•Ozone exhibited better pollutants and UV254 removal than chlorine and permanganate.•0.5mgO3mgDOC−1 led to an important elimination of fast ozone-reacting compounds.•Iron coagulation was more ...efficient than alum and removed high MW compounds.•PAC could effectively eliminate hydrophobic and aromatic contaminants.•Coupling coagulation with ozone significantly improved contaminants and EfOM removal.
One important disadvantage of using ultrafiltration (UF) and nanofiltration (NF) for reclamation of secondary effluents from municipal wastewater treatment plants (WWTPs) is the necessity to dispose of the UF and NF retentates. Different advanced treatments including coagulation (iron and alum), oxidation (chlorine, permanganate and ozone) and powdered activated carbon (PAC) adsorption were compared for their efficiencies in removing 11 selected micropollutants and effluent organic matter (EfOM) from UF and NF retentates generated in the filtration of secondary effluents. Ozone exhibited better micropollutants and UV254 removal efficiencies than chlorine and permanganate. Similar abatement of organics was observed when the same specific oxidant dose was applied to UF and NF retentates. Coagulation preferentially removed high molecular weight compounds, being ineffective for the elimination of most micropollutants. In general terms, iron coagulation was more efficient than alum, since iron achieved higher DOC and UV254 removal at lower molar doses. In addition, PAC was an effective method for removing micropollutants, especially hydrophobic and aromatic compounds. The hybrid coagulation/ozonation process improved micropollutants and EfOM (DOC and UV254) removal. A specific ozone dose of 1mgO3mgDOC−1 was able to almost completely remove selected micropollutants from the UF retentate. The final effluent, which is likely more biodegradable and less toxic, could be recirculated to biological treatment processes in the WWTP, avoiding the continuous discharge of non-biodegradable micropollutants through the WWTP effluents.
•The removal of 11 emerging contaminants (ECs) by MEUF was investigated.•Cationic surfactants improved the removal of hydrophobic and anionic ECs.•CPC provided the highest contaminants removal and ...permeate flux.•Dissolved organic matter exerted a slight influence on ECs removal.•MEUF can be optimized for the selective removal of ECs from different effluents.
The removal of 11 selected emerging contaminants (ECs, acetaminophen, metoprolol, caffeine, antipyrine, sulfamethoxazole, flumequine, ketorolac, atrazine, isoproturon, 2-hydroxybiphenyl and diclofenac) by micellar-enhanced ultrafiltration (MEUF) has been investigated. Anionic sodium dodecylsulfate (SDS), non-ionic surfactants Triton X-100 (TX-100) and Tween 20 (TW-20), and cationic surfactants cetylpyridinium chloride (CPC) and cetyl trimethyl ammonium bromide (CTAB) were used. The retention coefficients of the selected compounds were determined in order to evaluate the separation efficiency of ECs from surfactant micelles. It was found that cationic surfactants were more appropriated for the removal of negatively charged and hydrophobic ECs. However, the presence of surfactant decreased the permeate flux due to the concentration polarization and membrane fouling. Among surfactants, the best results in terms of lower membrane fouling and higher retention of ECs were obtained with CPC. In addition, the effects of the MWCO of UF membranes and the water matrix on ECs and CPC removal and on membrane fouling were also evaluated. The increase of the feed CPC concentration improved the removal of ECs, although the permeate flux decreased. The removal of ECs and CPC was not affected by trans-membrane pressure. According to these results, solubilisation of ECs in the micelles and retention of the micelles by the membrane govern the overall retention process.
► The removal of eleven emerging contaminants by combined treatments was investigated. ► PAC pre-treatment decreased membrane fouling and improved the quality of the permeate. ► Pre-coagulation with ...Fe(III) was slightly more favorable than with Al(III). ► The combinations PAC/UF and UF/GAC led to a significant removal of contaminants.
The removal of eleven emerging contaminants (acetaminophen, metoprolol, caffeine, antipyrine, sulfamethoxazole, flumequine, ketorolac, atrazine, isoproturon, 2-hydroxybiphenyl and diclofenac) present in a WWTP effluent by applying several combined treatments has been investigated. These combinations were constituted by PAC adsorption and/or coagulation pre-treatments followed by UF, as well as by an UF treatment followed by GAC adsorption post-treatment. PAC pre-treatment decreased membrane fouling, with the advantage that PAC was separated from the final effluent in the UF step. Low PAC dose in the range 10–50mgL−1 in the adsorption pre-treatment was enough in order to remove most of the emerging contaminants and to partially improve water quality parameters. However, if the goal is to reach a high improvement of water quality parameters in the pre-treatment step, a PAC dose above 500mgL−1 was required. Although coagulation pre-treatment did not increase appreciably the permeate flux in the UF step, the final quality of the permeate was improved, especially when the combination Fe(III)/UF was applied. Finally, a significant positive effect of the GAC post-treatment after the UF treatment was appreciated, which led to an increase in the removal of the water quality parameters and a significant elimination of emerging contaminants.
This study investigates the removal of 11 emerging contaminants dissolved in ultrapure water or in municipal secondary effluent by ultrafiltration and nanofiltration membranes. The influence of the ...most important operating variables (nature and MWCO of the membranes, transmembrane pressure, tangential velocity, pH and temperature) on the permeate flux and on the retention of the selected compounds was discussed. Most of the emerging compounds presented retentions above 70% with the selected NF membranes. However, lower retention coefficients were obtained with the UF membranes tested (<50%, except for hydroxybiphenyl). According to the results obtained for membrane fouling, retention coefficients and adsorption of contaminants on the membranes, while adsorption is the main mechanism for micropollutants retention by UF filtration membranes, size exclusion and electrostatic repulsion at high pH are dominant in the case of NF membranes. In addition, retention coefficients for parameters that measure the quality of the effluent (chemical oxygen demand, absorbance at 254
nm, turbidity, total nitrogen and total phosphorus) were also evaluated, and the results revealed that both UF and NF are feasible options for the treatment of municipal secondary effluent, leading to a permeate stream that can be reused in several applications.
Four UF membranes (denoted GH, GK, PT and PW with MWCO of 1000, 2000, 5000 and 20,000
Da, respectively) and four NF membranes (denoted DL, CK, DK and HL, with an approximate MWCO of 150–300
Da in all ...cases) were used for the filtration of an effluent generated in a municipal wastewater plant after a secondary treatment. The influence of the most important operating variables (nature and MWCO of the membranes, transmembrane pressure, tangential velocity, and temperature) on the permeate flux was widely discussed, and the resistances to the permeate flux were determined following the resistances in series model. Rejection coefficients for parameters that measure the global pollutant content of the effluent (chemical oxygen demand, total organic carbon, absorbance at 254
nm, turbidity, total nitrogen and total phosphorus) were also evaluated, and the results revealed that both UF and NF are feasible options for the treatment of this effluent, yielding a permeate stream that can be reused in several applications. Finally, 28 pharmaceutical compounds were initially detected in this effluent, and their respective rejection coefficients were determined, with eliminations higher than 75% in the case of NF with the HL membrane. Therefore, it is concluded that NF is an excellent option for the removal of toxic pharmaceuticals in municipal wastewaters.
The elimination of 11 selected emerging contaminants (acetaminophen, metoprolol, caffeine, antipyrine, sulfa-methoxazole, flumequine, ketorolac, atrazine, isoproturon, 2-hydroxybiphenyl and ...diclofenac) has been investigated by means of ultrafiltration membranes in a cross-flow equipment that operated in continuous regime. Two different aqueous systems were used for dissolving the selected pollutants: ultrapure water and a secondary effluent generated in a municipal wastewater treatment plant. The influence of the MWCO of the membranes, and the nature of the water matrix on the permeate flux was established, and the rejection coefficients of the selected compounds were determined. Additionally, in the UF of the secondary effluent, rejection coefficients of several quality parameters (turbidity, chemical oxygen demand, total nitrogen and phosphorus, and absorbance at 254 nm) were also evaluated. In order to enhance the efficiency of the single UF process, three different combined processes were also tested: two pre-treatments consisting in coagulation (by using aluminum sulfate) and adsorption (by using powdered active carbon) stages followed by the UF stage; and adsorption post-treatment (by using granular active carbon) that was conducted to the permeate of the UF stage. The improvements in the elimination of the selected compounds and the quality pollutant parameters were established and discussed.
