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In this article an assessment of the sediment metal pollution (cadmium, copper, chromium, lead, nickel, zinc) in the Veliki Backi canal (Serbia) was carried out using pseudo-total metal content, contamination factor (CF), pollution load index (PLI) and enrichment factor (EF). The study also encompassed pore-water metal concentrations and an assessment of sediment pollution based on the analysis of simultaneously extracted metals (SEM), acid volatile sulphides (AVS) and the sequential extraction procedure. The concentrations of metals are likely to result in harmful effects based on the comparison with sediment quality guidelines (Dutch, Canadian, US EPA - United States Environmental Protection Agency). The ratio of simultaneously extracted metals and volatile acid sulphides was found to be greater than 1 in only one location, which is already recognized as a place of high risk based on the criteria applied. Other samples had Σ[SEM]/[AVS]1, despite their high risk classification based on the applied criteria. According to the sequential extraction procedure, zinc and nickel exhibit high risk in most samples, whereas other metals show low and medium risk. The CF values for Cr, Cu and Zn were6 in most samples, which denotes very high contamination by these metals. The PLI values indicated moderate and high pollution. The EF values for all metals studied except for Cd in some cases were1.5, suggesting anthropogenic impact. The obtained results will be invaluable for future activities regarding sediment monitoring and will facilitate the selection of appropriate criteria when evaluating sediment quality.

This study attempts to determine the possibilities and limitations of the immobilization of galvanic wastes by their incorporation into clay-based materials. It focuses on the effects of several processing parameters such as the temperature of thermal treatment, the relative amount of sludge, and the physico-chemical aspects of the sample, on the fixing level of relevant metals (Zn, Ni, Fe, Mn, Pb, Cu, Cr) in thermally treated clay-based samples. The effectiveness of sludge inactivation was assessed by water-leaching test and conductivity measurements. In view of the potential use of the sludge stabilization products as construction materials, the linear shrinkage and bending strain of the fired samples was investigated. To characterize their morphology, mineralogy and composition, fired samples of clay and its mixtures with galvanic sludge were studied on a scanning electron microscope (SEM) coupled with an energy dispersive X-ray analyser (EDS) and X-ray diffractometer (XRD). It was found that the efficiency of metal immobilization is dependent on the clay composition and the temperature of the thermal treatment of the prepared mixtures. The thermal treatment of all samples at all temperatures resulted in the stabilization of all heavy metal ions (copper, nickel, iron, lead, manganese and zinc) with the exception of chromium.

The better the quality of raw water resources, the higher the safety of drinking water supply. In the Danube river basin more than 60% of the population depends on groundwater sources. Organic micropollutants play an important role in quality assessment since they might cause different toxic effects in humans. There are two groups of organic micropollutants: regulated and non-regulated. In recent years, a lot of scientific effort was made to quantify their risks. Their occurrence is site specific and depends on social and economic factors, industry, population density, environmental conditions etc. That is why legislation intervention is required both at national and international level. This paper presents a literature review on the presence and fate of organic micropollutants that have been recently investigated in numerous projects worldwide. Special attention is paid to their mobility and risk for groundwater resources. Data on Serbian groundwater quality is presented for the period 2004–2005. In comparison with knowledge in developed countries, one can conclude that there is a general lack of data. More data about organic micropollutants presence is required, as well as identification of the pressures which lead to quality deterioration. Future quality assessment should be based on evaluated risks made considering both experience from developed countries and local conditions.

In this paper GC/MS-SCAN was used to identify the crude oil components that persist after bioremediation treatment of contaminated soil and the metabolites generated during this process. The soil was treated in bioreactors inoculated with an adapted bacterial population. In the first of two sets of conditions used, the water phase of the reactor was circulated continuously at a flow rate of 7 l day −1 , and in the other case, it was circulated for a short period once a day to give the equivalent of 0.5 l day −1 . Data showed that acyclic, n- and substituted alkanes ⩾C12 were still present after one year of remediation, while the majority of substituted derivatives of polycyclic and aromatic hydrocarbons could not be detected by GC/MS-SCAN analysis. The number of components identified was about one-half of that initially observed. After treatment the same number of components was detected at the top and bottom of the reactor in which the water phase was circulated continuously, whereas a smaller number of metabolites were observed at the top rather than at the bottom of the reactor with discontinuous circulation. The analysis has pointed to the importance of n-alkanes, their substituted derivatives and polycyclic aromatic hydrocarbons as the most significant pollutants.

This study is concerned with the changes in the rate of chloroform formation during the reactions of groundwater natural organic matter (NOM) and sodium hypochlorite caused by different drinking water treatments schemes: coagulation with FeCl 3 , Al 2 (SO 4 ) 3 and polyaluminum chloride (PACl), filtration of the raw water through granular activated carbon (GAC) and filtration through the columns filled with strong base macroporous ion-exchange resins (Purolite A501P and A500P) with and without pretreatment by coagulation process. It was found that the change of the concentration of chloroform, within 2 h and c (Cl 2 )=100 mg l −1 , can be described by a kinetic equation of the form [CHCl 3 ]= a + bt c . On the basis of this equation rates of the reaction were calculated. All processes applied decreased the rate of chloroform formation (process of coagulation moderately decreased the rate of reactions, while GAC adsorption caused dramatically drop of the rate). Also, it was found that the resins have had a higher affinity towards slow-reacting chloroform precursors. The value of the chloroform formation potential was conventionally determined after a 7-day reaction at pH 7. In addition, the same parameter was estimated with a satisfactory deviation for raw water and for treated water on the basis of the kinetic constant ( k ) or by determining the chloroform concentration after 2 h (ChFP 2 ) under rigourous chlorination conditions at pH 8.4.

Granular biologically activated carbon (GBAC) is in principle suited for removal of phenolic substrate from wastewater. In this study a wastewater model was used and special attention was paid to the operation of separate aerobic bioregeneration of carbon and reuse of bioregenerated carbon in a new stage of the experiment. In order to assess the effectiveness of bioregeneration, the efficiency of the biosorption system both before and after its bioregeneration was monitored at the substrate concentrations ranging from 1.9 to 1053 mg l −1 . All kinetic parameters for the biosorption system were determined for both fresh and already used GBAC. A 92–100% efficiency of phenol removal was achieved irrespective of whether the fresh or bioregenerated GBAC was used. The process of bioregeneration for the once-used GBAC was faster than for the one that was used several times. It was also faster when phenol alone was used as substrate than in the case of a phenol mixture. Respirometric measurements indicated that a mixture of substituted phenols showed inhibition effects on microorganisms. Calculations based on these measurements, as well as the findings of GC/MS analysis, indicated that deterioration of the adsorbent quality was taking place continuously. It was concluded that bioregeneration, carried out as a separate operation, could not be recommended for practice.

This work describes the possibility of application of a biosorption system with granulated activated carbon (GAC) for the tertiary treatment of oil-field brine. In addition to the dissolved and dispersed oil, the oil-field brine contained about 29 g/l of mineral matter, mainly NaCl. The investigation was carried out on two columns, each containing 300 g of GAC. To form the biofilm on GAC use was made of the microorganisms from the setup for the purification of refinery wastewaters by activated sludge procedure. The wastewater flow-rate through the columns was 40, 70, 95 and 130 l/d. It was found that the activated carbon in the columns was capable of removing 2.6 times more organic matter than was its adsorption capacity, and its adsorption power was not thus exhausted. The results indicate that the microorganisms present in the biofilm on activated carbon oxidize the adsorbed pollutants and thus regenerate the carbon surface. The procedure employed was very efficient—the organic matter content in the effluent did not exceed 2.5 mg/l (BOD5).

The objective of the present work was the enhancement of the efficiency of microbiological processes in purification of high-salinity oil-field brine by adding the powdered activated carbon (PAC) to the bioreactor and by diluting the brine with surface water. The investigation was carried out in a laboratory setup. Results show that the nature of pollutants and the high salinity (about 29 g/l) of oil-field brine had an unfavourable effect on the activated sludge process. Higher hydraulic loads (above 2.5 d−1) increased wash-out of the activated sludge from the bioreactor, so that an increased concentration of the suspended matter in the settler was observed. The addition of PAC to the bioreactor, combined with the dilution of oil-field brine with surface water, produced a substantial improvement in the sludge volume index. Also, under the given conditions, it was possible to maintain the given concentration of the activated carbon in the bioreactor. The procedure involving PAC and dilution with surface water resulted in an increased rate of pollutant degradation. The positive effect of PAC on the process of oil-field brine purification with the activated sludge was explained by the possibility of immobilization of microorganisms on the activated carbon surface in the form of a biofilm.

The work describes a study of the possibility of removal of organo-phosphorus insecticide quinalphos and organochlorine herbicide lindane from water by using the biofilm formed on active carbon. It was established that two similtaneous processes took place in the biosorption column - adsorption and microbiological degradation of the adsorbed matter. At the shock concentrations of lindane in the influent, an inhibition of microbiological processes in the biofilm occurred. It was observed that the biosorption system was more efficient in the removal of the organo-phosphorus insecticide than of the organo-chlorine herbicide.