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This work aimed to determine the effect of organic foulants and fouling behavior on separation of multi-ions for nanofiltration (NF) membrane. Three model organic foulants (bovine serum albumin, lysozyme, and humic acid) were selected and studied in depth. The rejections of mono- and di-anions by virgin membrane varied with different organic foulants because of foulant-enhanced co-ion competition. Subsequent multi-ions separations by fouled membranes were different due to the zeta potential and structure of the fouling cake. In contrast to the single protein system, Cl−andrejection was reduced by HA fouled membrane. However, with added proteins in the HA solution, mixed systems experienced decreasing Cl−rejection and increasingrejection. In addition, solution chemistry (solution pH, ionic strength, and Ca2+) had marked effect on the cake layer composition, likely due to the changing interaction between foulant and foulant, as well as between foulant and NF membrane. The suitable foulant cake structure could result enhanced in multi-ions separation. The synergistic mechanisms of organic foulants and cake were analyzed by calculated cake hydraulic resistance and zeta potential of fouled membranes. [ABSTRACT FROM AUTHOR]

The fouling behavior of nanofiltration (NF) membranes by proteins bovine serum album (BSA), lysozyme (LYS), and humic acids (HA), as well as their mixtures was studied in a cross flow bench-scale cell. The similarities and differences of the effects of pH on single and mixed organic foulant systems were compared by analyzing the size distribution and zeta potential of foulants in the feed, and in conjunction with the characterization of fouled NF membranes, respectively. Results showed that the fouling behaviors of both single and the mixed systems were significantly correlative with solution pH, moreover BSA/LYS combined with HA appeared more aggravated fouling behavior than single foulant within the test pH range. For solution pH, this can affect interactions of foulants–foulants and foulants–membrane by changing zeta potential of them. Also, therefore, zeta potential value could be used to predict the fouling behavior of NF. Considering the experimental results, more severe fouling behavior by not only single (HA, BSA, and LYS), but mixed systems (BSA + HA and LYS + HA) occurred at acidic and neutral solution pH. [ABSTRACT FROM PUBLISHER]

Experiments were conducted to investigate the concentrations of PAHs and their adsorption characteristics by activated sludge in this study. Influence of sorption time, sludge concentration, and pH on PAHs adsorption was evaluated. Furthermore, the isotherms, kinetics of adsorption, and potential risk were also explored. Experimental results show that concentrations of 16 PAHs in coking wastewater sludge were 581.600–2201.633 μg/g, both Linear and Freundlich adsorption models were able to adequately describe the adsorption equilibriums of PAHs onto activated sludge. The adsorption process closely followed the pseudo-second-order kinetic model. The adsorption efficiencies of PAHs depended on the activated sludge concentration and sorption time, while that was not affected by pH. Hydrophobic interaction, distribution, and chemisorption were mainly responsible for the adsorption of PAHs, while the surface area and pore volume of activated sludge had little contribution. Results also indicate that the order of carcinogenic health risk was Benzo[a]pyrene > Dibenzo[a,h]anthracene > Benzo[b]fluoranthene > Indeno[1,2,3-cd]pyrene > Benzo[a]anthracene > Benzo[k]fluoranthene. [ABSTRACT FROM PUBLISHER]