scholarly journals Biogas Generation through Anaerobic Digestion of Compost Leachate in Semi-Continuous Completely Stirred Tank Reactors

Processes ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 635 ◽  
Author(s):  
Siciliano ◽  
Limonti ◽  
Curcio ◽  
Calabrò
Keyword(s):  
Anaerobic Digestion ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Anaerobic Treatment ◽  
Stirred Tank ◽  
Organic Load ◽  
Stirred Tank Reactors ◽  
Load Rate ◽  
Compost Leachate

The composting process of organic fraction of municipal solid waste, besides to the residual compost, generates a wastewater that is characterized by a high organic load. The application of anaerobic processes represents an advantageous solution for the treatment and valorization of this type of wastewater. Nevertheless, few works have been focused on the anaerobic digestion of compost leachate. To overcome this dearth, in the present paper an extensive experimental investigation was carried out to develop and analyse the anaerobic treatment of young leachate in completely stirred tank reactors (CSTR). Initially, it was defined a suitable leachate pretreatment to correct its acidic characteristics that is potentially able to inhibit methanogenic biomass activity. The pretreated leachate was fed to the digester over the start-up phase that was completed in about 40 days. During the operational period, the organic load rate (OLR) changed between 4.25 kgCOD/m3d and 38.5 kgCOD/m3d. The chemical oxygen demand (COD) abatement was higher than 90% for OLR values up to 14.5 kgCOD/m3d and around to 80% for applied loads equal to 24.5 kgCOD/m3d. At this OLR, it was reached the maximum daily biogas production of about 9.3 Lbiogas/(Lreactord). The CH4 fraction was between 70%–78% and the methane production yield in the range 0.34–0.38 LCH4/gCODremoved. The deterioration of biogas production started for OLR values that were over the threshold of 24.5 kgCOD/m3d when a volatile fatty acids (VFA) accumulation occurred and the pH dropped below 6.5. The maximum ratio between VFA and alkalinity (ALK) tolerable in the CSTR was identified to be 0.5 gCH3COOH/gCaCO3. Through an economic analysis, it was proven that the digestion of compost leachate could ensure significant economic profits. Furthermore, the produced digestate had characteristics that were compatible for agricultural applications.

scholarly journals Effects of Hydrothermal Pretreatment and Hydrochar Addition on the Performance of Pig Carcass Anaerobic Digestion

2021 ◽  
Vol 12 ◽  
Author(s):  
Jie Xu ◽  
Hongjian Lin ◽  
Kuichuan Sheng
Keyword(s):  
Anaerobic Digestion ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Ammonia Concentration ◽  
Hydrothermal Pretreatment ◽  
Biogas Yield ◽  
Stirred Tank Reactors ◽  
Liquid Products ◽  
Pig Carcasses

Proper disposal and utilization of dead pig carcasses are problems of public concern. The combination of hydrothermal pretreatment (HTP) and anaerobic digestion is a promising method to treat these wastes, provided that digestion inhibition is reduced. For this reason, the aim of this work was to investigate the optimal HTP temperature (140–180°C) for biogas production during anaerobic digestion of dead pigs in batch systems. In addition, the effects of hydrochar addition (6 g/L) on anaerobic digestion of pork products after HTP in continuous stirred tank reactors (CSTR) were determined. According to the results, 90% of lipids and 10% of proteins present in the pork were decomposed by HTP. In addition, the highest chemical oxygen demand (COD) concentration in liquid products (LP) reached 192.6 g/L, and it was obtained after 170°C HTP. The biogas potential from the solid residue (SR) and LP was up to 478 mL/g-VS and 398 mL/g-COD, respectively. A temperature of 170°C was suitable for pork HTP, which promoted the practical biogas yield because of the synergistic effect between proteins and lipids. Ammonia inhibition was reduced by the addition of hydrochar to the CSTR during co-digestion of SR and LP, maximum ammonia concentration tolerated by methanogens increased from 2.68 to 3.38 g/L. This improved total biogas yield and degradation rate of substrates, reaching values of 28.62 and 36.06%, respectively. The acetate content in volatile fatty acids (VFA) may be used as an index that reflects the degree of methanogenesis of the system. The results of the present work may also provide guidance for the digestion of feedstock with high protein and lipid content.

scholarly journals Psychrophilic Full Scale Tubular Digester Operating over Eight Years: Complete Performance Evaluation and Microbiological Population

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 151
Author(s):  
Jaime Jaimes-Estévez ◽  
German Zafra ◽  
Jaime Martí-Herrero ◽  
Guillermo Pelaz ◽  
Antonio Morán ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Biogas Production ◽  
Low Cost ◽  
Oxygen Demand ◽  
Mean Value ◽  
Organic Load ◽  
Microbiological Analysis ◽  
Complete Evaluation ◽  
Load Rate ◽  
Biogas Plants

Most biogas plants in the world run under psychrophilic conditions and are operated by small and medium farmers. There is a gap of knowledge on the performance of these systems after several years of operation. The aim of this research is to provide a complete evaluation of a psychrophilic, low-cost, tubular digester operated for eight years. The thermal performance was monitored for 50 days, and parameters such as pH, total volatile fatty acid (tVFA), chemical oxygen demand (COD) and volatile solids (VS) were measured every week for the influent and effluent. The digester operated at a stabilized slurry temperature of around 17.7 °C, with a mean organic load rate (OLR) equal to 0.52 kg VS/m3digester *d and an estimated hydraulic retention time (HRT) of 25 days. The VS reduction in the digester was around 77.58% and the COD reduction was 67 ± 3%, with a mean value for the effluent of 3.31 ± 1.20 g COD/Lt, while the tVFA decreased by 83.6 ± 15.5% and the presence of coliforms decreased 10.5%. A BioMethane potential test (BMP) for the influent and effluent showed that the digester reached a specific methane production of 0.40 Nm3CH4/kg VS and a 0.21 Nm3CH4/m3digester d with 63.1% CH4 in the biogas. These results, together with a microbiological analysis, show stabilized anaerobic digestion and a biogas production that was higher than expected for the psychrophilic range and the short HRT; this may have been due to the presence of an anaerobic digestion microorganism consortium which was extremely well-adapted to psychrophilic conditions over the eight-year study period.

Alkali pre-treatment of Sorghum Moench for biogas production

2013 ◽  
Vol 67 (9) ◽  
Author(s):  
Karina Michalska ◽  
Stanisław Ledakowicz
Keyword(s):  
Anaerobic Digestion ◽  
Chemical Oxygen Demand ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Total Phenolic ◽  
Methane Generation ◽  
Pre Treatment ◽  
Alkali Hydrolysis ◽  
Almost All

AbstractThis work studies the influence of the alkali pre-treatment of Sorghum Moench — a representative of energy crops used in biogas production. Solutions containing various concentrations of sodium hydroxide were used to achieve the highest degradation of lignocellulosic structures. The results obtained after chemical pre-treatment indicate that the use of NaOH leads to the removal of almost all lignin (over 99 % in the case of 5 mass % NaOH) from the biomass, which is a prerequisite for efficient anaerobic digestion. Several parameters, such as chemical oxygen demand, total organic carbon, total phenolic content, volatile fatty acids, and general nitrogen were determined in the hydrolysates thus obtained in order to define the most favourable conditions. The best results were obtained for the Sorghum treated with 5 mass % NaOH at 121°C for 30 min The hydrolysate thus achieved consisted of high total phenolic compounds concentration (ca. 4.7 g L−1) and chemical oxygen demand value (ca. 45 g L−1). Although single alkali hydrolysis causes total degradation of glucose, a combined chemical and enzymatic pre-treatment of Sorghum leads to the release of large amounts of this monosaccharide into the supernatant. This indicates that alkali pre-treatment does not lead to complete cellulose destruction. The high degradation of lignin structure in the first step of the pre-treatment rendered the remainder of the biomass available for enzymatic action. A comparison of the efficiency of biogas production from untreated Sorghum and Sorghum treated with the use of NaOH and enzymes shows that chemical hydrolysis improves the anaerobic digestion effectiveness and the combined pre-treatment could have great potential for methane generation.

Serial completely stirred tank reactors for improving biogas production and substance degradation during anaerobic digestion of corn stover

2017 ◽  
Vol 235 ◽  
pp. 380-388 ◽  
Author(s):  
YuQian Li ◽  
ChunMei Liu ◽  
Akiber Chufo Wachemo ◽  
HaiRong Yuan ◽  
DeXun Zou ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Corn Stover ◽  
Biogas Production ◽  
Stirred Tank ◽  
Stirred Tank Reactors

Effect of Ultrasonic Pretreatment for the Anaerobic Digestion of Sewage Sludge

2012 ◽  
Vol 531 ◽  
pp. 528-531 ◽  
Author(s):  
Na Wei
Keyword(s):  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Oxygen Demand ◽  
High Concentration ◽  
Ultrasonic Pretreatment ◽  
Soluble Chemical Oxygen Demand ◽  
Pre Treatment ◽  
Settling Characteristics

Anaerobic digestion is an economic and environmentally friendly technology for treating the biomass material-sewage sludge, but has some limitations, such as the low efficient biogass production. In this paper ultrasound was proposed as pre-treatment for effective sludge anaerobic digestion. Sludge anaerobic digestion experiments with ultrasonic pretreatment was investigated. It can be seen that this treatment effectively leaded to the increase of soluble chemical oxygen demand(SCOD) and volatile fatty acids(VFA)concentration. High concentration of VFA leaded to a increase in biogas production. Besides, the SV of sludge was reduced and the settling characteristics of sludge was improved after ultrasonic pretreatment. It can be concluded that sludge anaerobic digestion with ultrasonic pretreatment is an effective method for biomass material transformation.

Sludge electrooxidation as pre-treatment for anaerobic digestion

2016 ◽  
Vol 75 (4) ◽  
pp. 775-781 ◽  
Author(s):  
J. A. Barrios ◽  
U. Duran ◽  
A. Cano ◽  
M. Cisneros-Ortiz ◽  
S. Hernández
Keyword(s):  
Anaerobic Digestion ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Wastewater Sludge ◽  
Boron Doped Diamond ◽  
Boron Doped ◽  
Treatment Conditions ◽  
Volatile Solids ◽  
Pre Treatment

Anaerobic digestion of wastewater sludge is the preferred method for sludge treatment as it produces energy in the form of biogas as well as a stabilised product that may be land applied. Different pre-treatments have been proposed to solubilise organic matter and increase biogas production. Sludge electrooxidation with boron-doped diamond electrodes was used as pre-treatment for waste activated sludge (WAS) and its effect on physicochemical properties and biomethane potential (BMP) was evaluated. WAS with 2 and 3% total solids (TS) achieved 2.1 and 2.8% solubilisation, respectively, with higher solids requiring more energy. After pre-treatment, biodegradable chemical oxygen demand values were close to the maximum theoretical BMP, which makes sludge suitable for energy production. Anaerobic digestion reduced volatile solids (VS) by more than 30% in pre-treated sludge with a food to microorganism ratio of 0.15 g VSfed g−1 VSbiomass. Volatile fatty acids were lower than those for sludge without pre-treatment. Best pre-treatment conditions were 3% TS and 28.6 mA cm−2.

Experimental and Artificial Neural Network Modeling of a Upflow Anaerobic Contactor (UAC) for Biogas Production from Vinasse

2016 ◽  
Vol 14 (6) ◽  
pp. 1241-1254 ◽  
Author(s):  
Ousman R. Dibaba ◽  
Sandip K. Lahiri ◽  
Stephan T’Jonck ◽  
Abhishek Dutta
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Anaerobic Digestion ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Pilot Scale ◽  
Organic Loading Rate ◽  
Neural Network Modeling ◽  
Artificial Neural

Abstract A pilot scale Upflow Anaerobic Contactor (UAC), based on upflow sludge blanket principle, was designed to treat vinasse waste obtained from beet molasses fermentation. An assessment of the anaerobic digestion of vinasse was carried out for the production of biogas as a source of energy. Average Organic loading rate (OLR) was around 7.5 gCOD/m3/day in steady state, increasing upto 8.1 gCOD/m3/day. The anaerobic digestion was conducted at mesophilic (30–37 °C) temperature and a stable operating condition was achieved after 81 days with average production of 65 % methane which corresponded to a maximum biogas production of 85 l/day. The optimal performance of UAC was obtained at 87 % COD removal, which corresponded to a hydraulic retention time of 16.67 days. The biogas production increased gradually with OLR, corresponding to a maximum 6.54 gCOD/m3/day (7.4 % increase from initial target). A coupled Artificial Neural Network-Differential Evolution (ANN-DE) methodology was formulated to predict chemical oxygen demand (COD), total suspended solids (TSS) and volatile fatty acids (VFA) of the effluent along with the biogas production. The method incorporated a DE approach for the efficient tuning of ANN meta-parameters such as number of nodes in hidden layer, input and output activation function and learning rate. The model prediction indicated that it can learn the nonlinear complex relationship between the parameters and able to predict the output of the contactor with reasonable accuracy. The utilization of the coupled ANN-DE model provided significant improvement to the study and helps to study the parametric effect of influential parameters on the reactor output.

scholarly journals Fermentasi Anaerobik Biogas Dua Tahap Dengan Aklimatisasi dan Pengkondisian pH Fermentasi

2017 ◽  
Vol 1 (1) ◽  
pp. 1 ◽  
Author(s):  
Purwinda Iriani ◽  
Yanti Suprianti ◽  
Fitria Yulistiani
Keyword(s):  
Anaerobic Digestion ◽  
Anaerobic Fermentation ◽  
Biogas Production ◽  
Organic Load ◽  
Cow Dung ◽  
Activation Process ◽  
Two Stage ◽  
One Stage ◽  
Load Rate ◽  
Initial Ph

Produksi biogas pada skala rumah tangga umumnya menggunakan teknologi fermentasi anaerobik di dalam satu biodigester (satu tahap), yang mengakomodasi dua tahap utama prinsip pembentukan biogas, yakni tahap asetogenesis dan tahap metanogenesis. Permasalahan yang muncul dari penggunaan digester biogas satu tahap adalah ketidakseimbangan proses fermentasi (peningkatan laju beban organik, waktu retensi senyawa organik yang lebih cepat, dan produktivitas biogas yang menjadi tidak maksimal). Untuk mengatasi hal tersebut, dilakukan penelitian yang bertujuan melakukan produksi biogas melalui sistem fermentasi anaerobik dua-tahap (two-stage anaerobic digestion), yang didukung dengan pengaturan pH pada proses metanogenik. Pada penelitian ini telah dilakukan proses aklimatisasi (aktivasi) bakteri yang menunjang proses asetogenik dan metanogenik pada skala laboratorium (19 L), dan selanjutnya menjadi inokulum untuk proses fermentasi skala pilot dengan kapasitas biodigester asetogenik 125 L dan metanogenik 500 L. Hasil proses aklimatisasi bakteri asetogenik pada media kotoran sapi menunjukkan adanya kestabilan pH yang dibutuhkan untuk reaksi asetogenik, yaitu pada kisaran pH 5-6, sedangkan kontrol menunjukkan perubahan pH yang masih ada di rentang pH netral yaitu 6-7. Kotoran sapi yang telah melalui proses asetogenik selama 2 minggu (pH awal 5,5), menjadi bahan baku pembuatan biogas pada digester metanogenik. Hasil dari proses metanogenik menunjukkan terjadinya peningkatan volume biogas dan komposisi gas metana (CH4) di dalam biogas. Komposisi CH4 tertinggi diperoleh pada hari ke-20 yakni 74,82% dengan volume produksi biogas tertinggi ada pada hari ke-22, dengan laju 8,87 L/hari. Potensi energi tertinggi yang diperoleh mencapai 217,66 kJ/hari.Generally, biogas production on the household scale is using one-stage anaerobic fermentation technology, which accommodates two main processes of biogas production, namely acetogenesis and methanogenesis. An obstacle of using one-stage biogas digester is the imbalance of the fermentation process that indicated by the increase of organic load rate and shorter retention time that lead to un-optimal biogas productivity. This research undertook the application of two-stage anaerobic digestion, supported by adjusting the initial pH for both acetogenic and methanogenic processes. Firstly, the research initiated by acclimatization (activation) process of acetogenic and methanogenic bacteria via fermentation in laboratory scale (19 L) digesters, separately. The results of acetogenic bacteria acclimatization process on cow dung media showed the pH stability needed for the reaction acetogenic, in the range of 5-6, while the control showed the pH changes still in the neutral pH range (6-7). The substrate from lab-scale acetogenic and methanogenic digester, then used as a starter for pilot-scale digester (125 L and 500 L, respectively). The mixture of water and cow dung were adjusted at initial pH 5.5 on acetogenic digester for 2 weeks. Those material were used for biogas production in the methanogenic digester. The result of the methanogenic process showed an increasing volume of biogas and the composition of methane (CH4) in the biogas. The highest CH4 composition was obtained on the 20th day, which reached 74.82%, and the highest volume of biogas production was at day 22, with the rate of 8.87 L/day. The highest energy potential obtained was 217.66 kJ/day.

Anaerobic baffled reactor treatment of biodiesel-processing wastewater with high strength of methanol and glycerol: reactor performance and biogas production

2011 ◽  
Vol 65 (5) ◽  
Author(s):  
Darin Phukingngam ◽  
Orathai Chavalparit ◽  
Dararat Somchai ◽  
Maneerat Ongwandee
Keyword(s):  
Chemical Oxygen Demand ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Anaerobic Treatment ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
Reactor Performance ◽  
Electron Microscopic ◽  
Anaerobic Baffled Reactor

AbstractBiodiesel-processing factories employing the alkali-catalyzed transesterification process generate a large amount of wastewater containing high amount of methanol, glycerol, and oil. As such, wastewater has high potential to produce biogas using anaerobic treatment. The aim of this research was to investigate the performance of an anaerobic baffled reactor for organic removal and biogas production from biodiesel wastewater. The effect of different organic loading rates, varying from 0.5 kg m−3 d−1 to 3.0 kg m−3 d−1 of chemical oxygen demand, was determined using three 22 L reactors, each comprising five separate compartments. Wastewater was pretreated with chemical coagulants to partially remove oil prior to experimentation. Results show that the anaerobic baffled reactor operated at 1.5 kg m−3 d−1 of chemical oxygen demand and ten days of hydraulic retention time provided the best removal efficiencies of 99 % of chemical oxygen demand, 100 % of methanol, and 100 % of glycerol. Increasing the organic loading rate over 1.5 kg m−3 d−1 of chemical oxygen demand led to excessive accumulation of volatile fatty acids thereby making the pH drop to a value unfavorable for methanogenesis. The biogas production rate was 12 L d−1 and the methane composition accounted for 64–74 %. Phase-separated characteristics revealed that the highest chemical oxygen demand removal percentage was achieved in the first compartment and the removal efficiency gradually decreased longitudinally. A scanning electron microscopic study indicated that the most predominant group of microorganisms residing on the external surface of the granular sludge was Methanosarcina.

Anaerobic hydrolysis of a municipal wastewater in a pilot-scale digester

2003 ◽  
Vol 47 (12) ◽  
pp. 223-230 ◽  
Author(s):  
J.A. Álvarez ◽  
C.A. Zapico ◽  
M. Gómez ◽  
J. Presas ◽  
M. Soto
Keyword(s):  
Volatile Fatty Acids ◽  
Municipal Wastewater ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Pilot Scale ◽  
Organic Load ◽  
Active Volume ◽  
Santiago De Compostela ◽  
Load Rate ◽  
Pre Treatment

Raw domestic wastewater from the city of Santiago de Compostela (Northwest Spain) was fed into a pilot-scale hydrolytic up flow sludge bed (HUSB) digester with an active volume of 25.5 m3. The total influent chemical oxygen demand (COD) ranged from 360 to 470 mg/l, the influent SS varied from 190 to 370 mg/l, and the temperature was between 17° and 20°C. The organic load rate (OLR) applied increased step by step from 1.2 to 3.9 kgCOD/m3.d, while the hydraulic retention time (HRT) decreased from 7.1 h to 2.9 h. A high suspended solids (SS) removal of about 82-85% from the influent was reached, most of which (81 to 88%) was eliminated by hydrolysis, while the rest remained in the purge stream. The total COD removal ranged from 46 to 59%. On the other hand, a high acidification of the COD remaining in the effluent was obtained, so the percent COD in the form of volatile fatty acids (VFACOD) with respect to total effluent COD was about 43% for the highest HRT applied, and about 27% for the lowest HRT. The soluble to total COD ratio (CODs/CODt) increased from 25-32% for the influent to 71-86% for the effluent. The results obtained confirm the viability and interest of direct anaerobic hydrolytic pre-treatment of domestic wastewater.

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