Polycyclic aromatic hydrocarbons (PAHs) from petroleum and fossil fuels are one of the most dominant pollutants in the environment. Since aromatic fraction from petroleum diesel fuel is mainly composed of PAHs, it is important to discover new microorganisms that can biodegrade these compounds. This article describes the biodegradation of the aromatic fraction separated from petroleum diesel fuel using the strain Oerskovia sp. CHP-ZH25 isolated from petroleum oil-contaminated soil. The biodegradation was monitored by gravimetry and GC × GC-TOF MS. An innovative method was applied to visualize degraded compounds in the data provided by a GC × GC-TOF MS. It was shown that Oerskovia sp. CHP-ZH25 degraded 77.4% based on gravimetric analysis within 30 days. Average rate of degradation was 14.4 mg/L/day, 10.5 mg/l/day and 4.0 mg/l/day from 0 to 10 day, 10-20 and 20-30 day, respectively. The order of PAH degradation based on decrease in peak volume after 30 days of incubation was as follows: dibenzothiophene derivatives > benzo[b]thiophene derivatives > naphthalene derivatives > acenaphthene derivatives > acenaphthylene/biphenyl derivatives > fluorene derivatives > phenanthrene/anthracene derivatives. Here we demonstrated that Oerskovia sp. CHP-ZH25 could potentially be a suitable candidate for use in bioremediation of environments polluted with different PAHs.

Due to their extensive use, petroleum hydrocarbons are among the most common groundwater contaminants. Compared to the traditional methods of physical pumping of contamination from the aquifer and subsequent treatment (i.e., pump and treat), bioremediation is an economically cost-effective technology. The aim of this remediation approach is to transform biologically contaminants, most often by microbiological activity, into non-toxic compounds. More precisely, it is an active remediation process that involves biostimulation (increase of aquifer oxygenation, addition of nutrients) and/or bioaugmentation (injection of a concentrated and specialized population of microorganisms). Using both biostimulation and bioaugmentation, enhanced in situ groundwater bioremediation was applied at a hydrocarbon-contaminated site in Belgrade. The bioremediation treatment, applied over twelve months, was highly efficient in reducing the concentrations of total petroleum hydrocarbon (TPH) to acceptable levels. The concentration of TPH in the piezometer P-5 was reduced by 98.55 %, in the piezometer P-6 by 98.30 % and in the piezometer P-7 by 98.09 %. These results provided strong evidence on the potential of this remediation approach to overcome site-limiting factors and enhance microbiological activity in order to reduce groundwater contamination.

Concentrations of 10 potentially toxic trace elements were measured in soil samples collected from 18 sites in urban areas of Belgrade, the capital and the largest city in Serbia. Samples were analysed in order to assess the extent of soil contamination and to distinguish natural and anthropogenic input. The results demonstrated a general Zn, Pb, and Cd enrichment in surface samples, hence, after comparison with guidelines, it has been determined that there is a potential risk for human health. In the surface and buried samples, traces of cooper were detected. The highest concentrations of Cr (121 ± 12.3 mg/kg) and Ni (94.9 ± 12.6 mg/kg) were found at a sediment depth of 2 m and should be ascribed to geogenic sources. The results of HCA and PCA analysis supported a natural origin of Co, Cu, Mn, Cr, and Ni, while Cd, Zn, and Pb originated from anthropogenic inputs. Based on the pollution indices, Cd made the most dominant contribution, posing a high contamination risk in the studied area. Results of Nemerow pollution index (PI_N) and potential ecological risk index (PER) demonstrated that pollution by heavy metals in sediments on several sites is moderately intense.

The presented research includes the preparation, characterization, and implementation of magnetic biosorbent (Fe₃O₄/RWB), obtained from ragweed (Ambrosia artemisiifolia) biomass. Fe₃O₄/RWB was examined for the removal of a hazardous dye, malachite green (MG), from an aqueous solution in a batch system. The effects of the experimental parameters—initial dye concentration (10–300 mg/L), contact time (0–120 min), biosorbent dose (1–5 g/L), initial pH (2–10), ionic strength (0–1 mol/L), and temperature (298–318 K) on dye biosorption—were studied. The results showed that increases in biosorbent dose, contact time, and initial pH led to an increase in biosorption efficiency, while the increase in initial dye concentration, the ionic strength, and temperature had the opposite effect. The biosorption kinetics for MG on Fe₃O₄/RWB were analyzed with pseudo-first-order, pseudo-second-order, and Elovich kinetic models, while the Langmuir, Freundlich and Temkin isotherm models were used for equilibrium data analysis. It was observed that the MG biosorption followed the pseudo-second-order kinetic model, whereas the Langmuir model was the best fit for the equilibrium biosorption data of MG, with a Q_max of 34.1 mg/g. the desorption of MG from Fe₃O₄/RWB indicated reusability in five adsorption/desorption cycles, good performance, and potential in practical applications.

A dispersive solid-phase microextraction (DSPME) method based on amino-functionalized glycidyl methacrylate polymer was developed and optimized for preconcentration of the azo dye Congo Red (CR) from aqueous samples. Key factors affecting extraction efficiency, including sorbent amount, pH, extraction time, ionic strength, and eluent type, were studied. The method demonstrated good linearity, low limits of detection, and high enrichment factors. The DSPME method was successfully applied to tap water and industrial wastewater samples, showing its potential for environmental monitoring of azo dyes.