Biodiversity of diatoms and applicability of diatom indices in biomonitoring based on littoral epiphytic samples of Lake Modrac were investigated. Diatoms were taken mostly from Phragmites australis stems in 2017, during which physical and chemical parameters of the water were measured. A total of 85 diatom taxa were identified. Gomphonema (13 spp.), Navicula (11 spp.), and Nitzschia (8 spp.) were the most abundant genera. Obtained values of trophic indices (TID, TvD, and TDIL) pointed to meso-to eutrophic status for most localities, while values of the IBD, EPI, -D, and IPS indices indicated good ecological status, except for localities at the mouth of 2 main tributaries which had moderate or poor ecological status. Based on the hierarchical group average clustering and nonmetric multidimensional scaling, 4 groups were identified, mainly related to the sampling period, with higher spatial variation in species composition during summer. Since environmental legislation in Bosnia and Herzegovina still does not provide detailed instructions on using diatoms in biological assessment, results of this study can be useful for the development of biomonitoring tools for lakes in Bosnia and Herzegovina.

The aim of this paper was to investigate the possibility of obtaining oil from spent coffee grounds, which are left behind after the coffee is prepared, as the potential feedstock for biodiesel production. The effect of process parameters, such as are the type of solvent, the ratio of spent coffee grounds/solvent and the extraction time on oil yielded from coffee grounds was examined. The oil was obtained by maceration and extraction in the Soxhlet apparatus. The obtain results show that the spent coffee grounds could be used as an alternative raw material for biodiesel production, because it contains a significant amount of oil that can be extracted. The oil yield depends on the extraction (maceration) process parameters. The maximum oil yield obtained by the Soxhlet extraction with the n-hexane for the period of 5 h was 11.85% (the weight percentage of oil on dry mater), whereas with petroleum ether the oil yield was slightly lower and amounted to 10.44%. The yield of the oil extracted by maceration increases with the decrease of spent coffee grounds/solvent ratio from 1/3 to 1/7 g/cm3, and other parameters being constant. The oil yield increases with the duration of the maceration. Greater oil yield, ranging from 3 to 8.5%, can be obtained with n-hexane compared to the extraction with petroleum ether. Furthermore, n-hexane is less volatile and flammable, compared to petroleum ether, so it is more convenient to use

Water hardness and deposition of incrustation is a problem in households and industry. In this regard, several technologies have been developed with the purpose of water softening and preventing the deposition of incrustation. The ion exchange method is the most commonly used method and is considered a conventional method. However, due to the shortcomings of this method, there is a need to develop adequate alternative methods. The potential of the method using biosorbents such as moss Leucobryum glaucum and Spaghnum peat moss for the purpose of removing water hardness has recently become the subject of intensive research with growing interest. In this study, the method using Leucobryum glaucum as a biosorbent was tested and a comparison was made with the conventional method and previously conducted studies that used other biosorbents.

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