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.

Highly Efficient Anaerobic Digestion with Thermal Pretreatment

1985 ◽  
Vol 17 (4-5) ◽  
pp. 529-539 ◽  
Author(s):  
M. Hiraoka ◽  
N. Takeda ◽  
S. Sakai ◽  
A. Yasuda
Keyword(s):  
Fatty Acids ◽  
Anaerobic Digestion ◽  
Pilot Plant ◽  
Molecular Size ◽  
Gas Production ◽  
Thermal Pretreatment ◽  
Anaerobic Digestion Process ◽  
Digestion Process ◽  
Before And After ◽  
Pilot Plant Study

The effectiveness of an anaerobic digestion process with thermal pretreatment at a comparatively low temperature was examined. The waste activated sludge was thermally pretreated in the process. A laboratory scale experiment and a pilot plant study were conducted. Changes in volatile acids concentration, in major constituents of sludge and in molecular size distribution were examined before and after thermal pretreatment and anaerobic digestion. Thermal pretreatment resulted in an increase of more than 30 percent in digestion gas production. The major substrates decomposed were fats in the pilot plant study. Glyceride fatty acids are decomposed with thermal pretreatment and produce volatile acids such as acetic and propionic acids. The volatile acids are directly utilized by anaerobes to produce methane. Organic matter such as fats and carbohydrates are depolymerized with thermal pretreatment and produce soluble intermediate compounds such as higher fatty acids. The intermediates are utilized in the anaerobic digestion process. These two major effects facilitate the methane production process.

Upgrading of Anaerobic Digestion Processes for Night Soil

1986 ◽  
Vol 18 (7-8) ◽  
pp. 249-256 ◽  
Author(s):  
T. Noike ◽  
J. Matsumoto
Keyword(s):  
Anaerobic Digestion ◽  
Removal Rate ◽  
Field Investigation ◽  
Gas Production ◽  
Cod Removal ◽  
Two Phase ◽  
Anaerobic Digesters ◽  
Anaerobic Digestion Process ◽  
Digestion Process ◽  
Cod Removal Rate

The upgrading of night soil anaerobic digestion processes was studied by field investigation of the performance of anaerobic digesters in existing night soil treatment plants and by serai-continuous experiments with bench-scale digesters. Both the average monthly amount of collected night soil fed to a digester and the concentration of volatile solids in night soil increased in winter. A good correlation was found to exist between gas production and digestion temperature. The COD removal rate in the first digester was markedly higher than that in the second digester. The stirring period in the first digester in one plant differs from that in the other plant. Stirring the first digester for too long a period reduces the rate of COD removal by the second digester in the two-stage anaerobic digestion process. The first digester should be stirred for more than one hour per day in order to promote gas production. Gas production and CODCr removal rate in the second digester were hardly affected by reductions in retention time ranging from 15 days to 5 days. As night soil contains a large amount of cellulose and other refractory organics, some kind of pretreatment of the night soil fed to the digester may be necessary for the promotion of acidogenesis in the two-phase anaerobic digestion process.

Mathematical Modelling of the Anaerobic Digestion Process: Regulatory Mechanisms for the Formation of Short-Chain Volatile Acids from Glucose

1983 ◽  
Vol 15 (8-9) ◽  
pp. 209-232 ◽  
Author(s):  
F E Mosey
Keyword(s):  
Anaerobic Digestion ◽  
Mathematical Modelling ◽  
Redox Potential ◽  
Regulatory Mechanisms ◽  
Volatile Acid ◽  
Anaerobic Digestion Process ◽  
Digestion Process ◽  
Mathematical Expressions ◽  
Regulation Of Metabolism ◽  
Methane Bacteria

A model of the anaerobic digestion process is presented which attempts to explain the complex patterns of volatile acid production in the anaerobic digestion process. The hydrogen-utilising methane bacteria are identified as the controlling organisms for the redox potential of the process. Mathematical expressions for the regulation of metabolism by hydrogen are derived from the known redox potential of the NAD/NADH couple.

Anaerobic Digestion of Cheese Whey, Poultry Waste and Cattle Dung – A Study of the Use of Mixture of Adsorbents and/or Surfactants to Improve Digester Performance

1994 ◽  
Vol 5 (4) ◽  
pp. 379-385
Author(s):  
Manik Desai ◽  
Datta Madamwar
Keyword(s):  
Anaerobic Digestion ◽  
Silica Gel ◽  
Cheese Whey ◽  
Gas Production ◽  
Cattle Dung ◽  
Process Performance ◽  
Poultry Waste ◽  
Maximum Enhancement ◽  
Anaerobic Digestion Process ◽  
Digestion Process

This paper describes the improvement of anaerobic digestion process due to the addition of various surfactants and adsorbents in different combinations. Among the different combinations tested mixture of silica gel (2000 mg litre–1) and sodium lauryl sulphate (300 mg litre–1) showed maximum enhancement in gas production as well as methane content indicating better process performance.

scholarly journals MATHEMATICAL MODELLING OF A TWO-STAGE ANAEROBIC DIGESTION PROCESS WITH HYDROGEN AND METHANE PRODUCTION USING ADM1

2020 ◽  
pp. 18-29
Author(s):  
Milen Borisov ◽  
Dencho Denchev ◽  
Ivan Simeonov
Keyword(s):  
Anaerobic Digestion ◽  
Control Variable ◽  
Static Characteristics ◽  
Input Output ◽  
Software Environment ◽  
Two Stage ◽  
Anaerobic Digestion Process ◽  
Digestion Process ◽  
Proposed Model ◽  
Production Of Hydrogen

The aim of this study is to implement a mathematical model to simulate the dynamic behaviour of a two-stage anaerobic digestion process for simultaneous production of hydrogen and methane. The process is carried out in two connected continuously stirred bioreactors. The proposed model is developed by reducing the well known IWA Anaerobic Digester Model No 1 (ADM1). In the present study the original model concept was adapted and applied to replicate a two-stage process. The proposed model involves 13 ODEs for the 1st stage and 7 ODEs for the 2nd stage. The numerical coefficient values in the model are taken from specified literature and adapted to the case of wheat straw AD. Important input-output static characteristics and existence of maxima of the input-output static characteristics concerning the biohydrogen and biomethane production in function of the control variable (dilution rate) are presented. Supposing that both bioreactors are operating nearby these maxima the optimal ratio of the working volumes was obtained. Numerical simulations using a specially elaborated web-based software environment are presented to demonstrate the dynamic behavior of the model solutions.

scholarly journals Investigation of phase equations for anaerobic digestion process of anaerobic bioreactor landfill

2020 ◽  
Vol 170 ◽  
pp. 06005
Author(s):  
Priyanka R. Shinde ◽  
Sandip. T. Mali
Keyword(s):  
Mathematical Model ◽  
Anaerobic Digestion ◽  
Phase Distribution ◽  
Bioreactor Landfill ◽  
Chemical Parameters ◽  
Phase Equation ◽  
Anaerobic Bioreactor ◽  
Anaerobic Digestion Process ◽  
Digestion Process ◽  
Major Chemical

The anaerobic digestion process consists of four phases hydrolysis, acidogenesis, acetogenesis and methanogenesis. In the present work anaerobic digestion process of waste from anaerobic bioreactor landfill is considered and leachate is analyzed chemically for 268 days and out of all 17 parameters, seven major chemical parameters are studied for two reactors R4 and R5 for different reactor conditions and their phase distribution is done by two methods standard and transitory method. These phase distribution also gives phase wise equation, for optimization of entire process each phase equation is essential. The accuracy of curve equations is defined by R2 value. These equations help in formation of mathematical model using MATLAB. This model is useful for defining phase values of parameters. Further quality and quantity of chemical parameters are also defined by these phase values.

Sign in / Sign up

Export Citation Format

Share Document