Occurrence and fate of emerging wastewater contaminants in Western Balkan Region

This paper reports on a comprehensive reconnaissance of over seventy individual wastewater contaminants in the region of Western Balkan (WB; Bosnia and Herzegovina, Croatia and Serbia), including some prominent classes of emerging contaminants such as pharmaceuticals and personal care products, surfactants and their degradation products, plasticizers, pesticides, insect repellents, and flame retardants. All determinations were carried out using a multiresidue analytical approach, based on the application of gas chromatographic and liquid chromatographic techniques coupled to mass spectrometric detection. The results confirmed a widespread occurrence of the emerging contaminants in municipal wastewaters of the region. The most prominent contaminant classes, determined in municipal wastewaters, were those derived from aromatic surfactants, including linear alkylbenzene sulphonates (LAS) and alkylphenol polyethoxylates (APEO), with the concentrations in raw wastewater reaching into the mg/l range. All other contaminants were present in much lower concentrations, rarely exceeding few microg/l. The most abundant individual compounds belonged to several classes of pharmaceuticals (antimicrobials, analgesics and antiinflammatories, beta-blockers and lipid regulators) and personal care products (fragrances). Due to the rather poor wastewater management practices in WB countries, with less than 5% of all wastewaters being biologically treated, most of the contaminants present in wastewaters reach ambient waters and may represent a significant environmental concern.     

SIMULATION OF TURBULENT FLOW IN IRREGULAR GEOMETRIES USING A CONTROL-VOLUME FINITE-ELEMENT METHOD

A modified error indicator and a locally implicit scheme with anisotropic dissipation model on quadrilateral-triangular mesh are developed to study the supersonic turbulent flow over a backward-facing step. In the Cartesian coordinate system, the unsteady Favre-averaged Navier-Stokes equations with a low-Reynolds-number k –ε turbulence model are solved. The modified error indicator, in which the unified magnitude of substantial derivative of pressure and unified magnitude of substantial derivative of vorticity magnitude are incorporated, is applied to treat the new node spacing of mesh remeshing. To assess the present approach, the transsonic turbulent flow around an NACA 0012 airfoil is performed. According to the high-resolution result on the adaptive mesh, the structure of the back-step corner vortex, expansion wave, and oblique shock wave are distinctly captured.     

Occurrence, partition and removal of pharmaceuticals in sewage water and sludge during wastewater treatment

During 8 sampling campaigns carried out over a period of two years, 72 samples, including influent and effluent wastewater, and sludge samples from three conventional wastewater treatment plants (WWTPs), were analyzed to assess the occurrence and fate of 43 pharmaceutical compounds. The selected pharmaceuticals belong to different therapeutic classes, i.e. non-steroidal anti-inflammatory drugs, lipid modifying agents (fibrates and statins), psychiatric drugs (benzodiazepine derivative drugs and antiepileptics), histamine H2-receptor antagonists, antibacterials for systemic use, beta blocking agents, beta-agonists, diuretics, angiotensin converting enzyme (ACE) inhibitors and anti-diabetics. The obtained results showed the presence of 32 target compounds in wastewater influent and 29 in effluent, in concentrations ranging from low ng/L to a few μg/L (e.g. NSAIDs). The analysis of sludge samples showed that 21 pharmaceuticals accumulated in sewage sludge from all three WWTPs in concentrations up to 100 ng/g. This indicates that even good removal rates obtained in aqueous phase (i.e. comparison of influent and effluent wastewater concentrations) do not imply degradation to the same extent. For this reason, the overall removal was estimated as a sum of all the losses of a parent compound produces by different mechanisms of chemical and physical transformation, biodegradation and sorption to solid matter. The target compounds showed very different removal rates and no logical pattern in behaviour even if they belong to the same therapeutic groups. What is clear is that the elimination of most of the substances is incomplete and improvements of the wastewater treatment and subsequent treatments of the produced sludge are required to prevent the introduction of these micro-pollutants in the environment.     

Expression of genes involved in nucleotide excision repair and sensitivity to cisplatin and melphalan in human cancer cell lines

DNA repair has been proposed to be an important determinant of cancer cell sensitivity to alkylating agents and cisplatin (DDP). Nucleotide excision repair (NER), which represents one of the most important cellular DNA repair processes able to remove a broad spectrum of DNA lesions, is involved in the recognition and repair of the crosslinks caused by DDP and melphalan (L-PAM). In this study, the mRNA levels of the different genes involved in NER (ERCC1, XPA, XPB, XPC, XPD, XPF) were examined in a panel of eight different human cancer cell lines, together with the overall DNA repair capacity using a host cell reactivation assay of a damaged plasmid. A statistically significant correlation was observed between the relative expression of XPA/XPC (P < 0.05) and ERCC1/XPC (P < 0.05) mRNAs. No correlation was found between the DDP and L-PAM IC50S and the relative mRNA expression of the tested NER genes. When the overall cellular DNA repair capacity was studied, carcinomas seemed to have a higher repair activity than leukaemias; but this repair DNA activity correlated neither with the mRNA expression of the different NER genes nor with DDP and L-PAM IC50S. These data seem to suggest that even if the NER pathway is an important determinant for the cytotoxicity of alkylating agents, as demonstrated by the extremely high sensitivity to alkylating agents in cells lacking this repair system, other factors have to play a role in regulating the cellular sensitivity/resistance to these antitumour drugs.     

Calcium phosphate porous pellets as drug delivery systems: Effect of drug carrier composition on drug loading and in vitro release

Drug loaded porous calcium phosphate bone substitutes are studied for targeted drug delivery applications. In this study, porous hydroxyapatite and beta-tricalcium phosphate pellets were investigated as anti-inflammatory drug carriers and their ibuprofen adsorption and release properties were compared. While the adsorption equilibrium time of 1 h was obtained for both pellets, hydroxyapatite pellets showed a higher adsorption capacity than beta-tricalcium phosphate. The physico-chemical characterisations of loaded pellets confirmed an ibuprofen reversible physisorption on both hydroxyapatite and beta-tricalcium phosphate pellets. Moreover, higher adsorption capacity of hydroxyapatite was attributed to their physical differences. The in vitro ibuprofen release evaluation showed 100% release of ibuprofen from both hydroxyapatite and beta-tricalcium phosphate pellets which was found to be compatible with the obtained interactions between the pellets and ibuprofen.     

A time marching,finite area calculation of general quasi-one-dimensional flows

A numerical technique for calculating the quasi-one-dimensional steady flow of a viscous heat conducting compressible fluid, with allowance for wall friction and external heat transfer, is discussed. The time-dependent flow equations for a control volume are solved by an explicit, time marching, finite area method, basically of first order. The scheme's versatility is illustrated by calculating flows in convergent-divergent nozzles and, Fanno and Rayleigh line processes. The effects of the initial conditions and a relaxation factor used for increasing stability are assessed.     

Degradation of carbamazepine by Trametes versicolor in an air pulsed fluidized bed bioreactor and identification of intermediates

The paper describes the aerobic degradation of carbamazepine (CBZ), an anti-epileptic drug widely found in aquatic environment, from Erlenmeyer flask to bioreactor by the white-rot fungus Trametes versicolor. In Erlenmeyer flask, CBZ at approximately 9 mg L⁻¹ was almost completely eliminated (94%) after 6 d, while at near environmentally relevant concentrations of 50 μg L⁻¹, 61% of the contaminant was degraded in 7 d. Acridone, acridine, 10,11-dihydro-10,11-dihydroxy-CBZ, and 10, 11-epoxy-CBZ were identified as major metabolites, confirming the degradation of CBZ. The degradation process was then carried out in an air pulsed fluidized bioreactor operated in batch and continuous mode. Around 96% of CBZ was removed after 2 days in batch mode operation, and 10,11-dihydro-10,11-epoxycarbamazepine was found as unique metabolite. In bioreactor operated in continuous mode with a hydraulic retention time of 3 d, 54% of the inflow concentration (approx. 200 μg L⁻¹) was reduced at the steady state (25 d) with a CBZ degradation rate of 11.9 μg CBZ g⁻¹ dry weight d⁻¹. No metabolite was detected in the culture broth. Acute toxicity tests (Microtox) indicated that the final culture broth in both batch and continuous mode operation were non toxic, with 15 min EC50 values of 24% and 77%, respectively.     

Electrically Induced Disassembly of Electroactive Multilayer Films Fabricated from Water Soluble Polythiophenes

A novel approach to induce disassembly of electroactive multilayer films fabricated by the layer by layer assembly technique is reported. Electroactive multilayer films are constructed using water soluble polythiophenes, i.e., negatively charged poly[ammonium (3‐thienyl)ethoxypropanesulfonate] (SPT) and positively charged poly[3‐(3′‐thienyloxy)ethyltriethylammonium] (APT). “Induced” dissolution of the films in response to applied potential is investigated using a quartz crystal microbalance equipped with an electrochemical cell module (EC‐QCM‐D). Disassembly of the films is observed in response to three different potentials: +650, –650, and ±650 mV; however the time for dissolution varies as a function of the potential with films subject to +650 mV dissolving fully in 19 h compared to 42 h for films subject to –650 mV. These electroactive films and their controlled dissolution under applied potential represent an attractive architectural feature for bionic devices that could benefit from their conductivity and dissolution over time.     

Polar pollutants entry into the water cycle by municipal wastewater: a European perspective

The effluents of eight municipal wastewater treatment plants (WWTP) in Western Europe were analyzed by liquid-chromatography-mass spectrometry for the occurrence of 36 polar pollutants, comprising household and industrial chemicals, pharmaceuticals, and personal care products. In a long-term study of the effluents of three WWTP over 10 months, sulfophenyl carboxylates and ethylene diamino tetraacetate (EDTA) were detected above 10 microg/L on average, while benzotriazoles, benzothiazole-2-sulfonate, diclofenac, and carbamazepine showed mean concentrations of 1-10 microg/L, followed by some flame retardants, naphthalene disulfonates, and personal care products in the range of 0.1-1 microg/L. Half of the determined compounds were not significantly removed in tertiary wastewater treatment. By dividing the effluent concentration of a compound by its relative removal in WWTP a water cycle spreading index (WCSI) was calculated for each compound. We propose that this index provides a measure for the potential of a polar compound to spread along a partially closed water cycle after discharge with municipal wastewater and to occur in raw waters used for drinking water production. Polar pollutants in surface water samples of different catchments showed increasing concentration for compounds with increasing WCSI.     

Single-Material OECT-Based Flexible Complementary Circuits Featuring Polyaniline in Both Conducting Channels

The organic electrochemical transistor (OECT) with a conjugated polymer as the active material is the elementary unit of organic bioelectronic devices. Improved functionalities, such as low power consumption, can be achieved by building complementary circuits featuring two or more OECTs. Complementary circuits commonly combine both p- and n-type transistors to reduce power draw. While p-type OECTs are readily available, n-type OECTs are less common mainly due to poor stability of the n-type active channel material in aqueous electrolyte. Here, a complementary circuit is made using a pair of OECTs having polyaniline (PANI) as the channel material in both transistors. PANI, with a finite electrochemical window accessible at voltages lower than 1 V, exhibits a peak in current versus gate voltage when used as an active channel in an OECT. The current peak has two slopes, one n-like and one p-like, which correspond to different electrochemical regimes of the same underlying conjugated polymer. The electrochemistry enables the design of a complementary circuit using only PANI as the channel material. The PANI-based circuit is shown to have excellent performance with gain of ≈7 and is transferred on a flexible biocompatible chitosan substrate with demonstrated operation in aqueous electrolyte.