Evaluation of thermal steam-explosion key operation factors to optimize biogas production from biological sludge

2015 ◽  
Vol 72 (6) ◽  
pp. 937-945 ◽  
Author(s):  
S. I. Pérez-Elvira ◽  
I. Sapkaite ◽  
F. Fdz-Polanco

Thermal steam-explosion is the most extended hydrolysis pretreatment to enhance anaerobic digestion of sludge. Thermal hydrolysis key parameters are temperature (T) and time (t), and the generally accepted values reported from full-scale information are: 150–230 °C and 20–60 min. This study assesses the influence of different temperature–time–flash combinations (110–180 °C, 5–60 min, 1–3 re-flashing) on the anaerobic degradation of secondary sludge through biochemical methane potential (BMP) tests. All the conditions tested presented higher methane production compared to the untreated sludge, and both solubilization (after the hydrolysis) and degradation (by anaerobic digestion) increased linearly when increasing the severity (T–t) of the pretreatment, reaching 40% solubilization and degradation of the particulate matter at 180° C–60 min. However, for the 180 °C temperature, the treatment time impacted negatively on the lag phase. No influence of re-flashing the pretreated matter was observed. In conclusion, thermal steam-explosion at short operation times (5 min) and moderate temperatures (145 °C) seems to be very attractive from a degradation point of view thus presenting a methane production enhancement similar to the one obtained at 180°C and without negative influence of the lag phase.

2018 ◽  
Vol 64 (No. 3) ◽  
pp. 128-135 ◽  
Author(s):  
Radmard Seyed Abbas ◽  
Alizadeh Hossein Haji Agha ◽  
Seifi Rahman

The effects of thermal (autoclave and microwave irradiation (MW)) and thermo-chemical (autoclave and microwave irradiation – assisted NaOH 5N) pretreatments on the chemical oxygen demand (COD) solubilisation, biogas and methane production of anaerobic digestion kitchen waste (KW) were investigated in this study. The modified Gompertz equation was fitted to accurately assess and compare the biogas and methane production from KW under the different pretreatment conditions and to attain representative simulations and predictions. In present study, COD solubilisation was demonstrated as an effective effect of pretreatment. Thermo-chemical pretreatments could improve biogas and methane production yields from KW. A comprehensive evaluation indicated that the thermo-chemical pretreatments (microwave irradiation and autoclave- assisted NaOH 5N, respectively) provided the best conditions to increase biogas and methane production from KW. The most effective enhancement of biogas and methane production (68.37 and 36.92 l, respectively) was observed from MW pretreated KW along with NaOH 5N, with the shortest lag phase of 1.79  day, the max. rate of 2.38 l·day<sup>–1</sup> and ultimate biogas production of 69.8 l as the modified Gompertz equation predicted.


Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1094
Author(s):  
Marco Chiappero ◽  
Francesca Cillerai ◽  
Franco Berruti ◽  
Ondřej Mašek ◽  
Silvia Fiore

Biochar (BC) recently gained attention as an additive for anaerobic digestion (AD). This work aims at a critical analysis of the effect of six BCs, with different physical and chemical properties, on the AD of mixed wastewater sludge at 37 °C, comparing their influence on methane production and AD kinetics. AD batch tests were performed at the laboratory scale operating 48 reactors (0.25 L working volume) for 28 days with the addition of 10 g L−1 of BC. Most reactors supplemented with BCs exhibited higher (up to 22%) methane yields than the control reactors (0.15 Nm3 kgVS−1). The modified Gompertz model provided maximum methane production rate values, and in all reactors the lag-phase was equal to zero days, indicating a good adaptation of the inoculum to the substrate. The potential correlations between BCs’ properties and AD performance were assessed using principal component analysis (PCA). The PCA results showed a reasonable correlation between methane production and the BCs’ O–C and H–C molar ratios, and volatile matter, and between biogas production and BCs’ pore volume, specific surface area, and fixed and total carbon. In conclusion, the physic-chemical properties of BC (specifically, hydrophobicity and morphology) showed a key role in improving the AD of mixed wastewater sludge.


2017 ◽  
Vol 68 (6) ◽  
pp. 1294-1297 ◽  
Author(s):  
Gabriela Alina Dumitrel ◽  
Adrian Eugen Cioabla ◽  
Ioana Ionel ◽  
Lucia Ana Varga

Anaerobic digestion processes of agricultural resources, as single substrates (wheat bran and barley) or as combination of substrates (75 % corn&25% corn cob � named MIX1 and 40 % corn & 40 % wheat&20 % sunflower husks � named MIX2), were performed, at a mesophilic temperature in a batch reactor, at pilot scale. The results proved that the higher quantity of biogas yield was achieved for barley, followed by MIX1, and finally MIX2. The same order was obtained when the total methane production was evaluated. The performances of digesters were mathematically evaluated by using the modified Gompertz equation. The kinetic parameters, such as the methane production potential (MP), the maximum methane production rate (Rm) and the extent of lag phase (l) were calculated, for each experimental case. The values of the performance indicators confirmed that all the models fitted well with the experimental data.


Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 590
Author(s):  
Aiban Abdulhakim Saeed Ghaleb ◽  
Shamsul Rahman Mohamed Kutty ◽  
Gasim Hayder Ahmed Salih ◽  
Ahmad Hussaini Jagaba ◽  
Azmatullah Noor ◽  
...  

Man-made organic waste leads to the rapid proliferation of pollution around the globe. Effective bio-waste management can help to reduce the adverse effects of organic waste while contributing to the circular economy at the same time. The toxic oily-biological sludge generated from oil refineries’ wastewater treatment plants is a potential source for biogas energy recovery via anaerobic digestion. However, the oily-biological sludge’s carbon/nitrogen (C/N) ratio is lower than the ideal 20–30 ratio required by anaerobic digestion technology for biogas production. Sugarcane bagasse can be digested as a high C/N co-substrate while the oily-biological sludge acts as a substrate and inoculum to improve biogas production. In this study, the best C/N with co-substrate volatile solids (VS)/inoculum VS ratios for the co-digestion process of mixtures were determined empirically through batch experiments at temperatures of 35–37 °C, pH (6–8) and 60 rpm mixing. The raw materials were pre-treated mechanically and thermo-chemically to further enhance the digestibility. The best condition for the sugarcane bagasse delignification process was 1% (w/v) sodium hydroxide, 1:10 solid-liquid ratio, at 100 °C, and 150 rpm for 1 h. The results from a 33-day batch anaerobic digestion experiment indicate that the production of biogas and methane yield were concurrent with the increasing C/N and co-substrate VS/inoculum VS ratios. The total biogas yields from C/N 20.0 with co-substrate VS/inoculum VS 0.06 and C/N 30.0 with co-substrate VS/inoculum VS 0.18 ratios were 2777.0 and 9268.0 mL, respectively, including a methane yield of 980.0 and 3009.3 mL, respectively. The biogas and methane yield from C/N 30.0 were higher than the biogas and methane yields from C/N 20.0 by 70.04 and 67.44%, respectively. The highest biogas and methane yields corresponded with the highest C/N with co-substrate VS/inoculum VS ratios (30.0 and 0.18), being 200.6 mL/g VSremoved and 65.1 mL CH4/g VSremoved, respectively.


Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3573 ◽  
Author(s):  
Meneses-Quelal Orlando ◽  
Velázquez-Martí Borja

The objective of this research is to present a review of the current technologies and pretreatments used in the fermentation of cow, pig and poultry manure. Pretreatment techniques were classified into physical, chemical, physicochemical, and biological groups. Various aspects of these different pretreatment approaches are discussed in this review. The advantages and disadvantages of its applicability are highlighted since the effects of pretreatments are complex and generally depend on the characteristics of the animal manure and the operational parameters. Biological pretreatments were shown to improve methane production from animal manure by 74%, chemical pretreatments by 45%, heat pretreatments by 41% and physical pretreatments by 30%. In general, pretreatments improve anaerobic digestion of the lignocellulosic content of animal manure and, therefore, increase methane yield.


Catalysts ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 539 ◽  
Author(s):  
Renfei Li ◽  
Wenbing Tan ◽  
Xinyu Zhao ◽  
Qiuling Dang ◽  
Qidao Song ◽  
...  

Wood waste generated during the tree felling and processing is a rich, green, and renewable lignocellulosic biomass. However, an effective method to apply wood waste in anaerobic digestion is lacking. The high carbon to nitrogen (C/N) ratio and rich lignin content of wood waste are the major limiting factors for high biogas production. NaOH pre-treatment for lignocellulosic biomass is a promising approach to weaken the adverse effect of complex crystalline cellulosic structure on biogas production in anaerobic digestion, and the synergistic integration of lignocellulosic biomass with low C/N ratio biomass in anaerobic digestion is a logical option to balance the excessive C/N ratio. Here, we assessed the improvement of methane production of wood waste in anaerobic digestion by NaOH pretreatment, co-digestion technique, and their combination. The results showed that the methane yield of the single digestion of wood waste was increased by 38.5% after NaOH pretreatment compared with the untreated wood waste. The methane production of the co-digestion of wood waste and pig manure was higher than that of the single digestion of wood waste and had nonsignificant difference with the single-digestion of pig manure. The methane yield of the co-digestion of wood waste pretreated with NaOH and pig manure was increased by 75.8% than that of the untreated wood waste. The findings indicated that wood waste as a sustainable biomass source has considerable potential to achieve high biogas production in anaerobic digestion.


2011 ◽  
Vol 356-360 ◽  
pp. 2510-2514 ◽  
Author(s):  
Ming Fen Niu ◽  
Sai Yue Wang ◽  
Wen Di Xu ◽  
An Dong Ge ◽  
Hao Wang

In order to improve the rate of degradation of cellulose in corn straw, the study has an important significance that compost corn straw with inoculating high-efficient microbe agents. The experiment inoculated a cellulose-degrading strain F2 which was screened from compost into compost pretreatment, the VS of corn straw reduced from 93.14% to 71.69% after 15 days, the content of cellulose reduced from 34.12g·kg-1 to 25.66g·kg-1, the rate of degradation was 24.79% which was 10.60% higher than those without the strain. An anaerobic fermentation experiment was carried out with the two groups of composted corn straw and mixed pig feces with a certain ratio, and investigations of biogas production, pH, content of volatile fatty acids(VFA) and rate of methane production were conducted. The results were that the corn straw composted with the cellulose-degrading strain peaked 4 days earlier, the maximal daily biogas production was 1470mL, the cumulative biogas production reached 23641mL which was 16.87% higher and operated stably earlier. The study showed that the cellulose-degrading strain had a strong capacity to degrade cellulose in corn straw, and then improved the performance of anaerobic digestion.


2020 ◽  
Vol 14 (4) ◽  
pp. 551-557
Author(s):  
Yongku Li ◽  
Xiaomin Hu ◽  
Lei Feng

The changing parameters, as the biogas production rate, the methane production rate, the cumulative biogas amount, the cumulative methane amount, the biogas composition, pH etc. in high temperature anaerobic fermentation of chicken manure and stalks were analyzed by experiments with different mass ratios of chicken manure or livestock manure and stalks with a high C/N ratio. The methane production mechanism of high temperature anaerobic digestion of chicken manure and stalks was discussed in detail. It showed that not only the biogas production rates but also the methane production rates of R1–R7 demonstrated the trend of initial increase and then decrease after 50 d of high temperature anaerobic digestion. Besides, the gas production of R1 with pure chicken manure stopped on the 30th d of the reaction. The gas production of other groups R2–R7 also stopped on the corresponding 34th, 36th, 36th, 37th, 37th, and 37th day, respectively. At the end of the reaction, the cumulative biogas amounts and the cumulative methane amounts of R1–R7 were 411.58 and 269.54, 459.91 and 314.41, 425.32 and 294.11, 401.85 and 272.54, 382.63 and 257.07, 363.04 and 218.16, and 257.15 and 160.10 N ml/(g VS). The biogas slurry pH of R1–R7 all demonstrated a trend of initial decrease and then increase, e. g., pH of R2 reached the minimum of 5.94 on the 5th day. pH values of other groups were between 6.01 and 6.39. After the addition of 4 g of sodium bicarbonate on the 7th day, biogas slurry pH of R1–R7 all increased. pH was maintained between 7.16 and 7.44 until the end of the reaction.


2011 ◽  
Vol 697-698 ◽  
pp. 326-330 ◽  
Author(s):  
S.X. Zhou ◽  
Y.P. Dong ◽  
Y.L. Zhang

Microbial pretreatment was applied to enhance biogas production from corn stover through solid-state anaerobic digestion, but the price of microbial strains is high. The objective of this study was to find the effects on biogas production by the naturally microbial pretreatment method. The highest cumulative biogas yield for 60-day solid-state anaerobic digestion was obtained in B group (the pretreated corn straws with cow dung), which was 19.6% higher than that of the untreated samples. The D group(the pretreated corn straws with the sludge)cumulative biogas yield for 60-day solid-state anaerobic digestion was obtained, which was 18.87% higher than that of the untreted samples. The biogas of D group increased to the range of 55%~60% methane content, while B group with the range of 75%~80%.The results indicated that the pretreated corn straws mixing cow manure can improve both the biogas production yield and the content of methane in CH4。


Environments ◽  
2019 ◽  
Vol 6 (4) ◽  
pp. 44 ◽  
Author(s):  
John Loughrin ◽  
Nanh Lovanh

Digestion of wastes to produce biogas is complicated by poor degradation of feedstocks. Research has shown that waste digestion can be enhanced by the addition of low levels of aeration without harming the microbes responsible for methane production. This research has been done at small scales and without provision to retain the aeration in the digestate. In this paper, low levels of aeration were provided to poultry litter slurry through a sub-surface manifold that retained air in the sludge. Digestate (133 L) was supplied 0, 200, 800, or 2000 mL/day air in 200 mL increments throughout the day via a manifold with a volume of 380 mL. Digesters were fed 400 g of poultry litter once weekly until day 84 and then 600 g thereafter. Aeration at 200 and 800 mL/day increased biogas production by 14 and 73% compared to anaerobic digestion while aeration at 2000 mL/day decreased biogas production by 19%. Biogas quality was similar in all digesters albeit carbon dioxide and methane were lowest in the 2000 mL/day treatment. Increasing feed to 600 g/week decreased gas production without affecting biogas quality. Degradation of wood disks placed within the digesters was enhanced by aeration.


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