Improve Biogas Production Research Articles

Influence of moisture content of solid-state NaOH pretreatment and codigestion on methane production in the semi-dry anaerobic digestion of rose stalk

Large quantities of burned or abandoned rose stalks are leading to serious environmental pollution. In this study, the effect of the moisture content of a solid-state NaOH pretreatment on methane production was first determined by a biochemical methane potential test. Then, the effect of codigestion with pig manure on methane production was investigated under the optimal moisture via thermophilic semi-dry anaerobic digestion by leaching bed reactor. Biogas production kinetic was assessed by the first-order kinetic model and modified Gompertz model. An increase in methane yield and biogas production kinetics was shown in the solid-state NaOH pretreated biomass. There was no significant difference in methane production for the three moisture contents studied during pretreatment (54%, 70%, and 77%). The anaerobic codigestion of rose stalk and pig manure increased 41% to 52% for methane yields and improved biogas production kinetics compared with monodigestion of rose stalk. Anaerobic codigestion did not greatly change the process stability, except for NH4+-N. The optimal process for the anaerobic digestion of rose stalk was as follows. The rose stalk was initially pretreated via solid-state NaOH pretreatment with a moisture content of 70%. Then, the pretreated rose stalk was co-digested with pig manure at a total solids ratio of 1:1.

Improving Anaerobic Digestion of Sewage Sludge by Hydrogen Addition: Analysis of Microbial Populations and Process Performance

The effect of hydrogen pulse addition on digestion performance of sewage sludge was evaluated as a means for studying the increase in efficiency of methane production. Microbial communities were also evaluated to get an insight of the changes caused by the operational modifications of the digester. An energy evaluation of this alternative was performed considering the theoretical process of coupling bioelectrochemical systems (BES) for the treatment of wastewater along with hydrogen production and the subsequent anaerobic digestion. The addition of hydrogen to sewage sludge digestion resulted in an increase of 12% in biogas production over the control (1353 mL CH4 d−1 at an injection flow rate of 1938 mL H2 d−1). The liquid phase of the sludge reactor and the H2 supplemented one did not show significant differences, thus indicating that the application of hydrogen as the co-substrate was not detrimental. High-throughput sequencing analysis showed slight changes in archaeal relative abundance after hydrogen addition, whereas eubacterial community structure and composition revealed noteworthy shifts. The mass and energy balance indicated that the amount of hydrogen obtained from a hypothetical BES can be assimilated in the sludge digester, improving biogas production, but this configuration was not capable of covering all energy needs under the proposed scenario.

Metagenomic Approach: Transforming In-Silico Research for Improved Biogas Production

The complexity of the microbial communities and metabolic pathways involved in the microbiological process of biogas production is poorly understood and numerous microorganisms in the fermentation sample of the biogas plant are still unclassified or unknown. The structure and function of microbial communities and the effects of the addition of trace elements are needed to be known, to control and channel the energy sources microbes produce and to capture and store the useful by-products or for targeted screening of novel enzymes. In this review, we discussed an emerging idea that Metagenome sequence data from a biogas-producing microbial community residing in a fermenter of a biogas plant provide the basis for a rational approach to improve the biotechnological process of biogas production. The composition and gene content of a biogas-producing consortium can be determined through metagenomic approach which allows the design of the optimal microbial community structure for any biogas plant for the significant progress in the efficacy and economic improvement of biogas production and biofertilizer of either balanced nutrition or rich in specific element for plant growth produced from the sludge of biogas plant. Biogas-producing microbial community from different production-scale biogas plants supplied with different raw materials as substrates can be analyzed by polyphasic approach to find out the best raw material composition for biogas production. The phylogenetic structure of the microbial community residing in a fermentation sample from a biogas plant can be analysed by an integrated approach using clone library sequences and metagenome sequence data obtained by 454-pyrosequencing.
 Int. J. Appl. Sci. Biotechnol. Vol 7(1): 6-11

Improving methane production from Pennisetum hybrid by monitoring plant height and ensiling pretreatment

The biomass of grass-based Pennisetum hybrid commonly use for a biogas production via anaerobic digestion. However, it is necessary to determine a method to optimize the plant harvest time for high biogas production. Moreover, ensiling of biomass in the presence of diverse microbes may offer a solution to improve biogas production. In this study, whole plant of Pennisetum biomass (including stems and leaves) was collected at different harvesting time (plant heights of 70, 100, 150 cm), and then comparatively assessed for further ensiling and biogas production. Compared to leaves, stems exhibited a significant linear relationship (R2 = 0.99) with whole plants in terms of ensiling quality (i.e. pH and NH3-N). Microbial analysis further revealed that Lactobacillus was the dominant bacterial genus during ensiling of stems and whole plants, with the highest relative abundance of 50.08% obtained at the height of 100 cm. Ensiling of biomass at a height of 100 cm achieved the best digestion performance, with the methane yields of 316 ± 20 mL/g VS for leaves, 361 ± 43 mL/g VS for stems, and 356 ± 28 mL/g VS for whole plants. A harvesting time at the plant height of 100 cm was the optimal from the silage quality and anaerobic digestion performance.

Effect of co-digestion of milk-whey and potato stem on heat and power generation using biogas as an energy vector: Techno-economic assessment

Energy conversion strategies based on lignocellulosic and industrial waste streams is considered a challenge in many countries producing huge quantities of biomass. The production of biogas as an energy vector has been gaining attention in the industry sector due to the energy policies for wastes managements or the feasibility of using the biogas for electricity and steam generation. An interesting feedstock alternative for the biogas production is milk whey, one of the main residues of the dairy industry. Additionally the potato stem generated in the harvest stage can be an attractive raw material for biogas production. Co-digestion is the combination of biodegradable raw materials to improve the balance of nutrients in anaerobic digestion. In this context, the characteristics of milk whey and potato stem are not enough to consider it as a good single substrate. However, the synergetic use of these two residues can represent an improvement in biogas production. The biogas production was calculated in Aspen Plus software using stoichiometric and kinetic models based on the experimental characterization of both materials. Through seven different scenarios: potato stem digestion, milk whey digestion and five co-digestion relations of both materials. Heat and electricity generation using biogas was analyzed. Then the generation of heat and electricity was simulated, where the economic profit was evaluated in terms of the production cost, capital cost, revenues and net present value. In terms of biogas production, the scenarios that involved high organic load were the best. For the economic assessment the raw material cost had the most influence over the total processing cost (80% approximately). However, even if energy is produced it is necessary to include the valorization of the digestate as biofertilizer in order that the different scenarios present economic viability.

Hydrothermal pretreatment of rice straw at relatively lower temperature to improve biogas production via anaerobic digestion

Although the degradation mechanism of straw anaerobic digestion is still obscure, lower temperature thermophysical pretreatment might be a feasible way to improve biogas fermentation efficiency and net energy production in whole slurry. In this study, the performances of rice straw (RS) degradation and biogas production were examined at different pretreatment temperatures from 90 °C to 130 °C to identify the optimal process. With increasing pretreatment temperature, the change in cellulose and hemicellulose degradation in all the tests was directly related to volatile fatty acids (VFAs) content, but did not correspond to the variation in cumulative methane production. Both 100 °C and 130 °C presented similar ideal digestion performances with highest methane yields of 127.6 and 124.6 mL/g TS, respectively, which were 22.80% and 19.83% higher than that noted in the control. Although test at 100 °C pretreatment, which achieved 12.8% higher net energy production from RS than that observed in the control, could be considered as the optimal choice, the surplus biogas could only meet 75.9% of energy requirement for pretreated water temperature shift. Nevertheless, mesophilic or thermophilic fermentation, lower pretreatment water input, and reuse of excess heat are recommended as feasible working conditions for improving net biogas production.

Hydrothermal and alkaline thermal pretreatment at mild temperature in solid state for physicochemical properties and biogas production from anaerobic digestion of rice straw

The effect of hydrothermal pretreatment (HTP) and alkaline thermal pretreatment (TA) at mild temperature in the solid state was comparatively studied, through the analysis of physicochemical properties of rice straw and its biogas production during anaerobic digestion. The results indicated that TA visibly increased the biogas yield from HTP. The accumulative biogas production of volatile solids was the highest for TA3 up to 411.1 mL/g VS, in which increased 24.04% compared to control. Therefore, the use of TA is more favorable to improve biogas production rates of anaerobic fermentation with rice straw than HTP, however, the additives of calcium hydroxide are too high, but it is not conducive to promoting the biogas yield of rice straw. The best additives amount of Ca (OH)2 was 2% to consider the cost of pretreatment with straw. The research results provide technical support for pretreatment of anaerobic fermentation of lingo-cellulosic materials such as straw.

Biological treatment of lignocellulosic biomass by Chaetomium globosporum: Process derivation and improved biogas production.

Chaetomium globosporum was isolated from aeolian soil samples collected from semi-arid locations in the state of Rajasthan, India. The efficiency of fungal strain for biological treatment of biomass to improve biogas yield was screened by estimating laccase enzyme activity under submerged fermentation system. Further, lignocellulosic biomass(s) wheat and pearl millet straw were subjected to biological treatment and subsequent increase in release of reducing sugar as compared to untreated straw was determined. Optimization of biological treatment conditions was accomplished by employing response surface methodology with Box Behnken design of experiments. Impact of three parameters (temperature, residence time, moisture content) was analyzed using three severity levels on output response of biological treatment in terms of released reducing sugar (g/L). Observed values were well fitted with second order polynomial equation (R2 = 0.91) and predicted outcomes were in agreement with experimental results. Optimized treatment conditions were: 36 °C, 31 days residence time and 81% moisture. A 2.9 fold increase in reducing sugar was released when substrates were treated under these conditions. Our research findings emphasize importance of optimizing biological treatment conditions to achieve high biogas yield when using wheat and pearl millet straw as feedstocks and similar treatment could be carried out for other lignocellulosic feedstocks.

Multi‐substrate anaerobic co‐digestion of citrus pulp, lawn grass, and chicken manure—A batch study

Anaerobic digestion of organic waste is a promising alternative to landfilling and is being encouraged by current policies in India. However, nutritional imbalance of single waste as a substrate in anaerobic digestion is limiting the effective degradation in biogas production. Co‐digestion of multiple organic wastes where the digestion of two or more substrates is carried out in a single digester is a promising method to enhance the nutritional balance. The present study investigated the possibilities of improving biogas production with co‐digestion of citrus pulp (CP), lawn grass (LG), and chicken manure (CM) based on the total solid loading (TS %). The design of experiments and analysis of the co‐digestion effect were carried out with central composite design (CCD) and response surface methodology (RSM), respectively. Biogas production was found to vary more with respect to total solid loading (TS %) than C/N ratio of the co‐digestion mix. The low influence of C/N ratio may be due to prevalence of optimal C/N ratio of 16–33 in all co‐digestion mixes. The adopted central composite design–response surface methodology (CCD–RSM) led to maximum biogas production of 688 mL at CP of 0.28 (TS %), LG of 9.4 (TS %), and CM of 4 (TS %). The CCD–RSM is a suitable approach to maximize the biogas production in multi‐substrate anaerobic co‐digestion. © 2019 American Institute of Chemical Engineers Environ Prog, 38:e13146, 2019

Combining Microwave Pretreatment with Iron Oxide Nanoparticles Enhanced Biogas and Hydrogen Yield from Green Algae

The available energy can be effectively upgraded by adopting smart energy conversion measures. The biodegradability of biomass can be improved by employing pretreatment techniques; however, such methods result in reduced energy efficiency. In this study, microwave (MW) irradiation is used for green algae (Enteromorpha) pretreatment in combination with iron oxide nanoparticles (NPs) which act as a heterogeneous catalyst during anaerobic digestion process for biogas enhancement. Batch-wise anaerobic digestion was carried out. The results showed that MW pretreatment and its combination with Fe3O4 NPs produced highest yields of biogas and hydrogen as compared to the individual ones and control. The biogas amount and hydrogen % v/v achieved by MW pretreatment + Fe3O4 NPs group were 328 mL and 51.5%, respectively. The energy analysis indicated that synergistic application of MW pretreatment with Fe3O4 NPs produced added energy while consuming less input energy than MW pretreatment alone. The kinetic parameters of the reaction were scientifically evaluated by using modified Gompertz and Logistic function model for each experimental case. MW pretreatment + Fe3O4 NPs group improved biogas production potential and maximum biogas production rate.

PENGARUH PENAMBAHAN KOTORAN SAPI DAN ENCENG GONDOK (EICCHORNIA CRASSIPES) TERHADAP PRODUKSI BIOGAS DARI LIMBAH JEROAN IKAN

The purposed of this research to study effect of adding cow dung and waterhyacinth to improve biogas production from fish waste. The method of thisresearch used experimental method at batch anaerob reactor and absortion carbonatom used NaOH solution. The result of this research analysis used describtionmethod. The observed of parameter included accumulation of biogas productionand also parameter at slurry incuded temperature and pH. Qualitative parameter istest of flame of biogas. The conclusion value of pH from this research betweencontrol reactor, A1 reactor (fishwaste: cow dung: water hyacinth= 2:9:3), A2reactor (fishwaste: cow dung: water hyacinth= 1:4:2), A3 reactor (fishwaste: cowdung: water hyacinth= 1:3:3) is 5 to 10. Temperature range in 28 oC to 31oC. Theresult indicated the different composition of subtrat slurry from fishwaste, cowdung and water hyacinth in scale 2:9:3 (A1 reactor) produced biogas accumulationand metana the most than the others reactor.

Disintegration of Wastewater Activated Sludge (WAS) for Improved Biogas Production

Due to rapid urbanization, the number of wastewater treatment plants (WWTP) has increased, and so has the associated waste generated by them. Sustainable management of this waste can lead to the creation of energy-rich biogas via fermentation processes. This review presents recent advances in the anaerobic digestion processes that have led to greater biogas production. Disintegration techniques for enhancing the fermentation of waste activated sludge can be apportioned into biological, physical and chemical means, which are included in this review; they were mainly compared and contrasted in terms of the ensuing biogas yield. It was found that ultrasonic- and microwave-assisted disintegration provides the highest biogas yield (>500%) although they tend to be the most energy demanding processes (>10,000 kJ kg−1 total solids).

Improvement of biogas production from slaughterhouse wastewater using biosynthesized iron nanoparticles from water treatment sludge

This study was conducted to examine the feasibility of recovering ferric coagulant from drinking water treatment sludge (DWTS) for green synthesis of iron nanoparticles (NPs). Black tea extract was utilized for the bio-reduction of ferric chloride. The as-synthesized product was characterized and confirmed as iron NPs, using UV–vis spectrometry, XRD, FT-IR, SEM, and EDX analyses. The synthesized NPs were sphere-like with diameter in the range of 20–40 nm. The performance of the iron NPs as micronutrients supplements in anaerobic digestion of slaughterhouse wastewater was studied at three different concentrations. The results showed that the addition of iron NPs in all concentrations improved the biogas production and shortened the lag phase. The highest biogas yield was obtained from 9 mg L−1 of additive which corresponds to up to 37.6% enhancement over the control reactor. Moreover, iron NPs improved COD reduction efficiency to 42%.

Exhaustive characterization on chemical and thermal treatment of sawdust for improved biogas production

This work is aimed to the effective chemical pretreatment of sawdust hydrolysis for enhanced biogas production. Various chemical reagents were used for sawdust hydrolysis. NaOH was found to be the best among all in order to produce highest yield of soluble chemical oxygen demand (sCOD) and phenolic compounds. Therefore, NaOH prospective on delignification and rupture of cell wall of sawdust was determined experimentally using different approaches (NaOH addition, NaOH-microwave, and NaOH-autoclave). The NaOH-autoclave pretreatment showed pronounced effect on cellulose, hemicellulose, and lignin content of sawdust. XRD analysis revealed that 10% increase in crystallinity was observed after NaOH-autoclave treatment. SEM micrographs also depicted that cell wall surface was highly affected by NaOH-autoclave pretreatment. Optimum condition for highest lignin solubilization of 58.6% was found at 10% NaOH concentration and 90-min autoclaving time. Biogas yield was increased by 50.8% at optimum pretreatment condition in comparison to native sawdust. Rate constant and order of bioconversion into biogas was also increased after pretreatment. The maximum methane content in biogas for treated sawdust was found to be 62%.

Anaerobic Process.

A review of the literatures published in 2017 on topics relating to anaerobic process issues in the improvement of biogas production and fermentation efficiency of various kinds of organic waste. New process methodology and technology of digestion is also presented. This review is divided into the following sections: pretreatment, organic waste and co-digestion, multiple-stage process, process methodology and technology.

Laser Improves Biogas Production by Anaerobic Digestion of Cow Dung

This study investigates the digestion of cow dung (CD) for biogas production at laboratory scales. The study was carried out through anaerobic fermentation using cow dung as substrate. The digester was operated at ambient temperatures of 39.5 °C for a period of 10 days. The effect of iron powder in controlling the production of hydrogen sulfide (H2S) has been tested. The optimum concentration of iron powder was 4g/L with the highest biogas production. A Q – swatch Nd:YAG laser has been used to mix and homogenize the components of one of the six digesters and accelerate digestion. At the end of digestion, all digestions effluent was subjected to 5 laser pulses with 250mJ/pules to dispose waste biomass.

Temperature shapes the microbiota in anaerobic digestion and drives efficiency to a maximum at 45 °C

Throwing longstanding habits over the pile may be necessary to improve biogas production, in particular when it comes to the process temperature. Its effect on biogas production was investigated with lab-scale reactors operated in fed-batch mode (cattle slurry and maize straw) at 10–55 °C over six months. Biochemical and microbial changes were comprehensively investigated. Production was highest and most efficient at 45 °C with an average methane yield of 166 NL kg−1 VS, and thus 12.8% and 9.6% higher than at 37 and 55 °C. Temperature significantly affected the microbiota and higher temperature provoked a shift from Bacteroidetes/Proteobacteria to Firmicutes. A transition from hydrogenotrophic to acetoclastic methanogenesis was observed from 10 to 45 °C, while the trend was reversed at 55 °C. The results contest the textbook notion of preferred and most efficient temperatures for AD and suggest reconsideration of the temperature range around 45 °C for efficient manure-based co-fermentation.

Isolation, identification and characterization of lignocellulolytic aerobic and anaerobic fungi in one- and two-phase biogas plants

Aerobic and anaerobic fungi are among the most effective plant biomass degraders known and have high potential to increase the efficiency of lignocellulosic biomass utilization, such as for biogas generation. However, limited information is available on their contribution to such industrial processes. Therefore, the presence of fungi along the biogas production chain of one-phase and two-phase biogas plants in Germany was analyzed. Seventeen aerobic species of Zygomycota, Ascomycota and Basidiomycota were identified, including efficient producers of lignocellulases, such as Trichoderma capillare isolated from a hydrolysis tank and Coprinopsis cinerea from fibers separated from pressed digestate. Five anaerobic fungal species of the phylum Neocallimastigomycota (comprising two novel clades) were present in an slightly acidic fermenter of a biogas plant fed with cow manure displaying endoglucanase transcriptional activity. The broad fungal presence demonstrated in this study can serve developing bioaugmentation systems with relevant lignocellulolytic fungi to improve biogas production from recalcitrant fiber material.

Effect of hydrochar on anaerobic digestion of dead pig carcass after hydrothermal pretreatment

Incineration and burial are the current practices for pig carcasses disposal but are not environmentally friendly. Anaerobic digestion can be a better alternative if the process inhibition by carcass digestion can be ameliorated. This study successfully mitigated the inhibition in anaerobic digestion of carcasses by hydrochar addition and by co-digestion with RS and HRS. Biogas production from SP of the pretreated hydrothermal carcasses was enhanced by 60.7 to 90.8% through hydrochar addition. The highest biogas production of 450 mL/g-VS was obtained at 4 g-hydrochar/L addition. The methane content was also increased from 57.5% to up to 69.8%. Each gram of hydrochar removed 25 mg of ammonium and 50 mg of VFA. Hydrochar addition promoted the conversion of VFA to biogas by strengthening the intensity of functional groups and the immobilization of microbial biomass. Co-digestion of SP with RS or HRS also increased the biogas production, and the optimal production of 428 mL/g VS was obtained at 70% SP and 30% RS. The co-digestion of carcass SP with RS and the addition of hydrochar can be a promising solution for improving biogas production from a pig carcass, and can be potentially developed as a sustainable waste management method.

Antioxidant activity of plant extracts and their effect on methane fermentation in bioreactors

Abstract Extracts of Solidago virgaurea L. (European goldenrod), Lavandula angustifolia Mill. (lavender) and Arnica chamissonis Less. (arnica) were tested as potential additives for methane fermentation in bioreactors, as it was hypothesized that their antioxidant properties may improve biogas production efficiency. Hence, methane fermentation of maize silage with the addition of tested extracts was performed in eudiometers, and both the biogas volume and methane content in biogas were measured. In addition, antioxidant properties, such as reducing power and 1,1-diphenyl-2-picrylhydrazyl free radical-scavenging activity, were determined spectrophotometrically. The results showed that only the addition of a goldenrod crude extract caused a significant increase in biogas yield, despite the fact that it presented the lowest antioxidant activity of the three tested species. No significant differences in biogas yield were found between the other two additives and the control. Biogas production efficiency was not correlated with the antioxidant activity of the crude extracts. Hence, the increase in methane fermentation efficiency in the case of goldenrod supplementation might have resulted from some other non-antioxidant compounds occurring in this species.