Katalin Barkács

Polyphasic bacterial community analysis of an aerobic activated sludge removing phenols and thiocyanate from coke plant effluent

Biological purification processes are effective tools in the treatment of hazardous wastes such as toxic compounds produced in coal coking. In this study, the microbial community of a lab-scale activated sludge system treating coking effluent was assessed by cultivation-based (strain isolation and identification, biodegradation tests) and culture-independent techniques (sequence-aided T-RFLP, taxon-specific PCR). The results of the applied polyphasic approach showed a simple microbial community dominated by easily culturable heterotrophic bacteria. Comamonas badia was identified as the key microbe of the system, since it was the predominant member of the bacterial community, and its phenol degradation capacity was also proved. Metabolism of phenol, even at elevated concentrations (up to 1500mg/L), was also presented for many other dominant (Pseudomonas, Rhodanobacter, Oligella) and minor (Alcaligenes, Castellaniella, Microbacterium) groups, while some activated sludge bacteria (Sphingomonas, Rhodopseudomonas) did not tolerate it even in lower concentrations (250mg/L). In some cases, closely related strains showed different tolerance and degradation properties. Members of the genus Thiobacillus were detected in the activated sludge, and were supposedly responsible for the intensive thiocyanate biodegradation observed in the system. Additionally, some identified bacteria (e.g. C. badia and the Ottowia-related strains) might also have had a significant impact on the structure of the activated sludge due to their floc-forming abilities.

Direct determination of metal concentrations in freshwater algae by total reflection X-ray fluorescence spectrometry

A direct TXRF method for the determination of metal impurities by applying three different freshwater algae, viz., Chlorella keslerii, Synehococcus sp. and Cylindrospermopsis raciborskii, was developed. The applicability of the slurry sampling technique was confirmed by comparing the analytical results obtained with those obtained by total digestion of the algae. The concentration data showed an acceptable agreement for Cu, Fe, Mn and Zn. The calculated accumulation factors for the metals detected were highest for Chlorella keslerii.

Equilibrium and capacity data of clinoptilolite

Abstract The equilibrium and capacity data of natural clinoptilolite and clinoptilolite treated with sodium hydroxide were investigated. It was shown that the usual description of the selectivity as function of the equilibrium concentration can be replaced by equation (1), which is independent of the equilibrium concentration. Once constants K , n and Q o (see the equation) have been determined the equilibrium data can be calculated from equation (1) and the mass balance equation (2). The practical capacity has been found by pilot plant experiment, and it was demonstrated that if it is expressed as ‘layer not used’ ( Y ), it is only dependent upon the flow rate. Once the relation between y and the flow rate is established, it is easy to design a column. This procedure is considerably less cumbersome than the usually applied calculation on the basis of diffusion coefficient.

Ferrate treatment for inactivation of bacterial community in municipal secondary effluent

This paper demonstrates the effect of ferrate [Fe(VI)-compound], an environmental friendly multi-purpose reagent, in municipal secondary effluent treatment. The purpose was to study the inactivation capability of ferrate and for the first time to compare the effect and efficiency of Fe(VI) with the widely used disinfectant, chlorine gas on the indigenous bacterial community in the case of secondary effluents. The most probable number technique (MPN) was applied for the determination of cultivable heterotrophic bacterial abundance and terminal restriction fragment length polymorphism (T-RFLP) analysis for comparing bacterial communities. The study demonstrated that (i) ferrate and chlorine had different effect on the total bacterial community of secondary effluents, (ii) low ferrate dose [5 mg L(-1) Fe(VI)] was sufficient for >99.9% reduction of indigenous bacteria, and (iii) a similar dosage was also effective in the inactivation of chlorine-resistant bacteria.

Operation control of anaerobic digesters on the basis of enzyme activity tests

In our experimental work the pilot plant and full scale anaerobic bioreactors of a communal sewage treatment plant were tested by applying usual control parameters (pH, volatile acid content, alkalinity, gas composition), and enzyme activity (dehydrogenase, protease, lipase) measurements. Influence of temperature change was examined in pilot plant scale, while the effect of alteration in specific organic matter load both in pilot and full scale. Among the control parameters only the change of the volatile acid concentration reflected the occurred influences. During the temperature varying experimental phase the dehydrogenase enzyme activity excellently indicated the influence of the different conditions. The effect of altering substrate load onto the gas production was also well followed by the enzyme activity data (mainly protease, lipase), and more rapidly than by measuring volatile acid concentration. In practice it is expedient to use enzyme activity measurements in those cases, when changes in the substrate composition and load are frequent. Another advantage of these tests is that they can be carried out quickly and at a relative low cost.

Comparison of polyelectrolytes applied in drinking water treatment

Abstract The applicability of an inorganic, polyaluminium-type flocculent was tested comparing to polyacrylamides — an organic-type flocculent — used in the drinking water treatment process. The efficiency of this inorganic flocculent in the removal of suspended solids and also in minimizing the residual concentrations of the dissolved organic and inorganic micro-pollutants was checked in the case of purifying filter backwash water. Experimental data showed the advantage of the inorganic flocculent applying procedure as a part of recent water treatment technology. The applied polyaluminium-salt was economically competitive, improved the process stability and also ensured good water quality parameters.

Characterization of cyclodextrin containing nanofilters for removal of pharmaceutical residues

Due to the increasing amount of persistent organic pollutants (POPs) in general and pharmaceutical residues in particular in municipal wastewater, the efficiency of water treatment technologies should be improved. Following the biological treatment of wastewater nanofiltration offers a possible way for the removal of POPs. In this study β-cyclodextrin containing nanofilters having different chemical composition and thickness (1.5-3.5mm) were investigated. For their characterization, their adsorption capacity was determined applying ibuprofen containing model solution and total organic carbon (TOC) analyzer. It could be established that the regeneration of nanofilters with ethanol and the application of inorganic additives (NaCl, NaHCO3, NH4HCO3) increased the adsorption capacity of nanofilters. The best results were achieved with chemical composition of 30m/m% β-cyclodextrin polymer beads and 70m/m% ultra-high molecular weight polyethylene in the presence of 12mmol ammonium hydrogen carbonate/nanofilter.

Comparison of sample preparation methods applied for determination of atrazine in freshwater biofilms by gas chromatograph-mass spectrometer system

A sample preparation procedure was developed for the determination of atrazine in freshwater biofilms by gas chromatography-mass spectrometry. Different methods of sample preservation (immediate extraction, deep-freezing, cooling, vacuum-drying, freeze-drying) were tested for atrazine pretreated freshwater biofilms, followed by combined liquid- and solid-phase extraction (SPE). The immediate extraction of atrazine with acetonitrile, and a SPE, proved to be the best sample preparation procedure. Applying our method, atrazine pollution of the Lake Velence (Hungary) could be detected in the biofilms. At the same time in the lake freshwater samples, prepared by SPE and analyzed the same way, the atrazine concentration did not exceed the limit of detection.

Elemental analysis of Dikerogammarus villosus samples for river water monitoring

Dikerogammarus villosus (amphipod crustacean) samples were collected from the River Danube. The applicability of artificial substrates (gravel and clay filled containers translocated at the bottom of the river) and the effect of the applied colonization periods of short (3 weeks) and long (up to 30 weeks) terms were tested. Ag, As, Ba, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb and Zn concentrations of the amphipods were measured by inductively coupled plasma mass spectrometry (ICP-MS) after the digestion of some milligram samples. It was established that the artificial substrates did not influence the bioaccumulative processes of the elements investigated, and the short-term colonization period turned out to be sufficient for biomonitoring.

Reprint of "Characterization of cyclodextrin containing nanofilters for removal of pharmaceutical residues"

Due to the increasing amount of persistent organic pollutants (POPs) in general and pharmaceutical residues in particular in municipal wastewater, the efficiency of water treatment technologies should be improved. Following the biological treatment of wastewater nanofiltration offers a possible way for the removal of POPs. In this study β-cyclodextrin containing nanofilters having different chemical composition and thickness (1.5-3.5 mm) were investigated. For their characterization, their adsorption capacity was determined applying ibuprofen containing model solution and total organic carbon (TOC) analyzer. It could be established that the regeneration of nanofilters with ethanol and the application of inorganic additives (NaCl, NaHCO3, NH4HCO3) increased the adsorption capacity of nanofilters. The best results were achieved with chemical composition of 30 m/m% β-cyclodextrin polymer beads and 70 m/m% ultra-high molecular weight polyethylene in the presence of 1 2mmol ammonium hydrogen carbonate/nanofilter.