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Bratislava, Slovakia

Takacova A.,VURUP | Smolinska M.,Comenius University | Semerad M.,Comenius University | Matus P.,Comenius University
Petroleum and Coal | Year: 2015

Biological methods for wastewater treatment are becoming more accepted over the world. This study it was focused on the benzene, toluene, ethylbenzene and xylenes (BTEX) biodegradation under model conditions by Parachlorella kessleri. BTEX-mixture was added to the cultures as the sole carbon source, at concentration of 100 μg L-1. It was observed loss of BTEX after 24, 48 and 72 h, respect-tively. Benzene and xylenes of 40 % was degraded within 48 h. The highest toluene degradation of 63 % was achieved. Only 30 % of ethylbenzene was degraded after 72 h. On the other hand the elementary analysis of algal biomass was assayed before and after the biodegradation process. After biodegradation the ratio C/N was increased 2.7 times from the value of 14.69 to 39.68. These results favor the biomass after biodegradation process and make it attractive for further use as a suitable substrate for subsequent processing into biofuels of third generation. Source


Cvengros J.,Slovak University of Technology in Bratislava | Cvengrosova Z.,Slovak University of Technology in Bratislava | Augustinova J.,Slovak University of Technology in Bratislava | Vasilkovova B.,Slovak University of Technology in Bratislava | Mikulec J.,VURUP
Petroleum and Coal | Year: 2013

In this paper six new or innovated procedures of fatty acids methyl esters (FAME) preparation from natural triacylglycerols (TAG) with higher acidity are described. The extraction of soaps of free fatty acids (FFA) by a polar solvent such as glycerol (G), but primarily by the G-phase originating from own FAME production, is a simple procedure applicable mainly in small-scale production plants. The effective TAG deacidification is obtained also using FFA vacuum distillation in wiped film evaporators. Preliminary acidcatalyzed FFA esterification with methanol (MeOH) performed before alkali-catalyzed TAG transesterification to FAME allows a simple separation of reaction water, excess of MeOH, and acidic catalyst at appropriate reactant ratios. During FFA esterification at temperatures over 110 °C, ambient pressure and at continuous MeOH feeding to the reaction mixture, advantageous nonequilibrium conditions for effective mass and heat transfer are created. Ethanolamines, used in TAG degumming for technical application, form separable adducts with water and FFA. At high-temperature FFA esterification with G in acid oils, acidic functional groups are blocked. The mentioned procedures are technically feasible and allow decreasing TAG acidity down to 1.0 mg KOH/g or less. Conversion of acyl glycerols to FAME complies with the standard EN 14 214. Source


Takacova A.,VURUP | Takacova A.,Slovak University of Technology in Bratislava | Smolinska M.,Slovak University of Technology in Bratislava | Smolinska M.,Comenius University | And 3 more authors.
Central European Journal of Biology | Year: 2013

Although Benzo[a]Pyrene (BaP) released to soils tends to bind very strongly to soil particles, however, small amounts have been shown to leach into groundwaters. This polycyclic aromatic hydrocarbon is stable and can stay (and travel) in the environment for an extended period of time. Release of BaP into the environment therefore causes concern at a global environmental level. In this paper we evaluated the effect of BaP on the cell growth of Escherichia coli and Enterococcus faecalis in aerobic conditions. Irradiation of BaP increased its antibacterial activity which suggests that this process produced a singlet oxygen. This way would be able to speed up the processes of photochemical degradation of BaP. © 2013 Versita Warsaw and Springer-Verlag Wien. Source


Mikulec J.,VURUP | Polakovicova G.,Slovak University of Technology in Bratislava | Cvengros J.,Slovak University of Technology in Bratislava
Chemical Engineering and Technology | Year: 2015

Flocculation-sedimentation of five microalgae species was tested with high-molecular-weight cationic polyacrylamide flocculants. An apparent difference in the shape of flocculated particles was detected when comparing flocculation with increasing pH of the microalgae culture to that with polyacrylamide. In the case of flocculation with pH adjustment, the surface charge of the cells is neutralized. Polyacrylamides can cause induction of bridging and facilitate sedimentation. Significantly higher flocculation efficiency was found for microalgae with a cylindrical shape and with the ability to form colonies. Overdosing of the flocculant may lead to a reduction in the flocculation efficiency as a result of destabilization of the suspension of charge excess flocculant. If algogenic organic matter was removed, flocculant consumption was drastically reduced and sedimentation of large flocs occurred very fast. Microalgae may represent a promising future feedstock for biofuels or biogas production. The effect of high-molecular-weight cationic polyacrylamide flocculants with different cationicity on the flocculation of fresh microalgae cultures was evaluated. The efficiency of flocculation was found to be a function of the charge density of the polymeric flocculants. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Polakovicova G.,VURUP | Kusnir P.,VURUP | Nagyova S.,VURUP | Mikulec J.,VURUP
Chemical Engineering Transactions | Year: 2012

Combining algal cultivation and biogas (methane) generation is considered to be one of the prospective environmentally feasible options of creating perpetually renewable source of pure energy for industrial and human consumption. Methane and energy generated in anaerobic fermentation facilities can be utilized as replacement for fossil fuel energy, thus reducing greenhouse gas emissions. This is caused by the fact that carbon is a biologically degradable material and algae form an integral part of the carbon cycle. Carbon release into the atmosphere from biogas combustion is utilized by plants for their further growth. Selection of optimal strain of algae depends on cost, efficiency, growth rate of algae, and difficulties during cultivation. The best cost-effective strain is Chlorella, green algae, because after extraction of lipids further utilization of algae is possible. The anaerobic digestion of Chlorella vulgaris and Chlorella sorokiniana was studied using batch digesters. Standard analysis of chemical oxygen demand (COD), solids, pH were performed. Biogas composition and production were also determined. The conversion of biomass to biogas ranged from 40 - 73 % in COD. In general it is important to select the strain of algae that contains the most of chlorophyll and lipids (reservoir substances of algae). Copyright © 2012, AIDIC Servizi S.r.l. Source

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