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[en] This poster reviews the features of microbial activities on clays. Microbes remain active in a bentonite at a density of 2.0 g*cm-3 and can undergo a dose rate over 100 Gy/h. Clays become destabilized and release Fe(II) from crystal structure upon a microbial reduction of about 1.2 mmol Fe(III) per g clay. Clays are susceptible to transformation of smectite to illite within weeks at 25 C degrees and 0.1 MPa, and of smectite and illite to kaolinite within a few thousand years, as a result of microbial reduction of structural Fe(III). Clays show half-lives of about 0.1-2 million years when exposed to 1 mmol-1 of HS- produced by sulphate-reducing bacteria
[en] Based on bibliographical references, in a theoretical model based on a fermentation process, the relationship between the speed of oxygen transfer and the biochemistry demand is implemented, in order to discover the different conditions of aeration and of agitation speed, under those which the microbial growth is not affected by deficiency in the oxygen supply. This correlation was adapted to the cultivation of B. Thuringiensis, and of this form, maximum biomass concentration to the one, which is possible to supply oxygen efficiently with a group of defined operation conditions, could be estimated
[en] Highlights: • A model to evaluate the service area size of a waste recovery chain is proposed. • A recovery performance score is given per waste source. •The areas to be collected in priority are the sources with the highest score. • The score depends on the source's characteristics and the recovery technology. •Replacing anaerobic digestion by composting decreases the facility's spatial scale. - Abstract: Waste recovery is an integrated part of municipal solid waste management systems but its strategic planning is still challenging. In particular, the service area size of facilities is a sensitive issue since its calculation depends on various factors related to treatment technologies (output products) and territorial features (sources waste production and location). This work presents a systemic approach for the estimation of a chain's service area size, based on a balance between costs and recovery profits. The model assigns a recovery performance value to each source, which can be positive, neutral or negative. If it is positive, the source should be included in the facility's service area. Applied to the case of Montreal for food waste recovery by anaerobic digestion, the approach showed that at most 23 out of the 30 districts should be included in the service area, depending on the indicator, which represents around 127,000 t of waste recovered/year. Due to the systemic approach, these districts were not necessarily the closest to the facility. Moreover, for the Montreal case, changing the facility's location did not have a great influence on the optimal service area size, showing that the distance to the facility was not a decisive factor at this scale. However, replacing anaerobic digestion by a composting plant reduced the break-even transport distances and, thus, the number of sources worth collecting (around 68,500 t/year). In this way, the methodology, applied to different management strategies, gave a sense of the spatial dynamics involved in the recovery chain's design. The map of optimal supply obtained could be used to further analyse the feasibility of multi-site and/or multi-technology systems for the territory considered.
[en] Traditionally, anaerobic digestion has been used for the reduction of volatile suspended solids and mass of concentrated sludge produced in Waste Water Treatment Plants (WWTPs). In recent years, anaerobic biological treatment has been widely introduced due to biogas production and low energy cost. Furthermore, it has been extended to waste water treatment and other waste streams (e.g. agriculture and livestock waste) as different configurations such as Upflow Anaerobic Sludge Blanket (UASB) or Anaerobic Membrane Bioreactor (AnMBR). Nevertheless, there are some important factors to control in anaerobic treatment such as temperature, pH and inhibitory compounds so that the operation of these processes are not as robust as Conventional Activated Sludge (CAS).
[en] Highlights: • Data on long term operation of a system supplied with real biogas are presented. • Ex-situ biological methanation is feasible for biogas upgrading. • Gas quality obtained complies with strictest direct grid injection criteria. • Biomethane can act as flexible storage for renewable surplus electricity. - Abstract: The current study reports on biological biogas upgrading by means of hydrogen addition to obtain biomethane. A mesophilic (37 °C) 0.058 m"3 trickle-bed reactor with an immobilized hydrogenotrophic enrichment culture was operated for a period of 8 months using a substrate mix of molecular hydrogen (H_2) and biogas (36–42% CO_2). Complete CO_2 conversion (> 96%) was achieved up to a H_2 loading rate of 6.5 m_n"3 H_2/m"3_r_e_a_c_t_o_r _v_o_l_. × d, corresponding to 2.3 h gas retention time. The optimum H_2/CO_2 ratio was determined to be between 3.67 and 4.15. CH_4 concentrations above 96% were achieved with less than 0.1% residual H_2. This gas quality complies even with tightest standards for grid injection without the need for additional CO_2 removal. If less rigid standards must be fulfilled H_2 loading rates can be almost doubled (10.95 versus 6.5 m_n"3 H_2/m"3_r_e_a_c_t_o_r _v_o_l_. × d) making the process even more attractive. At this H_2 loading the achieved methane productivity was 2.52 m_n"3 CH_4/m"3_r_e_a_c_t_o_r _v_o_l_. × d. In terms of biogas this corresponds to an upgrading capacity of 6.9 m_n"3 biogas/m"3_r_e_a_c_t_o_r _v_o_l_. × d. The conducted experiments demonstrate that biological methanation in an external reactor is well feasible for biogas upgrading under the prerequisite that an adequate H_2 source is available.
[en] Highlights: • Grass yields from marginal land were comparable with those from good agricultural land. • Perennial rhizomatous grasses such as festulolium outyielded perennial ryegrass when grown on marginal land. • Grass from marginal land in Ireland could provide enough energy to power both the private car and the heavy goods vehicle fleets. - Abstract: The production of biomass feedstock from marginal land has attracted much attention as a means of avoiding conflict between the production of food and fuel. Yield potentials from marginal lands have generally not been quantified although it is generally assumed that lower biomass yields can be expected from marginal lands. A three year study was conducted in Ireland in order to determine if grass yields of perennial rhizomatous grasses (cocksfoot, tall fescue, reed canary grass, festulolium) for anaerobic digestion from three marginal land sites (very wet site, very dry site, site prone to flooding) could match yields from better soils. Randomised complete block designs were established on each site in 2012 with two varieties of each grass species as treatments. Three grass harvests were taken from each site in 2013 and in 2014. There was no significant difference between yields from the control site and those from the very dry site and the site prone to flooding. Biomass yields from the very wet site were 85% of those from the control site. Highest yields were obtained from festulolium which were significantly higher than yields from perennial ryegrass. An energy analysis showed that maximising the production of grass from low lying mineral marginal grassland in Ireland could provide enough energy to meet the energy requirements of both the private car fleet and the heavy goods vehicle fleet while avoiding conflict with food production which could be concentrated on conventional land.
[en] Complete text of publication follows. A number of factors compromise the health of modern people: stressful lifestyle, unbalanced nourishment, excessive consumption of refined foods with a big measure, admission of different chemical agents into the human body. These factors harm directly or indirectly the intestinal activity, that forms a considerable part of the immune system, including the production of essential substances that have beneficial effects on the human body. The role of the so-called prebiotics (e.g. inulin, various oligosaccharides, raffinose, resistant starch etc.) is to prevent and reduce the damage of useful microbes, which are termed as probiotics. These substances selectively facilitate the propagation of probiotic bacteria (e.g. Bifidobacterium bifidum, Bifidobacterium longum, Enterococcus faecium, Lactobacillus acidophilus), therefore increase the rate of the synthesis of vitamin B and of beneficial short chain fatty acids, improve the absorption of minerals, decrease the level of cholesterol, triglycerides, insulin, glucose, ammonia and uric acid and improve the functioning of the immune system. The majority of the examination results about prebiotics are based on clinical dietary and animal experiments. In contrast to this we simulated the process of digestion and the effect of prebiotics on probiotic and non-probiotic bacteria selected by us in an artificial digestion model, the Atlas Potassium reactor system. The instrument enabled the control of pH, temperature, dosage of digestion enzymes and juices (saliva, gastric juice, bile and duodenal juice) and anaerobity in the course of the experiment. In our experiments we investigated different bakery products and biscuits containing various prebiotic ingredients, e.g. inulin and other fructo oligosaccharides. In the digestion model the different bakery products and biscuits got through the simulated oral cavity (pH=6.8), stomach (pH=2-3) and intestine (pH=6.5-7) and might be modified in the course of this travel. Various mixes of the probiotic and non-probiotic bacterial strains (Bif. bifidum + E. coli, Bif. bifidum + Lac. acidophilus + E. coli, Bif. bifidum + Ent. faecium + Lac. acidophilus + E. coli) were added to the model in simulated colon phase, then the digestion continued on the appropriate temperature (37 deg C), pH and under anaerobic atmosphere. The pH decreasing effect of lactic acid producing bacteria was compensated by NaOH. The first sampling was carried out 24 hours after inoculation, whereas the second one was performed 36 hour after inoculation. At the same time preparation of dilution series and inoculation of the bacterial strains onto the adequate selective plates were performed. Based on the number of colonies counted on the selective plates we could see whether the prebiotics did help the propagation of probiotic strains against the non-probiotic strain.
[en] Highlights: • Lipid in municipal biomass would not inhibited the anaerobic digestion process. • A lipid concentration of 65% of total VS was the inhibition concentration. • The amount of Brevibacterium decreased with the increasing of the lipid contents. • Long chain fatty acids stacked on the methanogenic bacteria and blocked the mass transfer process. - Abstract: The influence of the lipid concentration on the anaerobic co-digestion of municipal biomass waste and waste-activated sludge was assessed by biochemical methane potential (BMP) tests and by bench-scale tests in a mesophilic semi-continuous stirred tank reactor. The effect of increasing the volatile solid (VS) concentration of lipid from 0% to 75% was investigated. BMP tests showed that lipids in municipal biomass waste could enhance the methane production. The results of bench-scale tests showed that a lipids concentration of 65% of total VS was the inhibition concentration. Methane yields increased with increasing lipid concentration when lipid concentrations were below 60%, but when lipid concentration was set as 65% or higher, methane yields decreased sharply. When lipid concentrations were below 60%, the pH values were in the optimum range for the growth of methanogenic bacteria and the ratios of volatile fatty acid (VFA)/alkalinity were in the range of 0.2–0.6. When lipid concentrations exceeded 65%, the pH values were below 5.2, the reactor was acidized and the values of VFA/alkalinity rose to 2.0. The amount of Brevibacterium decreased with increasing lipid content. Long chain fatty acids stacked on the methanogenic bacteria and blocked the mass transfer process, thereby inhibiting anaerobic digestion
[en] This study evaluated and compared the removal of antibiotics by industrial-scale composting and anaerobic digestion at different seasons. Twenty compounds belonged to three classes of widely used veterinary antibiotics (i.e., tetracyclines, sulfonamides, and quinolones) were investigated. Results show that of the three groups of antibiotics, tetracyclines were dominant in swine feces and poorly removed by anaerobic digestion with significant accumulation in biosolids, particularly in winter. Compared to that in winter, a much more effective removal (> 97%) by anaerobic digestion was observed for sulfonamides in summer. By contrast, quinolones were the least abundant antibiotics in swine feces and exhibited a higher removal by anaerobic digestion in winter than in summer. The overall removal of antibiotics by aerobic composting could be more than 90% in either winter or summer. Nevertheless, compost products from livestock farms in Beijing contained much higher antibiotics than commercial organic fertilizers. Thus, industrial composting standards should be strictly applied to livestock farms to further remove antibiotics and produce high quality organic fertilizer.