Oil derivatives are commonly used and they play a key role in the economy. They are used in many industries. Such big amounts of oil derivatives products generate vast quantity of pollution. Those pollutants can get into the ground and water beyond any control during catastrophes or due to inadequately managed waste and storage. The aim of the paper was to determine the level of oil derivatives pollution in the groundwater on the area of a former airbase, where between 1950 and 1990 the Soviet Army stationed. Analysis was carried out on groundwater samples from three piezometers placed on the area of the former airbase. In the samples some parameters were determined, i.e. temperature, reaction, electrolytic conductivity, the depth of groundwater surface, the content of aliphatic hydrocarbons, monoaromatic and polycyclic aromatic hydrocarbons. Determined amount of dissolved hydrocarbons was large what proves unsatisfactory effectiveness of previous rehabilitation processes.

The laboratory experiment was set up on a podzolic soil in two variants. In one of them non-sterile sewage sludge was introduced into the soil, and in the second - the same sludge but subjected previously to the process of sterilisation. In both variants the same doses of the sludge were applied: 30 (1%), 75 (2.5%), 150 (5%), 300 (10%) and 600 Mg·ha-1 (20%). Then, after 0.5, 1, 2, 3, 4 and 5 months, the soil of both experimental variants was analysed for the numbers of bacteria and fungi decomposing proteins, the rate of the process of ammonification, the rate of the process of nitrification, and for proteolytic activity. The results obtained revealed a stimulating effect of the sludge, both sterile and non-sterile, on the numbers of the microbial groups under study and on the rate of nitrification and protease activity. Only the process of ammonification was subject to inhibition. The observed effects of the sludge were the most pronounced in the case of the higher sludge doses. Significantly greater numbers of protein-decomposing fungi and higher activity of almost all (except for ammonifcation) analysed biochemical parameters in the soil with non-sterile sludge compared to that with sterile sludge indicate an effect of microorganisms from the sludge on the microbiological transformations of nitrogen in soil amended with sewage sludge.

The removal of benzene (B) and toluene (T) from aqueous solution by multi walled, single walled, and hybrid carbon nanotubes (MWCNTs, SWCNTs, and HCNTs) was evaluated for a nanomaterial dose of 1 g/l, concentration of 10-100 mg/l, and pH 7. The equilibrium amount removed by SWCNTs (B: 9.98 mg/g and T: 9.96 mg/g) was higher than for MWCNTs and HCNTs. Toluene has a higher adsorption tendency on CNTs than benzene, which is related to the increasing water solubility and the decreasing molecular weight of the compounds. The SWCNTs performed better for B and T sorption than the MWCNTs and HCNTs. Isotherms study based on isofit program indicate that the Generalized Langmuir-Freundlich (GLF) isotherm expression provides the best fit for benzene sorption, and that Brunauer-Emmett-Teller (BET) isotherm is the best fit for toluene adsorption by SWCNT. SWCNTs are efficient B and T adsorbents and possess good potential applications to water and wastewater treatment and maintain water of high quality that could be used for cleaning up environmental pollution.

The aim of this study was to determine the effect of the soil tillage system on soil enzymatic activity. The performed investigations, employing two soil tillage systems: classical (ploughing) and simplified (no-tillage), were carried out on Luvisols and Arenosols differing typologically, with regard to their kind and species. The activity of the following five enzymes was determined in soil samples: dehydrogenases, acid phosphatase, alkaline phosphatase, urease and protease. The applied enzymes tests turned out to be good indicators differentiating the examined soil objects depending on the employed tillage system. The employment of the simplified tillage system stimulated significantly the activity of the analysed enzymes irrespective of the soil type. This effect was particularly apparent in the top layer (0-10 cm) of the soil. An exceptionally wide range of activity was obtained for dehydrogenases indicating the usefulness of this group of enzymes for the evaluation of changes in the soil environment under the influence of the soil tillage system. The observed activity stimulation of the examined enzymes was accompanied by advantageous changes in soil chemical conditions.

Water and bottom sediment samples collected from a few fish-breeding ponds/reservoirs were subjected to tests. The aim of this paper was to determine the total content of aluminium and its fractions in the samples tested to estimate the potential risk to fish caused by the toxic forms of aluminium. The monomeric inorganic aluminium in waters was determined using the ion exchange and extraction-colorimetric method with oxychinoline according to Barnes's-Driscoll's procedure. The bottoms were fractionated using a three-step sequential extraction procedure and the microwave mineralisation. The total content of aluminium in waters and extracts was determined using the spectrophotometric method with eriochromocyanine R, and comparatively using the ICP OES technique. The results were subjected to statistical analysis. The level of concentration of labile Al in the waters about 26-34 μg/dm3 and content of exchangeable Al 5-34 mg/g range in bottom sediments are possibly hazardous to aquatic organisms.

The Timok River (202 km long, 4547 km2 basin area) is located in East Serbia. It is a right tributary of the Danube River and one of the most polluted watercourses in Serbia. On the basis of the data provided by the Republic Hydrometeorological Service of Serbia, the paper presents an analysis of water quality and pollution using the combined physico-chemical WPI index (Water Pollution Index) calculated for two periods - 1993-96 and 2006-2009 at four hydrological stations: Zaječar-Gamzigrad (Crni Timok River), Zaječar (Beli Timok River), Rgotina (Borska Reka River) and Čokonjar (Timok River). The following parameters were taken into consideration: dissolved O2, O2 saturation, pH, suspended sediments, Five Day Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (CODMn), nitrites, nitrates, orthophosphates, ammonium, metals (Cu, Fe, Mn, Hg, Ni, Zn, Cd), sulphates and coliform germs. The average WPI values were calculated for the observed periods based on the comparison of the annual average values of the listed parameters and defined standard values for the I water quality class (according to the Regulation on the Hygienic Acceptability of Potable Water of the Republic of Serbia). The highest pollution degree was recorded in the Borska Reka River, where heavy metal levels (especially manganese and iron) were significantly increased. These metals are indicators of inorganic pollution (primarily caused by copper mining). Also, increased values of the organic pollution indicators (ammonium, coliform germs, Five-Day Biological Oxygen Demand - BOD5) in the Borska Reka and the Timok rivers are the result of uncontrolled domestic wastewater discharge.

Disinfectants are commonly used in households, hospitals, in drug manufacturing, in food processing. With the ever-increasing antibiotic-resistance of microorganisms, it is crucial to rationally apply disinfectants in suitable concentrations, with proper active substance, as not all substances affect various organisms in the same way. Among the microorganisms that are particularly difficult to kill, there are bacteria producing spores - forms that have different structure and sensitivity to disinfectants than the vegetative forms. The aim of the study has been to examine the influence of frequently used disinfectant compounds upon the spores of bacteria of the Bacillus genus: B. cereus, B. mycoides, and B. subtilis. In the study of disinfectants the findings showed that the disinfectants with the best results against spores are: peracetic acid, hydrogen peroxide in concentrations of 30% as well as 5%, and Lysoformin 3000. The least efficient in fighting spores proved to be Isopropanol and Promanum N. Differentiation has been found to exist in the reaction of specific species to the preparation Rafasept, as B. subtilis occurred to be very sensitive to that compound, whereas Rafasept turned out to be ineffective in the case of B. mycoides and B. cereus.

The factor which essentially affects sludge biodegradation rate is the degree of fluidization of insoluble organic polymers to the solved form, which is a precondition for availability of nutrients for microorganisms. The phases which substantially limit the rate of anaerobic decomposition include hydrolytic and methanogenic phase.

Subjecting excess sludge to the process of initial disintegration substantially affects the effectiveness of the process of anaerobic stabilization. As a result of intensification of the process of hydrolysis, which manifests itself in the increase in the value and rate of generating volatile fatty acids (VFA), elongation of methanogenic phase of the process and increase in the degree of fermentation of modified sludge can be observed. Use of initial treatment of sewage sludge i.e. thermal disintegration is aimed at breaking microorganisms' cells and release of intracellular organic matter to the liquid phase. As a result of thermal hydrolysis in the sludge, the volatile fatty acids (VFA) are generated as early as at the stage of the process of conditioning. The obtained value of VFA determines the course of biological hydrolysis which is the first phase of anaerobic stabilization.

The aim of the present study was to determine the effect of thermal disintegration of excess sludge on the effectiveness of the process of hydrolysis in anaerobic stabilization i.e. the rate of production of volatile fatty acids, changes in the level of chemical oxygen demand (COD) and increase in the degree of reduction in organic matter. During the first stage of the investigations, the most favourable conditions of thermal disintegration of excess sludge were identified using the temperatures of 50°C, 70°C, 90°C and heating times of 1.5 h - 6 h. The sludge was placed in laboratory flasks secured with a glass plug with liquid-column gauge and subjected to thermal treatment in water bath with shaker option. Another stage involved 8-day process of anaerobic stabilization of raw and thermally disintegrated excess sludge. Stabilization was carried out in mesophilic temperature regime i.e. at 37°C, under periodical conditions. In the case of the process of anaerobic stabilization of thermally disintegrated excess sludge at the temperature of 50°C and heating time of 6 h (mixture B) and 70°C and heating time of 4.5% (mixture C), the degree of fermentation of 30.67% and 33.63%, respectively, was obtained. For the studied sludge, i.e. mixture B and mixture C, maximal level of volatile fatty acids i.e. 874.29 mg CH3COOH/dm3 and 1131.43 mg CH3COOH/dm3 was found on the 2nd day of the process. The maximal obtained value of VFA was correlated on this day with maximal COD level, which was 1344 mg O2/dm3 for mixture B and 1778 mg O2/dm3 for mixture C.

The study of the effectiveness of the removal of anionic natural organic matter (fulvic acids-FA and humic acids-HA) and inorganic anions (F-, Br-, NO3-) in MIEX®DOC process was performed. The influence of physico-chemical parameters of feed water on the process performance was investigated. The ion exchange process was carried out using strongly basic, macroporous polystyrene resin MIEX® by Orica Watercare. The synthetic feed waters differ in composition, i.e. concentration of FA and HA (ca. 6 and 12 mg/L), anions content (F-, Br-, NO3-) and of various alkalinity (ca. 20 and 120 mg/L as CaCO3) were used. The study confirmed the possibility of application of MIEX®DOC process for removal of anionic contaminants from water. It also showed the significant impact of feed water parameters on the process effectiveness. Moreover, the strong dependence of anions (F-, Br-, NO3-) removal, FA and HA concentration on the resin dose was revealed.

One of the methods of sewage sludge disposal, which is based on its fertilizing properties, is its use in nature, e.g. in farming (if all the permissible standards are met). However, the sludge used for soil fertilization might also contain heavy metals, pathogenic microorganisms, thus causing contamination in soil foundation and deterioration of the conditions for development of indigenous organisms. Particular threat is posed by the existence of drug-resistant microorganisms in sewage sludge. This problem has not been researched in detail yet.

The authors of the present study aimed to determine qualitative changes in drug-resistant microorganisms in sandy soil fertilized with selected sewage sludge. Sewage sludge after different types of drying process (natural and solar) was added to the degraded sandy soil. The effect of the methods of sewage sludge drying on concentration of drug-resistant microorganisms in soil fertilized with the sludge was analysed.

The study demonstrated that sewage sludge dried naturally in drying beds pose threat to soil environment and, potentially, to people and animals which have contact with fertilized soils. In sandy soils fertilized with these types of sewage sludge, pathogenic forms which exhibit resistance to first-line antibiotics can be found.