Evaluation of potential human health risks from exposure to volatile organic compounds in contaminated urban groundwater in the Sava river aquifer, Belgrade, Serbia.

The oil pollutant in the Sava River aquifer in the residential area of Belgrade, Serbia was investigated in order to analyze the extent, origin and spatial distribution of the pollution, with the aim to estimate potential human health risks from exposure to the compounds detected. Analytical methods indicated that the dominant compounds in this oil pollutant were gasoline range organic compounds. Benzene, toluene, ethylbenzene and xylenes (BTEX) were identified as compounds of concern and quantified by headspace gas chromatography. The concentrations of benzene measured at all sampling points were higher than the remediation value while the maximum concentrations of BTEX quantified were among the highest concentrations of these compounds reported in the petroleum-contaminated aquifers in the world. The assessment of the human health risks from exposure to BTEX-covered industrial scenario for adult receptors and residential scenario for adult receptors and children. The exposure routes analyzed were dermal contact with and ingestion of contaminated water, considering both cancer and non-cancer effects. The analysis of the lifetime incremental cancer risk indicated the potential for adverse health effects for human exposure at the investigated location, and because of that it was interpreted as an unacceptable risk level or risks of high priority which required immediate consideration for remedial measures at this location. A complete set of mitigation measures was proposed including: groundwater decontamination treatment, installation of filters for tap water, development of the system for monitoring of BTEX in the groundwater and development of the emergency response capacities at this location.

Study on the assessment of humification processes during biodegradation of heavy residual fuel oil.

The aim of this study was to investigate the creation of humic substances during biodegradation of heavy residual fuel oil, because there are indications that substances similar to humic substances are generated during biodegradation of polycyclic aromatic hydrocarbons. In the study, which lasted for 110 days, biodegradation of heavy residual fuel oil was carried out in a layer of artificial soil substrate. The initial concentration of the total petroleum hydrocarbon in the prepared artificial soil substrate (biopile) was 23.1 g kg-1 dry weight (d.w.). At the end of the process, the total petroleum hydrocarbons were reduced to 8.1 g kg-1 d.w. in the inoculated biopile, while the content of humic acids increased during bioremediation from 3.15 g kg-1 d.w. to 4.95 g kg-1 d.w. The humic acids extracted from biopile during the biodegradation process were characterized by various chemical techniques (elemental analysis, spectrofluorimetric analysis, electrochemical measurements, and size exclusion chromatography). The results showed that levels of C, H and the H/C ratio decreased as the biodegradation process progressed. This indicated that humic acids aromatization process took place and this was confirmed by the spectrofluorimetric analysis. The increase of oxygen percentage and the O/C ratio in the humic acids after the biodegradation treatment indicated an increase in functional oxygen groups. Additional analyses of humic acids from the inoculated biopile showed that they were transformed during the bioremediation process. They had greater redox and buffering capacities and a larger portion of the fractions had high molecular mass. Also, the humification parameters (the CHAs/CFAs ratio and CHAs/Corg ratio) increased during the biodegradation. This is one of the few studies that describes the generation of humic substances during the biodegradation of oil compounds.

Autochthonous Enterococcus durans PFMI565 and Lactococcus lactis subsp. lactis BGBU1-4 in Bio-Control of Listeria monocytogenes in Ultrafiltered Cheese.

Nowadays, consumers are interested in cheese produced without chemical additives or high-temperature treatments, among which, protective lactic acid bacteria (LAB) cultures could play a major role. In this study, the aims were to isolate, identify and characterize antilisterial LAB from traditionally produced cheese, and utilize suitable LAB in cheese production. Among 200 isolated LAB colonies, isolate PFMI565, with the strongest antilisterial activity, was identified as Enterococcus durans. E. durans PFMI565 was sensitive to clinically important antibiotics (erytromicin, tetracycline, kanamycin, penicillin, vancomycin) and had low acidifying activity in milk. E. durans PFMI565 and the previously isolated bacteriocin producer, Lactococcus lactis subsp. lactis BGBU1-4, were tested for their capability to control Listeria monocytogenes in experimentally contaminated ultrafiltered (UF) cheeses during 35 days of storage at 4 °C. The greatest reductions of L. monocytogenes numbers were achieved in UF cheese made with L. lactis subsp. lactis BGBU1-4 or with the combination of L. lactis subsp. lactis BGBU1-4 and E. durans PFMI565. This study underlines the potential application of E. durans PFMI565 and L. lactis subsp. lactis BGBU1-4 in bio-control of L. monocytogenes in UF cheese.

Bacterial diversity in typical abandoned multi-contaminated nonferrous metal(loid) tailings during natural attenuation.

Abandoned nonferrous metal(loid) tailings sites are anthropogenic, and represent unique and extreme ecological niches for microbial communities. Tailings contain elevated and toxic content of metal(loid)s that had negative effects on local human health and regional ecosystems. Microbial communities in these typical tailings undergoing natural attenuation are often very poorly examined. The diversity and inferred functions of bacterial communities were examined at seven nonferrous metal(loid) tailings sites in Guangxi (China), which were abandoned between 3 and 31 years ago. The acidity of the tailings sites rose over 31 years of site inactivity. Desulfurivibrio, which were always coupled with sulfur/sulfide oxidation to dissimilate the reduction of nitrate/nitrite, were specific in tailings with 3 years abandonment. However, genus beneficial to plant growth (Rhizobium), and iron/sulfur-oxidizing bacteria and metal(loid)-related genera (Acidiferrobacter and Acidithiobacillus) were specific within tailings abandoned for 23 years or more. The increased abundance of acid-generating iron/sulfur-oxidizing and metal(loid)-related bacteria and specific bacterial communities during the natural attenuation could provide new insights for understanding microbial ecosystem functioning in mine tailings. OTUs related to Sulfuriferula, Bacillus, Sulfurifustis, Gaiella, and Thiobacillus genera were the main contributors differentiating the bacterial communities between the different tailing sites. Multiple correlation analyses between bacterial communities and geochemical parameters indicated that pH, TOC, TN, As, Pb, and Cu were the main drivers influencing the bacterial community structures. PICRUSt functional exploration revealed that the main functions were related to DNA repair and recombination, important functions for bacterial adaptation to cope with the multi-contamination of tailings. Such information provides new insights to guide future metagenomic studies for the identification of key functions beyond metal-transformation/resistance. As well, our results offers novel outlooks for the management of bacterial communities during natural attenuation of multi-contaminated nonferrous metal(loid) tailings sites.

China's most typical nonferrous organic-metal facilities own specific microbial communities.

The diversity and function of microorganisms have yet to be explored at non-ferrous metal mining facilities (NMMFs), which are the world's largest and potentially most toxic sources of co-existing metal(loid)s and flotation reagents (FRs). The diversity and inferred functions of different bacterial communities inhabiting two types of sites (active and abandoned) in Guangxi province (China) were investigated for the first time. Here we show that the structure and diversity of bacteria correlated with the types of mine sites, metal(loid)s, and FRs concentrations; and best correlated with the combination of pH, Cu, Pb, and Mn. Combined microbial coenobium may play a pivotal role in NMMFs microbial life. Arenimonas, specific in active mine sites and an acidophilic bacterium, carries functions able to cope with the extreme conditions, whereas Latescibacteria specific in abandoned sites can degrade organics. Such a bacterial consortium provides new insights to develop cost-effective remediation strategies of co-contaminated sites that currently remain intractable for bioremediation.

Efficient removal of priority, hazardous priority and emerging pollutants with Prunus armeniaca functionalized biochar from aqueous wastes: Experimental optimization and modeling.

This paper investigates the ability of the phosphoric acid functionalized Prunus armeniaca stones biochar (AsPhA) prepared by thermochemical activation to remove lead (Pb2+), cadmium (Cd2+), nickel (Ni2+), naproxen and chlorophenols from aqueous wastes. The engineered biochar was characterized using the Scanning Electron Microscopy, Energy-dispersive X-ray Spectroscopy, Fourier Transform Infrared Spectroscopy and Brunauer, Emmett and Teller technique. The batch studies were performed by varying the initial pH of the solution (2-9), adsorbent dosage (0.2-10gL-1), contact time (5-60min), temperature (22, 32 and 42°C) and initial adsorbate concentration (5-500mgL-1). With the optimal process conditions, the adsorption efficiency was over 95% (100mgL-1). The results were fitted with three kinetic and three equilibrium theoretical adsorption models. The adsorption process has good correlation with pseudo-second-order reaction kinetics. Adsorption mechanism was found to be controlled by pore, film and particle diffusion, throughout the entire adsorption period. The monolayer adsorption capacities were found to be 179.476, 105.844 and 78.798mgg-1 for Pb2+, Cd2+ and Ni2+, respectively. Thermodynamic parameters such as Gibbs energy, enthalpy and entropy were also calculated. Additionally, preliminary results indicated a strong affinity of the biochar for selected organic micropollutants: naproxen and chlorophenols. Based on desorption study results, biochar was successfully regenerated in 3cycles with diluted phosphoric acid produced as a waste stream during washing of the biochar after thermochemical activation. The experimental results were applied in a two-stage completely stirred tank reactor design. Cost estimation of AsPhA production substantiated its cost effectiveness and adsorption costs of selected pollutants were 5 times lower than with the commercial activated carbons. Based on the low-cost and high capacity, engineered biochar can be used as a highly efficient eco-friendly adsorbent for removal of heavy metal and organic micropollutants from wastewaters systems.