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Kaluza L.,Kolicevo Karton | Sustarsic M.,Pulp and Paper Institute | Rutar V.,Pulp and Paper Institute | Zupancic G.D.,Institute for Environmental Protection and Sensors
Bioresource Technology | Year: 2013

The possibility of introducing the thermo-alkali hydrolysis of Waste-Activated Sludge (WAS) was investigated, in order to enable the use of its solid residue as a raw material in cardboard production and the use of its liquid portion for anaerobic digestion in an UASB reactor. The evaluation of the hydrolysis at pH>12 and T=70°C showed that the microbe cells were disrupted with more than 90% efficiency in less than 2h. The solid portion was hygienised, therefore making it possible to integrate it into the cardboard production as a raw material for less demanding cardboards. Up to 6% addition of the liquid portion of hydrolysed WAS to wastewater decreased the specific biogas production in a pilot-scale UASB from 0.236 to 0.212m3/kgCOD, while the efficiency of the COD removal decreased from 80.4% to 76.5%. These values still guarantee an adequate treatment of the wastewater and an increased biogas production by 16%. © 2013 Elsevier Ltd. Source

Lobnik A.,University of Maribor | Korent Urek S.,Institute for Environmental Protection and Sensors
Journal of Nano Research | Year: 2011

The development of nanoscale materials for optical chemical sensing applications has emerged as one of the most important research areas of interest over the past decades. Nanomaterials exhibit highly tunable size- and shape-dependent chemical and physical properties, show unique surface chemistry, thermal and electrical properties, high surface area and large pore volume per mass unit area. Because of their unique and advantageous features they can help to improve sensitivity, response time and detection limit of sensors. In this review, recently developed photoluminescence-based optical chemical nanosensors are presented. Some future trends of the nanomaterial-based optical chemical sensors are given. © (2011) Trans Tech Publications,Switzerland. Source

Sorsak E.,University of Maribor | Valh J.V.,University of Maribor | Urek S.K.,Institute for Environmental Protection and Sensors | Lobnik A.,University of Maribor | Lobnik A.,Institute for Environmental Protection and Sensors
Analyst | Year: 2015

The need for an improved sensor performance is always encouraging us towards exploring new materials. Following the invention of dendrimers, the possibility was recognised of using them for improving optical sensor performance. Their more important aspects are their two main structural properties: three-dimensional structure and multiple terminal functional groups. In this review, firstly a brief introduction to dendrimers is provided with the focus on PAMAM dendrimers and optical sensors. Recent advances have been reported in those PAMAM dendrimer-based optical sensors, which are used for the detection of pH, cations, and other analyte. This journal is © The Royal Society of Chemistry 2015. Source

Widmer S.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Widmer S.,University of Basel | Dorrestijn M.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Camerlo A.,Empa - Swiss Federal Laboratories for Materials Science and Technology | And 5 more authors.
Analyst | Year: 2014

This study focuses on the development of an optical ammonia gas sensor, the sensing mechanism of which is based on Förster resonance energy transfer (FRET) between coumarin and fluorescein. The dyes were immobilized into an organically modified silicate matrix during polymerizing methyltriethoxysilane with trifluoropropyltrimethoxysilane on a poly(methyl methacrylate) substrate. The resulting dye-doped xerogel films were exposed to different gaseous ammonia concentrations. A logarithmic decrease of the coumarin fluorescence emission band at 442 nm was observed with increasing gaseous ammonia concentrations, which was due to enhanced FRET between coumarin and fluorescein. The coumarin/fluorescein composition was optimized in order to obtain the best ammonia sensitivity. First experiments in a flow cell gas sensor setup demonstrated a sensitive and reversible response to gaseous ammonia. This journal is © the Partner Organisations 2014. Source

Zupancic G.D.,Slovenian National Institute of Chemistry | Zupancic G.D.,Institute for Environmental Protection and Sensors | Skrjanec I.,University of Ljubljana | Marinsek Logar R.,University of Ljubljana
Bioresource Technology | Year: 2012

The anaerobic co-digestion of brewery yeast using granular biomass was studied on the lab, pilot and full-scale. The study shows no adverse effects in the co-digestion of yeast and wastewater in concentrations up to 1.1 (v/v)%. In concentrations up to 2.3% the process is manageable; however, not advisable. In concentrations over 2.8% the process exhibits failure due to the overload with suspended solids. An average specific biogas production of 0.560m3kg-1 of volatile solids was achieved. Full-scale operation with 0.7% yeast concentration showed a 38.5% increase in the biogas production and a 26.2% increase in the organic loading rate, which resulted in an increase of the biomethane/natural-gas substitute ratio from 10% to 16%. The influence of the yeast addition on the structure of the microbial biomass showed up to 7% dissimilarity in the archaeal and a 32% dissimilarity in the bacterial biomass community, which did not present any difficulties. © 2012 Elsevier Ltd. Source

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