Fractionation of secondary effluents of wastewater treatment plants in view of the evaluation of membrane fouling in a further ultrafiltration step

Abstract

BACKGROUND Ultrafiltration 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. RESULTS The 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. CONCLUSIONS The proposed fractionation system enabled determination of the contribution of the different fractions to the DOM. © 2017 Society of Chemical Industry

Contaminants of Emerging Concern Removal in an Effluent of Wastewater Treatment Plant under Biological and Continuous Mode Ultrafiltration Treatment

“…Diuron and caffeine were selected among the low-concentration CEC, telmisartan and losartan among those of medium concentration, and sulfamethoxazole and trimethoprim among those of high concentration. The q irr value represents the amount irreversibly retained in the filtration membrane and not removed during washing, causing fouling [25]. In general, q irr approaches q ∞ at extreme values (high and/or low), leading to a low removal yield.…”

“…Currently, membrane filtration technologies and the use of advanced oxidation processes (AOPs) are widely studied for the removal of micropollutants, either in wastewater or in drinking water [14][15][16][17]. Among these treatments, the most relevant processes are: ozonation [18,19], UV/H 2 O 2 /Fe 3+ photocatalysis [20], electrochemical reactions [20,21], membrane bioreactors [22], nanofiltration or ultrafiltration, reverse osmosis [23][24][25] and adsorption [26]. Technologies based on hydrogen peroxide oxidation, such as Fenton, or others activated by UV [21,27,28] and ultrasound [29], have also proved significant.…”

A Step Forward to the Characterization of Secondary Effluents to Predict Membrane Fouling in a Subsequent Ultrafiltration

“…On the other hand, the protocol followed in the present work is that described by Ferrer-Polonio et al [19]. In this method, the effluent obtained after DAX-8 adsorption was introduced into the XAD-4 column and the effluent of this fractionation step was treated in the IRA-958 column.…”

“…In this way, S2 was characterized by lower COD, TOC, protein, carbohydrate and humic substance concentrations than those measured in S1 (Table 3). Both samples were fractionated following the methodology reported by Ferrer-Polonio et al [19]. Table 3 shows the stream characterization resulting from the treatment with the three resins of the secondary effluents.…”

“…Imai et al [17] divided the EfOM into six fractions (hydrophobic and hydrophilic neutrals, acids and bases). Further works aimed to simplify and adapt this fractionation procedure to obtain information that could correlate the groups of these substances with the membrane fouling potential of the secondary effluent [18,19]. It has to be taken into account that the objective of this work is not to divide the EfOM into the highest number of fractions, nor recover them, but to gain insight on its characteristics in order to predict the membrane fouling.…”