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[EN] BACKGROUNDUltrafiltration is used as tertiary treatment in wastewater treatment plants (WWTP) for wastewater reclamation. However, membrane fouling is the main drawback of the process. In this work a new effluent organic matter fractionation procedure with adsorption resins (XAD-8, XAD4 and IRA-958) has been applied without recovering the adsorbed fractions. In this way, strong and weak hydrophobic and charged hydrophilic substances of the dissolved organic matter (DOM) were removed for further ultrafiltration, in order to know the most fouling fraction. For this, secondary effluents of two WWTP and two membranes with different molecular weight cut-offs (100 kDa and 3 kDa) were used in ultrafiltration experiments in a laboratory plant. RESULTSThe hydrophobic substances (especially the strong hydrophobics) predominated over the hydrophilic compounds. Membrane fouling was higher for the membrane with the highest molecular weight cut-off (100 kDa). Thus, flux decline was around 25-47% higher than that measured for the 3 kDa membrane. The charged hydrophilic substances (CHi) were identified as the most fouling compounds with 100 kDa membrane. Reversible fouling was predominant. CONCLUSIONSThe proposed fractionation system enabled determination of the contribution of the different fractions to the DOM. (c) 2017 Society of Chemical Industry, This work was supported by the Spanish Ministerio de Economia y Competitividad (CTM2014-54546-P).

[EN] BACKGROUND Membrane fouling is the main limiting factor for the application of ultrafiltration (UF) to wastewater treatment as tertiary treatment or in membrane bioreactors. Soluble microbial products (SMP) play the more important role on membrane fouling. In this work, four sequencing batch reactors were operated in parallel using two different simulated wastewaters under operating conditions maximizing and minimizing SMP production. The aim was to study the influence of the wastewater type, which until now has hardly been considered, on SMP production and, consequently, on membrane fouling. RESULTS AND CONCLUSION Results showed that organic matter (OM) type in wastewater greatly influenced SMP production and composition (protein : carbohydrate ratio). The food¿to¿microorganisms (F : M) ratio also significantly influenced SMP production. The lowest protein : carbohydrate ratio was achieved for wastewater containing sodium acetate as OM source at a F : M = 0.2. Finally, both mixed liquor and treated effluent were subjected to an ultrafiltration (UF) process and it was confirmed that the carbohydrate concentration in SMP was the main parameter influencing membrane fouling when the reactor effluent was fed to the UF process., This work was supported by the Spanish Ministerio de Economia y Competitividad. (CTM2014-54546-P).