Contamination, microbial microorganisms causing

Microbial contamination is mainly caused by the presence of the microorganisms used in the biological process and can be eliminated by using ultra/microfiltration membrane bioreactors. The membrane effectively retains the microbial culture inside the reactor so that it may be operated under low hydraulic residence time. It has been previously demonstrated that the membrane bioreactor ensures a high nitrate removal rate (up to 7.7 Kg NO /m reactor-day) and a residual concentration of nitrate and nitrite, in the treated water, below the maximum admissible values (Barreiros et al., 1998). 

Other Important Considerations with Membranes Oxidizers such as sodium hypochlorite (i.e., CIO2), bromine, iodine, and ozone, which are typically used in the disinfection of wastewater, are not well tolerated by thin-hlm membranes. Such disinfectants can thus influence the efficacy of membranes in removing contaminants such as PPCPs. Furthermore, membranes can become fouled by microorganisms that can metabolize the membrane material. Thus, microbial counts of >100 cells/mL can be problematic. Likewise, dead-cell debris can also cause fouling. Membranes can also be fouled by heavy metals such as chromium. Thus, if heavy metals are deemed a problem, they should be precipitated from the wastewater prior to the filtration with membranes. 

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