•The impact of bioaugmentation on methane production from spent grain was examined.•Methane production elevated for 17.8% with P. xylanivorans Mz5T bioaugmentation.•Bioaugmentation enhances the ...hydrolysis of brewery spent grain.•Changes in bacterial and archaeal communities were detected during biogas process.•Bioaugmentation enables successful biogas production from brewery spent grain.
Lignocellulosic substrates are widely available but not easily applied in biogas production due to their poor anaerobic degradation. The effect of bioaugmentation by anaerobic hydrolytic bacteria on biogas production was determined by the biochemical methane potential assay. Microbial biomass from full scale upflow anaerobic sludge blanket reactor treating brewery wastewater was a source of active microorganisms and brewery spent grain a model lignocellulosic substrate. Ruminococcus flavefaciens 007C, Pseudobutyrivibrio xylanivorans Mz5T, Fibrobacter succinogenes S85 and Clostridium cellulovorans as pure and mixed cultures were used to enhance the lignocellulose degradation and elevate the biogas production. P. xylanivorans Mz5T was the most successful in elevating methane production (+17.8%), followed by the coculture of P. xylanivorans Mz5T and F. succinogenes S85 (+6.9%) and the coculture of C. cellulovorans and F. succinogenes S85 (+4.9%). Changes in microbial community structure were detected by fingerprinting techniques.
In the current study, the toxicity mechanism of nanosized CuO (nCuO) to the freshwater ciliated protozoa Tetrahymena thermophila was studied. Changes in fatty acid profile, lipid peroxidation ...metabolites and reactive oxygen species (ROS) were measured. Bulk CuO and CuSO4 served as controls for size and solubility and 3,5-dichorophenol (3,5-DCP) as a control for a chemical known to directly affect the membrane composition. Exposure to all copper compounds induced the generation of ROS, whereas nCuO was most potent. The latter effect was not solely explained by solubilized Cu-ions and was apparently particle-related. 24 h exposure of protozoa to 80 mg/L of nCuO (EC50) significantly decreased the proportion of two major unsaturated fatty acids (UFA) (C18:3 cis-6,9,12, C18:2 cis-9,12), while it increased the relative amount of two saturated fatty acids (SFA) (C18:0, C16:0). Analogous effect was not observed when protozoa were exposed to equitoxic suspensions of bulk CuO, Cu-ions or 3,5-DCP. As changes in the UFA:SFA upon exposure of protozoa to nCuO were not detected at 2 h exposure and no simultaneous dose- or time-dependent lipid peroxidation occurred, it is likely that one of the adaptation mechanisms of protozoa to nCuO was lowering membrane fluidity by the inhibition of de novo synthesis of fatty acid desaturases. This is the first study of the effects of nanoparticles on the membrane fatty acid composition.
▶ A stable stripping of ammonia from the anaerobic wastewater treatment plant effluent was obtained. ▶ Stripping of ammonia was continuous, with removal rate up to 92.8%. ▶ The most influence on ...stripping had high pH level, then air flow rate and finally temperature. ▶ High removal of ammonia nitrogen enables the final treatment of the anaerobic centrate in the municipal wastewater treatment plant.
A stable continuous stripping of ammonia from the anaerobic wastewater treatment plant effluent was obtained in the ammonia stripping bench plant. The effects of temperature, amount of air and pH level on the removal of ammonium from the effluent were examined in the experiments. The operating parameters in the trials were chosen in respect of the economically feasible operating conditions in a biogas plant. The results of ammonium removal were compared with theoretically calculated values of free ammonia in these conditions. Ammonia stripping bench plant continuously removed up to 92.8% of ammonium and 88.3% of total nitrogen from the anaerobic digestion effluent. High pH had the most significant effect on stripping, causing the change of the ammonia/ammonium ratio in favour of ammonia. The second important factor was the amount of air passing through the stripping bench plant promoting the transition of ammonia from the liquid phase to the gas phase. The temperature within the examined range had the least significant effect on ammonia stripping. Continuous stripping of nitrogen from the anaerobic digestion effluent could considerably reduce the area required for the application of nitrogen-rich digestate after the biogas production and enable the treatment of the anaerobically digested effluent in the wastewater treatment plant.
Sheep wool is keratin-rich by-product of sheep breeding and textile industry. Due to complex structure of keratin, this wastes are quite resistant to degradation and represent a serious environmental ...problem. Waste wool is often converted to different hydrolysates, which are mainly prepared by environmental unfriendly physico-chemical treatments, resulting in destruction of some amino acids and energy loss. Use of biotechnological approaches, such as microbial or enzymatic pretreatment, and composting, can significantly reduce the environmental impact, and produce useful products, such as fertilizers or substrates for biogas production, and high-added value products (peptides, amino acids and keratinolytic enzymes). In this review we compare different ways of waste wool processing, focused on biotechnological applications.
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•H2 production was investigated in anaerobic packed-bed reactor at acidic conditions.•Produced hydrogen yields (mol H2/mol glucose) were 1.80 (R1)>1.74 (R2)>1.46 (R3).•Main metabolic ...products were found to be acetic acid, butyric acid and ethanol.•Higher hydrogen yield correlates with low acetate-to-butyrate (HAc/HBu) ratio.•Quantity of attached biomass (gTVS/gsupport) were 0.06 (R1), 0.04 (R2) and 0.035 (R3).
This study assesses the impact of different support materials (Mutag BioChip™, expanded clay and activated carbon) on microbial hydrogen production in an anaerobic packed-bed reactor (APBR) treating synthetic waste water containing glucose as the main carbon source at low pH value. The APBRs were inoculated with acid pretreated anaerobic sludge and operated at pH value of 4±0.2 and hydraulic retention time (HRT) of 3h. The maximum hydrogen yield of 1.80mol H2/mol glucose was achieved for the APBR packed with Mutag BioChip™ (R1), followed by expanded clay (R2, 1.74mol H2/mol glucose) and activated carbon (R3, 1.46mol H2/mol glucose). It was observed that the investigated support materials influenced the immobilization of hydrogen producing bacteria and consequently hydrogen production performance as well as composition of soluble metabolites. The main metabolic products were acetic acid and butyric acid accompanied with a smaller content of ethanol. The data indicated that in reactors with higher hydrogen yield (R1 and R2), acetate/butyrate (HAc/HBu) ratios were 1.7 and 1.6, respectively, while in the reactor with the lowest hydrogen yield (R3) the obtained HAc/HBu ratio was 4.8. Finally, stable hydrogen and organic acids production throughout the steady-state operation period at low pH values was achieved in all reactors.
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► Brewery yeast was used to produce biogas in an upflow granular anaerobic reactor. ► Mixtures up to 1.1v/v% yeast are anaerobically degradable without adverse effects. ► In ...full-scale operation biogas production increased by 38.5%. ► Up to 16% natural gas were replaced in brewery operation. ► Up to 7% in archeal and a 32% dissimilarity in bacterial community were shown.
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.
Anaerobic digestion of brewery spent grain as a mono-substrate was studied. Brewery spent grain is a substrate consisting largely of cellulose, hemicellulose and lignin, which are difficult to ...degrade anaerobically, mostly due to the presence of degradation products, such as phenolic compounds, which cause process inhibition. Therefore, a two-stage system was used for anaerobic digestion. Anaerobic digestion was phase separated in a solid-state anaerobic digestion reactor, where microbiological hydrolysis and acidogenesis occurred and in a granular biomass reactor where mostly methanogenesis was performed. The overall process exhibited total solids degradation efficiency between 75.9 and 83.0%. Average specific biogas production was 414 ± 32 L/kg, whereas biomethane production was 224 ± 34 L/kg of added total solids. Granular biomass after adaptation exhibited stable operation at substrate C/N ratios in range 0.16–4.68. p-cresol was present in concentrations up to 45 mg/L and during the process was successfully degraded by granular biomass. The excellent adaptability of granular biomass was confirmed by 68.2% shift in bacterial and a 31.8% shift in archaeal community structure in a granular biomass reactor. The structure of the bacterial community from granular biomass reactor and solid-state anaerobic digestion reactor remained 79.4% similar at the end of the experiment, whereas archaeal community was only 31.6% similar. The process exhibited stable operation for 198 days, which shows that brewery spent grain can be successfully anaerobically digested and used for biogas production.
•Long–term and stable biogas production from brewery spent grain is possible.•Up to 472 L of biogas per kg of brewery spent grain total solids can be produced.•The granular biomass is able to operate at very low C/N ratios between 0.16 and 4.68.•p-cresol as inhibitory intermediate degradation product is successfully degraded.•Bacterial and archaeal microbial communities adapted successfully to BSG substrate.
Anaerobic digestion, despite its preferable use as a treatment for high organic matter polluted waste streams, is susceptible to inhibitors, salt included. Therefore, two different experiments were ...conducted to observe the responses of bacterial and archaeal communities to hypersaline environments. In the first experiment, salt was added gradually, while in the second experiment, salt was added rapidly (so-called salt shocks were performed). The results of the gradual addition of salt showed a recovery of methane production after the salt concentration decreased. The NaCl concentration of 28.2 g/L seems to be the limit between stable operation and occurrence inhibition. The specific biogas production varied between 0.490 and 0.562 m3/kgtCOD during the stepwise salt addition, depending on the salt concentration, while the maximal achieved COD removal was 79.8%. The results of the rapid salt addition showed good recovery of the bacterial community, while a reduction of salt-sensitive species was observed in the archaeal community. The trend of specific biogas production during rapid salt addition was stable with an average value of 0.590 m3/kgtCOD, and it was observed that higher concentrations of up to 39.4 g/L of NaCl were tolerated. The maximum COD removal achieved during rapid salt addition was 83.1%. In conclusion, certain bacterial and archaeal communities were well-adapted to the hypersaline environment and remained active during the anaerobic digestion of substrates with high salt concentration.
In contrast to the general aerobic detoxification of industrial effluents containing cyanide, anaerobic cyanide degradation is not well understood, including the microbial communities involved. To ...address this knowledge gap, this study measured anaerobic cyanide degradation and the rearrangements in bacterial and archaeal microbial communities in an upflow anaerobic sludge blanket (UASB) reactor biomass treating brewery waste water using bio-methane potential assays, molecular profiling, sequencing and microarray approaches. Successful biogas formation and cyanide removal without inhibition were observed at cyanide concentrations up to 5 mg l−1. At 8.5 mg l−1 cyanide, there was a 22 day lag phase in microbial activity, but subsequent methane production rates were equivalent to when 5 mg l−1 was used. The higher cumulative methane production in cyanide-amended samples indicated that part of the biogas was derived from cyanide degradation. Anaerobic degradation of cyanide using autoclaved UASB biomass proceeded at a rate more than two times lower than when UASB biomass was not autoclaved, indicating that anaerobic cyanide degradation was in fact a combination of simultaneous abiotic and biotic processes. Phylogenetic analyses of bacterial and archaeal 16S rRNA genes for the first time identified and linked the bacterial phylum Firmicutes and the archaeal genus Methanosarcina sp. as important microbial groups involved in cyanide degradation. Methanogenic activity of unadapted granulated biomass was detected at higher cyanide concentrations than reported previously for the unadapted suspended biomass, making the aggregated structure and predominantly hydrogenotrophic nature of methanogenic community important features in cyanide degradation. The combination of brewery waste water and cyanide substrate was thus shown to be of high interest for industrial level anaerobic cyanide degradation.
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•Granulated biomass degraded higher cyanide concentrations than suspended biomass.•Biotic and abiotic processes compete simultaneously in anaerobic cyanide degradation.•Firmicutes and Methanosarcina were linked to anaerobic cyanide degradation.•Hydrogenotrophic methanogens were indeed less sensitive to cyanide toxicity.•Substrate combination is of interest for industrial scale anaerobic cyanide degradation.
Microalgae biomass has a great potential in search for new alternative energy sources. They can be used as a substrate for the biogas production in anaerobic digestion. When using microalgae, the ...efficiency of this process is hampered due to the resistant cell wall. In order to accelerate the hydrolysis of cell wall and increase the efficiency of biogas production we applied two different pretreatments - biological and thermal under mesophilic and thermophilic conditions. During biological pretreatment we incubated microalgae with anaerobic hydrolytic bacteria Pseudobutyrivibrio xylanivorans Mz5T. In thermal pretreatment we incubated microalgae at 90 °C. We also tested a combined thermal and biological pretreatment in which we incubated P. xylanivorans Mz5T with thermally pretreated microalgae. Thermal pretreatment in mesophilic and thermophilic process has increased methane production by 21% and 6%, respectively. Biological pretreatment of microalgae has increased methane production by 13%, but only under thermophilic conditions (pretreatment under mesophilic conditions showed no effect on methane production). Thermal-biological pretreatment increased methane production by 12% under thermophilic conditions and by 6% under mesophilic conditions.
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