CN1461733A

CN1461733A - Dynamic control method for actirated sludge process

Info

Publication number: CN1461733A
Application number: CN02121077A
Authority: CN
Inventors: 周楚洋; 张宁
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-05-31
Filing date: 2002-05-31
Publication date: 2003-12-17

Abstract

A dynamic control method for the activated sludge process features that when a redox potential sensor arranged in aeration pool detects the predefined redox potential value, the pre-treated sewage is pumped in the aeration pool, where reaction takes place until the stop condition is met, and a solid substance sensor is used to hold the concentration of solid substance in suspension to a proper range. Its advantages are accuracy control, low cost and high effect.

Description

The kinetic controlling equation method of active sludge program

Technical field

The present invention relates to a kind of method of wastewater treatment, be particularly related to a kind of kinetic controlling equation method of active sludge program, this method is to utilize the influent stream of oxidation reduction potential control influent stream water and with mixed stream suspension solid concentration control activity sludge reflux, reach the target that improves processing efficiency and reduce organic concentration in the water of releasing.

Background technology

Wastewater treatment must be faced the concentration of unsettled flow, fluctuating and the composition that is difficult to predict simultaneously, in addition, more need meet the standard of releasing and take into account economic benefit.Have only in the design of handling procedure and management and constantly keep on improving to satisfy actual demand.In various handling procedure, considerable role is being played the part of in biological treatment, and is wherein the longest with the activated sludge process developing history again, the history in existing 80 years of practical application.

Probe into the development of active sludge program, can be divided into three main period; Originally, relevant PHE only utilizes some easy strategies to manage the active sludge program, for example, controls its organic loading or controls its sludge loading etc., and these operating strategies were still used widely in today; The emphasis of subordinate phase is the application in chemical kinetics, originally the phenomenon variation of active sludge program is only described with the kinetics equation of single order, follow nonlinear differential equation of higher order formula and be developed, be used for describing the phenomenon in the active sludge program; The emphasis of phase III development is the application of chemistry and the research and development of follow-up biochemical program, be accompanied by development trend and what come is a large amount of matrix equation formula, stoichiometry constant and other numerical value, again because the development of PC still can be used the mathematics formula of accelerating huge day by day effectively.

Active sludge is made up of bacterium, fungi, protozoon, wheel animalcule, sometimes also having nematode occurs, therefore, active sludge is the mixed culture body that xenogenesis groups of individuals Institute of Micro-biology constitutes, on handling, serve as at first the role for decomposing and assimilating organic bacterium class, Mycophyta, afterwards, part bacterium or fungi are preyed on by protozoon, occur metazoans such as wheel animalcule and roundworm class at last.

Bacterium is responsible for the growth of organic stable and glue plumage, and most of activated sludge glue plumage is to form by the growth of micelle bacillus, and the micelle bacillus is mostly combined by bacterium and fungi; But, also can form the expanded possibility of mud if the micelle bacillus forms too much can not be decomposed by the protozoon predation smoothly.

Which kind of bacterium is organism characteristic in the waste water determine preponderate, and easily produces alkali bacillus, flavobacterium and Bacillaceae as the waste water that protein content is higher, and carbohydrate waste water is easily given birth to false pseudomonas bacillus.

At the higher waste water of biochemical oxygen demand (BOD) (BOD), low pH value and malnourished waste water, can promote the growth of fungi, and most of Mycophyta all is hyphomycetes, can harm the formation of glue plumage, non-hyphomycetes in some trade effluent but, can form good active sludge as yeast, have normal settleability.

When handling waste water, protozoon there is no the usefulness of direct stable organic matter matter, but its energy predator bacteria, when the bacterium raised growth, free-swimming ciliate will be preponderated, then free-swimming ciliate will be replaced by the cup-shaped ciliate when bacterium reduces, and this is that less food can not be supplied the required of high-octane free-swimming ciliata.We can occur in a large number from ciliate, judge that active sludge is in the ripening stage in the aerator tank.

In the Sludge System the organic metabolic process of microbiological degradation can be divided into lag phase, logarithmic phase, subtract the vegetative period of declining, body internal respiration phase four-stage:

1, the lag phase: when microorganism began to contact organic waste water, for adapting to new environment, microbial biomass did not significantly increase, and dissolved organic matter does not significantly reduce yet, and this stage is called the lag phase.

2, logarithmic phase: decomposing organic matter forms new cell rapidly after microorganism conforms, at this moment microbial biomass and number are the increase of geometricprogression, the utilization ratio of oxygen also increases, organism obviously reduces, but the microbiological gum plumage in this stage is dispersion state, eat little ratio and be about more than 2.5, this stage is called logarithmic phase.

3, subtract the vegetative period of declining: thereafter, the organism amount is decrescence few, and also along with gradually few, at this moment the speed of microbial growth becomes proper proportion with remaining organism to the propagation of microorganism, can become coacervation at this stage microbiological gum plumage, and this stage is called and subtracts the vegetative period of declining.

4, the body internal respiration phase: afterwards, the organism in the waste water gradually lacks, and microorganism then is in starvation, and at this moment just utilize and store in intravital nutrition branch, the metabolism Decomposition that continues, till necrocytosis, this stage is called the body internal respiration phase.This moment, microorganism was because of carrying out body internal respiration effect, and made microorganism by the maximum amount that subtracts the vegetative period of declining minimizing a little again.

And the program of active sludge commonly used at present as shown in Figure 1, influent stream water just is meant after pre-process (as trash rack, settling pit, initial settling tank, adjustment pond or neutralization tank etc.), the waste water that still contains dissolved organic matter, this waste water flow in the aeration tank with the pond in be suspension growth the aerobic micropopulation contact, dissolved organic matter is promptly become stable material by microbiological degradation or utilizes with replicating microorganism, and the microorganism through breeding is in the final tank precipitate and separate.The mud of precipitate and separate, a part is back to the aeration tank, (claiming returned sluge again); Another part is discharged otherwise processed, (claiming waste sludge again).

Wherein, aeration has two functions, and one for to dissolve in oxygen in the water, and making has enough oxygen that microbial growth and organic oxidation are provided in the water.Another purpose is for mixing biology and the organism in the cell body and making particulate present suspended state.General aeration is to see through equipment such as machine or air compressor machine, and the requirement of oxygen is suitable with the oxygen amount that organic oxidation is required in theory.

But this practice, because of its with every day several times at regular time and quantity mode control influent stream water and flow into the aeration tank, carry out by the microbiological degradation precipitate and separate, reflux or manual emission mud at regular time and quantity mode again, its shortcoming is correctly to control molten gas concentration and the required orthochronous of aerating wastewater in the water, aeration is not enough more can to cause precipitation improperly except that can making molten gas decline, and not only the over-drastic aeration does not help established glue plumage to be broken on the contrary to the raising of efficient, reduces the settleability of mud and causes waste on the energy.

Sasaki in 1993 etc. point out that the concentration of molten gas is a key parameter in the water in the active sludge program.The concentration deficiency can make thread fungus preponderate and the phenomenon that causes sludge settling variation and sludge activity to reduce.Not only too high molten gas has improperly eddy current the glue plumage is broken up, and also can waste energy.

Summary of the invention

The invention provides a kind of kinetic controlling equation method of dirt mud, this method is controlled the influent stream of water by redox potential, the concentration of while Controlling System mixed liquor suspended solid, MLSS, the organic loading of system is controlled within the ideal scope, improves processing efficiency and the target that reduces organic concentration in the water of releasing to reach.

This method is with the influent stream water through pre-process, the aeration tank of flowing through, and when being provided with the redox potential sensor in the pond and arriving the setting point of influent stream with the detecting redox potential, promptly start inflow pump, to react in the waste water suction aeration tank, when stopping the setting point of influent stream, promptly stop influent stream, in addition with mixing liquid suspension solid substance sensor detecting mixing liquid suspension solid substance, make the mixing liquid suspension solid concentration in the reactive tank maintain a suitable operating restraint, by this, can effectively save manpower, control accurately, simple to operate, cost is low, reliable for effect.

Description of drawings

Fig. 1 is the traditional active sludge system flowchart.

Fig. 2 is the schema and the equipment therefor distribution plan of the present invention's method.

Embodiment

See also shown in Figure 2, in the equipment used in the present invention, aeration tank 1, settling tank 2, storage pool 3, inflow pump 4, sludge reflux pump 5, sensor 6 and automatic control device 7 are arranged, this sludge reaction groove is made of aeration tank 1, settling tank 2 and storage pool 3, the influent stream water of digestion in the aeration tank 1 being finished in the mode of overflow overflows to settling tank 2 and precipitates, and it is temporary that the upper strata liquid of settling tank 2 then overflows to storage pool 3.

In aeration tank 1, be provided with mixing liquid suspension solid substance sensor 61 and redox potential sensor 62, be equipped with aerating apparatus 11 in the bottom, be provided with the usefulness of overflow weir 12 as overflow in addition in the pond side, the influent stream water that digestion is finished overflows to settling tank 2 and precipitates.

Settling tank 2 also has an overflow weir 21 with the overflow weir 12 corresponding positions of aeration tank 1, the bottom is provided with a mudhole 22, make influent stream water in the aeration tank 1 finish digestion after overflow weir 21 to settling tank 2 precipitate, and the clear liquor of settling tank 2 can overflow to storage pool 3, then draws back aeration tank 1 by the mudhole 22 of conical lower portion with sludge reflux pump 5 at the active sludge that settling tank 2 precipitates.

Inflow pump 4 is with in the influent stream water suction aeration tank 1.

Sludge reflux pump 5 main functions are that the active sludge that settling tank 2 precipitates is drawn back in the aeration tank 1 to supply mixing liquid suspension solid concentration.

Sensor 6 includes the redox potential sensor 62 that is used for reading the mixing liquid suspension solid substance sensor 61 of activated sludge concentration in the aeration tank 1 immediately and is used for measuring immediately the redox potential value of system in the aeration tank 1.

Wherein, mixing liquid suspension solid substance sensor 61 is to utilize near infrared light to come suspension solid substance in the water sensing, the standard signal of output 4-20mA, this sensor 61 needs to proofread and correct at the solid substance that desire is measured before use, finds out the relation between output signal and the mixing liquid suspension solid concentration; And redox potential sensor 62 exports is voltage signal, for asking the consistence of signal, uses the signal of amplifier general-500mV-500mV to be converted to the signal of 4-20mA.

Automatic control device 7 comprises control computer 71 and controlling box 73.Wherein, controlling box 73 mainly contains three parts, is respectively power supply, rly. and efferent, and on control panel, each output unit has independent switch independently to cut off so that keep in repair in addition.

When inflow pump 4 is reacted in influent stream water suction aeration tank 1, the water of releasing reaction is finished after overflow weir 12 enters in the settling tank 2, through post precipitation, supernatant liquid overflows in the storage pool 3 and stores, and sedimentary active sludge is drawn back aeration tank 1 by sludge reflux pump 5 by settling tank 2 belows and kept concentration of activated sludge.

With redox potential sensor 62 place aerating apparatus 11 tops be for measure can the representative system state redox potential, the scope that can enter mixing liquid suspension solid substance sensor 61 infrared inductions for fear of redox potential sensor 62, and the mixing liquid solid substance sensor 61 that suspends is placed inclined to one side position in the middle of 1 wall of aeration tank.

When redox potential sensor 62 measured redox potentials reached the setting point of influent stream, starting inflow pump 4 will react in the waste water suction aeration tank 1, when treating that redox potential reaches the setting point that stops influent stream, closes inflow pump 4.

Mixing liquid suspension solid substance sensor 61 measured signals can shake because of the disturbance of current in the reactive tank and aeration, utilize mud to reflux as desire the mixing liquid suspension solid concentration in the reactive tank is fixed on a set(ting)value, must cause sludge reflux pump 5 numbers of starts too frequent, so, not only can't reach controlled target, easily cause the damage of pump on the contrary, therefore, the actual execution side of mixing liquid suspension solid substance (MLSS) the concentration control of reactive tank will set the concentration input to become MLSSsp in sequence of control, MLSSsp ± appropriate value is made as the operation bound, the mixing liquid suspension solid concentration that measures in the reactive tank when mixing liquid suspension solid substance sensor 61 is lower than operation down in limited time, open sludge reflux pump 5, the mixing liquid suspension solid concentration that liquid suspension solid substance sensor 61 to be mixed measures in the reactive tank reaches till the operation upper limit.This kind mud reflux type is to be interfered and to cause the startup frequency of sludge reflux pump too high for fear of mixing liquid suspension solid substance sensor 61.

Wherein, the present invention can overcome the organic concentration problem of unstable of waste water, and then the system that keeps the stable of water water quality of releasing, in addition, the influent stream system of aeration tank is often because of the crystalline problem, cause influent stream amount shakiness and influence the accuracy of controlling, then can not be subjected to the restriction of fluctuations in discharge because of redox potential sensor control influent stream is arranged.

Claims

1, a kind of kinetic controlling equation method of active sludge program, this method is with the influent stream water through pre-process, the aeration tank of flowing through, when being provided with the redox potential sensor in the pond and reaching the setting point of influent stream with detecting redox potential value, starting inflow pump will react in the waste water suction aeration tank, when the redox potential value in the aeration tank reaches the setting point that stops influent stream, stop the influent stream action of inflow pump, be arranged in the aeration tank with mixing liquid suspension solid substance sensor in addition, the mixing liquid suspension solid concentration that measures in the reactive tank when mixing liquid suspension solid substance sensor is lower than operation down in limited time, just open sludge reflux pump, active sludge is drawn back the aeration tank, and the mixed stream suspension solid concentration that liquid suspension solid substance sensor to be mixed measures in the reactive tank reaches till the operation upper limit.

2, according to the kinetic controlling equation method of the described a kind of active sludge program of claim 1, it is characterized in that: the actual execution side of the mixing liquid suspension solid concentration control in the reactive tank will set concentration to be input as MLSSsp on sequence of control, MLSSsp ± appropriate value is made as the operation bound.