CN102147834A - Septic tank calculating method and mathematical model - Google Patents
Septic tank calculating method and mathematical model Download PDFInfo
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- CN102147834A CN102147834A CN2010101210475A CN201010121047A CN102147834A CN 102147834 A CN102147834 A CN 102147834A CN 2010101210475 A CN2010101210475 A CN 2010101210475A CN 201010121047 A CN201010121047 A CN 201010121047A CN 102147834 A CN102147834 A CN 102147834A
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- septic tank
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Abstract
The invention provides a septic tank calculating method and a mathematical model. The septic tank calculating method is mainly characterized in that the method comprises the following steps: (1) constraining boundary conditions of digestion; (2) establishing a dynamics relationship under the principle of mass conservation; (3) analyzing the relation of materials remained in a septic tank; (4) establishing the mathematical model of the septic tank; and W=Naqt/24*1000+(1-b) K2 [alpha TaNK1/(1-b)1000+S(1-e)1000]; (5) determining the total content S of degradable sludge accumulated in T time; (6) establishing a corresponding relationship among data through a calculated result of the mathematical model; and (7) establishing a data corresponding relationship table of the septic tank or using the mathematical model to make calculating application software of the septic tank. The invention provides the calculating method and the mathematical model for calculation of prolonging the retention period of the sludge in the septic tank.
Description
Technical field
The invention belongs to the category of sewage and Treatment of Sludge in the environmental protection field, relate to a kind of dynamics calculation method and mathematical model of digester.
Technical background:
The present invention is applied to the calculating of sewage and Treatment of Sludge technical parameter, mainly is applicable to the data computation of digester, septic tank design.
Septic tank is basic elementary sewage treatment process, uses generally, and the organism that sanitary sewage carries obtains digestion process in septic tank, and water quality obtains improvement to a certain degree.Organism is inner through complicated non-linear digestion process at septic tank, and the time of digestion process is long, is not easy to calculate, in real world applications, to calculate and use in order to simplify, mainly adopted according to standard and determined the relevant parameter value, adopt linear mathematical model to calculate then.
In China, the septic tank design atlas that the construction of septic tank is mainly concentrated according to the national building standard design drawing of Ministry of Construction's issue, wherein, the corresponding computing formula that comprises septic tank volume and type selecting, its basic mathematical logic is under the prerequisite according to relevant plumbing design specifications and technical standard, under a certain temperature conditions, the useful volume of septic tank is divided into sewage and mud two parts volume, by bringing the calculating of different parameters numerical value into, obtain the septic tank respective value of relevant model, and as the foundation of design selection.
The computation process of septic tank design drawing centralization manure pit is as follows:
The calculating of septic tank volume:
The useful volume of septic tank: W=W1+W2
In the formula:
W---septic tank useful volume, m
3
Sewage partial volume in W1---the septic tank, m
3
Sludge part volume in W2---the septic tank, m
3
The sewage volume:
In the formula:
N---septic tank design total number of persons, people;
Q---no one's sewage every day quota, L/ people d;
T---sewage is the residence time in septic tank, presses 12h, and 24h calculates;
A---the actual number of sanitary apparatus and the number percent of design total number of persons of using;
Mud volume:
In the formula:
α---interflow coefficient, α=0.7L/ people d; Diverting coefficient, α=0.4L/ people d;
B---moisture percentage in sewage sludge;
C---concentrate the back moisture percentage in sewage sludge;
K---mud coefficient of diminution during the corruption;
T---mud is drawn the cycle clearly, presses 90d, 180d, 360d meter;
1.2---draw the volumetric coefficient that 20% ripe sludge is considered to stay in the back clearly;
The design of septic tank model
After determining the septic tank useful volume, the value of selected q, a, t, T is according to the total number of persons of W=W1+W2 computerized manure pit design.
At last, in the septic tank atlas,, septic tank volume, number, draw technical parameters such as cycle, dwell time of sewage, foul water system, ration standard clearly and gather, and formulate the form of corresponding data relationship according to result of calculation.When septic tank designs, can use type selecting according to corresponding data.
In actual use, we find that the actual conditions of septic tank and the technical parameter situation in the standard collective drawings there are differences, show according to the septic tank atlas, the cycle of drawing was generally 90 days clearly in septic tank design in the GB atlas, 180 days, 360 days, but in real world applications, the cycle of drawing clearly of septic tank often exceeds design and draws the cycle clearly.Under short situation of septic tank cleaning cycle, just need expend more financial resources, material resources are drawn clearly, simultaneously, the mud of drawing out clearly also is faced with the problem of sludge disposal.So, in the designing and calculating pattern that traditional septic tank design drawing is concentrated, do not demonstrate fully the function of septic tank digested sludge, also be unfavorable for the objective use of instructing septic tank.Based on such technical background, be necessary the septic tank applicable cases that draw in the scope cycle length Changqing is more calculated and designed.
Summary of the invention:
The objective of the invention is provides dynamics calculation method and mathematical model for septic tank.
Computing method provided by the invention and mathematical model, start with from following several respects:
(1), boundary condition is retrained.
Boundary condition constraint be meant with respect to the relevant environment condition of destination object assert, the determining of modes such as supposition, agreement.
For digester technology, at first carry out the constraint of emphasis boundary condition, mainly consider the constraint of physical boundary conditions and chemical boundary condition.
Under boundary condition constraint principle, can select the calculating principle of two kinds of forms, 1, take all factors into consideration the nonlinear computation of physical process and chemical process all sidedly; 2, retrain for the physical process that is easy to quantification and mensuration, reduce the complicacy of nonlinear computation, under the situation of physical boundary constraint, biochemical process is set up mathematical model and calculate.
As to follow the mass conservation be exactly a kind of boundary constraint, in the calculating of septic tank, and can be to precipitation, the dissolving of sewage and mud, spread, separate out etc. that physical process is ignored or the constraint of quantification.
(2) set up kinetics relation under the mass conservation principle.
The conservation of matter concerns that situation is in the digestion process:
M=M
Go into-M
Go out
M
Go into---enter the amount of digester;
M
Go out---discharge the amount of digester;
Amount in M---the digester;
The material of discharging digester comprises digestion gas and mixed liquor; The material of retaining in the digester comprises water, other compounding substances;
M＝M1+M2
In the formula:
M1---other mixture qualities in the digester beyond the water;
M2---the amount of water in the digester;
In the septic tank technology of continuous working, the amount that enters septic tank is relatively stable, can carry out quantity constraints, and the useful volume of septic tank determines, when sewage enters septic tank, discharges combined sewage in the septic tank in the mode of plug-flow.
The sewage total amount that enters septic tank every day is that constraint is quantitative, enters sewage quantity * T that the sewage of septic tank enters total amount=every day through the T time, and the carry-over quality in the septic tank equals the carry-over quality summation of T accumulated time.
The amount of retaining digester can be divided into water and other potpourris.
(3) analyze retaining the material relation in the septic tank;
Combined sewage in the septic tank is made up of water and potpourri, and potpourri is made up of organism and mixing sludge, and potpourri also can be divided into degradable substance and non-degradable material.Carry out constraint, do not consider the influence of hydraulics, the non-degradable material is as the accumulation material, and the non-degradable thing does not change in time, is the form that linearity adds up.Degradable substance is divided into the precipitate Buddhist monk undegraded material of degrading through the biochemical action of certain hour, prolongation in time, and still undegraded material is tending towards degrading fully.Except water, retention material in the septic tank mainly is a non-degradable material Buddhist monk undegraded material, and still undegraded material is present in organism and the mud, from the conservative angle of calculating, to retain material and all consider, be divided into degradable mud and non-degradable mud according to the mud form.
In septic tank mud calculates, consider to carry out value from maximal value, be similar to the sludge quantity of the unit interval of septic tank is set at mixture M 1 in the septic tank.
Septic tank sludge quantity=M1=m+m '
In the formula:
M---unit degradable sludge quantity;
M '---unit non-degradable sludge quantity;
So the septic tank mud total amount of elapsed time T is M
T=TM
1
M
T＝(m
1+m
2+m
3+……+m
T)+T·m′
In the formula, in time T, non-degradable sludge quantity linearity in time adds up, and the degradable sludge quantity adds up in nonlinear mode in time, at corresponding digestion condition with in the time, and m
TProgressively go to zero.
Then:
Convergence;
Generally speaking, for the sewage of specific condition of water quality, the non-degradable material is a definite value.
Carry out the content constraint, approx material in the septic tank is divided into sewage part and sludge part.
The useful volume of septic tank: W=W1+W '+W "
In the formula:
W---septic tank useful volume, m
3
Sewage partial volume in W1---the septic tank, m
3
Non-degradable sludge part volume in W '---the septic tank, m
3
W "---degradable sludge part volume in the septic tank, m
3
(4) set up the mathematical model of septic tank
The useful volume of septic tank: W=W1+W '+W "
The sewage volume:
Non-degradable sludge part volume:
W′＝α·T·a·N(1-b)·K1·K2/(1-d)1000
In the formula:
D---the water percentage of the non-degradable mud after concentrating;
The non-degradable rate of K1---mixing sludge;
K2---the digester potpourri rejection of flowing through;
Degradable sludge part volume:
W″＝S·(1-b)K2/(1-e)1000
In the formula:
The degradable mud total amount of accumulation in S---the T time;
E---concentrate the water percentage of back degradable mud;
Septic tank volume mathematical model:
W＝W1+W′+W″
＝Naqt/24×1000+(1-b)K2[αTaNK1/(1-d)1000+S/(1-e)1000]
(5) the degradable mud total amount S's that T was accumulated in the time determines
The definite available following several method of degradable mud total amount is determined in the T time:
1) with the method for testing, under the same environmental conditions of certain specific water quality and sewage, according to experimental result,
The working curve that obtains being similar to, the degradable sludge quantity when obtaining T.
The method of 2) usefulness experiment, experience, mathematics combination; Under field conditions (factors), the degradation process of the degradable substance in the sewage is quite very long, and the process complexity, and water quality and environmental baseline also there are differences, and is difficult to obtain by experiment the overall process data.Labile organic compound in the process of digestion, on the one hand degraded, synthesising biological flora on the other hand, biological flora self also can carry out biochemical metabolism, after the cell death, is utilized by other bacteriums, realizes the digestion process of secondary matrix.Labile organic compound progressively obtains convergence and digests degraded completely in metabolic process repeatedly.According to this situation, set up the computing method of approximate degradable mud.1,, determines the degradable degree of sewage with empirical data or experimental data; 2, determining the digestion period of organism under the certain environment condition, mainly is the new required time of sludge fermentation under the uniform temperature condition; 3, in a fermentation period, the economy of degradable mud or digestibility; 4, the old mud of supposition enters the degradation period of endogenous digestion and secondary matrix after through a fermentation stage; 5, second fermentation of the organism of secondary substrate degradation experience digestion period possesses corresponding mud economy; 6, digestion period circulates successively and carries out, and progressively is tending towards the catapepsis reduction.7, the mud in the digestion period that ferments is successively added up, determine the degradable mud total amount of T time.8, check result of calculation, adopt the method for statistics, the parameter of existing septic tank actual working state is carried out data statistics and checked.9, revise data,, the value of technical parameter in the mathematical model is revised according to the contrast of result of calculation and septic tank actual conditions.10, parameter value and numerical value correction are carried out in the influence of environmental changes such as periodicity temperature.
Degradable sludge quantity under these computing method:
S＝S
1(1-K)+S
1(1-K)
2+S
1(1-K)
3+……S
1(1-K)
n
In the formula:
S
1---the degradable mud total amount that enters septic tank of a fermentation period time period;
K---fermentation stage digestion economy;
Set up the corresponding relation of degradable sludge quantity and sludge retention time by formula.
(6) set up corresponding relation between the data by the result of calculation of mathematical model
The data of correlated condition parameter or fiducial value are calculated for the mathematical model of people's septic tank, obtained the data corresponding relation of each parameter.
(7) set up the data correspondence table of septic tank or utilize mathematical model to make the computing application software of septic tank.
Usefulness of the present invention is to provide a kind of computing method and mathematical model for the digestion of sewage sludge, provides reference in particular for the calculating that prolongs sludge retention time in the septic tank.
Embodiment:
Embodiments of the present invention can be carried out according to the step of calculating.
(1), the boundary condition to digestion retrains;
(2) set up kinetics relation under the mass conservation principle;
M=M
Go into-M
Go out
Material in the expression digester is to enter the digester material and discharge the poor of digester material.
(3) analyze retaining the material relation in the septic tank;
W＝W1+W′+W″
Formulate: the useful volume of septic tank be equivalent to sewage volume in the septic tank, degradable mud volume, non-degradable mud volume and.
(4) set up the mathematical model of septic tank;
W＝W1+W′+W″
＝Naqt/24×1000+(1-b)K2[αTaNK1/(1-d)1000+S/(1-e)1000]
(5) the degradable mud total amount S's that T was accumulated in the time determines;
S＝S
1(1-K)+S
1(1-K)
2+S
1(1-K)
3+……S
1(1-K)
n
(6) set up corresponding relation between the data by the result of calculation of mathematical model;
(7) set up the data correspondence table of septic tank or utilize mathematical model to make the computing application software of septic tank.
Claims (2)
1. septic tank computing method and mathematical model is characterized in that calculating with process in accordance with the following methods:
(1), the boundary condition that digestion is calculated retrains;
Boundary condition constraint be meant with respect to the relevant environment condition of destination object assert, the determining of modes such as supposition, agreement.
(2) set up kinetics relation under the digester mass conservation principle;
M=M
Go into-M
Go out
Material in the expression digester is to enter the digester material and discharge the poor of digester material.
(3) relation of the material in the septic tank is retrained and analyzes;
W＝W1+W′+W″
Formulate: the useful volume of septic tank be equivalent to sewage volume in the septic tank, degradable mud volume, non-degradable mud volume and.
(4) set up the mathematical model of septic tank;
W＝W1+W′+W″
＝Naqt/24×1000+(1-b)K2[αTaNK1/(1-d)1000+S/(1-e)1000]
In the formula:
W---septic tank useful volume, m
3
Sewage partial volume in W1---the septic tank, m
3
Non-degradable sludge part volume in W '---the septic tank, m
3
W "---degradable sludge part volume in the septic tank, m
3
N---septic tank design total number of persons, people;
Q---no one's sewage every day quota, L/ people d;
T---sewage is the residence time in septic tank, presses 12h, and 24h calculates;
A---the actual number of sanitary apparatus and the number percent of design total number of persons of using;
α---interflow coefficient, α=0.7L/ people d; Diverting coefficient, α=0.4L/ people d;
B---moisture percentage in sewage sludge;
T---mud is drawn the time clearly, day;
D---the water percentage of the non-degradable mud after concentrating;
The non-degradable rate of K1---mixing sludge;
K2---the digester potpourri rejection of flowing through;
The degradable mud total amount of accumulation in S---the T time;
E---concentrate the water percentage of back degradable mud;
(5) the degradable mud total amount S's that T was accumulated in the time determines;
S＝S
1(1-K)+S
1(1-K)
2+S
1(1-K)
3+……S
1(1-K)
n
Degradable sludge quantity S convergence.
In the formula:
S
1---the degradable mud total amount that enters septic tank of a fermentation period time period;
K---digest economy between yeast phase;
(6) set up corresponding relation between the data by the result of calculation of mathematical model;
(7) set up the data correspondence table of septic tank or utilize mathematical model to make the computing application software of septic tank.
2. a kind of septic tank computing method according to claim 1 and mathematical model is characterized in that definite method of the degradable sludge quantity S of described T accumulated time:
The convergency value of degradable mud total amount determines that available following two kinds of methods are definite in the T time:
1) with the method for testing, under the same environmental conditions of certain specific water quality and sewage, according to experimental result, the working curve that obtains being similar to, the degradable sludge quantity when obtaining T.
The method of 2) usefulness experiment, experience, mathematics combination; Set up the computing method and the mathematical model of approximate degradable mud, computing method are 1, with empirical data or experimental data, determine the degradable degree of sewage; 2, determining the digestion period of organism under the certain environment condition, mainly is the new required time of sludge fermentation under the uniform temperature condition; 3, in a fermentation period, the economy of degradable mud or digestibility; 4, the old mud of supposition enters the degradation period of endogenous digestion and secondary matrix after through a fermentation stage; 5, second fermentation of the organism of secondary substrate degradation experience digestion period possesses corresponding mud economy; 6, digestion period circulates successively and carries out, and progressively is tending towards the catapepsis reduction.7, the mud in the digestion period that ferments is successively added up, determine the degradable mud total amount of T time.8, check result of calculation, adopt the method for statistics, the parameter of existing septic tank actual working state is carried out data statistics and checked.9, revise data,, the value of technical parameter in the mathematical model is revised according to the contrast of result of calculation and septic tank actual conditions.10, parameter value and numerical value correction are carried out in the influence of environmental changes such as periodicity temperature.
Degradable sludge quantity under these computing method:
S＝S
1(1-K)+S
1(1-K)
2+S
1(1-K)
3+……S
1(1-K)
n
In the formula:
S
1---the degradable mud total amount that enters septic tank of a fermentation period time period;
K---fermentation stage digestion economy;
Set up the corresponding relation of degradable sludge quantity and sludge retention time by formula.
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|---|---|---|---|
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|---|---|---|---|
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110208458A (en) * | 2019-05-16 | 2019-09-06 | 四川大学 | For studying the experimental rig and method that Degradation Coefficients of Organic Pollutants In A changes under hydrodynamic conditions |
-
2010
- 2010-02-05 CN CN2010101210475A patent/CN102147834A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110208458A (en) * | 2019-05-16 | 2019-09-06 | 四川大学 | For studying the experimental rig and method that Degradation Coefficients of Organic Pollutants In A changes under hydrodynamic conditions |
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Application publication date: 20110810 |