Temperature effect on anaerobic digestion of bedding straw in a one phase system at different inoculum concentration

To test whether hyperthermophilic treatment promotes polylactide (PLA) dissolution and methane conversion under anaerobic digestion conditions, a single thermophilic control reactor (55 °C) and a two-phase system consisting of a hyperthermophilic reactor (80 °C) and a thermophilic reactor (55 °C) were continuously fed with a mixture of PLA and artificial kitchen garbage. In Runs 1 and 2, the PLA dissolution ratios in the two-phase system were 79.2 ± 6.5% and 85.2 ± 7.0%, respectively, higher than those of the control. Batch experimental results indicated that hyperthermophilic treatment could promote PLA dissolution to a greater degree as compared with single thermophilic treatment and that ammonia addition also had a promotional effect on PLA dissolution. In the two-phase system, after hyperthermophilic treatment, dissolved PLA was converted to methane gas under the subsequent thermophilic condition.

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Temperature effect on rose downy mildew development under environmental controlled conditions

Agronomía Colombiana ◽

10.15446/agron.colomb.v32n1.41362 ◽

2014 ◽

Vol 32 (1) ◽

pp. 29-35 ◽

Cited By ~ 2

Author(s):

Juan José Filgueira D. ◽

Angélica Zambrano

Keyword(s):

Temperature Effect ◽

Downy Mildew ◽

Wide Temperature Range ◽

Environmental Conditions ◽

Commercial Variety ◽

Inoculum Concentration ◽

Controlled Conditions ◽

Different Temperatures ◽

The Rose ◽

Downy Mildew Disease

The rose downy mildew disease, caused by Peronospora sparsa Berkeley, is one of the most important that affect rose crops in Colombia. To manage this disease, flower growers must deal with high-costs due to the excessive application of fungicides, but without good results. Studies on P. sparsa behavior have shown its narrow relationship with environmental conditions. In this study, the temperature effect was evaluated during the infection and sporulation of P. sparsa in Charlotte leaflets, a susceptible commercial variety, through an environmental controlled conditions system. Infection and sporulation were observed at different temperatures in a range of from 4 to 40°C. Infection with the absence of or very low sporulation was observed at 4°C. The most favorable pathogen responses were between 15 and 18°C in terms of inoculum concentration and sporulation percentage. There was no infection or leaflet change above 35°C. According to the results, sporulation can occur from 4 to 33°C, confirming the fact that P. sparsa is able to reproduce throughout a wide temperature range.

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Comparison of One-Phase and Two-Phase Anaerobic Digestion Processes in Characteristics of Substrate Degradation and Bacterial Population Levels

Water Science & Technology ◽

10.2166/wst.1991.0567 ◽

1991 ◽

Vol 23 (7-9) ◽

pp. 1157-1166 ◽

Cited By ~ 39

Author(s):

Tian Cheng Zhang ◽

Tatsuya Noike

Keyword(s):

Anaerobic Digestion ◽

Bacterial Population ◽

Removal Rate ◽

Cod Removal ◽

Phase System ◽

Two Phase ◽

Experimental Conditions ◽

Substrate Degradation ◽

Cod Removal Rate ◽

The One

The comparison of one-phase and two-phase anaerobic digestion processes in the characteristics of substrate degradation and the bacterial population levels was investigated by using the chemostat-type reactors to which starch was fed as substrate when both processes were operated under the same experimental conditions. By decreasing the SRTs of both systems from 10.2 d to 5 d, 2.5 d and 1.75 d. it was found that the two-phase system was more stable to the change in pH than one-phase system. The CH4 recovery rates and COD removal rates in the two-phase system increased by 4 to 9% and 3 to 10%. respectively, although the CH4 recovery rate and the COD removal rate in the one-phase system were slightly higher than those in the two-phase system at the SRT of 10.2 d. The concentration of propionate in the effluent of the one-phase system was 30 to 50% higher than that in the two-phase system; while the concentrations of acetate and butyrate in the one-phase system were slightly lower than those in the two-phase one. The enumeration of the bacteria was performed by the MPN method. The population levels of acidogenic bacteria in both systems were in the same order (108 to 1010 MPN/ml). the population levels of hydrogenotrophs were also in the same order as the acidogenic bacteria in the two-phase system, while the population levels of hydrogenotrophs were 10 to 100 fold less than that of acidogenic bacteria in the one-phase system. The number of HAc-utilizing methanogens in the methanogenesis of the two-phase system were 2 to 10 times higher than that in the one-phase system. Therefore, the one-phase system cannot be regarded simply as the sum of acidogenesis and methanogenesis.

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A hybrid two-phase system for anaerobic digestion of food waste

Water Science & Technology ◽

10.2166/wst.2002.0422 ◽

2002 ◽

Vol 45 (12) ◽

pp. 159-165 ◽

Cited By ~ 21

Author(s):

J.Y. Wang ◽

H.L. Xu ◽

J.H. Tay

Keyword(s):

Anaerobic Digestion ◽

Food Waste ◽

Batch Reactor ◽

Upflow Anaerobic Sludge Blanket ◽

Uasb Reactor ◽

Anaerobic Sludge ◽

Phase System ◽

Bioreactor Landfills ◽

Two Phase ◽

Methanogenic Phase

A hybrid two-phase system, consisting of a solid waste reactor as the acidification reactor and a wastewater reactor, i.e. an upflow anaerobic sludge blanket (UASB) reactor, as the methanogenic reactor, for anaerobic digestion of food waste was investigated. After the pre-acidification stage, COD and total VFA removals in the methanogenic phase were in the ranges of 74-93% and 77-100%, respectively, while leachate COD and total VFA concentrations in the acidification phase decreased by 95% and 97-99%, respectively. Some 99% of the total CH4 generated was from the methanogenic phase with the CH4 content of 68-70%. About 77-79% of TOC, 57-60% of volatile solids and 79-80% of total COD were removed. The results of this laboratory-scale study show that the hybrid two-phase anaerobic batch reactor system is suitable for effective conversion of food waste into CH4 and CO2. The hybrid two-phase system can be further developed into an effective and efficient way to enhance waste stabilization in operating bioreactor landfills.

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Evaluation of Effectiveness of Two-Phase Anaerobic Digestion Process Degrading Complex Substrate

Water Science & Technology ◽

10.2166/wst.1987.0211 ◽

1987 ◽

Vol 19 (1-2) ◽

pp. 311-322 ◽

Cited By ~ 24

Author(s):

Keisuke Hanaki ◽

Tomonori Matsuo ◽

Michihiko Nagase ◽

Yoshihisa Tabata

Keyword(s):

Anaerobic Digestion ◽

Phase System ◽

Batch Experiments ◽

Optimal Range ◽

Two Phase ◽

Egg Albumin ◽

Carbohydrate Degradation ◽

Constant Ph ◽

Acidogenic Reactor ◽

Propionate Degradation

The effectiveness of two-phase anaerobic digestion in degrading complex substrates was studied by using a continuous acidogenic reactor and batch experiments. When 4,600 mg COD/l of milk consisting of carbohydrates, proteins and lipids, was fed to the acidogenic reactor, carbohydrates were easily converted to acids although protein degradation was insufficient and lipids were not degraded. The condition which gave greater than 95% carbohydrate degradation was a pH of not less than 4.5 at a constant HRT of 18 hours, and HRT longer than 6 hours at a constant pH of 6.0. Low pH or short HRT within the optimal range brought about the production of more n-butyrate instead of propionate. Degradation of egg albumin in the two-phase system required a longer HRT (about 5 days) than the ordinary acidogenic reactor. Batch experiments using the mixed liquor from the acidogenic reactor suggest that phase separation is not very effective for the degradation of carbohydrates and proteins, but it can prevent the inhibition caused by lipids.

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EXTREMUM SEEKING CONTROL OF TWO-STAGE ANAEROBIC DIGESTION SYSTEM: A MINI REVIEW

10.32006/eeep.2021.2.1225 ◽

2021 ◽

Vol 2021 (2/2021) ◽

pp. 12-25

Author(s):

Nicolai Christov ◽

Haoping Wang ◽

Ivan Simeonov

Keyword(s):

Anaerobic Digestion ◽

Automatic Control ◽

Extremum Seeking ◽

Phase System ◽

Optimal Conditions ◽

Two Stage ◽

Two Phase ◽

Extremum Seeking Control ◽

Ch4 Production ◽

Production Of Hydrogen

Anaerobic digestion (AD) is a biotechnological process, in which microorganisms degrade organic matter under anaerobic conditions to produce biogas. It has long been known that the two main species (acidogenic and methanogenic) in the community of microorganisms in AD differ in many aspects and the optimal conditions for their growth and development are different. Therefore, in AD in a single bioreactor (BR) (single-phase process), the optimal conditions are selected taking into account the slow-growing methanogens at the expense of fast-growing acidogens, which affects the efficiency of the whole process. This has led in recent years to the development of two-stage AD (TSAD), in which processes are divided into a cascade of two separate BRs. It is known that this division of the processes into two consecutive BRs leads to significantly higher energy yields for the two-phase system (H2 + CH4), compared to the traditional single-stage CH4 production process. In our previous studies different mathematical models of the TSAD have been developed. It was shown that in both BRs the input-output characteristics have a clear maximum, which allows the yields to increase significantly if operations are provided around the maximum points. However, in order to maintain the sustainability of the biogas plants work, it is necessary to introduce automatic control with sophisticated extremum seeking control (ESC) algorithms. This paper presents the pioneering research on ESC of AD process with production of hydrogen and methane. This research has been realized by the Department of Biotechnology at The Stephan Angeloff Institute of Microbiology (SAIM) and the French-Chinese Laboratory on Automatic Control and Signal Processing (LaFCAS), in collaboration with the Laboratory of Signals and Systems (L2S) at the French National Center of Scientific Research CNRS.

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Anaerobic biodigestion of sugarcane vinasse under mesophilic conditions using manure as inoculum

Ambiente e Agua - An Interdisciplinary Journal of Applied Science ◽

10.4136/ambi-agua.1897 ◽

2016 ◽

Vol 11 (4) ◽

pp. 763 ◽

Cited By ~ 9

Author(s):

Carlos Eduardo De Farias Silva ◽

Ana Karla De Souza Abud

Keyword(s):

Anaerobic Digestion ◽

Oxygen Demand ◽

Treatment Method ◽

Inoculum Concentration ◽

Total Solids ◽

Consequent Reduction ◽

Solids Content ◽

Harmful Effects ◽

Sugarcane Vinasse ◽

Mesophilic Conditions

Sugarcane vinasse is one of the most polluting residues produced by Brazilian ethanol industries, mainly because of its harmful effects on the environmental, such as high organic matter load and acidity. Anaerobic digestion is a highly efficient wastewater treatment method that could potentially be used to treat sugarcane vinasse. This study examined the anaerobic biodigestion of sugarcane vinasse in mesophilic conditions (30 - 45°C) by varying the inoculum concentration (0.5 to 5.5%) and pH (6 - 8). Changes of Chemical Oxygen Demand (COD), total solids content, and yield and composition of biogas after the biodigestion of the vinasse were assessed. The vinasse was efficiently digested under mesophilic anaerobic conditions over a 23-day Hydraulic Retention Time (HRT) and a 5-day acidogenic phase with a consequent reduction of COD (54 - 83%) and total solids (52 - 87%). Statistical analyses at a confidence level of 95% suggested that temperature, pH and inoculum concentration did not influence on the anaerobic biodigestion of the vinasse. The optimal operating parameters were found to be temperatures of 30 - 35°C, inoculum concentration of 0.5% and pH of 6 - 7. The results emphasize the promising use of the treated sugarcane vinasse as a biofertilizer for agriculture, indicating that the anaerobic digestion process is an excellent alternative for Brazilian ethanol industries.

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Development of a two phase anaerobic digester for the treatment of mixed abattoir wastes

Water Science & Technology ◽

10.2166/wst.1999.0016 ◽

1999 ◽

Vol 40 (1) ◽

pp. 69-76 ◽

Cited By ~ 20

Author(s):

C. J. Banks ◽

Z. Wang

Keyword(s):

Anaerobic Digestion ◽

Retention Time ◽

High Rate ◽

Phase System ◽

Second Phase ◽

Two Phase ◽

Single Pass ◽

Liquid Retention ◽

Solids Retention ◽

Overall Performance

A two phase anaerobic digestion system was developed for the treatment of mixed abattoir wastes composed of mixtures of cattle blood and cattle gut fill (rumen paunch contents). The reactor system, and its mode of operation, overcame the problems associated with a single pass anaerobic digestion process by alleviating toxicity problems associated with the accumulation of volatile fermentation intermediates and high ammonia concentrations. The principle of operation of the two phase system was to separate the hydrolysis reactions from those of methanogenesis and, by introducing a hydraulic flush regime, to prevent accumulation of intermediate products in the first phase of the process. The hydraulic flush operates in such a manner whereby the liquid retention time in the first reactor was significantly shorter than the solids retention of the fibrous components of the feedstock. The first phase reactor was run in this mode using solids retention times of 5, 10, 15, 20 and 30 days with a liquid retention time of 2 days. Up to 87% solids reductions were achieved compared to a maximum 50% when control reactors were operated in a single pass mode with solids and liquid retention times of equal duration. The performance of the first phase hydrolysis reactor was also monitored in terms of volatile fatty acid production, COD removal efficiency and ammonia accumulation potential. The liquefied effluent from the hydraulic flush reactor was found to be a suitable substrate for a second phase high rate methanogenic reactor operated over a range of retention times of between 2 - 10 days; this gave equivalent process loadings of 1.4 - 7.0 kg COD/m3/day. Methane conversion efficiencies of around 0.3 m3 CH4/kg COD removed were achieved. By use of the two phase system it was possible to operate at a loading to the first phase of 7.22 kgTS/m3/day with a resultant effluent from the second phase with a COD of 4270 mgl−1. The overall performance of the system showed a process loading of 3.6 kgTS/m3/day was achievable with a methane production rate of 0.27 m3CH4/kgTS added and 63% TS destruction. The results suggest that further optimisation of the two phases might further improve this overall performance.

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