Anaerobic Digestion of Piggery Wastes

1992 ◽  
Vol 25 (1) ◽  
pp. 9-16 ◽  
Author(s):  
A. D. Andreadakis
Keyword(s):  
Anaerobic Digestion ◽  
Anaerobic Degradation ◽  
Gas Production ◽  
Feasible Method

Anaerobic digestion can be an attractive and economically feasible method for the treatment of piggery wastes, provided that maximization of gas production and efficient subsequent utilization can be attained. Expedience from anaerobic digestion of domestic sludges can not be directly transferred to the design of digestion treating piggery wastes, due to the particular characteristics of the latter. The sequential anaerobic degradation of these wastes favours the adoption of short retention times for maximum gas production while at the same time satisfactory stabilization can be obtained.

Gasification as an optimum alternative for the sludge management

2011 ◽  
Vol 6 (4) ◽  
Author(s):  
C. Peregrina ◽  
J. M. Audic ◽  
P. Dauthuille
Keyword(s):  
Power Generation ◽  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Combined Heat And Power ◽  
Gas Production ◽  
Waste Reduction ◽  
Fluidised Bed ◽  
Sludge Management ◽  
Gas Cleaning ◽  
Cleaning System

Assimilate sludge to a fuel is not new. Sludge incineration and Combined Heat and Power (CHP) engines powered with sludge-derived anaerobic digestion gas (ADG) are operations widely used. However, they have a room of improvement to reach simultaneously a positive net power generation and a significant level of waste reduction and stabilization. Gasification has been used in other realms for the conversion of any negative-value carbon-based materials, that would otherwise be disposed as waste, to a gaseous product with a usable heating value for power generation . In fact, the produced gas, the so-called synthetic gas (or syngas), could be suitable for combined heat and power motors. Within this framework gasification could be seen as an optimum alternative for the sludge management that would allow the highest waste reduction yield (similar to incineration) with a high power generation. Although gasification remains a promising route for sewage sludge valorisation, campaigns of measurements show that is not a simple operation and there are still several technical issues to resolve before that gasification was considered to be fully applied in the sludge management. Fluidised bed was chosen by certain technology developers because it is an easy and well known process for solid combustion, and very suitable for non-conventional fuels. However, our tests showed a poor reliable process for gasification of sludge giving a low quality gas production with a significant amount of tars to be treated. The cleaning system that was proposed shows a very limited removal performance and difficulties to be operated. Within the sizes of more common WWTP, an alternative solution to the fluidised bed reactor would be the downdraft bed gasifier that was also audited. Most relevant data of this audit suggest that the technology is more adapted to the idea of sludge gasification presented in the beginning of this paper where a maximum waste reduction is achieved with a great electricity generation thanks to the use of a “good” quality syngas in a CHP engine. Audit show also that there is still some work to do in order to push sludge gasification to a more industrial stage. Regardless what solution would be preferred, the resulting gasification system would involve a more complex scenario compared to Anaerobic Digestion and Incineration, characterised by a thermal dryer and gasifier with a complete gas cleaning system. At the end, economics, reliability and mass and energy yields should be carefully analysed in order to set the place that gasification would play in the forthcoming processing of sewage sludge.

A Mathematical Model for the Anaerobic Digestion Process Applied to a Mixture of Night Soil and Septic Tank Sludge

1986 ◽  
Vol 18 (7-8) ◽  
pp. 239-248 ◽  
Author(s):  
Sung Ryong Ha ◽  
Dwang Ho Lee ◽  
Sang Eun Lee
Keyword(s):  
Mathematical Model ◽  
Anaerobic Digestion ◽  
Biomass Concentration ◽  
Gas Production ◽  
Septic Tank ◽  
Volatile Acid ◽  
Hydraulic Residence Time ◽  
Anaerobic Digestion Process ◽  
Digestion Process ◽  
Proposed Model

Laboratory scale experiments were conducted to develop a mathematical model for the anaerobic digestion of a mixture of night soil and septic tank sludge. The optimum mixing ratio by volume between night soil and septic tank sludge was found to be 7:3. Due to the high solids content in the influent waste, mixed-liquor volatile suspended solids (MLVSS) was not considered to be a proper parameter for biomass concentration, therefore, the active biomass concentration was estimated based on deoxyribonucleic acid (DNA) concentration in the reactor. The weight ratio between acidogenic bacteria and methanogenic bacteria in the mixed culture of a well-operated anaerobic digester was approximately 3:2. The proposed model indicates that the amount of volatile acid produced and the gas production rate can be expressed as a function of hydraulic residence time (HRT). The kinetic constants of the two phases of the anaerobic digestion process were determined, and a computer was used to simulate results using the proposed model for the various operating parameters, such as BOD5 and volatile acid concentrations in effluent, biomass concentrations and gas production rates. These were consistent with the experimental data.

Biological nutrient removal wastewater treatments and sewage sludge anaerobic mesophilic digestion performances

2002 ◽  
Vol 46 (10) ◽  
pp. 199-208 ◽  
Author(s):  
D. Bolzonella ◽  
L. Innocenti ◽  
F. Cecchi
Keyword(s):  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Economic Assessment ◽  
Gas Production ◽  
Anaerobic Digester ◽  
Biological Nutrient Removal ◽  
Energetic Balance ◽  
Mesophilic Digestion ◽  
The Difference ◽  
Energy Balances

The paper deals with the performances of the mesophilic anaerobic digestion treatment of sewage sludge from a full scale BNR process without primary settling (nominally 300,000 PE). A relation between the activated sludge observed yields, Yobs, and the anaerobic digester performance was preliminarily found: for values of Yobs of 0.25 kgVSS/kgCOD the anaerobic digester specific gas production showed the best performances (0.22 m3/kgVSfed). This has to be confirmed with wider future studies. It was also shown the level of sludge pre-thickening to be reached for the self-sustaining warming of the digester also in wintertime. According to the energetic balance and to a comparison with an aerobic stabilisation process, it was pointed out as when a co-generation unit for heat and energy production was introduced about 3.4 kWh/PE y of energy were produced in the anaerobic digestion process. On the other hand, 4.3 kWh/PE y were spent if an aerobic stabilisation process was applied. The economic assessment, carried out on the basis of the energy balances, showed that the anaerobic digestion is always economically advantageous if compared to aerobic stabilisation processes, also for small WWTPs. According to the energetic evaluations an environmental balance was assessed, in terms of CO2 emissions. The difference between anaerobic and aerobic processes was about 5.3 kgCO2/PE y in favour of anaerobic processes application.

Sludge accumulation and methanogenic activity in an anaerobic lagoon

2000 ◽  
Vol 42 (10-11) ◽  
pp. 247-255 ◽  
Author(s):  
J. Paing ◽  
B. Picot ◽  
J. P. Sambuco ◽  
A. Rambaud
Keyword(s):  
Anaerobic Digestion ◽  
Methane Production ◽  
Anaerobic Degradation ◽  
Volatile Fatty Acids ◽  
Anaerobic Fermentation ◽  
Methanogenic Activity ◽  
Start Up ◽  
Anaerobic Lagoon ◽  
Methane Production Rate ◽  
Sludge Accumulation

Sludge accumulation and the characteristics of anaerobic digestion in sludge had been investigated in a primary anaerobic lagoon. Methanogenic potential of sludge was evaluated by an anaerobic digestion test which measured the methane production rate. Sludge was sampled at several points in the lagoon to determine spatial variations and with a monthly frequency from the start-up of the lagoon to observe the development of anaerobic degradation. Maximum amounts of sludge accumulated near the inlet. The mean methane production of sludge was 2.9 ml gVS–1 d–1. Sludge near the outlet presented a greater methanogenic activity and a lesser concentration of volatile fatty acids than near the inlet. The different stages of anaerobic degradation were spatially separated, acidogenesis near the inlet and methanogenesis near the outlet. This staged distribution seemed to increase efficiency of anaerobic fermentation compared with septic tanks. Methane release at the surface of the lagoon was estimated to be very heterogeneous with a mean of 25 l m–2 d–1. The development of performance and sludge characteristics showed the rapid beginning of methanogenesis, three months after the start-up of the anaerobic lagoon. Considering the volume of accumulated sludge, it could however be expected that methanogenic activity would further increase.

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.

scholarly journals Heat Exchanger for Bio-Digester under Thermophilic Range

2019 ◽  
Vol 5 ◽  
pp. 79-88
Author(s):  
Prajwal Sapkota ◽  
Laxman Poudel
Keyword(s):  
Heat Exchanger ◽  
Anaerobic Digestion ◽  
Heat Exchangers ◽  
Heating System ◽  
Gas Production ◽  
Cow Dung ◽  
Digestion Rate ◽  
Digestion Process ◽  
Different Temperatures ◽  
Long Time

Bio-gas has been one of the sources of renewable energy and has been used from long time. It is produced by the anaerobic digestion or decomposition of organic compounds and has different process. The digestion process is carried out by bacteria present in the waste and it is highly dependent on the bacteria which work differently on different temperatures. The rate of anaerobic digestion is highest at hemophilic temperature (55°C). Similarly, it is moderate at mesophilic temperature (35°C) and is lowest at psychrophilic (below 20°C). Thus, to attain the highest digestion rate a thermophilic heating system has beend eveloped. The heating system uses five heat exchangers to heat the influent at digester which is of 35m3 volume, to maintain temperature at 56°C. The volume of bio-gas production from this system which uses cow dung as digestingmaterial is about 28 m3 per day.

scholarly journals Numerical Comparison of a Combined Hydrothermal Carbonization and Anaerobic Digestion System with Direct Combustion of Biomass for Power Production

Processes ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 43 ◽  
Author(s):  
Mohammad Heidari ◽  
Shakirudeen Salaudeen ◽  
Omid Norouzi ◽  
Bishnu Acharya ◽  
Animesh Dutta
Keyword(s):  
Anaerobic Digestion ◽  
Rankine Cycle ◽  
Hydrothermal Carbonization ◽  
Gas Production ◽  
Numerical Comparison ◽  
Fuel Gas ◽  
Operational Conditions ◽  
Unit Process ◽  
Direct Combustion ◽  
Balance Analysis

Two of the methods for converting biomass to fuel are hydrothermal carbonization (HTC) and anaerobic digestion (AD). This study is aimed at designing and analyzing two scenarios for bioenergy production from undervalued biomass (sawdust). In one of the scenarios (direct combustion or DC), raw biomass is burned in a combustor to provide the heat that is required by the Rankine cycle to generate electricity. In the other scenario (HTC-AD), the raw biomass first undergoes HTC treatment. While the solid product (hydrochar) is used to produce power by a Rankine cycle, the liquid by-product undergoes an AD process. This results in fuel gas production and it can be used in a Brayton cycle to generate more power. Energy and mass balance analysis of both scenarios were developed for each unit process by using Engineering Equation Solver (EES). The required data were obtained experimentally or from the literature. The performances of the proposed systems were evaluated, and a sensitivity analysis was presented to help in finding the best operational conditions.

Sludge Thickening Prior to Anaerobic Digestion

1984 ◽  
Vol 16 (12) ◽  
pp. 419-432 ◽  
Author(s):  
H Kapp
Keyword(s):  
Anaerobic Digestion ◽  
Federal Republic ◽  
Gas Production ◽  
Operating Parameters ◽  
Federal Republic Of Germany ◽  
Digestion Time ◽  
Sludge Treatment ◽  
Retention Period ◽  
Solids Content ◽  
Sludge Thickening

In the Federal Republic of Germany the average solids content in digested sludges is about 3%. Increasing the solids content to 6-8% by pre-dewatering would mean that the sludge volume would be reduced to 40-50%. For the same retention period the volume of new digesters will be reduced and the necessary energy for heating decreased. Overloaded sludge treatment plants can be upgraded, as digestion time becomes longer and gas production increases. As pre-dewatering machines, first of all decanting centrifuges and screens can be recommended. The addition of coagulant aids is necessary to some extent. In the case of two practical examples, the operating parameters of raw sludge thickening as well as the economic advantages of the operating procedure are shown.

Studies of the Production of Volatile Fatty Acids in the Anaerobic Digestion of Municipal Sludge

1986 ◽  
Vol 21 (1) ◽  
pp. 58-70 ◽  
Author(s):  
P.H. Jones ◽  
J. Szekely
Keyword(s):  
Fatty Acids ◽  
Anaerobic Digestion ◽  
Volatile Fatty Acids ◽  
Gas Production ◽  
Municipal Sludge ◽  
Anaerobic Digesters ◽  
Effect Of Ph ◽  
Commercial Value

Abstract Volatile fatty acids (VFA’s) produced during anaerobic digestion of sludge have higher commercial value than methane produced subsequently. Therefore it was decided to determine conditions necessary to maximise production of VFA’s. Five anaerobic digesters were operated in parallel in the laboratory to investigate the effect of pH on the formation of VFA’s. Concentrations of individual fatty acids were measured. Both VFA production as well as gas production was favoured by pH approaching neutrality.

Pretreatment followed by anaerobic digestion of secondary sludge for reduction of sewage sludge volume

2013 ◽  
Vol 67 (11) ◽  
pp. 2527-2533 ◽  
Author(s):  
Naoki Abe ◽  
Yue-Qin Tang ◽  
Makoto Iwamura ◽  
Shigeru Morimura ◽  
Kenji Kida
Keyword(s):  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Thermal Treatment ◽  
Low Pressure ◽  
Gas Production ◽  
Wet Oxidation ◽  
Thermophilic Anaerobic Digestion ◽  
Sludge Pretreatment ◽  
Secondary Sludge ◽  
Digestion Efficiency

The influence of two pretreatment methods, thermal treatment and low-pressure wet oxidation, on the sludge digestion efficiency was examined. Batch thermophilic anaerobic digestion was used to evaluate the effectiveness of the pretreatment methods in terms of volatile suspended solids (VSS) digestion efficiency and gas production. The results showed that the gas production was not proportional to the VSS degradation efficiency of either thermal treatment or low-pressure wet oxidation. Low-pressure wet oxidation treatment at 150 °C along with 40% of the theoretical oxygen required to oxidize organic carbon gave the highest gas production and the VSS digestion efficiency of 77% at a VSS loading rate of 8 g l−1 d−1. The digestion efficiency was about 30% higher than that of thermophilic anaerobic digestion without sludge pretreatment. Sewage sludge could be treated effectively at a high VSS digestion efficiency with this pretreatment followed by thermophilic anaerobic digestion.

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