Biodegradation of persistent polar pollutants in wastewater: comparison of an optimised lab-scale membrane bioreactor and activated sludge treatment.
ABSTRACT The biodegradation of selected non-adsorbing persistent polar pollutants (P(3)) during wastewater (WW) treatment was studied by comparing a lab-scale membrane bioreactor (MBR) running in parallel to activated sludge treatment (AST). The investigated P(3) are relevant representatives or metabolites from the compound classes: pesticides, pharmaceuticals, insect repellents, flame retardants and anionic surfactants. Analyses of all these P(3) at low ng L(-1) levels with sufficient standard deviations was performed in WW influents and effluents. Non-degradable micropollutants, such as EDTA and carbamazepine were not eliminated at all during WW treatment by any technique. However, the MBR showed significant better removals compared to AST for the investigated poorly biodegradable P(3), such as diclofenac, mecoprop and sulfophenylcarboxylates. An application of such an in terms of sludge retention time optimised MBR may lead to a reduction of these P(3) in the watercycle.
Full-textDOI: · Available from: Marco Bernhard, Jun 30, 2015
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ABSTRACT: N,N-diethyl-m-toluamide (DEET), the active component of many insect repellents, is among the most frequently detected compounds in aqueous environments with concentrations reported in the ngL(-1) to μgL(-1) range. However, DEET is often detected in blanks and reported concentrations differ significantly depending on the analytical technique employed. In addition, relatively sparse data are available regarding the seasonal variability of DEET concentrations in water and there are apparent inconsistencies with expected use patterns. Therefore, the present study investigates potential interferences affecting the detection and quantification of DEET then the geographical and seasonal variations of DEET concentrations. To examine potential analytical interferences, DEET was analyzed in five geographically-diverse wastewater effluents using both gas chromatography and liquid chromatography coupled to mass spectrometric detectors. At times, the concentrations quantified by the employed analytical methods varied significantly. Five compounds with similar molecular weights and structures as DEET were investigated as potential mimics and some were shown to induce an overestimation of DEET. Further experimentation suggested that the solvents used in sample preparation and HPLC analysis are another possible source of interference. Besides potential interferences, the seven-month weekly monitoring of DEET in the primary effluent of a wastewater treatment plant demonstrated a clear seasonal trend with decreasing concentration from summer to winter. These data collectively demonstrate that there are many challenges in the quantification of DEET in complex environmental samples and that co-occurrence of similarly structured substances present in the water sample and/or the solvents used for the analysis could induce analytical bias. Copyright © 2015 Elsevier Ltd. All rights reserved.Chemosphere 03/2015; 127C:238-245. DOI:10.1016/j.chemosphere.2015.02.025 · 3.50 Impact Factor
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ABSTRACT: Microbial fuel cells (MFCs) and microbial electrolysis cells (MECs) are two types of microbial bioelectrochemical systems (BESs) that use microorganisms to convert chemical energy in wastewaters into useful energy products such as (bio)electricity (MFC) or hydrogen gas (MEC). These two systems were evaluated for their capacity to attenuate trace organic compounds (TOrCs), commonly found in municipal wastewater, under closed circuit (current generation) and open circuit (no current generation) conditions, using acetate as the carbon source. A biocide was used to evaluate attenuation in terms of biotransformation versus sorption. The difference in attenuation observed before and after addition of the biocide represented biotransformation, while attenuation after addition of a biocide primarily indicated sorption. Attenuation of TOrCs was similar in MFCs and MECs for eight different TOrCs, except for caffeine and trimethoprim where slightly higher attenuation was observed in MECs. Electric current generation did not enhance attenuation of the TOrCs except for caffeine, which showed slightly higher attenuation under closed circuit conditions in both MFCs and MECs. Substantial sorption of the TOrCs occurred to the biofilm-covered electrodes, but no consistent trend could be identified regarding the physico-chemical properties of the TOrCs tested and the extent of sorption. The octanol-water distribution coefficient at pH 7.4 (log DpH 7.4) appeared to be a reasonable predictor for sorption of some of the compounds (carbamazepine, atrazine, tris(2-chloroethyl) phosphate and diphenhydramine) but not for others (N,N-Diethyl-meta-toluamide). Atenolol also showed high levels of sorption despite being the most hydrophilic in the suite of compounds studied (log DpH 7.4 = -1.99). Though BESs do not show any inherent advantages over conventional wastewater treatment, with respect to TOrC removal, overall removals in BESs are similar to that reported for conventional wastewater systems, implying the possibility of using BESs for energy production in wastewater treatment without adversely impacting TOrC attenuations. Copyright © 2015. Published by Elsevier Ltd.Water Research 01/2015; 73C:56-67. DOI:10.1016/j.watres.2015.01.013 · 5.32 Impact Factor
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ABSTRACT: Municipal wastewater reclamation and reuse has become an important solution in many places around the world to deal with water scarcity problems. Among the available treatment approaches, membrane bioreactor (MBR) has a great potential to become a key element in municipal wastewater reclamation and reuse schemes due to its significantly higher treated effluent quality as compared to the conventional activated sludge process. As great concerns have been raised to some emerging trace pollutants found in aquatic environment in the last decade, notably the pharmaceuticals, removal of pharmaceutical micropollutants by MBR or MBR-related processes should be evaluated to further understand the status of MBR in different wastewater treatment and reuse schemes. This paper gives an overview on removal of pharmaceutical micropollutants by MBR or MBR-related processes, such as activated carbon-assisted MBR and combined membrane bioreactor and reverse osmosis process.Desalination and water treatment 06/2014; DOI:10.1080/19443994.2014.926839 · 0.99 Impact Factor