The influence of total solid contents during anaerobic mesophilic treatment of the organic fraction of municipal solid waste (MSW) has been studied in this work. The work was performed in batch ...reactors of 1.7
L capacity, during a period of 85–95 days. Two different organic substrate concentrations were studied: 931.1
mgDOC/L (20% TS) and 1423.4
mgDOC/L (30% TS). Experimental results showed that the reactor with 20% total solids content had significantly higher performance. Thus, the startup phase ended at 14 days and the total DOC removal was 67.53%. The startup in reactor R30 ended at 28 days obtaining 49.18% DOC removal. Also, the initial substrate concentration contributed substantially to the amount of methane in the biogas. Hence, the total methane production in the methanogenic phase was 7.01
L and 5.53
L at the end of the experiments for R20 and R30, respectively.
The aim of this paper was to analyze the biomethanization process of food waste (FW) from a university campus restaurant in six reactors with three different total solid percentages (20%, 25% and 30% ...TS) and two different inoculum percentages (20–30% of mesophilic sludge). The experimental procedure was programmed to select the initial performance parameters (total solid and inoculum contents) in a lab-reactor with V: 1100mL and, later, to validate the optimal parameters in a lab-scale batch reactor with V: 5000mL. The best performance for food waste biodegradation and methane generation was the reactor with 20% of total solid and 30% of inoculum: give rise to an acclimation stage with acidogenic/acetogenic activity between 20 and 60 days and methane yield of 0.49L CH4/g VS. Also, lab-scale batch reactor (V: 5000mL) exhibit the classical waste decomposition pattern and the process was completed with high values of methane yield (0.22L CH4/g VS). Finally, a protocol was proposed to enhance the start-up phase for dry thermophilic anaerobic digestion of food waste.
► The maximum hydrogen production is reached at 1.9-days HRT. ► The maximum solubilized organic carbon concentration is reached at 1.9-day HRT. ► The ratio ASC/DOC allows further interpretation of ...process limitations.
The main objective of this work has been to analyze the effect of hydraulic retention time (HRT) on the hydrogen production from the organic fraction of municipal solid waste (OFMSW) coming from a full-scale mechanical–biological-treatment (MBT) plant. Furthermore, it has also been studied, simultaneously, the effect of HRT on the solubilization of organic matter.
Experiments were conducted in an anaerobic continuous stirred tank reactor (CSTR) operating at thermophilic-dry conditions (55°C and 20% in total solids concentration respectively). A decreasing sequence of nine HRTs, from 15days to 1.5days, was imposed to evaluate its influence on the hydrogen production (HP), the specific hydrogen production (SHP) and the solubilized organic matter expressed in form of acidogenic substrate as carbon (ASC), dissolved organic carbon (DOC) and dissolved acid carbon (DAC).
The results have shown that the best results were obtained at 1.9-day HRT with a feeding regime of twice a day (type-C). At these conditions, the HP and the SHP was 1.077L H2/Lreactorday and 24.3mL H2/g VSadded, respectively. Maximum concentrations obtained of solubilized organic matter were: 1201mg/L for ASC, 1936mg/L for DOC and 735mg/L for DAC.
As novelty, the parameter ASC and, specially, the ratio ASC/DOC have shown to be adequate for analyzing and interpreting the behavior of the process and, concretely, to determine if hydrolysis and acidogenesis are coupled (stable process) or decoupled (transitory stage).
The anaerobic mesophilic degradation of municipal waste has been studied in discontinuous lab-reactors with two different initial concentrations of OFMSW: R20, with 931.1
mg DOC/L (20% TS), and R30, ...with 1423.4
mg DOC/L (30% TS). The anaerobic digestion process was favoured when it was carried on material with a total solids content of 20% in comparison to a similar process with 30% TS. A higher level of organic matter, in terms of DOC and VFA, 18.18% and 8.09% respect, was removed in the system with the lower amount of solids. The kinetics parameters showed higher active biomass and a higher coefficient for the production of methane at the lower loading. The highest maximum specific growth rate for the microorganisms (
μ
MAX) in the reactors with 20% TS, a value of 0.192
d
−1, was achieved in comparison to 0.131
d
−1 in the reactors with 30% TS. The inverse of the F:M ratio was higher in the R20 system with a value of 0.0104 (cf. 0.0006 in R30) and, as a result, the R30 system required longer hydrolytic and acidogenic stages.
X
V
0
/
Y
X
/
S
and the yield coefficient for product generation (
α
P/S) were higher, by around 53%, for the R20 digester.
•Biohythane was obtained from sulphate-containing organic industrial solid wastes.•Different organic loading rates and hydraulic retention times (HRTs) were carried out.•Maximum of 1.9lH2/l/d and ...5.4lCH4/l/d were obtained in the process.•The lower HRT the greater acidogenic stage takes place in the second reactor.•Acetogens and Archaea were dominated over sulphate-reducing bacteria in second phase.
Microbial population dynamics and anaerobic digestion (AD) process to eight different hydraulic retention times (HRTs) (from 25d to 3.5d) in two-phase dry-thermophilic AD from sulphate-containing solid waste were investigated. Maximum values of gas production (1.9±0.2lH2/l/d; 5.4±0.3lCH4/l/d and 82±9mlH2S/l/d) and microbial activities were obtained at 4.5d HRT; where basically comprised hydrolysis step in the first phase (HRT=1.5d) and acidogenic step finished in the second phase as well as acetogenic–methanogenic steps (HRT=3d). In the first phase, hydrolytic–acidogenic bacteria (HABs) was the main group (44–77%) and Archaea, acetogens and sulphate-reducing bacteria (SRBs) contents were not significant; in the second phase (except to 2d HRT), microbial population was able to adapt to change in substrate and HRTs to ensure the proper functioning of the system and both acetogens and Archaea were dominated over SRBs. Decreasing HRT resulted in an increase in microbial activities.
The influence of different organic fraction of municipal solid wastes during anaerobic thermophilic (55°C) treatment of organic matter was studied in this work: food waste (FW), organic fraction of ...municipal solid waste (OFMSW) and shredded OFMSW (SH_OFMSW). All digester operated at dry conditions (20% total solids content) and were inoculated with 30% (in volume) of mesophilic digested sludge. Experimental results showed important different behaviours patterns in these wastes related with the organic matter biodegradation and biogas and methane production. The FW reactor showed the smallest waste biodegradation (32.4% VS removal) with high methane production (0.18 LCH4/gVS); in contrast the SH_OFMSW showed higher waste biodegradation (73.7% VS removal) with small methane production (0.05 LCH4/g VS). Finally, OFMSW showed the highest VS removal (79.5%) and the methane yield reached 0.08 LCH4/g VS. Therefore, the nature of organic substrate has an important influence on the biodegradation process and methane yield. Pre-treatment of waste is not necessary for OFMSW.
We propose an analog-digital quantum simulation of fermion-fermion scattering mediated by a continuum of bosonic modes within a circuit quantum electrodynamics scenario. This quantum technology ...naturally provides strong coupling of superconducting qubits with a continuum of electromagnetic modes in an open transmission line. In this way, we propose qubits to efficiently simulate fermionic modes via digital techniques, while we consider the continuum complexity of an open transmission line to simulate the continuum complexity of bosonic modes in quantum field theories. Therefore, we believe that the complexity-simulating-complexity concept should become a leading paradigm in any effort towards scalable quantum simulations.
•Microbial abundance was established.•Improved biogas productivity.•Very low solids retention times in the system.•The optimum HRT is lower than acetogens and methanogens doubling times.
Different ...high feed organic loading rates (OLRs) (from 5.7g to 46.0g TVS/l/d) or hydraulic retention times (HRTs) (from 15d to 2d) in single-phase dry-thermophilic anaerobic digestion (AD) of organic fraction municipal solid waste (OFMSW) were investigated. The specific gas production (SGP) values (0.25–0.53m3/kg TVS) and the percentages of Eubacteria, Archaea, H2-utilising methanogens (HUMs) and acetate-utilising methanogens (AUMs) were stable within the ranges 80.2–91.1%, 12.4–18.5%, 4.4–9.8% and 5.5–10.9%, respectively. A HUM/AUM ratio greater than 0.7 seems to be necessary to maintain very low partial pressures of H2 required for dry AD process. Increasing OLR resulted in an increase in all the populations, except for propionate-utilising acetogens (PUAs). Optimal conditions were obtained at 3d HRT (OLR=30.7g TVS/l/d), which is lower than the doubling time of acetogens and methanogens. The methane production (MP) was clearly higher than those reported in AD of OFMSW.
•H2 was produced from thermophilic anaerobic co-digestion of OFMSW and sewage sludge.•Enhanced H2 production was achieved for OFMSW+sewage sludge co-fermentation.•Mixed sludge was the best ...co-substrate (with OFMSW) among the sludge types studied.•Best hydrogen yield was achieved at 20% TS concentration.•Highest H2 yield was achieved at OFMSW to mixed sludge ratio of 5:1.
Batch dry-thermophilic anaerobic co-digestion (55°C) of organic fraction of municipal solid waste (OFMSW) and sewage sludge (SS) for hydrogen production was studied under several sludge combinations (primary sludge, PS; waste activated sludge, WAS; and mixed sludge, MS), TS concentrations (10–25%) and mixing ratios of OFMSW and SS (1:1, 2.5:1, 5:1, 10:1). The co-digestion of OFMSW and SS showed a 70% improvement in hydrogen production rate over the OFMSW fermentation only. The co-digestion of OFMSW with MS showed 47% and 115% higher hydrogen production potential as compared with OFMSW+PS and OFMSW+WAS, respectively. The maximum hydrogen yield of 51mLH2/gVSconsumed was observed at TS concentration of 20% and OFMSW to MS mixing ratio of 5:1, respectively. The acetic and butyric acids were the main acids in VFAs evolution; however, the higher butyric acid evolution indicated that the H2 fermentation was butyrate type fermentation.
A series of batch anaerobic digestion assays were implemented to determine the influence of total solids concentration on the anaerobic digestion of sugar beet by-products and their co-digestion with ...two kind of livestock manures (pig and cow manures). The two total solid concentrations studied were 8% and 5%. Total solids contents above 8% were not evaluated because of the inappropriate rheological behaviour of sugar beet by-products at these concentrations. The best total solid content tested corresponded to 8%, achieving specific methane yields of 464.3 and 451.4mL/g VSadded for co-digestion with pig manure and cow manure respectively. These data were 1.5 times higher than that obtained for reactors operating with 5% total solids content. For individual digestion of sugar beet by-products, final methane yields operating at 8% were also higher than those measured at 5% total solids concentration. However, in these tests, a large delay in the start of biogas production was registered due to the inhibition caused by the accumulation of volatile fatty acids. No significant differences in the organic matter removal efficiencies were observed for the two total solids contents studied.
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•Mesophilic anaerobic digestion of sugar beet byproducts was studied.•Co-digestion of sugar beet byproducts with two livestock manures was conducted.•Influence of two total solid contents of 8% and 5% on the process was evaluated.•Operation at TS content of 8% showed better results than 5% TS.
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