Average Methane Yield Research Articles

Microbial dynamics and methanogenic potential of co-digestion of sugarcane vinasse and dairy secondary effluent in an upflow anaerobic sludge blanket reactor

Co-digestion is a strategy that may prevent microbial inhibition during the anaerobic treatment of sugarcane vinasse, a substrate with highly biodegradable organic load, acidity, and toxic compound levels (e.g., sulfates, phenols). In this context, this study evaluated the microbial dynamics and methanogenic potential throughout the co-digestion of sugarcane vinasse and secondary effluent from the dairy industry in a mesophilic lab-scale upflow anaerobic sludge blanket (UASB) reactor. Periodic next-generation sequencing (NGS) analyses revealed an increase in the relative abundance of the phylum Euryarchaeota (+8.6 % after inoculation), predominating hydrogenotrophic methanogens (Methanobacterium and Methanobrevibacter) at the end of the operation. Moreover, the average methane yield was 221 mLCH4 gCODrem-1, with 69 % of organic matter removal. These results evidenced a progressive acclimation of the anaerobic microbial community to the substrate and a stable operation. Therefore, the proposed experiment demonstrates energy advantages for the agro-industrial sector by implementing a similar but full-scale treatment plant.

Bioaugmentation of Methanosarcina thermophila grown on biochar particles during semi-continuous thermophilic food waste anaerobic digestion under two different bioaugmentation regimes

This study presents the effect of bioaugmentation of thermophilic anaerobic digestion of food waste with Methanosarcina thermophila grown on a wood-derived biochar. Two different supplementation regimes were tested, namely a single bioaugmentation (SBABC) in which 10% v/v of the microbes grown on biochar (1 g/L) is added at setup of the reactors, versus a routine bioaugmentation (RBABC) wherein the same amount of supplements were added over 10 feeding cycles. The optimally performing ‘R’ and ‘S’ reactors had increased methane yields by 37% and 32% over their respective controls while reactors SBABC 2 and 3 produced 21.89% and 56.09% higher average methane yield than RBABC 2 and 3, respectively. It appears that a single dose bioaugmentation is advantageous for improving AD as analysed in terms of average methane yield and VFA production. This study provides the basis for understanding how biochar and bioaugmentation can be used for engineering sustainable pilot-scale AD processes.

Semi-continuous mesophilic-thermophilic two-phase anaerobic co-digestion of food waste and spent mushroom substance: Methanogenic performance, microbial, and metagenomic analysis

The methanogenic efficiency and system stability of anaerobic co-digestion of food waste (FW) and spent mushroom substance (SMS) are important for its application. A 90-day semi-continuous study was conducted to compare the co-digestion performance of an ethanologenic-methanogenic two-phase system and an acidogenic-methanogenic system using FW and SMS as substrates. The results showed that the ethanologenic-methanogenic system increased the contents of ethanol and acetate in the hydrolytic acidification phase. Microbial-community analysis showed that ethanologenic-methanogenic system enriched hydrolytic acidifying bacteria and methanogens such as Methanoculleus, resulting in an increase in the average methane yield of methanogenic phase by 1.91–2.43 times at the same organic loading rate (OLR = 3.0–4.0 g-VS·L-1·d-1). Metagenomic analysis indicated that the ethanologenic-methanogenic system increased the abundance of enzyme-encoding genes and promoted the degradation of acetate and CO2/H2, thereby enhancing methanogenic metabolic pathways, compared to the acidogenic-methanogenic system.

Novel anaerobic digestion of waste activated sludge via isoelectric-point pretreatment: Ultra-short solids retention time and high methane yield

The prolonged reaction period and low methane yield have become a pivotal bottleneck in the anaerobic digestion (AD) of waste activated sludge (WAS), severely limiting its use in bioenergy. This study evaluated the long-term semi-continuous AD of WAS with isoelectric-point (pI) pretreatment in terms of the reaction period, methane yield, material resource recovery, and economic and environmental benefits. The experimental results show that after pI pretreatment, at the same solids retention time (SRT), the average methane yield and methane content in the biogas of WAS increased by 120.9% and 15.5%, respectively. The average methane yield from AD with pI pretreatment at a 5-day SRT was 1.6 times that of the AD without pI pretreatment at a 15-day SRT, indicating that pI pretreatment significantly (P < 0.001) increased the methane yield from the AD of WAS at different SRTs, even at an ultra-short SRT. Statistical analyses of the changes in the concentrations of soluble organic matter in the AD process with and without pI pretreatment confirmed that pI pretreatment enhanced the biochemical reactions related to the transformation of sludge organic matter during the whole AD process, but not the initial organic solubilisation and hydrolysis of the sludge. Furthermore, pI pretreatment recovered the NaHCO3, Na2S, and multivalent metals from the sludge, indicating that AD with pI pretreatment efficiently recovered both bioenergy and material resources from the sludge. Economic and environmental analyses of AD with and without pI pretreatment further indicated that with pI pretreatment, the annual economic benefit of AD increases by 162% and carbon emissions decreases by approximately 2.63 × 107 kg CO2/year compared with conventional AD. These findings serve as an important reference for the development of a novel AD technology for sludge that incorporates second-generation pretreatment and operates at an ultra-short SRT.

Effects of organic loading rates on the anaerobic co-digestion of fresh vinegar residue and pig manure: Focus on the performance and microbial communities

The 70 L mesophilic semi-continuous stirred tank reactor (semi-CSTR) for co-digestion of fresh vinegar residue (FVR) and pig manure (PM) was operated for 180 days to evaluate the behavior of process stability, inhibition and recovery, as well as the succession of microbial community structures with the increasing organic loading rates (OLRs). The maximum tolerable OLR for co-digestion was determined to be 5.0 g-VS/(L·d), achieving an average methane yield (MY) of 233.77 mL/g-VS. The feeding was paused for 7 days due to the accumulation of volatile fatty acids (VFAs), and then recovered at 5.5 g-VS/(L·d) with the maximum MY of 230.09 mL/g-VS. Meanwhile, the effect of OLRs on the microbial community was analyzed. It showed that there is a significant correlation between most of the major bacteria and VFA. PCA showed that stopping feeding and reducing OLR could change the bacterial community, but not archaeal community. The aceticlastic Methanosaeta was dominant at stable stage, and gradually replaced by the hydrogenotrophic methanogen, leading to the accumulation of acetate with increasing OLR. In the recovery stage, Methanosarcina became dominant to utilize the residual acetate. Due to the vigorous aceticlastic pathway of methanogenesis, the hydrogenotrophic pathway was depressed and the H2 pressure increased, causing the accumulation of propionate in a short time. With the relative abundance of Methanosarcina increasing constantly, the VFA except propionate decreased, suggesting that Methanosarcina transformed acetate and hydrogen into methane during the recovery stage.Supplementary Material_V4.doc

Inhibition mechanisms of ammonia and sulfate in high-solids anaerobic digesters for food waste treatment: Microbial community and element distributions responses

The horizontal flow anaerobic digester indicated that high ammonia (2923 mg/L) and SO42− (3653 mg/L) would influence the performance of methane production with food waste as substrates. Therefore, bottle anaerobic digestion reactors were carried out to investigate the effect of ammonia/sulfate concentrations on the methane production. Experimental results manifested that the anaerobic digesters with an ammonia concentration of 3500 mg/L or sulfate of 1600 mg/L showed the best performance of methane production, with an average methane yield of 0.32 and 0.33 L (g VS)−1 d−1, respectively. Specifically, a higher ammonia (6500 mg/L) or sulfate (1600-3500 mg/L) level hindered the bioconversion of C from liquid to gas phase (2.68% or 1.73% CH4-Gas, respectively), while insignificantly for the hydrolyzation of C and N from solid to liquid phase. Similar to sulfate, high ammonia nitrogen seriously inhibited the methanation process, leading to a significant carbon accumulation in the anaerobic reactor, especially for propionic acid. The predominant archaea Methanosarcina at genus level indicated that aceticlastic methanogenesis was the major methanogenic pathway. Meanwhile, high ammonia level suppressed the activity of Methanosarcina, while modest sulfate improved H2-consuming methanogens activity. A large fraction of unclassified bacteria within the Firmicutes (43.78%-63.17%) and Bacteroidetes (24.20%-33.30%) phylum played an important role in substrates hydrolysis.

Transition Metal Doping Induces Ti3+ to Promote the Performance of SrTiO3 @TiO2 Visible Light Photocatalytic Reduction of CO2 to Prepare C1 Product.

Transition metal Fe, Co, Ni and Cu doped strontium titanate-rich SrTiO3 @TiO2 (STO@T) materials were prepared by hydrothermal method. The prepared doped materials exhibit better photocatalytic CO2 reduction to CH4 ability under visible light conditions. Among them, Fe-doped and undoped SrTiO3 @TiO2 under visible light conditions CO2 reduction products only CO, while M-STO@T (M=Co, Ni, Cu) samples converted CO2 to CH4 . The average methane yield of Ni-doped STO@T samples are as high as 73.85 μmol g-1 h-1 . The production of methane is mainly due to the increase in the response of the doped samples to visible light. And the increase in the separation rate of photogenerated electrons and holes and the efficiency of electron transport caused by the generation of impurity levels. The impurity level caused by Ti3+ plays an important role in the production of methane by CO2 visible light reduction. Ni doping effectively improves the photocatalytic performance of STO@T and CO2 reduction mechanism were explained.

Recirculating Anaerobic Dynamic Membrane Bioreactor Treatment of Municipal Wastewater

A recirculating anaerobic dynamic membrane bioreactor system was evaluated at the lab scale for the treatment of simulated and real municipal wastewater (MWW). The bioreactor contained a filtration structure with meshes to support the development of a biofilm or dynamic membrane through which bulk liquid was continuously recirculated. This approach aimed to overcome high fouling and dissolved methane oversaturation, challenges typical of mainstream anaerobic membrane bioreactor technologies. At hydraulic retention times ranging from 4 to10 h, the system achieved average effluent suspended solids levels of 20 mg/L (simulated MWW) and 22 mg/L (real MWW), while also achieving average chemical oxygen demand (COD) concentrations of 71 mg/L (simulated MWW) and 84 mg/L (real MWW). The system demonstrated minimal dissolved methane oversaturation, and the average total methane yield was 0.29 L CH4/g COD removed for simulated MWW and 0.18 L CH4/g COD removed for real MWW. The observed filtration resistance rate (approximately 1 × 108 m–1 h–1) was one to two orders of magnitude lower than those reported for MWW treatment by anaerobic membrane bioreactor approaches. Operation at low transmembrane pressure and high flux was possible without intervention to control fouling for over 450 days. If the lab-scale results reported here can be achieved at the full-scale level, the recirculating anaerobic dynamic membrane bioreactor will allow for net positive energy generation over a range of MWW characteristics (0.180 to 0.658 kWh/m3). Therefore, we conclude that the recirculating anaerobic dynamic membrane bioreactor strategy deserves further study as an emerging option for low-footprint, energy-positive treatment of dilute wastewaters like MWW.

Predicting enteric methane emission in lactating Holsteins based on reference methane data collected by the GreenFeed system

Methane emission is not included in the current breeding goals for dairy cattle mainly due to the expense and difficulty in obtaining sufficient data to generate accurate estimates of the relevant traits. While several models have been developed to predict methane emission from milk spectra using reference methane data obtained by the respiration chamber, SF6 and sniffer methods, the prediction of methane emission from milk mid-infrared (MIR) spectra using reference methane data collected by the GreenFeed system has not yet been explored. Methane emission was monitored for 151 cows using the GreenFeed system. Prediction models were developed for daily and average (for the trial period of 12 or 14 days) methane production (g/d), yield (g/kg DM intake (DMI)) and intensity (g/kg of fat- and protein-corrected milk) using partial least squares regression. The predictions were evaluated in 100 repeated validation cycles, where animals were randomly partitioned into training (80%) and testing (20%) populations for each cycle. The best performing model was observed for average methane intensity using MIR, parity and DMI with validation coefficient of determination (R2val) and RMSE of prediction of 0.66 and 4.7 g/kg of fat- and protein-corrected milk, respectively. The accuracy of the best models for average methane production and average methane yield were poor (R2val = 0.28 and 0.12, respectively). A lower accuracy of prediction was observed for methane intensity and production (R2val = 0.42 and 0.17) when daily records were used while prediction for methane yield was comparable to that for average methane yield (R2val = 0.16). Our results suggest the potential to predict methane intensity with moderate accuracy. In this case, prediction models for average methane values were generally better than for daily measures when using the GreenFeed system to obtain reference methane emission measurements.

Pilot-scale anaerobic co-digestion of food and garden waste: Methane potential, performance and microbial analysis

Among the organic waste sources used for energy recovery through anaerobic digestion, food waste can be emphasized, as they are the result of the growing demand for food in the world. Additionally, lignocellulosic waste is one of the major energy sources available in urban and rural areas. In this context, the objective of this research was to evaluate the effects of food and garden waste co-digestion in the anaerobic process performance and also in the microbial community involved, by comparing two pilot scale reactors (500 L). To enable the comparison between mono-digestion and co-digestion, one reactor was operated only with food waste as a substrate while in the other, 20% of the ORL from the food waste was substituted by garden waste. The results showed a better performance in co-digestion, with a removal of 83% in VS, an average specific methane yield of 0.47 LCH4 gVS−1, a biogas production rate of 86 L d−1, with an average methane content of 67% and a delay in the system acidification when an OLR of 0.24 kgVS m−3d−1 was applied. The SEM images showed that the microorganisms were attached to garden waste particles as support medium for biofilm formation, favoring the development of certain species of microorganisms more resistant to external variations and, consequently, delaying the acidification of the reactor. The analysis of the microbial community in the reactors indicated a higher presence of hydrogenotrophic methanogenic archaea (Methanospirillum, Methanobacterium, Methanobrevibacter and Methanoculleus).

Оценка энергетического потенциала свалочного газа

The purpose of the work was to compare the potential of biogas generation at MSW landfills, determined by the most commonly used methods, and to determine the energy potential of landfill gas in the country's energy system, provided that it is fully used to generate electricity. Based on the equation of the chemical reaction of biogas formation, equations are proposed for calculating the specific yield of biogas components from 1 kg of waste and their shares in volume percent. Calculations according to the proposed formulas showed that the yield of biogas from a ton of waste for Russian MSW, the composition of which is accepted from different sources, varies significantly, from 312 to 433 m3. The composition of biogas changes little, and the theoretical content of methane in it ranges from 53% to 57%. The yield and composition of biogas was estimated using the Tabasaran-Rettenberger equation, LandGEM, DOD (IPCC), CLEEN models and Russian regulatory methods. The average total biogas yield was 195 m3/t waste with a variation coefficient of 38%, the average methane yield was 95 m3/t waste with a variation coefficient of 46%, and the average calorific value of biogas, related to 1 ton of waste from which it was formed, was 3 400 MJ/t of waste with a coefficient of variation of 44%. With a conversion efficiency of 39%, landfill gas from 1 ton of waste can generate 368 kWh of electricity. The total volume of municipal solid waste in Russia, subject to the full collection and use of biogas, makes it possible to generate 22.1 billion kWh of electricity, which is about 2% of the total energy consumption in the country. For a number of countries, the energy potential of landfill gas ranged from 0.05% (China) to 4.5% (Spain). Thus, landfill gas is a significant source of electricity in the overall energy balance.

Species composition of semi‐natural mesic grasslands as a factor influencing the methane yield of plant biomass (Central Europe)

AbstractSemi‐natural lowland and mountain mesic meadows are grasslands rich in species, and their conservation status depends on treatments such as mowing or grazing livestock. In many countries, the condition of grasslands is deteriorating because of their inappropriate use or abandonment. This study aimed to determine the effects of the species composition of plant communities and functional plant groups on the methane yield from biomass harvested from mesic grasslands in the Sudetes Mountains. Biogas potential analysis was performed based on biomass samples collected from Poland and the Czech Republic. The biogas potential was determined in 40 day‐long batch anaerobic digestion tests. The average methane yield obtained from the biomass was 246 ± 16 NL CH4 kg−1 VS, whereas the methane yield per hectare was 870 ± 203 m3 CH4 ha−1. Plant communities comprising different dominant species had no effect on the methane yield but affected the methane yield per hectare. Additionally, the species composition of grasslands with a higher percentage of forbs had lower biomass yield, resulting in lower methane yields per hectare. The continuity of the low‐intensity management of mountain grassland, which can be provided by the utilization of their biomass for bioenergy production, sustains high biodiversity and ensures appropriate meadow conservation.

Enzymatic Pretreatment of Byproducts from Soapstock Splitting and Glycerol Processing for Improvement of Biogas Production.

This study investigated acid splitting wastewater (ASW) and interphase (IF) from soapstock splitting, as well as matter organic non glycerol (MONG) from glycerol processing, as potential substrates for biogas production. Batch and semicontinuous thermophilic anaerobic digestion experiments were conducted, and the substrates were preliminary treated using commercial enzymes kindly delivered by Novozymes A/C. The greatest enhancement in the batch digestion efficiency was achieved when three preparations; EversaTransform, NovoShape, and Lecitase were applied in the hydrolysis stage, which resulted in the maximum methane yields of 937 NL/kg VS and 915 NL/kg VS obtained from IF and MONG, respectively. The co-digestion of 68% ASW, 16% IF, and 16% MONG (wet weight basis) performed at an organic loading rate (OLR) of 1.5 kg VS/m3/day provided an average methane yield of 515 NLCH4/kg VSadded and a volatile solid reduction of nearly 95%. A relatively high concentration of sulfates in the feed did not significantly affect the digestion performance but resulted in an increased hydrogen sulfide concentration in the biogas with the peak of 4000 ppm.

Modified biochar promotes the direct interspecies electron transfer between iron-reducing bacteria and methanogens in high organic loading co-digestion

High organic loading (HOL) could reduce substrate degradation and methane production. The objective of this study was to investigate the promotion mechanism of iron-modified biochar in HOL co-digestion. The results showed that the specific surface area of iron-modified biochar prepared at 500 ⁰C (500Fe@BC) was 131.7 m2/g. In 12% (w/w) of HOL co-digestion, 500Fe@BC addition enhanced methanogenesis by both aceticlastic and hydrogenotrophic pathways and showed the best methane yield performance. Compared with the non-biochar addition group, an increase of 56.6% and 11% in average methane content and cumulative methane yield was observed in the presence of 500Fe@BC during 25 days of hydraulic retention time. Furthermore, the buffer capacity of HOL co-digestion has been intensified, which attributed to the 500Fe@BC accelerated the hydrolysis of substrates and promoted the consumption of the volatile fatty acids. Moreover, 500Fe@BC promoted the enrichment of iron-reducing bacteria (Clostridium_sensu_stricto_1, Romboutsia) and methanogens (Methanosarcina, Methanobacterium).

The effect of temperature and styrene concentration on biogas production and degradation characteristics during anaerobic removal of styrene from wastewater

In the current study, styrene was removed anaerobically from wastewaters at temperatures of 35 ℃, 25 ℃, and 15 ℃ and concentration range of 20–150 ppm in the presence of ethanol as a co-substrate and co-solvent. Maximum styrene removal of 93% was achieved at 35 ℃. The volatilization of styrene was negligible at about 2% at all experimented temperatures. The average special methane yield (SMY) at 35 ℃ was 4.14- and 225-times higher than that of at T = 25 ℃ and T = 15 ℃, respectively, but no methane was produced in the absence of ethanol. The proteins content of the soluble microbial product (SMP) and extracellular polymeric substance (EPS) was much higher than the carbohydrate content. At styrene concentration > 80 ppm, SMY, SMP, and EPS dropped sharply. The results confirmed the well performance of anaerobic microorganisms in removing styrene from wastewater and biogas production at mesophilic condition.

Co-digestion of microbial biomass with animal manure in three-stage anaerobic digestion

Microbial biomass (MB) was co-digested with different animal manures namely, chicken manure (CM), pig manure (PM) and cow dung (CD) at the ratios of 1:1:1:1, 2:1:1:1 and 3:1:1:1, and analyzed for biogas production. Maximum biogas yield and methane concentration were found at the ratio of 1:1:1:1. The optimization of biogas production was carried out using different pH values, temperatures, and substrate concentrations. The yield of methane was measured at different temperatures (35, 40, 50 and 55 ˚C). The optimum was 40 ˚C giving 62% CH4/d yield on the 6th day. The result of this study showed that co-digestion with microbes is beneficial for maximizing biogas production when compared to the anaerobic digestion of animal manure alone. A digester with a three-stage anaerobic digesting facility was designed, fabricated and analyzed for biogas production using the co-digestion of yeast biomass with pig manure. The reactor had separate chambers for hydrolysis, acidogenesis and methanogenesis. Each of them was optimized independently for simultaneous production and improvement of biogas and to analyze the performance of the reactor. The average methane yield with a three-stage anaerobic digester was 0.442 L/gVS. Higher volatile solids (VS) reduction of about 68% was seen at the third stage pf anaerobic digesting. Based on the findings from this study, the three stage anaerobic digestion was identified to be advantageous for high solids anaerobic digestion of microbial biomass with animal manure. Solid organic matters in the substrate was solubilized which leads to the formation of improved biogas production and volatile fatty acids.

Accelerated Biomethane Potential assay for straw with artificially flocculated sludge and defined ‘synthetic manure’

A Biomethane Potential (BMP) assay for lignocellulosic material was elaborated with milled wheat straw (WS) as reference substrate. The generally used cow manure as co-substrate was replaced with a buffering salt solution having trace elements called ‘synthetic manure’. The inoculum sludge was artificially flocculated and thickened to accelerate the BMP assay and to favour microbial syntrophy. The chemical stoichiometric formula for WS was estimated to be C3.71H6.04O2.79N0.044S0.005 and this was used to calculate the theoretically possible 100% methane yield being 293.4 mLSTP CH4 gVS−1, after the non-degradable lignin portion (23.05%) was subtracted. Experimentally, an average specific methane yield of 287.1 mLSTP CH4 gVS−1 was obtained at about 98%. This result indicated a 100% degradation, if the microbially generated biomass during the BMP assay was considered. Methanization was completed after 15 days only, instead of mostly 60 days as shown by novel in-situ methane sensors.

Coupling anaerobic fluidized membrane bioreactors with microbial electrolysis cells towards improved wastewater reuse and energy recovery

Anaerobic Membrane Bioreactors (AnMBRs) combine the advantages of anaerobic processes and MBR technology to improve effluent quality and energy recovery. However, these systems are associated with operational challenges such as membrane fouling and loss of dissolved methane that increases operation and energy expenses. In this study, a new configuration was developed combining AnMBRs with Microbial Electrolysis Cells (MECs). The effectiveness of the coupled AnFMBR-MEC system was tested by monitoring several indicators during the treatment of synthetic wastewater. The new configuration exhibited a 25-day shorter startup period, a 56% enhanced average methane yield, and a reduced membrane fouling with a maximum transmembrane pressure value nearly 6.5 folds lower than that exhibited by the AnFMBR alone. AnFMBR-MEC had an average CE of 40% and both reactors achieved around 90% COD removal. Similar bacterial communities existed in both reactors but with different relative abundance and localization. In the AnFMBR-MEC, the Direct Interspecies Electron Transfer was the likely dominant route for acetate consumption due to the abundance of Geobacter and Methanosarcina on the granular activated carbon and in suspension. The new system offers a promising technology with less fouling and improved resource recovery from wastewater due to the presence of different environmental niches (GAC, anode, cathode) for microbial colonization and growth, which resulted in the reduction of biomass in suspension and the proliferation of electroactive bacteria and methanogens as biofilms.

Anaerobic digestion of hydrothermal liquefaction wastewater from spent coffee grounds

Spent coffee grounds (SCG) are high water content lignocellulosic residues generated in large amounts by the instant coffee production industry. Recent interest in the use of SCG as biomass for biocrude oil production via hydrothermal liquefaction (HTL) pointed to the generation of an aqueous effluent rich in organic matter of high aromaticity, denominated post hydrothermal wastewater (PHWW). The anaerobic digestion of PHWW was investigated as a treatment option and was evaluated for its energy recovery potential through methane production. Sequencing batch reactors were subjected to increasing initial chemical oxygen demand (COD) levels from 1000 mg COD L−1 to 8000 mg COD L−1, to allow for gradual biomass adaptation to the substrate recalcitrance and toxicity. The highest COD removal rate was observed for an initial COD level of 4000 mg COD L−1. Under this condition, the average methane yield was 187 ± 13 mLCH4 g−1 CODadded, with average COD and total phenols removal efficiencies of 60 ± 1% and 48 ± 4%, respectively. A kinetic evaluation revealed that the methane yield decreased sharply for initial phenolic compounds concentrations above 900 mg GAE L−1. Methane production represented a 22.8% increase in the energy recovered from SCG.

High-solid digestion from cellulosic ethanol stillage with activated sludge of simultaneous propionate degradation and methanogenesis

High solid anaerobic digestion (HSAD) was an emerging bioconversion technology which had the advantages of small digester, less digestate and low heating energy. A one-stage anaerobic system in CSTR by inoculating activated sludge of simultaneous propionate degradation and methanogenesis was proposed to improve the high-solid digestion performance and to stabilize the reaction process. Semi-continuous mode was successfully used to perform HSAD from cellulosic ethanol whole stillage at an initial substrate loading of 15.4% (w/w) dry matter content with different OLRs from 1.5 to 5.0 gVS·L−1 d−1 at an HRT of 30 days. The average methane yield during whole digestion reached 349.9 mL⋅gVS−1 with a total VS removal rate of 61.3%. The acclimation mechanism of multifunctional activated sludge was also explored by analyzing the functional property, physiological activity and microbial community structure. The results indicated the feasibility and efficiency of multifunctional activated sludge in a semi-continuous high-solid stirred tank reactor system.