Factors affecting the removal of organic micropollutants from wastewater in conventional treatment plants (CTP) and membrane bioreactors (MBR)

As a consequence of insufficient removal during treatment of wastewater released from industry and households, different classes of organic micropollutants are nowadays detected in surface and drinking water. Among these micropollutants, bioactive substances, e.g., endocrine disrupting compounds and pharmaceuticals, have been incriminated in negative effects on living organisms in aquatic biotope. Much research was done in the last years on the fate and removal of those compounds from wastewater. An important point it is to understand the role of applied treatment conditions (sludge retention time (SRT), biomass concentration, temperature, pH value, dominant class of micropollutants, etc.) for the efficiency of conventional treatment plants (CTP) and membrane bioreactors (MBR) concerning the removal of micropollutants such as pharmaceuticals, steroid- and xeno-estrogens. Nevertheless, the removal rates differ even from one compound to the other and are related to the physico-chemical characteristics of the xenobiotic

Aesthetic aspects in representation lace from traditional Moldovan towel

Interest in national values increases with interest in culture, diversity, national identity. The handcrafted Moldovan towel (romanian – ”prosop”) is part of the national heritage of the Republic of Moldova. He belongs to the group of ceremonial textiles and represents a symbol of national culture. A special significance has the handcrafted towels, made of vegetable textile fibers. Of great interest are the laces (horboțică) with which their terminations are decorated. Towels decorated on two sides, on 3 and 4 sides, are identified. Depending on the occasion, they vary according to the complexity and type of ornamental elements used, but also their width. For example, towels given by young married people to godparents have ornaments reproduced in lace such as peacock, turkey, cuckoo, complex floral ensembles, with a width of 30-40 cm

Impact of bio-augmentation with Sphingomonas sp. strain TTNP3 in membrane bioreactors degrading nonylphenol

This study evaluates the potential of bio-augmentation to improve the degradation of recalcitrant nonylphenol during the wastewater treatment in membrane bioreactors (MBR). One MBR containing activated sludge was bio-augmented using multistep inoculation with freeze dried Sphingomonas sp. strain TTNP3, whereas a second control reactor contained activated sludge solely. The 14C-labeled-nonylphenol isomer (4-[1-ethyl-1,3-dimethylpentyl]phenol) was applied as a single pulse. Bio-augmentation resulted in an immediate increase of dissolved radioactivity in the effluent in comparison to the control reactor (13% and 2% of initially applied radioactivity after 1day, respectively). After 5days of operation, the retentate of the bio-augmented reactor contained only 7% of the initial radioactivity in contrast to 50% in the control reactor. The radioactivity associated to the mixed liquor suspended solids, i.e., the suspension of biomass and other solids on the retentate side of the membrane, was mainly found as non-extractable residues that were increasingly formed during prolonged reactor operation, especially for the control MBR. HPLC-LSC and GC-MSn analyses revealed that the bio-augmented reactor produced more polar hydroquinone as main degradation intermediate, whereas the control reactor effluent contained a complex mixture of apolar compounds with shortened oxidized alkyl chains. Thus, the apparent differences in the behavior of nonylphenol between the reactors were due to the catabolism of nonylphenol conferred by bio-augmentation with Sphingomonas sp. strain TTNP

Investigation by thermodesorption spectroscopy of hydrogen accumulation features in Zr-1%Nb zirconium alloy during gas-phase hydrogenation

Modern trends in human development require more and more electricity to maintain the pace of economic and scientific development. One of the most environmentally friendly methods of electricity production is the use of nuclear power plants (NPPs). In connection with high impact on structural materials of nuclear power plants cores there is uncontrolled degradation of core material. Understanding the degradation processes will help predict and prevent various man-made disasters. The purpose of this work is to study the accumulation of hydrogen in the zirconium alloy Zr-1%Nb (E110). In this work, we studied the processes of hydrogen sorption and desorption by the zirconium alloy Zr-1%Nb

Removal of trace organics by MBR treatment: The role of molecular properties

This study examined the relationship between specific molecular features of trace organic contaminants and their removal efficiencies by a laboratory scale membrane bioreactor (MBR). Removal efficiencies of 40 trace organic compounds were assessed under stable operating conditions. The reported results demonstrate an apparent correlation between chemical structures and the removal of trace organic contaminants by the laboratory scale MBR system. The removal of all 14 very hydrophobic (Log D \u3e 3.2) trace organic compounds selected in this study was consistently high and was above 85%. The occurrence and types of electron withdrawing or donating functional groups appear to be important factors governing their removal by MBR treatment. In this study, all hydrophilic and moderately hydrophobic (Log D \u3c 3.2) compounds possessing strong electron withdrawing functional groups showed removal efficiency of less than 20%. In contrast, high removal efficiencies were observed with most compounds bearing electron donating functional groups such as hydroxyl and primary amine groups. A qualitative framework for the assessment of trace organic removal by MBR treatment was proposed to provide further insights into the removal mechanisms

Studies on the behaviour of endocrine disrupting compounds in a membrane bioreactor

The present research focuses on the fate of hydrophobic micropollutants in a membrane bioreactor (MBR) and their removal in it. MBR represents one of the most promising innovations in the field of wastewater treatment because of the high efficiency in removal of organics and nutrients. The high quality of the effluent is obtained by the complete retention of suspended solids, the almost complete removal of pathogens, and the possibility to increase biodegradation of micropollutants because of the higher sludge retention time in MBR, in comparison to the conventional activated sludge treatment. For the micropollutants which have hydrophobic properties the challenge is to distinguish the real biodegradation from abiotic physico-chemical phenomena like adsorption and volatilisation during the membrane bioreactor treatment. In order to achieve it, the application of radiolabelled hydrophobic model markers is considered to be a powerful technique. In this study the possible fate of NP during wastewater treatment by using a lab-scale MBR was investigated. After a single pulse of the 14C-labelled-NP isomer (4-[1-ethyl-1,3-dimethylpentyl]phenol) as radiotracer, the applied radioactivity was monitored in the MBR system over 34 days. The balance of radioactivity at the end of the study showed that 42% of the applied radioactivity was recovered in the effluent as degradation products of NP, 21% was removed with the daily excess sludge from the MBR, and 34% was recovered as adsorbed in the component parts of the MBR. A high amount of NP was associated to the sludge during the test period, while degradation products were mainly found in the effluent. Partial identification of these metabolites by means of HPLC-tandem mass spectrometry coupled to radio-detection showed that they were alkyl-chain oxidation products of NP. The use of a radiolabelled test compound in a lab-scale MBR was found suitable to demonstrate that the elimination of NP through mineralization and volatilization processes under the applied conditions was negligible (both less than 1%). However, the removal of NP via sorption and the continuous release of oxidation products of NP in the permeate were highly relevant. The fate of two differently labelled radioactive forms of 17alpha-ethinylestradiol (EE2), one with the ring and the other one with the ethinyl group labelled was studied during the membrane bioreactor (MBR) process. The system was operated using a synthetic wastewater representative for the pharmaceutical industry and the activated sludge was obtained from a large-scale MBR treating pharmaceutical wastewater. Before the five days radioactive experiment, the activated sludge was adapted for 29 days continuously to non-labelled EE2. Balancing of radioactivity could demonstrate that mineralization amounted to less than 1% of the applied radioactivity. The EE2 residues remained mainly sorbed in the reactor, resulting in a removal of approximately 80% relative to the concentration in the influent. The same metabolite pattern in the radiochromatograms of the two differently labelled 14C-EE2 molecules led to the assumption that the elimination pathway does not involve the removal of the ethinyl group from the EE2 molecule. The bioaugmentation of membrane bioreactor in order to improve the degradation of recalcitrant nonylphenol during the wastewater treatment was studied. The 14C-labelled NP isomer 4-[1-ethyl-1,3-dimethylpentyl]phenol was applied as single pulse to the membrane bioreactor bioaugmented with the bacterium Sphingomonas sp. strain TTNP3. The effects of five successive inoculations of the membrane bioreactor with this strain able to degrade NP were investigated in comparison to a non-bioaugmented reactor. Results showed that the radioactivity spiked in the bioaugmented system was retrieved mostly in the effluent (56%), followed by fractions sorbed to the system (25%), associated with the excess sludge (9%) and collected from the gas phase as CO2 resulting from mineralization (2.3%). The degradation products identified in the treated effluent and in the MLSS were specific metabolites of catabolism of the NP by Sphingomonas, e.g. hydroquinone resulting from ipso-substitution. The capacity of this bacterium to excrete biosurfactants and to increase nonylphenol bioavailability was investigated. The presence and persistence of the strain in the membrane bioreactor was examined by performing polymerase chain reaction–denaturing gradient gel electrophoresis (PCR-DGGE)