▶ 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.
Imunski sistem je ključen pri nadzoru nastanka in rasti malignih celic. Z imunoterapijo z zaviralci imunskih kontrolnih točk je imunski sistem postal eden pomembnejših tarč onkološkega zdravljenja. ...Sorazmerno visok delež onkoloških bolnikov na to zdravljenje še vedno ne odgovori. Črevesna mikrobiota bi glede na zadnja spoznanja lahko postala način premagovanja odpornosti na imunoterapijo. Možni načini modulacije mikrobiote so prehranska strategija, probiotiki in fekalna transplantacija mikrobiote. Ovire pri raziskovanju mikrobiote in njene uporabe pri zdravljenju z zaviralci imunskih kontrolnih točk so zaenkrat nestandardizirani pristopi k analizi mikrobiote, geografske razlike v mikrobioti, vpliv kulture ter načina življenja itd. V teku so številne predklinične in klinične raziskave, nekatere že z obetavnimi rezultati. Z obdelavo mikrobiote bi bila lahko obravnava onkoloških bolnikov še bolj personalizirana in holistična.
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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.
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.
•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.
Liquid fraction produced in anaerobic digestion (AD) of biodegradable waste can be treated on-site with microalgae, which can be recycled back as substrate to the biogas plant. For this research, a ...pilot high rate algal pond (HRAP) was set with connections to a full scale biogas plant that enabled the use of waste heat and CO2 from a combined heat and power gen-set (CHP). The microalgal mix produced in the thermophilic anaerobic digestate supernatant was tested as a substrate for biogas production in the thermophilic AD (i.e. untreated, bioaugmented with anaerobic bacteria Clostridium thermocellum, and thermally pretreated, respectively). The methane potential of the untreated microalgal mix was low (157.5 ± 18.7 mL CH4/g VS). However, after the thermal pretreatment of the microalgae, methane production increased by 62%, while in the bioaugmentation with C. thermocellum under thermophilic conditions (T = 55 °C) it was elevated by 12%. The outcome of our pilot trial suggests that microalgae produced in the thermophilic biogas digestate represent a prospective alternative AD feedstock. At the same time, microalgae reduce the digestate nitrogen and COD to the level sufficient for the outflow to meet the quality required by the sewage system (ammonia-nitrogen max 200 mg/L, nitrite max 10 mg/L).
•A pilot plant for treating thermophilic anaerobic digestate supernatant with microalgae was constructed outdoor (89 m2).•The removal efficiency by algal treatment of digestate was 83–97% for NH4-N, and 81–95% for COD.•By a continuous 63-day treatment under favorable weather conditions 22.5 g of TS/day/m2 of a microalgal mix was produced.•Biomethane potential of thermally pretreated microalgal mix showed significantly elevated methane production (+62%).•Bioaugmentation with Clostridium thermocellum increased methane production from microalgal mix by 12%.
The presence of endocrine-disrupting compounds in wastewater, surface water, groundwater and even drinking water has become a major concern worldwide, since they negatively affect wildlife and ...humans. Therefore, these substances should be effectively removed from effluents before they are discharged into surface water to prevent pollution of groundwater, which can be a source of drinking water. Furthermore, an efficient control of endocrine-disrupting compounds in wastewater based on biological and analytical techniques is required. In this study, a yeast estrogen screen (YES) bioassay has been introduced and optimized with the aim to assess potential estrogenic activity of waters. First, assay duration, concentration of added substrate to the assay medium and wavelength used to measure the absorbance of the substrate were estimated. Several compounds, such as 17-β-estradiol, 17-α-ethinylestradiol, bisphenol A, nonylphenol, genisteine, hydrocortisone, dieldrin, atrazine, methoxychlor, testosterone and progesterone were used to verify its specificity and sensitivity. The optimized YES assay was sensitive and responded specifically to the selected estrogenic and nonestrogenic compounds in aqueous samples. Potential estrogenicity of influent and effluent samples of two wastewater treatment plants was assessed after the samples had been concentrated by solid-phase extraction (SPE) procedure using Oasis® HLB cartridges and methanol as eluting solvent. Up to 90 % of relative estrogenic activity was detected in concentrated samples of influents to wastewater treatment plants and estrogenic activity was still present in the concentrated effluent samples. We found that the introduced YES assay is a suitable screening tool for monitoring the potential estrogenicity of effluents that are discharged into surface water. Key words: endocrine-disrupting compounds, estrogenic activity, monitoring, solid-phase extraction, yeast estrogen screen assay, water
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