scholarly journals Effect of Hydraulic Retention Time on Anaerobic Digestion of Wheat Straw in the Semicontinuous Continuous Stirred-Tank Reactors

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Xiao-Shuang Shi ◽  
Jian-Jun Dong ◽  
Jun-Hong Yu ◽  
Hua Yin ◽  
Shu-Min Hu ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Wheat Straw ◽  
Retention Time ◽  
Hydraulic Retention Time ◽  
Methane Content ◽  
Stirred Tank ◽  
Crystalline Cellulose ◽  
Stirred Tank Reactors ◽  
Continuous Stirred Tank ◽  
Continuous Stirred Tank Reactors

Three semicontinuous continuous stirred-tank reactors (CSTR) operating at mesophilic conditions (35°C) were used to investigate the effect of hydraulic retention time (HRT) on anaerobic digestion of wheat straw. The results showed that the average biogas production with HRT of 20, 40, and 60 days was 46.8, 79.9, and 89.1 mL/g total solid as well as 55.2, 94.3, and 105.2 mL/g volatile solids, respectively. The methane content with HRT of 20 days, from 14.2% to 28.5%, was the lowest among the three reactors. The pH values with HRT of 40 and 60 days were in the acceptable range compared to that with HRT of 20 days. The propionate was dominant in the reactor with HRT of 20 days, inhibiting the activities of methanogens and causing the lower methane content in biogas. The degradation of cellulose, hemicellulose, and crystalline cellulose based on XRD was also strongly influenced by HRTs.

scholarly journals MINI DIGESTER UNTUK PENGOLAHAN LIMBAH ORGANIK MENJADI BIOGAS DAN DAMPAK TERHADAP PENGURANGAN EMISI (MINI DIGESTION TO PRODUCE BIOGAS FROM ORGANIC WASTE AND IMPACT ON REDUCING EMISSIONS)

2020 ◽  
Vol 8 (1) ◽  
pp. 022
Author(s):  
Rinjani Rakasiwi ◽  
Wivina Ivontianti ◽  
Eva Sitanggang
Keyword(s):  
Anaerobic Digestion ◽  
Retention Time ◽  
Organic Waste ◽  
Hydraulic Retention Time ◽  
Biogas Production ◽  
Stirred Tank ◽  
Continuous Stirred Tank Reactor ◽  
Stirred Tank Reactor ◽  
Tank Reactor ◽  
Continuous Stirred Tank

Abstract Organic waste is material that has no value but can be used as raw material to produce biogas. It is easier to handle by anaerobic processing. The advantages of biogas by using anaerobic digestion process are minimizes the effects of environmental pollutions, reduce emissions and increase the value of the benefits of waste. The purposes of this research are to design a digester for processing organic waste into biogas and find out the impact of biogas production on emissions reduction. Biogas production was analyzed using gas Chromatography (GC) and emission reductions were calculated using the AP-42 (Compilation of Air Pollutant Emissions Factors) equation. The digester used is a CSTR which is suitable for liquid phase and for organic chemical reactions with large conversions. Parameters that affect the performance of the reactor are the residence time on the flow of substances in the reactor, Hydraulic Retention Time (HRT). HRT can affect the growth of fermentative bacteria corelation with the production of biogas. The optimum volume of biogas of 16.52 Liters / Day with the acquisition of CH4 of 75,893.36 ppm was on the 13th day in a variation of HRT 20. Every 20 kg of organic waste that has been processed in the digester, it will be reducing 76.5 g / day of CO emissions. Keywords: anaerobic digestion, CSTR (Continuous Stirred Tank Reactor), HRT (Hydraulic Retention Time), trashAbstrakSampah organik merupakan bahan yang tidak mempunyai nilai atau tidak berharga tetapi dapat dijadikan sebagai bahan baku pembuatan biogas, karena lebih mudah untuk ditangani dan dapat dilakukan dengan proses anaerobik. Kelebihan dari biogas dengan menggunakan proses anaerobic digestion akan meminimalkan efek dari pencemaran lingkungan, mengurangi emisi dan meningkatkan nilai manfaat dari limbah. Tujuan penelitian ini adalah merancang digester untuk pengolahan sampah organik menjadi biogas dan mengetahui dampak produksi biogas yang dihasilkan terhadap pengurangan emisi. Produksi biogas dianalisa menggunakan Chromatografi gas (GC) dan pengurangan emisi dihitung menggunakna persamaan AP-42 (Compilation of Air Polutant Emissions Factors). Digester yang digunakan merupakan reaktor tipe alir tangki berpengaduk/CSTR untuk reaksi fase cair dan juga digunakan untuk reaksi kimia organik dengan konversi yang besar. Parameter yang mempengaruhi kinerja reaktor yaitu waktu tinggal pada zat alir di dalam reaktor atau disebut dengan Hydraulic Retention Time (HRT). HRT dapat mempengaruhi pertumbuhan bakteri fermentatif yang terkait dengan hasil produksi biogas. Hasil volume biogas optimum sebesar 16,52 Liter/Hari dengan perolehan CH4 sebesar 75.893,36 ppm berada di hari ke- 13 pada variasi HRT 20. Sampah organik sebanyak 20 kg diolah di digester mengurangi 76,5 g/hari emisi CO. Kata kunci: anaerobic digestion, CSTR (Continuous Stirred Tank Reactor), HRT (Hydraulic Retetion Time), sampah.

Removal of lead by sulfate-reducing bacteria in anaerobic continuous stirred tank reactors

2016 ◽  
Vol 14 (3) ◽  
pp. 557-561
Author(s):  
Nguyễn Thị Yên ◽  
Kiều Thị Quỳnh Hoa
Keyword(s):  
Sulfate Reducing Bacteria ◽  
Stirred Tank ◽  
Synthetic Wastewater ◽  
Terminal Electron Acceptor ◽  
Stirred Tank Reactors ◽  
Sulfate Reducing ◽  
Sulfide Production ◽  
Continuous Stirred Tank ◽  
Continuous Stirred Tank Reactors ◽  
Reducing Bacteria

Lead contaminated wastewater negatively impacts to living organisms as well as humans. In recent years, a highly promising biological process using the anaerobic production of sulfide ions by sulfate-reducing bacteria has presented itself as an alternative option for the removal of lead. This process is based on microbial utilization of electron donors, such as organic compounds (carbon sources), and sulfate as the terminal electron acceptor for sulfide production. The biogenic hydrogen sulfide reacts with dissolved heavy metals to form insoluble metal sulfide precipitates Removal of lead by an enriched consortium of sulfate-reducing bacteria (DM10) was evaluated sulfate reduction, sulfide production and lead precipitation. Four parallel anaerobic continuous stirred tank reactors (CSTR, V = 2L) (referred as R1 - R4) were fed with synthetic wastewater containing Pb2+ in the concentrations of 0, 100, 150 and 200 mg L-1 of lead and operated with a hydraulic retention time of 5 days for 40 days. The loading rates of each metal in R1- R4 were 0, 20, 30 and 40 mg L-1 d-1, respectively. The results showed that there was no inhibition of SRB growth and that lead removal efficiencies of 99-100% for Pb2+ were achieved in R2 (100 mg L-1) and R3 (150 mg L-1) throughout the experiment. For the highest lead concentration of  200 mg L-1, a decrease in efficiency of removal (from 100 to 96%) was observed at the end of the experiment. The obtained result of this study might help for a better control operation and performance improvements of reactors.

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.

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