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Budapest, Hungary

Benedek T.,Szent Istvan University | Tancsics A.,Szent Istvan University | Szilagyi N.,Organica Technologies Inc. | Toth I.,Organica Technologies Inc. | And 5 more authors.
World Journal of Microbiology and Biotechnology | Year: 2014

In this study molecular microbiological and multivariate statistical analyses were carried out to determine the structure and dynamics of bacterial communities through a biofilm based, pilot-scale wastewater treatment cascade system comprised of eight reactors. Results indicated a vertical as well as horizontal differentiation of biofilm bacterial communities within individual reactors and through the reactor series, respectively. The richness of biofilm samples taken from dissolved oxygen rich sections of reactors were relatively lower than of samples taken from less oxygenized sections (one-way ANOVA P = 0.07). The Euclidean distance based one-way ANOSIM pointed out that in bacteriological point of view: (1) no statistically significant difference could be observed among the first five reactors (P ≥ 0.1); (2) the first seven reactors differed significantly from the last reactor, (P ≤ 0.03); (3) reactors 1 and 2 differed significantly from reactors 6 and 7 (P ≈ 0.02) and (4) reactor 3 from reactor 7 (P ≈ 0.03). 16S rRNA gene cloning revealed that through the cascade system the initially dominant heterotrophic bacteria (Acinetobacter, Acidovorax, Parabacteroides, Thauera, Desulfobacterium and Desulfomicrobium) were gradually replaced or supplemented by autotrophic nitrifying bacteria (Nitrosomonas, 'Candidatus Nitrotoga' and Nitrospira). Our results indicate that the vertical alteration of bacterial community structure within a particular reactor was driven by the alteration of dissolved oxygen concentration, while the horizontal alteration of bacterial community structure through the cascade system was driven mainly by the gradually decreasing dissolved organic matter content and increasing dissolved oxygen concentration. © 2013 Springer Science+Business Media Dordrecht.

Jurecska L.,Eotvos Lorand University | Barkacs K.,Eotvos Lorand University | Kiss T.,Eotvos Lorand University | Gyulai G.,Eotvos Lorand University | And 4 more authors.
Microchemical Journal | Year: 2013

Biofilm containing fix-bed systems are frequently applied for intensifying biological treatment in wastewater purification. In these operational units a lot of different biofilm carriers have been used and tested; among them, however, the polymer fiber-based materials are barely investigated. The authors studied four carriers: three types of polypropylene (PP) fibers and a polyester (PES) fiber were compared relating their physical-chemical characteristics and biofilm colonization properties. For the physical-chemical characterization surfactants release, wettability, methylene blue bromophenol blue and protein (bovine serum albumin) adsorption were measured as well as the surface charges of the biofilm carriers were determined by zeta potential examinations. Colonization experiments were carried out in a pilot plant scale biological municipal wastewater treatment system consisting of eight cascade reactors for 18 days. Each of the four tested fibers were placed into the reactors, and biofilm colonization was followed by measuring the dry biomass content and TTC (triphenyl tetrazolium chloride) enzyme activity of the biofilms adhered to the polymer fibers. During the colonization experiments pH, chemical oxygen demand (COD), concentration of total suspended solids (TSS), various nitrogenous compounds and dissolved oxygen were also monitored in the water phase of the reactors. Among the four different fibers one of the PP carriers turned to be the most favorable in colonization tests. This carrier, having surface and wetting properties differing from the other ones colonized the maximum biofilm mass, and the biofilm grown on this fiber had also the highest total enzyme activity all along the purification process, both in organic material degrading and in nitrifying reactors. © 2012 Elsevier B.V.

Szilagyi N.,Organica Technologies Inc. | Szilagyi N.,Budapest University of Technology and Economics | Kovacs R.,Organica Technologies Inc. | Kenyeres I.,Organica Technologies Inc. | And 4 more authors.
Water Practice and Technology | Year: 2012

As more and more wastewater treatment plants (WWTPs) arrive to a point in their lifecycles when their original capacities are not sufficient anymore, the demand for good WWTP retrofitting solutions becomes increasingly critical. One of the typical problems is the suspended solids overload of secondary clarifiers, which is one of the main concerns at the South Pest WWTP as well. Pilot scale studies were carried out at the WWTP with a biofilm based technology applying biofilm carriers imitating plant root structures in order to characterize the potentials of clarifier TSS load reduction while maintaining the existing biodegradation performance of the activated sludge stage. The research demonstrated that the clarifier load can be reduced by more than 90%, while the original biodegradation performance of the system does not decrease. In addition to this, it was demonstrated that the biomass amount in the reactors can be increased substantially opening potentials for further biodegradation capacity. © IWA Publishing 2012.

Szilagyi N.,Organica Technologies Inc. | Szilagyi N.,Budapest University of Technology and Economics | Kovacs R.,Organica Technologies Inc. | Kenyeres I.,Organica Technologies Inc. | Csikor Zs.,Budapest University of Technology and Economics
Water Science and Technology | Year: 2013

Biofilm development in a fixed bed biofilm reactor system performing municipal wastewater treatment was monitored aiming at accumulating colonization and maximum biofilm mass data usable in engineering practice for process design purposes. Initially a 6 month experimental period was selected for investigations where the biofilm formation and the performance of the reactors were monitored. The results were analyzed by two methods: for simple, steady-state process design purposes the maximum biofilm mass on carriers versus influent load and a time constant of the biofilm growth were determined, whereas for design approaches using dynamic models a simple biofilm mass prediction model including attachment and detachment mechanisms was selected and fitted to the experimental data. According to a detailed statistical analysis, the collected data have not allowed us to determine both the time constant of biofilm growth and the maximum biofilm mass on carriers at the same time. The observed maximum biofilm mass could be determined with a reasonable error and ranged between 438 gTS/m2 carrier surface and 843 gTS/m2, depending on influent load, and hydrodynamic conditions. The parallel analysis of the attachment-detachment model showed that the experimental data set allowed us to determine the attachment rate coefficient which was in the range of 0.05-0.4 m d-1 depending on influent load and hydrodynamic conditions. © IWA Publishing 2013.

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