Biological degradation of pharmaceuticals in municipal wastewater treatment: proposing a classification scheme.
ABSTRACT A simple classification scheme is suggested to characterize the biological degradation of micropollutants such as pharmaceuticals, musk fragrances and estrogens during wastewater treatment. The scheme should be a basis for the discussion about potential removal efficiencies. Hence, the biological degradation of 25 pharmaceuticals, hormones and fragrances was studied in batch experiments at typical concentration levels using activated sewage sludge originating from nutrient-eliminating municipal wastewater treatment plants. Since pseudo first-order degradation kinetics was observed for all compounds down to ng L(-1) levels, the removal rates can be predicted for various reactor configurations. Therefore dilution of wastewater (e.g. by extraneous water) is expected to reduce the degree of biological removal. Wastewater segregation and treatment at the source are therefore to be favoured for elimination of persistent micropollutants over centralized end-of-pipe treatment. For reactor configurations typical for nutrient removal in municipal wastewater, the derived formula for predicting removal allows the identification of three groups of micropollutants according to their degradation constant k(biol): compounds with k(biol)<0.1 L g(SS)(-1)d(-1) are not removed to a significant extent (<20%), compounds with k(biol)>10 L g(SS)(-1)d(-1) transformed by >90% and in-between moderate removal is expected. Based on the degradation of a heterogeneous group of 35 compounds (including literature data), state of the art biological treatment schemes for municipal wastewater are not efficient in degrading pharmaceuticals: only 4 out of 35 compounds are degraded by more than 90% while 17 compounds are removed by less than 50%.
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ABSTRACT: This study investigated the applicability of bulk organic parameters like dissolved organic carbon (DOC), UV absorbance at 254 nm (UV254), and total fluorescence (TF) to act as surrogates in predicting trace organic compound (TOrC) removal by granular activated carbon in water reuse applications. Using rapid small-scale column testing, empirical linear correlations for thirteen TOrCs were determined with DOC, UV254, and TF in four wastewater effluents. Linear correlations (R(2) > 0.7) were obtained for eight TOrCs in each water quality in the UV254 model, while ten TOrCs had R(2) > 0.7 in the TF model. Conversely, DOC was shown to be a poor surrogate for TOrC breakthrough prediction. When the data from all four water qualities was combined, good linear correlations were still obtained with TF having higher R(2) than UV254 especially for TOrCs with log Dow>1. Excellent linear relationship (R(2) > 0.9) between log Dow and the removal of TOrC at 0% surrogate removal (y-intercept) were obtained for the five neutral TOrCs tested in this study. Positively charged TOrCs had enhanced removals due to electrostatic interactions with negatively charged GAC that caused them to deviate from removals that would be expected with their log Dow. Application of the empirical linear correlation models to full-scale samples provided good results for six of seven TOrCs (except meprobamate) tested when comparing predicted TOrC removal by UV254 and TF with actual removals for GAC in all the five samples tested. Surrogate predictions using UV254 and TF provide valuable tools for rapid or on-line monitoring of GAC performance and can result in cost savings by extended GAC run times as compared to using DOC breakthrough to trigger regeneration or replacement. Copyright © 2015 Elsevier Ltd. All rights reserved.Water Research 03/2015; 76:76-87. DOI:10.1016/j.watres.2015.02.019 · 5.32 Impact Factor
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ABSTRACT: PHARMACEUTICALS are designed to have a physiological effect …..on humans and animals in trace concentrations. Persistence against biological degradation and their biological activity are key properties of these pollutants. Increasing consumption of pharmaceutical active compounds (PhACs) and their discharge to the municipal wastewater via excrete are a growing danger for water quality and thus for the health of citizens. The entire discharge volume of medicines into the sewage net and the inefficiency of suitable wastewater treatment solutions to face such a problem, leads to high pharmaceuticals content in the drinking water. Due to its low degradability, 80% of these substances are raw discharged by excretion and flushed to the toilets and sewers to the sewage plants, where no rejection takes place, thus leading to growth of bacterial resistance. This leads to high pharmaceuticals content in the drinking water, people assimilate these substances, resulting in every time higher difficulties when treating common illnesses. The aim of the present article is to review the issue of PhACs in the environment. The review focuses on the source, presence, fate, elimination, and treatment of PhACs in water and wastewater. This review includes: characteristics, occurrence and pathways of PhACs in water and wastewater, fate in the oriented sanitation, environmental and public health impacts. Furthermore, preventing pharmaceuticals in drinking-water, treatment technologies for their removal, knowledge gaps and future research for pharmaceuticals in drinking-water are also discussed. Advanced oxidation techniques, biological treatment systems, separation and treatment of urine for PhACs removal as effective tools are evaluated.
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ABSTRACT: The fates of the most commonly used brominated flame retardant, tetrabromobisphenol A (TBBPA), in wastewater treatment plants is obscure. Using a 14C-tracer, we studied TBBPA transformation in nitrifying activated sludge (NAS). During the 31-day incubation, TBBPA transformation (half-life 10.3 days) was accompanied by mineralization (17% of initial TBBPA). Twelve metabolites, including those with single benzene-ring, O-methyl TBBPA ether, and nitro-compounds, were identified. When allylthiourea was added to the sludge to completely inhibit nitrification, TBBPA transformation was significantly reduced (half-life 28.9 days), formation of the polar and single-ring metabolites stopped, but O-methylation was not significantly affected. Abiotic experiments confirmed the generation of mono- and di-nitro-brominated forms of bisphenol A in NAS by the abiotic nitration of TBBPA by nitrite, a product of ammonia-oxidizing microorganisms (AOMs). Three biotic (type II ipso-substitution, oxidative skeletal cleavage, and O-methylation) and one abiotic (nitro-debromination) pathways were proposed for TBBPA transformation in NAS. Apart from O-methylation, AOMs were involved in three other pathways. Our results are the first to provide information about the complex metabolism of TBBPA in NAS and they are consistent with a determining role for nitrifiers in TBBPA degradation, by initiating its cleavage into single-ring metabolites that are substrates for the growth of heterotrophic bacteria.Environmental Science and Technology 03/2015; DOI:10.1021/es5059007 · 5.48 Impact Factor