Siniša N. Dodić

Bioethanol production from intermediate products of sugar beet processing with different types of Saccharomyces cerevisiae

The use of biofuels as an alternative to fossil fuels has expanded in the last few decades. The aim of this study was to examine the application of different strains and forms of Saccharomyces cerevisiae for raw, thin and thick juice fermentation in order to produce bioethanol. According to the obtained results the strain applied in the form of pressed blocks with 70 % w/w moisture, attained higher value of the specific growth rate and lower value of ethanol yield in comparison with strains applied in dried form. In all culture media attained efficiency of sugar utilization was at least from 98-99 % w/w. Maximum productivity was achieved around 30th hour of fermentation and amounted ≈1.8 g l¹ h¹ for all applied yeast strains. Therefore, optimal duration of the process in technical and economic terms should be considered.

Process model and economic analysis of ethanol production from sugar beet raw juice as part of the cleaner production concept.

The batch fermentation process of sugar beet processing intermediates by free yeast cells is the most widely used method in the Autonomous Province of Vojvodina for producing ethanol as fuel. In this study a process and cost model was developed for producing ethanol from raw juice. The model can be used to calculate capital investment costs, unit production costs and operating costs for a plant producing 44 million l of 99.6% pure ethanol annually. In the sensitivity analysis the influence of sugar beet and yeast price, as well as the influence of recycled biomass on process economics, ethanol production costs and project feasibility was examined. The results of this study clearly demonstrate that the raw material costs have a significant influence on the expenses for producing ethanol. Also, the optimal percentage of recycled biomass turned out to be in the range from 50% to 70%.

Assessment of the effectiveness of policy implementation for sustainable energy development in Southeast Europe

Using solely economic indicators as a measure of development as a whole is no longer justified and acceptable. The survey covered 11 countries in the region of Southeast Europe—in the region for which indicators of sustainable energetic development were defined. The authors propose a specific way of expressing their needs for treatment using the method of weight coefficients. The results indicate that the efficiency of energetic policy in the region varies widely. Countries at higher level of economic development record a high dependence on energy imports. Countries in the region at a similar stage of development show different energy consumption per capita and the different intensity of energy production from renewable resources. Research shows that energetic efficiency policies in the region, apart from the available energy resources, largely depends on the degree of economic development that a country wants to achieve. Countries at lower level of development show higher degree of sustainability in terms of energy management and vice versa. The most favorable situation was observed in Bulgaria. Negative trends were observed in Greece and Hungary, while in Slovenia the indicators were on the border of sustainability. Data used for research refer to the year 2010.

Exploitation of biogas power plant—Clean Development Mechanism project, Vizelj, Serbia

This case study of biogas power plant is designed in accordance with the existing energy policy that recognizes producers of energy from renewable sources as producers with privileged status and guarantees the purchase of energy at subsidized prices. The investor company revised its own energy policy and aligned it with the priorities of sustainable energy policy of Serbia. The paper presents an analysis of biogas power plant output (electrical and thermal energy), balance, sale, and potential prices on the market that are consistent with the incentives of energy policy of Serbia. In addition, special emphasis is given to the revenues that a biogas power plant realizes by using another mechanism of energy policy, which promotes gaining revenues by reducing pollution of the atmosphere. The authors also show the procedure, costs, and expected effects from the qualification of this power plant project for the Clean Development Mechanism project categories. Investing in a biogas power plant in Serbia costs 95...

Wastewaters from rose wine production as substrate for xanthan production

Wineries and other grape processing industries annually generate large amounts of solid and liquid waste streams. Winery wastewaters are the waste product of many independent processing and cleaning operations in wineries. As a consequence of the working period and the winemaking technologies, as well as the cleaning practices, volumes and composition of winery wastewaters greatly vary over the year. Due to high organic load, the disposal of these effluents in the environment causes several issues. The bioconversions of winery wastewaters in valuable products are an important alternative to overcome these ecological problems. The aim of this study was to examine the possibility of xanthan production from media based on four wastewaters obtained from different stages of the rose wine production process, i.e. wastewaters collected during the washing of the crusher, press and tanks after clarification of must and fermentation. Process efficacy was estimated based on raw xanthan yield and rheological characteristics of media. In applied experimental conditions, raw xanthan yields were in the range between 8.03 g/L and 17.52 g/L. Also, all cultivation media showed pseudoplastic behavior. Obtained results suggest that wastewaters from rose wine production have a great potential to be used as a substrate for production of this high value biopolymer.

The application of natural organic compounds in bakery industry

Investigations include the analysis of the impact of commercial products: complex additive (0.1, 0.3, and 0.5%), L-ascorbic acid (0.002, 0.004 and 0.012%), diacetyl ester of tartaric acid with monoglycerides (DATEM E472e, 0.1, 0.3, and 0.5%), α-amylase (0.002, 0.006 and 0.012%), xylanase (0.004, 0.012 and 0.024%), alcohol extract of rosemary, thyme or sage (0.5, 1.0 and 2.0%), as well as the combination of complex additive and rosemary, thyme and sage extract on rheological characteristics of dough. The study includes amylograph, farinograph and extensograph analysis of dough with and without additives (control sample). The volume of lost CO2 gas (mL) is the lowest in dough samples with an added combination of complex additive and thyme extract (0.05 and 0.5%) and rosemary extract (2.0%). In the samples with thyme extract (1.0%) added, the volume of lost gas is at a level of samples with added complex additive, DATEM, and L-ascorbic acid.

Optimization of cultivation medium composition for production of bioactive compounds effective against Penicillium sp.

Biological control is one of the best alternatives to pesticides as it avoids their weak points in plant disease control. In this study, the composition of cultivation medium for production of bioactive compounds by Bacillus subtilis ATCC 6633 was optimized. The produced bioactive compounds were tested against a phytopathogenic Penicillium sp. known for infesting different agricultural products and causing substantial crop losses. Antimicrobial activity assaying was carried out using the diffusion-disc method, and inhibition zone diameters were measured as direct indicators of antifungal activity. The response surface methodology (RSM) was used to evaluate the effects of different contents of initial nutrients (glycerol, NaNO2 and K2HPO4) in cultivation medium on inhibition zone diameter. Optimization was carried out using the desirability function method in order to maximize bioactive compounds yield and to minimize residual nutrients contents. The optimized concentrations of the selected nutrients in cultivation medium for production of bioactive compounds were: glycerol 20 g/l, NaNO2 1 g/l and K2HPO4 15 g/l.

Mogućnost primene ksantana za uklanjanje jona metala iz otpadnih voda

Biopolimeri poseduju sposobnost apsorpcije velike kolicine vode ili bioloskih fluida pri cemu bubre i formiraju hidrogelove. Zahvaljujuci tome nasli su siroku primenu u razlicitim granama industrije, a između ostalog koriste se i za uklanjanje jona metala iz vode. Zbog svoje jedinstvene strukture i izuzetnih reoloskih karakteristika, ksantan, komercijalno najznacajniji mikrobioloski biopolimer,mogao bi se primenjivati i za preciscavanje otpadnih voda jer bi se strukture formirane u prisustvu metala mogle lako odvojiti mehanickim putem. Stoga su istraživanja iz okvira ovog rada izvedena u cilju ispitivanja mogucnosti umrežavanja sirovog ksantana razlicitim jonima metala. Na osnovu uspesnosti umrežavanja i stabilnosti formiranih strukturaprocenjeno je daje primenomovog biopolimera moguce ukloniti jone olova i gvožđa iz otpadnih voda.

Production of nigericin and niphimycin by soil isolate Streptomyces sp. MS1: Anti-Candida bioassay guided response surface methodology for the optimized culture medium

Anti-Candida bioassay guided optimization of the culture medium was used in order to enhance the antifungal activity of the soil isolate MS1. Its morphological, physiological and biochemical characteristics, as well as 16S rDNA sequencing, assigned an MS1 isolate to genus Streptomyces. Optimization of the culture medium was achieved by experimental factorial design and response surface methodology. Maximal antifungal components production was obtained with starch, soybean meal and phosphates content of 40.52, 5.10 and 2.21 g/L, respectively. Chromatography and 1H and 13CNMR spectroscopy were employed for purification and structural characterization of antifungal antibiotics concurrently produced by this strain. These antibiotics were identified as polyether carboxylic antibiotic nigericin and guanidyl-polyol macrolide, niphimycin.

Environmental biotechnology for the treatment of waste effluents from biofuels production

Bioethanol, biodiesel and biogas represent very significant alternatives to fossil fuels in order to reduce carbon- dioxide emissions, so there is a need to develop energy efficient technologies, equipment and waste management procedures to make production profitable by reducing production costs. One way to accomplish this is to solve the problem of waste effluents by using them to obtain high-value products. All biotechnological processes are energy intensive to some extent, so saving energy becomes one of the main goals of all biotechnological processes in addition to preserving the environment and the management or reuse of waste. The availability of waste effluents from the production of biofuels, such as distillery stillage and crude glycerol, will increase over the next few years due to the growth of the biofuel industry and will provide a great possibility for the biotechnological production of high-value products.