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EN
Among the waste produced by municipal wastewater treatment plants, the largest technological problem is caused by the excessive sludge, the management of which consumes almost half of the costs of the entire installation. Regardless of the final disposal route, which may be, for example, reclamation of degraded areas, the the sludge derived from a wastewater treatment plant should be firstly subjected to a series of processes aimed at: reducing its volume, improving selected physical properties, recovering energy, rot preventing (stabilization) or eliminating epidemiological threats (hygenizing). These goals could be implemented using commonly known technologies, including: dewatering, liming, thermoconditioning, methanogenesis or composting. One of the alternative solutions is the use of ozonation of raw excess sludge, which, in principle, may lead to the simultaneous resolution of several above-mentioned problems, such as: drainage properties improvement, increase the bioavailability of organic matter for biogas production, as well as the removal of undesirable microorganisms. Confirmation of the hygenizing effects usually requires arduous microbiological methods; therefore, the fast and reliable tools of molecular biology could prove their usefulness in this case. In this study, the possibility of determining the dynamics of selected groups of microorganisms (including changes in total bacteria amount, Proteobacteria, Bacteroidetes, Firmicutes and Actinobacteria) after sewage sludge ozonation, by using the semi-quantitative RealTime polymerase chain reaction (qPCR), wasinvestigated.
EN
Toxic effects of polycyclic aromatic hydrocarbons (PAHs) have been extensively studied in fish, although knowledge concerning biological activities of phenanthrene and its derivatives remains still incomplete. The aim of this work was to evaluate lethal and sublethal effects of benzo(a)pyrene, phenanthrene and phenanthrene derivatives (1-methylphenanthrene, 4-methylphenanthrene, 1-phenylphenanthrene and 4-phenylphenanthrene) on zebrafish (Danio rerio) larvae. We conducted acute toxicity test, using 96h static renewal exposure to a series of the PAH concentrations (0.05, 0.50, 5.00, 50.00µmol*l-1), to determine the No Effect Concentration (NEC) value for each compound examined. The mean NEC estimates obtained in the study were 5.16۪.45µmol*l-1 (B[a]P), 4.88۪.13µmol*l-1 (Ph), 40.24䔰.93µmol*l-1 (1P-Ph), 47.92ۭ.61µmol*l-1 (1M-Ph), 24.31۱.33µmol*l-1 (4P-Ph) and 3.11۫.01µmol*l-1 (4M-Ph) and suggested the following order of PAH toxicities on Danio rerio larvae: 4M-Ph>Ph˜B[a]P>4PPhᲙP-Ph>1M-Ph. To gain insight into possible molecular mechanisms of apparent toxicity of phenanthrene derivatives on zebrafish larvae, we examined mRNA expression of cyp1a, cyp1b1, and vtg genes in the larvae exposed for 48h to a PAH concentration of 0.50µmol*l-1. Whereas the larvae exposed to each tested PAH displayed many developmental abnormalities (i.e. pericardial and yolk sac edema, dorsal curvature, or tail malformations), no significant upregulation of cyp1a and cyp1b1 mRNA was observed, except for zebrafish exposed to B[a]P. However, significant reduction of vtg mRNA was observed in the larvae exposed to phenanthrene and its 4P- derivative. The results may contribute to the development of a new knowledge about effects of structurally diverse phenanthrene derivatives on vertebrate organisms.
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