A kind of preprocess method being suitable to percolate stock solution evaporative crystallization
Technical field
The present invention relates to sewage treatment area, particularly relate to a kind of preprocess method being suitable to percolate stock solution evaporative crystallization.
Background technology
Percolate composition is sufficiently complex, has the features such as water quality and quantity fluctuation is big, pollutant load is high, nutrient is unbalance so that intractability up to standard is big, and operation cost is high.Therefore, the Environmental capacity of percolate is always up the thorny problem in domestic and international City refuse management system.Particularly China in 2008 issues " household refuse landfill sites Environmental capacity standard " (GB16889-2008) that implement, and the emission request of percolate is stricter.
Current domestic Refuse Leachate Treatment Plant business, main employing " pretreatment+biochemistry+film " technique, comprise multiple treatment process such as pretreatment, anaerobism, aerobic, ultrafiltration (MBR), NF/RO, system complex, impacted many factors, and owing to the film response rate is limited, operation also will produce the concentrated solution of high pollution concentration more than 30%.And compared with this traditional handicraft, percolate stock solution direct evaporation crystallization processes has that technique unit is few, it is little to take up an area, produces without concentrated solution, by the advantage such as little, the strong adaptability of impact of water quality and quantity fluctuation, the process for percolate provides an ideal mode.But SS about 2000 ~ 15000mg/L in percolate stock solution, turbidity is also up to 2000 ~ 8000NTU, such high suspended matter, high concentrtion value the not preprocessed direct evaporation of percolate can cause having a strong impact on the frequent generation of the phenomenons such as heat exchanger blocking, fouling of evaporator vapo(u)rization system efficient stable and run.The author's research shows, conventional coagulant sedimentation is extremely difficult to desirably go turbid effect, though added amount of chemical up to 20g/L, sedimentation time up to 1h, its reason is in that too high turbidity, sludge output and difficult settleability.Therefore, research and probe go out a kind of efficiently, stable and easy turbidity and the high preprocess method of SS clearance be very necessary.
Summary of the invention
The technical problem to be solved in the present invention is the deficiency overcoming percolate stock solution direct evaporation crystallization treatment technique, it is provided that a kind of flow process is simple, the cycle is shorter, strong adaptability, turbidity and SS have the preprocess method of significant removal effect.
It is an object of the invention to be achieved through the following technical solutions:
A kind of preprocess method being suitable to percolate stock solution evaporative crystallization, comprises the steps:
1. percolate stock solution being sent into and stir pond soon, add inorganic coagulant and backflow centrifugal clear liquid in mass ratio stirring soon in pond, quickly stirring makes coagulant disperse rapidly and mix homogeneously;
Or by percolate stock solution, inorganic coagulant and backflow centrifugal clear liquid, in pipe-line mixer, it is re-fed into stirring soon pond after preliminary mixing in mass ratio;
2. the percolate after 1. step processes stirs pond slowly from inflow, adds organic coagulant aid in mass ratio to stirring slowly in pond, through being slowly stirred so that the step 1. middle a large amount of small flco formed fully condenses;
3. percolate after step 2. being processed sends into centrifugal dehydrator, obtains the higher solid phase of solid content and the relatively low clear liquid of turbidity, and centrifugal clear liquid is back to partly as diluent and stirs pond soon, and remainder enters follow-up percolate evaporation and crystallization system.
Preferably, above-mentioned inorganic coagulant is mineral-type aluminium salt or iron salt.
Preferably, above-mentioned mineral-type aluminium salt is aluminium polychlorid (PAC);Described iron salt is bodied ferric sulfate (PFS) or PAFC (PAFC).
Preferably, above-mentioned organic coagulant aid is anion-polyacrylamide (APAM) or cationic-type polyacrylamide (CPAM).
Preferably, the dosage of above-mentioned inorganic coagulant is 3 ~ 8g/L.
Preferably, the dosage of above-mentioned organic coagulant aid is 3 ~ 10mg/L.
Preferably, the mass ratio of above-mentioned centrifugal clear liquid is: percolate stock solution centrifugal clear liquid=1 (0.6 ~ 2.5).
Preferably, the above-mentioned time of staying stirring pond soon is 30s ~ 3min, and speed of agitator is 150 ~ 250r/min, and the described time of staying stirring pond slowly is 5 ~ 20min, and speed of agitator is 30 ~ 50r/min.
Preferably, above-mentioned centrifuge is horizontal spiral discharge sedimentation centrifuge, separating factor > 2000, form can be downflow type or reverse-flow.
Preferably, above-mentioned percolate stock solution includes garbage burning factory percolate stock solution and percolate from garbage filling field stock solution.
The invention has the beneficial effects as follows:
1, the present invention first by dilution, flocculation, centrifugal combine, flow process is simple, the cycle is shorter, strong adaptability, effect stability, and it is successfully applied to the pretreatment of percolate stock solution evaporative crystallization, overcome the problems such as the added amount of chemical that conventional flocculation precipitation pretreatment technique exists is big, deposition efficiency is low, turbidity removal effect is desirable not to the utmost.
2, diluent of the present invention is the centrifugal clear liquid that pretreatment system is self-produced, is equivalent to internal recycle, it is not necessary to extraneous introducing, nor affects on the treatment scale of whole system simultaneously.
3, the present invention can effectively remove the float in percolate and colloid, the clearance of turbidity and SS is up to more than 99%, COD clearance is also up to 20 ~ 30%, can effectively slow down the phenomenons such as heat exchanger blocking, fouling of evaporator, it is possible to the efficient stable for next step evaporative crystallization of percolate runs and final qualified discharge creates highly beneficial condition.
4, the present invention process before and after percolate pH, electrical conductivity substantially unchanged, after the medicament that adds plays flocculation, mostly discharge system with the form of dewatered sludge, substantially without introducing new pollutant.
Accompanying drawing explanation
Fig. 1 is the percolate stock solution pretreating process flow chart of the present invention.
Detailed description of the invention
In order to make the purpose of the present invention, technical scheme and advantage become apparent from understanding, below in conjunction with drawings and Examples, the preprocess method of the percolate stock solution evaporative crystallization of the present invention is further elaborated.Should be appreciated that therefore specific embodiment described herein is only in order to explain the present invention, do not limit the scope of the invention.
Embodiment 1
With Beijing garbage burning factory percolate stock solution for processing object, its parameters is: COD is 72000 ~ 76000mg/L, and ammonia nitrogen is 2200 ~ 2500mg/L, turbidity is 5400 ~ 6300NTU, SS is 8000 ~ 12000mg/L, pH is 5.97 ~ 6.13, and electrical conductivity is 32.4 ~ 35.6ms/cm.
As it is shown in figure 1, the preprocess method being suitable to percolate stock solution evaporative crystallization of the present invention comprises the following steps:
First, percolate stock solution is sent into and stirs pond soon, at the described inorganic coagulant PAC stirring soon in pond and adding 8g/L, and the centrifugal clear liquid of 0.6 times of stock solution inlet amount, make the most suspended substances in described percolate stock solution and the flocculation of colloid pollution thing form substantial amounts of small flco after mixing abundant, quick.The described time of staying stirring pond soon is 1min, and speed of agitator is 180r/min.
Secondly, described percolate that pond processed will be stirred stir pond through too fast slowly from flowing into, to the described organic coagulant aid CPAM stirring slowly in pond and adding 10mg/L, be adequately mixed reaction and make stirring a large amount of small flco cohesion that pond formed soon to be bulky grain floccule body.The described time of staying stirring pond slowly is 15min, and speed of agitator is 30r/min.
Finally, the described percolate processed through stirring pond slowly is sent into centrifugal dehydrator, and under the centrifugal action that high speed rotating of transferring shares produces, the floccule body that proportion is bigger is got rid of to be attached to transfers shares on inwall, forming solid circular layer, the moisture that proportion is less forms pendular ring layer inside solid circular layer.Gu the mud of circular layer is slowly discharged by auger conveyor, then drained into sludge storage pool by screw pump and carry out post processing.The clear liquid of pendular ring layer by after gravity discharge centrifuge, is equivalent to the clear liquid of stock solution inlet amount 0.6 times and is back to as diluent and stirs pond soon, and remainder enters follow-up percolate evaporation and crystallization system and processes.Described centrifuge is horizontal spiral discharge sedimentation centrifuge, and design maximum separating factor is 3630, and form is downflow type.
After above-mentioned garbage burning factory percolate stock solution is processed by " dilution+coagulation+be centrifuged " method adopting the present invention, clear liquid COD is 52700mg/L, and ammonia nitrogen is 2296mg/L, and turbidity is 27NTU, SS be 19mg/L, pH is 6.12, and electrical conductivity is 34.6ms/cm.Wherein COD, ammonia nitrogen, turbidity, SS clearance respectively may be about 28.3%, 6.1%, 99.5%, 99.8%, and pH and electrical conductivity are substantially unchanged.
Embodiment 2
With Beijing garbage burning factory percolate stock solution for processing object, its parameters is: COD is 72000 ~ 76000mg/L, and ammonia nitrogen is 2200 ~ 2500mg/L, turbidity is 5400 ~ 6300NTU, SS is 8000 ~ 12000mg/L, pH is 5.97 ~ 6.13, and electrical conductivity is 32.4 ~ 35.6ms/cm.
As it is shown in figure 1, the preprocess method being suitable to percolate stock solution evaporative crystallization of the present invention comprises the following steps:
First, percolate stock solution is sent into and stirs pond soon, at the described inorganic coagulant PAC stirring soon in pond and adding 5g/L, and the centrifugal clear liquid of 1.2 times of stock solution inlet amounies, make the most suspended substances in described percolate stock solution and the flocculation of colloid pollution thing form substantial amounts of small flco after mixing abundant, quick.The described time of staying stirring pond soon is 3min, and speed of agitator is 150r/min.
Secondly, described percolate that pond processed will be stirred stir pond through too fast slowly from flowing into, to the described organic coagulant aid CPAM stirring slowly in pond and adding 3mg/L, be adequately mixed reaction and make stirring a large amount of small flco cohesion that pond formed soon to be bulky grain floccule body.The described time of staying stirring pond slowly is 5min, and speed of agitator is 50r/min.
Finally, the described percolate processed through stirring pond slowly is sent into centrifugal dehydrator, and under the centrifugal action that high speed rotating of transferring shares produces, the floccule body that proportion is bigger is got rid of to be attached to transfers shares on inwall, forming solid circular layer, the moisture that proportion is less forms pendular ring layer inside solid circular layer.Gu the mud of circular layer is slowly discharged by auger conveyor, then drained into sludge storage pool by screw pump and carry out post processing.The clear liquid of pendular ring layer by after gravity discharge centrifuge, is equivalent to the clear liquid of stock solution inlet amount 1.2 times and is back to as diluent and stirs pond soon, and remainder enters follow-up percolate evaporation and crystallization system and processes.Described centrifuge is horizontal spiral discharge sedimentation centrifuge, and design maximum separating factor is 3630, and form is downflow type.
After above-mentioned garbage burning factory percolate stock solution is processed by " dilution+coagulation+be centrifuged " method adopting the present invention, clear liquid COD is 53950mg/L, and ammonia nitrogen is 2280mg/L, and turbidity is 38NTU, SS be 42mg/L, pH is 6.14, and electrical conductivity is 33.2ms/cm.Wherein COD, ammonia nitrogen, turbidity, SS clearance respectively may be about 26.6%, 6.7%, 99.3%, 99.6%, and pH and electrical conductivity are substantially unchanged.
Embodiment 3
With Heilungkiang percolate from garbage filling field stock solution for processing object, its parameters is: COD is 17600 ~ 36000mg/L, and ammonia nitrogen is 2700 ~ 2900mg/L, turbidity is 3500 ~ 5000NTU, SS is 3000 ~ 6000mg/L, pH is 7.1 ~ 7.5, and electrical conductivity is 25.6 ~ 28.3ms/cm.
As it is shown in figure 1, the preprocess method being suitable to percolate stock solution evaporative crystallization of the present invention comprises the following steps:
First, percolate stock solution is sent into and stirs pond soon, at the described inorganic coagulant PAC stirring soon in pond and adding 3g/L, and the centrifugal clear liquid of 2.5 times of stock solution inlet amounies, make the most suspended substances in described percolate stock solution and the flocculation of colloid pollution thing form substantial amounts of small flco after mixing abundant, quick.The described time of staying stirring pond soon is 3min, and speed of agitator is 250r/min.
Secondly, described percolate that pond processed will be stirred stir pond through too fast slowly from flowing into, to the described organic coagulant aid APAM stirring slowly in pond and adding 5mg/L, be adequately mixed reaction and make stirring a large amount of small flco cohesion that pond formed soon to be bulky grain floccule body.The described time of staying stirring pond slowly is 20min, and speed of agitator is 50r/min.
Finally, the described percolate processed through stirring pond slowly is sent into centrifugal dehydrator, and under the centrifugal action that high speed rotating of transferring shares produces, the floccule body that proportion is bigger is got rid of to be attached to transfers shares on inwall, forming solid circular layer, the moisture that proportion is less forms pendular ring layer inside solid circular layer.Gu the mud of circular layer is slowly discharged by auger conveyor, then drained into sludge storage pool by screw pump and carry out post processing.The clear liquid of pendular ring layer by after gravity discharge centrifuge, is equivalent to the clear liquid of stock solution inlet amount 2.5 times and is back to as diluent and stirs pond soon, and remainder enters follow-up percolate vapo(u)rization system and processes.Described centrifuge is horizontal spiral discharge sedimentation centrifuge, and design maximum separating factor is 3630, and form is downflow type.
After above-mentioned garbage burning factory percolate stock solution is processed by " dilution+coagulation+be centrifuged " method adopting the present invention, clear liquid COD is 14750mg/L, and ammonia nitrogen is 2570mg/L, and turbidity is 50NTU, SS be 39mg/L, pH is 7.48, and electrical conductivity is 26.3ms/cm.Wherein COD, ammonia nitrogen, turbidity, SS clearance respectively may be about 26.5%, 5.5%, 98.9%, 99.3%, and pH and electrical conductivity are substantially unchanged.
Embodiment 4
With Heilungkiang percolate from garbage filling field stock solution for processing object, its parameters is: COD is 17600 ~ 36000mg/L, and ammonia nitrogen is 2700 ~ 2900mg/L, turbidity is 3500 ~ 5000NTU, SS is 3000 ~ 6000mg/L, pH is 7.1 ~ 7.5, and electrical conductivity is 25.6 ~ 28.3ms/cm.
As it is shown in figure 1, the preprocess method being suitable to percolate stock solution evaporation and concentration of the present invention comprises the following steps:
First, percolate stock solution is sent into and stirs pond soon, at the described inorganic coagulant PAC stirring soon in pond and adding 8g/L, and the centrifugal clear liquid of 2 times of stock solution inlet amounies, make the most suspended substances in described percolate stock solution and the flocculation of colloid pollution thing form substantial amounts of small flco after mixing abundant, quick.The described time of staying stirring pond soon is 30s, and speed of agitator is 150r/min.
Secondly, described percolate that pond processed will be stirred stir pond through too fast slowly from flowing into, to the described organic coagulant aid APAM stirring slowly in pond and adding 10mg/L, be adequately mixed reaction and make stirring a large amount of small flco cohesion that pond formed soon to be bulky grain floccule body.The described time of staying stirring pond slowly is 10min, and speed of agitator is 40r/min.
Finally, the described percolate processed through stirring pond slowly is sent into centrifugal dehydrator, and under the centrifugal action that high speed rotating of transferring shares produces, the floccule body that proportion is bigger is got rid of to be attached to transfers shares on inwall, forming solid circular layer, the moisture that proportion is less forms pendular ring layer inside solid circular layer.Gu the mud of circular layer is slowly discharged by auger conveyor, then drained into sludge storage pool by screw pump and carry out post processing.The clear liquid of pendular ring layer by after gravity discharge centrifuge, is equivalent to the clear liquid of stock solution inlet amount 2 times and is back to as diluent and stirs pond soon, and remainder enters follow-up percolate vapo(u)rization system and processes.Described centrifuge is horizontal spiral discharge sedimentation centrifuge, and design maximum separating factor is 3630, and form is downflow type.
After above-mentioned garbage burning factory percolate stock solution is processed by " dilution+coagulation+be centrifuged " method adopting the present invention, clear liquid COD is 15120mg/L, and ammonia nitrogen is 2595mg/L, and turbidity is 42NTU, SS be 23mg/L, pH is 7.34, and electrical conductivity is 27.1ms/cm.Wherein COD, ammonia nitrogen, turbidity, SS clearance respectively may be about 24.7%, 4.6%, 99.1%, 99.6%, and pH and electrical conductivity are substantially unchanged.