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Spent mineral oil-based metalworking fluids are waste products of the machining processes and contribute substantially to the global industrial pollution with petroleum oil products. Wastewaters containing oily emulsions are ecologically hazardous and thus a variety of methods have been implemented to prevent these effluents from affecting the natural environment. Most of these methods rely upon physical-chemical treatment and phase separation; however, none of them proved to be effective enough to meet tightening environmental regulations. Therefore, novel technologies need to be elaborated and there is growing interest in implementing biological treatment methods based on microbial bioremediation. In this study an oil/water emulsion obtained from a waste stream of the metal-processing industry was tested for biodegradability of its organic constituents. This liquid waste was found non-toxic to bacterial consortia and was colonized with indigenous microorganisms (approx. 10 7 cfu · cm -3). The total load of organic content was determined as a chemical oxygen demand (COD) value of 48 200 mg O2 · dm -3. Emulsion treatment was carried out using a threefold wastewater dilution and employing two variants of biostimulated aerobic bacterial communities: (1) uninoculated emulsion, where bioremediation was carried out by the autochthonous bacteria alone, and (2) wastewater samples inoculated with a ZB-01 microbial consortium which served as a source of specialized bacteria for process bioaugmentation. Biodegradation efficiency achieved in a 14-day test was monitored by measuring both the COD parameter and the concentration of high-boiling organic compounds. Both approaches yielded satisfactory results showing significant reduction of the emulsion organic fraction; however, the resultant decrease of wastewater load tended to be more efficient for the case where the process was bioaugmented with the inoculated consortium. Gas chromatography analyses coupled with mass spectrometric detection (GC-MS) confirmed high degradation yields obtained for both cases studied (58 and 71%, respectively) in a 28-day test. It is concluded that oil-based metalworking emulsions can undergo efficient biological treatment under conditions enabling aerobic bacterial proliferation and that xenobiotic biodegradation kinetics can be accelerated by bioaugmenting the process with allochthonous microbial consortia.

A yeast isolate revealing unique enzymatic activities and substrate-dependent polymorphism was obtained from autochthonous microflora of soil heavily polluted with oily slurries. By means of standard yeast identification procedures the strain was identified as Trichosporon cutaneum. Further molecular PCR product analyses of ribosomal DNA confirmed the identity of the isolate with the genus Trichosporon. As it grew on methanol as a sole carbon source, the strain appeared to be methylotrophic. Furthermore, it was also able to utilize formaldehyde. A multi-substrate growth potential was shown with several other carbon sources: glucose, glycerol, ethanol as well as petroleum derivatives and phenol. Optimum growth temperature was determined at 25 degrees C, and strong inhibition of growth at 37 degrees C together with the original soil habitat indicated lack of pathogenicity in warm-blooded animals and humans. The unusually high tolerance to xenobiotics such as diesel oil (>30 g/l), methanol (50 g/l), phenol (2 g/l) and formaldehyde (7.5 g/l) proved that the isolate was an extremophilic organism. With high-density cultures, formaldehyde was totally removed at initial concentrations up to 7.5 g/l within 24 h, which is the highest biodegradation capability ever reported. Partial biodegradation of methanol (13 g/l) and diesel fuel (20 g/l) was also observed. Enzymatic studies revealed atypical methylotrophic pathway reactions, lacking alcohol oxidase, as compared with the conventional methylotroph Hansenula polymorpha. However, the activities of glutathione-dependent formaldehyde dehydrogenase, formaldehyde reductase, formate dehydrogenase and unspecific aldehyde dehydrogenase(s) were present. An additional glutathione-dependent aldehyde dehydrogenase activity was also detected. Metabolic and biochemical characteristics of the isolated yeast open up new possibilities for environmental biotechnology. Some potential applications in soil bioremediation and wastewater decontamination are discussed.

Presented research aimed at investigating the effect of short-term contact with petroleum-derived substances (PDSs) on life parameters of Porcellio scaber Latr. (Isopoda) and accumulation of polycyclic aromatic hydrocarbons (PAHs) in its body. The influence of presence of P. scaber on the total petroleum hydrocarbons (TPH) content in soil was also determined. The following objects were established: control—unpolluted soil; soil polluted with petrol; soil polluted with diesel fuel and soil polluted with used engine oil. Every pollutant was used in the amounts equal to 6000 mg of fuel/kg d.m. of soil 15 months earlier. In the laboratory, survival and body mass change of P. scaber reared in investigated soils were observed. The delivered food was not contaminated with PDSs. P. scaber reveals a considerable resistance in a short (4 weeks) contact with PDSs, evidenced as high survivability (from 68% on the soil polluted with engine oil to 77% on the soil polluted with diesel fuel) and undisturbed increase in body mass (on the level similar to control). It indicates the potential usefulness of this animal as a monitoring organism. No positive correlation was observed between TPH depletion in the soils contaminated with PDSs and P. scaber presence during 4 weeks of the experiment. PAH level in P. scaber bodies was generally very low (with the highest level of anthracene 0.40 μg/g of wet mass—after 4 weeks of rearing on the diesel fuel–contaminated soil), which may confirm the thesis about considerable abilities of isopods for biotransformation of these pollutants and low susceptibility to these xenobiotic penetration through integuments. However, a tendency for accumulation for phenanthrene and anthracene in conditions of soil polluted with diesel fuel was observed respectively 0.07 and 0.21 μg/g of wet mass for phenanthrene and 0.22 and 0.40 μg/g of wet mass for anthracene, observed successively in the 2nd and 4th week of rearing.