Modelling of anaerobic digestion using self-organizing maps and artificial neural networks

2000 ◽  
Vol 41 (12) ◽  
pp. 149-156 ◽  
Author(s):  
P. Holubar ◽  
L. Zani ◽  
M. Hagar ◽  
W. Fröschl ◽  
Z. Radak ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Production Rate ◽  
Regression Coefficient ◽  
Gas Production ◽  
Neural Nets ◽  
Organic Loading Rate ◽  
Self Organizing Map ◽  
Gas Composition ◽  
Volatile Fatty Acid Concentration ◽  
Self Organizing

In this work the training of a self-organizing map and a feed-forward back-propagation neural network was made. The aim was to model the anaerobic digestion process. To produce data for the training of the neural nets an anaerobic digester was operated at steady state and disturbed by pulsing the organic loading rate. Measured parameters were: gas composition, gas production rate, volatile fatty acid concentration, pH, redox potential, volatile suspended solids and chemical oxygen demand of feed and effluent. It could be shown that both types of self-learning networks in principle could be used to model the process of anaerobic digestion. Using the unsupervised Kohonen self-organizing map, the model's predictions could not follow the measurements in all details. This resulted in an unsatisfactory regression coefficient of R2= 0.69 for the gas composition and R2= 0.76 for the gas production rate. When the supervised FFBP neural net was used the training resulted in more precise predictions. The regression coefficient was found to be R2= 0.74 for the gas composition and R2== 0.92 for the gas production rate.

Rheology of sludge from double phase anaerobic digestion of organic fraction of municipal solid waste

2000 ◽  
Vol 41 (3) ◽  
pp. 51-59 ◽  
Author(s):  
P. Battistoni ◽  
P. Pavan ◽  
J. Mata-Alvarez ◽  
M. Prisciandaro ◽  
F. Cecchi
Keyword(s):  
Anaerobic Digestion ◽  
Municipal Solid Waste ◽  
Solid Waste ◽  
Pilot Scale ◽  
Gas Production ◽  
Organic Loading Rate ◽  
Second Phase ◽  
Organic Fraction ◽  
Double Phase ◽  
Long Term Experiment

In this paper experimental results on the anaerobic digestion of sewage sludge and organic fraction of municipal solid waste (OFMSW) by using a double phase process are reported. The long-term experiment has been carried out on a pilot scale plant, performed in different sets of operative conditions, during which granulometric distributions of particles in sludges and rheological properties of sludges were monitored. A significant fluidification of sludge was evidenced in the meso-thermo process, especially taking into account the variation in sludge behaviour from the first to the second phase. In the thermo-thermo process a fluidification higher than that shown in meso-thermo conditions is not observed, this suggesting that better results in terms of sludge conditioning can be obtained in a long time spent in thermophilic anaerobic digestion. Total volatile solids (TVS) and total fixed solids (TFS) become the most important parameters when mathematical modelling is applied to these processes.In the acidogenic phase, hydraulic retention time (HRT) and temperature are used to determine rigidity coefficient (RC), while only temperature is needed for yield stress (YC). Organic loading rate (OLR) and specific gas production (SGP) exert an important role in methanogenic phase description.

Study of Methane Production by High Temperature Anaerobic Fermentation of Chicken Manure and Stalks

2020 ◽  
Vol 14 (4) ◽  
pp. 551-557
Author(s):  
Yongku Li ◽  
Xiaomin Hu ◽  
Lei Feng
Keyword(s):  
High Temperature ◽  
Anaerobic Digestion ◽  
Production Rate ◽  
Methane Production ◽  
Anaerobic Fermentation ◽  
Biogas Production ◽  
Gas Production ◽  
Chicken Manure ◽  
Biogas Slurry ◽  
Production Rates

The changing parameters, as the biogas production rate, the methane production rate, the cumulative biogas amount, the cumulative methane amount, the biogas composition, pH etc. in high temperature anaerobic fermentation of chicken manure and stalks were analyzed by experiments with different mass ratios of chicken manure or livestock manure and stalks with a high C/N ratio. The methane production mechanism of high temperature anaerobic digestion of chicken manure and stalks was discussed in detail. It showed that not only the biogas production rates but also the methane production rates of R1–R7 demonstrated the trend of initial increase and then decrease after 50 d of high temperature anaerobic digestion. Besides, the gas production of R1 with pure chicken manure stopped on the 30th d of the reaction. The gas production of other groups R2–R7 also stopped on the corresponding 34th, 36th, 36th, 37th, 37th, and 37th day, respectively. At the end of the reaction, the cumulative biogas amounts and the cumulative methane amounts of R1–R7 were 411.58 and 269.54, 459.91 and 314.41, 425.32 and 294.11, 401.85 and 272.54, 382.63 and 257.07, 363.04 and 218.16, and 257.15 and 160.10 N ml/(g VS). The biogas slurry pH of R1–R7 all demonstrated a trend of initial decrease and then increase, e. g., pH of R2 reached the minimum of 5.94 on the 5th day. pH values of other groups were between 6.01 and 6.39. After the addition of 4 g of sodium bicarbonate on the 7th day, biogas slurry pH of R1–R7 all increased. pH was maintained between 7.16 and 7.44 until the end of the reaction.

Design of the Solar Energy-Heated Biogas Digester

2014 ◽  
Vol 953-954 ◽  
pp. 103-106
Author(s):  
Jin Yang Li ◽  
Jian Li ◽  
Qing Yu Liu ◽  
Hao Zheng
Keyword(s):  
Anaerobic Digestion ◽  
Solar Energy ◽  
Production Rate ◽  
Northern China ◽  
Gas Production ◽  
Raw Material ◽  
Solar Thermal ◽  
Biogas Slurry ◽  
Optimum Temperature ◽  
Working Principle

Heating biogas digester is essential in northern China, especially during the winter. Solar energy-heated biogas digester is a facility that radiates heat by the solar thermal, which maintains the temperature of the biogas digester. The working principle behind this facility is the division of the traditional biogas digester into three parts, namely, raw material storage section, biogas slurry storage section, and anaerobic digestion section. We only heat the anaerobic digestion section to decrease the heating volume and reduce the heat dissipating surface, thereby saving energy. Solar energy is unstable, and the anaerobic digestion section needs to be maintained at its best temperature, thus, we control the raw material inlet at its optimum temperature. This biogas digester improves the anaerobic digestion condition and enhances gas production rate, which enables the efficient function of the digester during winter.

Comparison of dry and wet digestion for solid waste

2003 ◽  
Vol 48 (4) ◽  
pp. 15-20 ◽  
Author(s):  
L. Luning ◽  
E.H.M. van Zundert ◽  
A.J.F. Brinkmann
Keyword(s):  
Anaerobic Digestion ◽  
Organic Waste ◽  
Gas Production ◽  
Organic Loading Rate ◽  
Inert Material ◽  
Environmental Standards ◽  
Dry Process ◽  
Wet Process ◽  
Crucial Difference ◽  
Mechanical Separation

To reduce the amount of MSW going to landfills a number of technologies have been developed. Two main types of anaerobic digestion processes are distinguished for MSW organic waste, which are generally referred to as “wet” (10-15% DM) and “dry” (24-40% DM) anaerobic digestion processes. The input is conditioned to the appropriate DM content by adding process water as required. This article compares a full-scale dry process, Valorga in La Coruña, Spain and a wet process, Vagron in Groningen, The Netherlands. A crucial difference is that the Vagron facility applies a washing step prior to the AD process to remove inert materials for re-use and to prevent damage of the installation. In the Valorga facility the organic fraction of the mechanical separation process is fed directly to the AD process. Both processes can be considered proven technology. Specific gas production is practically identical. Waste water production is higher in the wet process, as is to be expected, but this is compensated by a smaller amount of digestate to be disposed of and the separation of inert materials suitable for recycling. The organic loading rate for the Vagron process appears to be higher and the required reactor volume smaller in comparison to the dry Valorga process. The applicability of AD processes is strongly determined by the environmental standards set for the products from digestion. The German standards for digestate result in a lower potential for recycling of inert material separated from organic MSW.

Anaerobic co-digestion of sewage sludge and food waste using temperature-phased anaerobic digestion process

2004 ◽  
Vol 50 (9) ◽  
pp. 107-114 ◽  
Author(s):  
H.-W. Kim ◽  
S.-K. Han ◽  
H.-S. Shin
Keyword(s):  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Production Rate ◽  
Food Waste ◽  
Batch Reactor ◽  
Hydrolytic Activity ◽  
Organic Loading Rate ◽  
Methanogenic Activity ◽  
Ch4 Production ◽  
Low Efficiency

This study was performed to overcome the low efficiency of anaerobic digestion of sewage sludge and food waste by combining temperature-phased digestion, sequencing batch operation, and co-digestion technology. It was demonstrated that the temperature-phased anaerobic sequencing batch reactor (TPASBR) system for the co-digestion of sewage sludge and food waste resulted in enhanced volatile solids (VS) reduction and methane production rate. At the organic loading rate (OLR) of 2.7 g VS/l/d, the TPASBR system showed the higher VS reduction (61.3%), CH4 yield (0.28 l/g VSadded) and CH4 production rate (0.41 l CH4/l/d) than those (0.29 l CH4/l/d) of the mesophilic two-stage ASBR (MTSASBR). In the specific methanogenic activity (SMA) tests on thermophilic biomass of the TPASBR system, the average SMA of acetate (93 ml CH4/gVSS/d) was much higher than those of propionate (46 ml CH4/g VSS/d) and butyrate (76 ml CH4/g VSS/d). Also, higher specific hydrolytic activity (SHA, 217 mg COD/g VSS/d) of the biomass supported fast hydrolysis under thermophilic conditions. The track study revealed that the most active period of the 24 h cycle was between 6 and 12 h. The enhanced performance of the TPASBR system could be attributed to longer solids retention time, fast hydrolysis, higher CH4 conversion rate, and balanced nutrient condition of co-substrate. It was verified that this combination could be a promising and practical alternative for the simultaneous recycling of two types of organic fraction of municipal solid waste (OFMSW) with high stability.

On-line monitoring of anaerobic digestion: application of a device for continuous measurement of bicarbonate alkalinity

1994 ◽  
Vol 30 (12) ◽  
pp. 1-10 ◽  
Author(s):  
Freda R. Hawkes ◽  
Alan J. Guwy ◽  
Dennis L. Hawkes ◽  
Alberto G. Rozzi
Keyword(s):  
Anaerobic Digestion ◽  
Accurate Determination ◽  
Gas Production ◽  
Stable Operation ◽  
Anaerobic Digesters ◽  
Ph Buffering ◽  
Volatile Fatty Acid Concentration ◽  
On Line ◽  
Bicarbonate Alkalinity

Alkalinity or pH buffering capacity in anaerobic digesters is chiefly a function of bicarbonate levels, and should be within 10 to 50 mM for stable operation. A novel on-line instrument for measuring bicarbonate alkalinity has been developed, independent of titration techniques. Using a 10 litre anaerobic filter digester operating on ice-cream wastewater, on-line measurements were made of bicarbonate alkalinity, pH, gas production and % CO2 and hydrogen concentration in the biogas during periods of organic overload. The bicarbonate alkalinity monitor was shown to be an effective instrument for monitoring instability of anaerobic digestion, and a useful tool for early warning of overloading. Moreover, in digesters fed with wastewaters containing low potential alkalinity, it allows indirect on-line determination of variations in volatile fatty acid concentration. Finally, used in conjunction with a sensor that measures CO2 in the gas, it allows an indirect but accurate determination of pH in those solutions where fouling of electrodes is severe.

A Potential Treatment Alternative for Swine Wastewater in the Tropics

1985 ◽  
Vol 17 (4-5) ◽  
pp. 819-831 ◽  
Author(s):  
P. Y. Yang ◽  
S. Y. Nagano
Keyword(s):  
Anaerobic Digestion ◽  
Production Rate ◽  
Algal Biomass ◽  
Energy Production ◽  
Loading Rate ◽  
Gas Production ◽  
Energy Utilization ◽  
Swine Wastewater ◽  
N Removal ◽  
The Tropics

Development of a low-cost and effective swine waste management system in the tropics is the main objective of this study. Because of the apppropriate temperature environment and abundance of sunlight, an integration of an anaerobic digestion and an algal biomass process was selected and investigated. A pilot, plant integrating a 20 m3 anaerobic digester with sludge recycling and a 120 m3 algal-biomass raceway were installed and evaluated. Maximum gas production rate of 1.527 liter/liter/day (69% methane content) can be achieved by a TVS loading rate of 4.23 gram/liter/day. A sludge production rate of 0.82-2.62 g TS/liter is obtained from a TVS loading rate of 0.76-4.23 g TVS/liter/day. Critical SRT for maximum gas production rate is 2.67. For the algal biomass raceway, a loading rate of 0.097 g SCOD/liter/day or 0.017 g NH4-N/liter/day would achieve SCOD and NH4-N removal efficiencies of 94.44% and 98.42%, respectively. Combining the previous analysis of energy input and land requirement for an algal biomass raceway and mass balance of energy production and utilization, integrating the energy production (anaerobic digestion) and energy utilization (dehydration of digested sludge and power requirement of raceway) provides a great potential for a swine wastewater treatment in the tropics.

Simultaneous treatment of sewage sludge and food waste by the unified high-rate anaerobic digestion system

2006 ◽  
Vol 53 (6) ◽  
pp. 29-35 ◽  
Author(s):  
H.-W. Kim ◽  
S.-K. Han ◽  
H.-S. Shin
Keyword(s):  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Production Rate ◽  
Food Waste ◽  
High Rate ◽  
Organic Loading Rate ◽  
Simultaneous Treatment ◽  
Methanogenic Activity ◽  
Ch4 Production ◽  
Methane Production Rate

This study aimed to evaluate the performance of the unified high-rate anaerobic digestion (UHAD) system treating co-substrate of sewage sludge and food waste. A 24-hr operating sequence consisted of four steps including fill, react, settle, and draw. The effects of co-substrate and organic loading rate (OLR) on the performance were investigated to verify the system applicability. In each OLR, the UHAD system showed higher CH4 recovery (>70%), CH4 yield (0.3 L CH4/g VSadded) and CH4 production rate (0.6 L CH4/L/d) than the control system. In the specific methanogenic activity (SMA) tests on thermophilic biomass of the UHAD system, the average SMA of acetate (102 mL CH4/gVSS/d) was much higher than those of butyrate (85 mL CH4/g SS/d) and propionate (42 mL CH4/gVSS/d). It was demonstrated that the UHAD system for co-digestion resulted in higher methane yield and methane production rate due to sequencing batch operation, thermophilic digestion, and co-digestion. The enhanced performance could be attributed to longer retention time of active biomass, faster hydrolysis, higher CH4 conversion rate, and balanced nutrient conditions of co-substrate in the UHAD system. Consequently, this optimized unification could be a viable option for the simultaneous treatment of two types of OFMSW with high stability.

scholarly journals An experimental study on Bio-gas production by anaerobic digestion of RiceMill Wastewater (RMW)

2020 ◽  
Vol 23 (1) ◽  
pp. 35-42
Keyword(s):  
Anaerobic Digestion ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Gas Production ◽  
Anaerobic Digester ◽  
Organic Loading Rate ◽  
Anaerobic Sludge ◽  
Working Volume ◽  
Mesophilic Temperature ◽  
Rice Mill Wastewater

<p>With the rising interest for sustainable power source and ecological security, anaerobic digestion of biogas technology has attracted considerable attention within the scientific researchers. This paper proposes a new research achievement on biogas production from Rice Mill Wastewater (RMW) with the utilization of anaerobic digester. An anaerobic digester is maintained with RMW and distillery anaerobic sludge at mesophilic temperature condition for 15 days as stabilization mode. After attaining stabilization stage, studies continued to examine the effect of Organic Loading Rate (OLR) and Hydraulic Retention Time (HRT) on the mesophilic anaerobic digestion of RMW. The OLR of the anaerobic reactor increased stepwise from 0.25 to 3.91 Kg COD/m3/dayand HRT ranged from 1 to 32.0 days. The total chemical oxygen demand (TCOD) utilized was higher than 75% and the CH4 percentage of the biogas was 62.00-63.00% for the OLRs studied. The efficient working volume of the digester is preserved as 25% of distillery anaerobic sludge and 75% of rice mill wastewater, loaded at Mesophilic temperature conditions for study purpose. By changing the conditions of OLR and HRT, biogas production, methane yield and percentage of COD reduction is examined. An anaerobic sludge is utilized as a seeding material to biodegrade the organic pollutants present in the wastewater. It will enhance the biological treatment of effluent with anaerobic sludge in a continuous mode of activity.The result showed that the proposed analysis obtains more biogas production with reduced COD when compared with existing approaches.</p>

scholarly journals The ManureEcoMine pilot installation: advanced integration of technologies for the management of organics and nutrients in livestock waste

2016 ◽  
Vol 75 (6) ◽  
pp. 1281-1293 ◽  
Author(s):  
Cristina Pintucci ◽  
Marta Carballa ◽  
Sam Varga ◽  
Jimena Sarli ◽  
Lai Peng ◽  
...  
Keyword(s):  
Production Rate ◽  
Biogas Production ◽  
Liquid Fraction ◽  
Swine Manure ◽  
Integrated Approach ◽  
Gas Production ◽  
Phosphorus Recovery ◽  
Organic Loading Rate ◽  
Livestock Waste ◽  
Nitrogen And Phosphorus

Manure represents an exquisite mining opportunity for nutrient recovery (nitrogen and phosphorus), and for their reuse as renewable fertilisers. The ManureEcoMine proposes an integrated approach of technologies, operated in a pilot-scale installation treating swine manure (83.7%) and Ecofrit® (16.3%), a mix of vegetable residues. Thermophilic anaerobic digestion was performed for 150 days, the final organic loading rate was 4.6 kgCOD m−3 d−1, with a biogas production rate of 1.4 Nm3 m−3 d−1. The digester was coupled to an ammonia side-stream stripping column and a scrubbing unit for free ammonia inhibition reduction in the digester, and nitrogen recovery as ammonium sulphate. The stripped digestate was recirculated daily in the digester for 15 days (68% of the digester volume), increasing the gas production rate by 27%. Following a decanter centrifuge, the digestate liquid fraction was treated with an ultrafiltration membrane. The filtrate was fed into a struvite reactor, with a phosphorus recovery efficiency of 83% (as orthophosphate). Acidification of digestate could increment the soluble orthophosphate concentration up to four times, enhancing phosphorus enrichment in the liquid fraction and its recovery via struvite. A synergistic combination of manure processing steps was demonstrated to be technologically feasible to upgrade livestock waste into refined, concentrated fertilisers.

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