scholarly journals Biogas Production from Sunflower Head and Stalk Residues: Effect of Alkaline Pretreatment

Molecules ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 164 ◽  
Author(s):  
Marinela Zhurka ◽  
Apostolos Spyridonidis ◽  
Ioanna A. Vasiliadou ◽  
Katerina Stamatelatou
Keyword(s):  
Biogas Production ◽  
Liquid Fraction ◽  
Alkaline Pretreatment ◽  
Second Phase ◽  
Lignocellulosic Substrate ◽  
Stirred Tank Reactors ◽  
Batch Tests ◽  
Volatile Solids ◽  
Negative Effect ◽  
Whole Slurry

Sunflower residues are considered a prominent renewable source for biogas production during anaerobic digestion (AD). However; the recalcitrant structure of this lignocellulosic substrate requires a pretreatment step for efficient biomass transformation and increased bioenergy output. The aim of the present study was to assess the effect of alkaline pretreatment of various parts of the sunflower residues (e.g., heads and stalks) on their methane yield. Experimental data showed that pretreatment at mild conditions (55 °C; 24 h; 4 g NaOH 100 g−1 total solids) caused an increase in the biochemical methane potential (BMP) of both heads and stalks of the sunflower residues as determined in batch tests. The highest methane production (268.35 ± 0.11 mL CH4 g−1 volatile solids) was achieved from the pretreated sunflower head residues. Thereafter; the effect of alkaline pretreatment of sunflower head residues was assessed in continuous mode; using continuous stirred-tank reactors (CSTRs) under two operational phases. During the first phase; the CSTRs were fed with the liquid fraction produced from the pretreatment of sunflower heads. During the second phase; the CSTRs were fed with the whole slurry resulting from the pretreatment of sunflower heads (i.e., both liquid and solid fractions). In both operating phases; it was observed that the alkaline pretreatment of the sunflower head residues had a negligible (phase I) or even a negative effect on biogas production; which was contradictory to the results of the BMP tests. It seems that; during alkaline pretreatment; this part of the sunflower residues (heads) may release inhibitory compounds; which induce a negative effect on biogas production in the long term (e.g., during continuously run digesters such as CSTR) but not in the short-term (e.g., batch tests) where the effect of the inoculum may not permit the inhibition to be established.

scholarly journals Co-Digestion of Extended Aeration Sewage Sludge with Whey, Grease and Septage: Experimental and Modeling Determination

2021 ◽  
Vol 13 (16) ◽  
pp. 9199
Author(s):  
Gérard Merlin ◽  
Jonathan Outin ◽  
Hervé Boileau
Keyword(s):  
Biogas Production ◽  
Mechanistic Model ◽  
Treatment Plant ◽  
Second Step ◽  
Stirred Tank Reactors ◽  
Positive Effects ◽  
Secondary Sludge ◽  
Negative Effect ◽  
Methane Potential ◽  
Continuous Stirred Tank

The potential of co-digestion mixing thickened secondary sludge (TS) from extended aeration wastewater treatment plant and locally available substrates (whey, grease and septage) has been studied in this work, using three steps. The first step was a batch test to determine the biological methane potential (BMP) of different mixtures of the three co-substrates with TS. The second step was carried out with lab-scale reactors (20 L), simulating anaerobic continuous stirred tank reactors, fed by three mixtures of co-substrates that were determined according to the previous step results. Modeling was applied in the third step, using ADM1 as a mechanistic model to help understand the co-digestion process. According to the BMP step, septage used as a co-substrate has a negative effect on performance, and the addition of 10–30% grease or whey would lead to a gain of around 60–70% in the production of methane. The results from the reactor tests did not validate the positive effects observed with the BMP assay but confirmed good biodegradation efficiency (> 85%). The main purpose of co-digestion in this scenario is to recover energy from waste and effluents that would require even more energy for their treatment. The protein and lipid percentages of particulate biodegradable COD are important variables for digester stability and methane production, as predicted by modeling. The results of simulations with the ADM1 model, adapted to co-digestion, confirmed that this model is a powerful tool to optimize the process of biogas production.

scholarly journals Enhanced biogas production potential of microalgae and swine wastewater using co-digestion and alkaline pretreatment

2018 ◽  
Vol 78 (1) ◽  
pp. 92-102 ◽  
Author(s):  
K. Panyaping ◽  
R. Khiewwijit ◽  
P. Wongpankamol
Keyword(s):  
Biogas Production ◽  
Oxygen Demand ◽  
Electrical Energy ◽  
Pilot Scale ◽  
Major Effect ◽  
Alkaline Pretreatment ◽  
Swine Wastewater ◽  
Biogas Yield ◽  
Volatile Solids ◽  
Vs Removal

Abstract Biogas yield obtained from anaerobic digestion of swine wastewater (SWW) needs to be increased to produce electrical energy. To enhance biogas and prevent pollution, use of mixed culture microalgae grown in wastewater (MWW) with SWW has attracted a lot of interest. This research was focused on the possibility of utilizing MWW. Six experiments using raw SWW and MWW, and their co-digestion were conducted on a laboratory scale in one-litre reactors with the ratio of inoculum and substrate of 70:30 under without and with alkaline pretreatment (using 3% NaOH for pH adjustment every 15 min at pH 11 for 3 h). The results showed that co-digestion had the major effect on increasing biogas and methane yields (0.735 and 0.326 m3/kg of volatile solids (VS) removed), and the highest chemical oxygen demand and VS removal (60.29% and 63.17%). For pretreatment, the effect of ammonia inhibition at a high pH of 11 had more influence on biodegradation than the effect of destruction of MWW's cell walls, resulting in a low biogas production of pretreated MWW and pretreated co-digestion. These findings affirm the potential of co-digestion, and the possibility of using both single and co-substrate MWW. Pretreatment could be improved at a lower alkaline pH condition. A pilot scale of co-digestion should be performed.

scholarly journals Biogas Production from Physicochemically Pretreated Grass Lawn Waste: Comparison of Different Process Schemes

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 296 ◽  
Author(s):  
Georgia Antonopoulou ◽  
Dimitrios Vayenas ◽  
Gerasimos Lyberatos
Keyword(s):  
Biogas Production ◽  
Economic Assessment ◽  
Methane Yield ◽  
Biochemical Methane Potential ◽  
Naoh Pretreatment ◽  
Volatile Solids ◽  
Methane Potential ◽  
Whole Slurry ◽  
Almost All ◽  
Pretreated Biomass

Various pretreatment methods, such as thermal, alkaline and acid, were applied on grass lawn (GL) waste and the effect of each pretreatment method on the Biochemical Methane Potential was evaluated for two options, namely using the whole slurry resulting from pretreatment or the separate solid and liquid fractions obtained. In addition, the effect of each pretreatment on carbohydrate solubilization and lignocellulossic content fractionation (to cellulose, hemicellulose, lignin) was also evaluated. The experimental results showed that the methane yield was enhanced with alkaline pretreatment and, the higher the NaOH concentration (20 g/100 gTotal Solids (TS)), the higher was the methane yield observed (427.07 L CH4/kg Volatile Solids (VS), which was almost 25.7% higher than the BMP of the untreated GL). Comparing the BMP obtained under the two options, i.e., that of the whole pretreatment slurry with the sum of the BMPs of both fractions, it was found that direct anaerobic digestion without separation of the pretreated biomass was favored, in almost all cases. A preliminary energy balance and economic assessment indicated that the process could be sustainable, leading to a positive net heat energy only when using a more concentrated pretreated slurry (i.e., 20% organic loading), or when applying NaOH pretreatment at a lower chemical loading.

Recovering biomethane and nutrients from anaerobic digestion of water hyacinth (Eichhornia crassipes) and its co-digestion with fruit and vegetable waste

2015 ◽  
Vol 73 (2) ◽  
pp. 355-361 ◽  
Author(s):  
M. A. Hernández-Shek ◽  
L. S. Cadavid-Rodríguez ◽  
I. V. Bolaños ◽  
A. C. Agudelo-Henao
Keyword(s):  
Anaerobic Digestion ◽  
Water Hyacinth ◽  
Biogas Production ◽  
Organic Loading Rate ◽  
Vegetable Waste ◽  
Fruit And Vegetable ◽  
Biogas Yield ◽  
Stirred Tank Reactors ◽  
Volatile Solids ◽  
Bmp Test

The potential to recover bioenergy from anaerobic digestion of water hyacinth (WH) and from its co-digestion with fruit and vegetable waste (FVW) was investigated. Initially, biogas and methane production were studied using the biochemical methane potential (BMP) test at 2 g volatile solids (VS) L−1 of substrate concentration, both in the digestion of WH alone and in its co-digestion with FVW (WH-FVW ratio of 70:30). Subsequently, the biogas production was optimized in terms of total solids (TS) concentration, testing 4 and 6% of TS. The BMP test showed a biogas yield of 0.114 m3 biogas kg−1 VSadded for WH alone. On the other hand, the biogas potential from the WH-FVW co-digestion was 0.141 m3 biogas kg−1 VSadded, showing an increase of 23% compared to that of WH alone. Maximum biogas production of 0.230 m3 biogas kg−1 VSadded was obtained at 4% of TS in the co-digestion of WH-FVW. Using semi-continuously stirred tank reactors, 1.3 m3 biogas yield kg−1 VSadded was produced using an organic loading rate of 2 kg VS m−3 d−1 and hydraulic retention time of 15 days. It was also found that a WH-FVW ratio of 80:20 improved the process in terms of pH stability. Additionally, it was found that nitrogen can be recovered in the liquid effluent with a potential for use as a liquid fertilizer.

scholarly journals Co-digestion of Extended Aeration Sewage Sludge With Whey, Grease and Septage: Experimental and Modelling Determination

2021 ◽  
Author(s):  
Gérard Merlin ◽  
Jonathan Outin ◽  
Hervé Boileau
Keyword(s):  
Biogas Production ◽  
Mechanistic Model ◽  
Treatment Plant ◽  
Stirred Tank Reactors ◽  
Positive Effects ◽  
Secondary Sludge ◽  
Lipid Fractions ◽  
Negative Effect ◽  
Methane Potential ◽  
Continuous Stirred Tank

Potential of co-digestion mixing thickened secondary sludge (TS) from extended aeration wastewater treatment plant and locally available substrates (whey, grease and septage) has been studied using three steps. The first step was a batch test to determine biological methane potential (BMP) of different mixtures of the three co-substrates with TS. The second step has been carried out with lab-scale reactors (20 L) simulating anaerobic continuous stirred tank reactors fed by three mixtures of co-substrates determined according to previous step results. Modelling using ADM1 as a mechanistic model was applied in the third step to help understanding the co-digestion process. According to BMP step, septage used as co-substrate has a negative effect on performance and addition of 10 to 30% grease or 10% whey would lead to a higher production of biogas and with an increase of the methane content. The results from the reactor showed less evi-dence of the positive effects observed with the BMP assay. Protein and lipid fractions of particu-late biodegradable COD are important variables for digester stability and methane production as predicted by modelling. Results of simulations with ADM1 model adapted to co-digestion confirmed that this model is a powerful tool to optimize the process of biogas production.

Effect of thermal and alkaline pretreatment of giant miscanthus and Chinese fountaingrass on biogas production

2015 ◽  
Vol 73 (4) ◽  
pp. 849-856 ◽  
Author(s):  
Valentine Nkongndem Nkemka ◽  
Yongqiang Li ◽  
Xiying Hao
Keyword(s):  
Soil Conservation ◽  
Biogas Production ◽  
Energy Crops ◽  
Alkaline Pretreatment ◽  
Untreated Sample ◽  
Naoh Pretreatment ◽  
Miscanthus Giganteus ◽  
Volatile Solids ◽  
Giant Miscanthus ◽  
Pennisetum Alopecuroides

Giant miscanthus (Miscanthus×giganteus) and Chinese fountaingrass (Pennisetum alopecuroides (L.) Spreng), cultivated for landscaping and soil conservation, are potential energy crops. The study investigated the effect of combined thermal and alkaline pretreatments on biogas production of these energy crops. The pretreatment included two types of alkali (6% CaO and 6% NaOH) at 22, 70 and 100 °C. The alkaline pretreatment resulted in a greater breakdown of the hemicellulose fraction, with CaO more effective than NaOH. Pretreatment of giant miscanthus with 6% CaO at 100 °C for 24 h produced a CH4 yield (313 mL g−1 volatile solids (VS)) that was 1.7 times that of the untreated sample (186 mL g−1 VS). However, pretreatment of Chinese fountaingrass with 6% CaO or 6% NaOH at 70 °C for 24 h resulted in similar CH4 yields (328 and 302 mL g−1 VS for CaO and NaOH pretreatments) as the untreated sample (311 mL g−1 VS). Chinese fountaingrass was more easily digestible but had a low overall CH4 yield per hectare (1,831 m3 ha−1 y−1) compared to giant miscanthus (6,868 m3 ha−1 y−1). This study demonstrates the potential of thermal/alkaline pretreatment and the use of giant miscanthus and Chinese fountaingrass for biogas production.

Hydrothermal, acidic, and alkaline pretreatment of waste flower-mix for enhanced biogas production: a comparative assessment

2021 ◽  
Author(s):  
Avantika Agarwal ◽  
Kunwar Paritosh ◽  
Pragati Dangayach ◽  
Priyanka Gehlot ◽  
Nidhi Pareek ◽  
...  
Keyword(s):  
Biogas Production ◽  
Comparative Assessment ◽  
Alkaline Pretreatment

scholarly journals Biochemical Methane Potential of Cork Boiling Wastewater at Different Inoculum to Substrate Ratios

2021 ◽  
Vol 11 (7) ◽  
pp. 3064
Author(s):  
Roberta Mota-Panizio ◽  
Manuel Jesús Hermoso-Orzáez ◽  
Luis Carmo-Calado ◽  
Gonçalo Lourinho ◽  
Paulo Sérgio Duque de Brito
Keyword(s):  
Anaerobic Digestion ◽  
Biogas Production ◽  
Treatment Plant ◽  
Organic Substrates ◽  
Biochemical Methane Potential ◽  
Volatile Solids ◽  
Working Volume ◽  
Methane Potential ◽  
Bmp Test ◽  
Cork Industry

The present study evaluates the digestion of cork boiling wastewater (CBW) through a biochemical methane potential (BMP) test. BMP assays were carried out with a working volume of 600 mL at a constant mesophilic temperature (35 °C). The experiment bottles contained CBW and inoculum (digested sludge from a wastewater treatment plant (WWTP)), with a ratio of inoculum/substrate (Ino/CBW) of 1:1 and 2:1 on the basis of volatile solids (VSs); the codigestion with food waste (FW) had a ratio of 2/0.7:0.3 (Ino/CBW:FW) and the codigestion with cow manure (CM) had a ratio of 2/0.5:0.5 (Ino/CBW:CM). Biogas and methane production was proportional to the inoculum substrate ratio (ISR) used. BMP tests have proved to be valuable for inferring the adequacy of anaerobic digestion to treat wastewater from the cork industry. The results indicate that the biomethane potential of CBWs for Ino/CBW ratios 1:1 and 2:1 is very low compared to other organic substrates. For the codigestion tests, the test with the Ino/CBW:CM ratio of 2/0.7:0.3 showed better biomethane yields, being in the expected values. This demonstrated that it is possible to perform the anaerobic digestion (AD) of CBW using a cosubstrate to increase biogas production and biomethane and to improve the quality of the final digestate.

scholarly journals Process Engineering of the Acetone-Ethanol-Butanol (ABE) Fermentation in a Linear and Feedback Loop Cascade of Continuous Stirred Tank Reactors: Experiments, Modeling and Optimization

Fuels ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 108-129
Author(s):  
Katja Karstens ◽  
Sergej Trippel ◽  
Peter Götz
Keyword(s):  
Feedback Loop ◽  
Early Stage ◽  
Formation Rate ◽  
Abe Fermentation ◽  
Operating Conditions ◽  
Stirred Tank ◽  
Second Phase ◽  
Stirred Tank Reactors ◽  
Continuous Stirred Tank ◽  
Continuous Stirred Tank Reactors

The production of butanol, acetone and ethanol by Clostridium acetobutylicum is a biphasic fermentation process. In the first phase the carbohydrate substrate is metabolized to acetic and butyric acid, in the following second phase the product spectrum is shifted towards the economically interesting solvents. Here we present a cascade of six continuous stirred tank reactors (CCSTR), which allows performing the time dependent metabolic phases of an acetone-butanol-ethanol (ABE) batch fermentation in a spatial domain. Experimental data of steady states under four operating conditions—with variations of the pH in the first bioreactor between 4.3 and 5.6 as well as the total dilution rate between 0.042 h−1 and 0.092 h−1—were used to optimize and validate a corresponding mathematical model. Beyond a residence time distribution representation and substrate, biomass and product kinetics this model also includes the differentiation of cells between the metabolic states. Model simulations predict a final product concentration of 8.2 g butanol L−1 and a productivity of 0.75 g butanol L−1 h−1 in the CCSTR operated at pHbr1 of 4.3 and D = 0.092 h−1, while 31% of the cells are differentiated to the solventogenic state. Aiming at an enrichment of solvent-producing cells, a feedback loop was introduced into the cascade, sending cells from a later state of the process (bioreactor 4) back to an early stage of the process (bioreactor 2). In agreement with the experimental observations, the model accurately predicted an increase in butanol formation rate in bioreactor stages 2 and 3, resulting in an overall butanol productivity of 0.76 g L−1 h−1 for the feedback loop cascade. The here presented CCSTR and the validated model will serve to investigate further ABE fermentation strategies for a controlled metabolic switch.

Anaerobic thermophilic digestion of sewage sludge with a thickened sludge recycle

2012 ◽  
Vol 65 (3) ◽  
pp. 403-409 ◽  
Author(s):  
A. Ya. Vanyushina ◽  
Yu. A. Nikolaev ◽  
A. M. Agarev ◽  
M. V. Kevbrina ◽  
M. N. Kozlov
Keyword(s):  
Retention Time ◽  
Municipal Wastewater ◽  
Hydraulic Retention Time ◽  
Biogas Production ◽  
Wastewater Sludge ◽  
Recycling Process ◽  
Digested Sludge ◽  
Volatile Solids ◽  
Solids Retention ◽  
Thermophilic Digestion

The process of anaerobic thermophilic digestion of municipal wastewater sludge with a recycled part of thickened digested sludge, was studied in semi-continuous laboratory digesters. This modified recycling process resulted in increased solids retention time (SRT) with the same hydraulic retention time (HRT) as compared with traditional digestion without recycling. Increased SRT without increasing of HRT resulted in the enhancement of volatile substance reduction by up to 68% in the reactor with the recycling process compared with 34% in a control conventional reactor. Biogas production was intensified from 0.3 L/g of influent volatile solids (VS) in the control reactor up to 0.35 L/g VS. In addition, the recycling process improved the dewatering properties of digested sludge.

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