace organic contam- inants is still unclear, there is no more doubt that it has significant adverse consequences for public health. For example, antibiotics and their metabo- lites can significantly increase antibiotic resistance in the population. Syn- thetic hormones can act as endocrine disruptors by mimicking or blocking hormones and disrupting the body’s normal functions. Due to their polarity, they can be eliminated during wastewater treatment only incompletely. Polar poorly degradable compounds were detected in high and comparable con- centrations in the effluents of numerous WWTPs all over Europe. A proper wastewater treatment as mandatory in the European Union due to the Urban Wastewater Treatment Directive (91/271/EEC) will not eliminate polar pollu- tants completely [135]. Therefore, to avoid such contaminants, emissions with WWTP effluents would have to be reduced by their advanced treatment or by avoidance and replacement measures for the respective pollutant. One of the 70 J. Radjenovi´c et al. most promising technologies is MBR technology. The potential of MBR to ef- ficiently remove hazardous substances from wastewater is often highlighted. Besides the fact that there is a physical retention of all the molecules larger than the molecular weight cut-off (MWCO) of the membrane, hydrophobic substances also tend to accumulate onto the sludge and therefore they are re- moved from the effluent. Furthermore, as all the bacteria are held back, there are better adapted to mineralizing of micropollutants present in the reactor. tải về 0.95 Mb. Chia sẻ với bạn bè của bạn:
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