Dissolved organic carbon ultrafiltration

Municipal landfill leachate typically contains dissolved organic carbon (DOC) concentrations up to several thousand (typically >1700 ppm), even in a landfill that is decades old (Christensen et al. 1998). More than 200 organic compounds have been identified in municipal landfill leachate (Paxe us 2000). Therefore, an effective chemical characterization of landfill leachate by numerous analytical techniques requires a previous isolation procedure in order to remove possible interferences. In our previous study, we tested the advantage of the ultrafiltration... 

An approach such as that suggested for the re-examination of the molecular weight distribution of dissolved organic carbon in seawater (Carlson et al., 1985) has been successfully adapted to evaluate the performance of ultrafiltration in the study of radionuclide speciation ... 

Cai, Y., Size distribution measurements of dissolved organic carbon in natural waters using ultrafiltration technique, Water Res., 33, 3056-3060, 1999. 

Table V. Two Systems of Simultaneous Equations Used to Solve Sequential Ultrafiltration Mass Balance for Dissolved Organic Carbon in Mass Units...

Presently, the precise determination of the true dissolved Th fraction in water samples remains a challenge. Results from ultrafiltration experiments on organic-rich water samples from the Mengong river tend to demonstrate that Th concentration is less than 15 ng/L in absence of DOC (Table 2 and Viers et al. 1997), and that Th is still controlled by organic carbon in the final filtrate of the ultrafiltration experiments. The latter conclusion is also supported by the results obtained for the Kalix river (Porcelli et al. 2001). These results therefore not only raised the question of the determination of the amount of dissolved Th in water but also of the nature of Th chemical speciation. 

Ultrafiltration was applied to examine the size fractionation of Al, Ca, Cu, Fe, K, Na, and Pb in white and red wines [91]. Metal determinations were performed on the unfiltered wine, the 0.45 p,m membrane-filtered wine and each ultrafiltrate fraction. Aluminum was determined by ET-AAS, while FAAS was employed for Cu and Fe. An electroanalytical technique, stripping potentiometry, was selected for Pb measurement, whereas flame photometry was chosen for K and Na quantification. Fractionation patterns were evaluated and discussed. Castineira et al. [92] combined on-line tangential-flow multistage ultrafiltration with a home-built carbon analyzer and ICP-MS for size fractionation of nonvolatile dissolved organic compounds and metal species in three German white wines. The study showed that the major part of the elements investigated (up to 25) were dissolved in the size fraction of < 1 kDa, with the exception of Ba, Pb, and Sr, which also appeared in other fractions. 

M. M. Castineira, P. Burba, N. Jakubowski, J. Andersson, Size fractionation of nonvolatile dissolved organic compounds and metal species in German white wines by combining on-line tangential-flow multistage ultrafiltration, a home-built carbon analyzer, and inductively coupled plasma mass spectrometry, Anal. Bioanal. Chem., 376 (2003), 174-181. 

Powdered activated carbon may also be coupled to ultrafiltration (UF). This hybrid system, referred to in the literature as the PAC/UF process, incorporates the adsorption capabilities of activated carbon and the microorganism and particle removal ability of the UF membranes [71]. Combined with coagulation as a pre-treatment, tlie coupling has been successfully applied to the treatment of domestic wastewater [72]. Mdtivier-Pignon et al. [73] have proposed a combination of ultrafiltration with activated carbon cloth to treat complex aqueous solutions with suspended solids, colloids and dissolved organic molecules, like highly colored wastewaters from ink manufacture. 

---