KR100891023B1 - The coagulating and dehydration method of sludge and apparatus thereof - Google Patents

Abstract

A method for cohesion and dehydration of sludge and an apparatus thereof are provided to offer a floc of a minute hole type by using a high cohesion apparatus with singular sludge and a flocculant. A method for cohesion and dehydration of sludge and an apparatus thereof are comprises the following steps. The sludge and flocculant are divided and injected. The sludge is cohered and dehydrated. The sludge and flocculant are mixed with over 700 rpm of a reaction speed during a first cohesion reation. An apparatus for cohesion and dehydration of sludge comprises the followings: a control valve of a sludge rate(11) for dividing into double sludge and injecting of the sludge; control valves of a flocculant flow(21,22,23) for dividing into triple sludge and injecting; and a moment high-speed agitator(30) equipped with astirring speed controller(31) and an agitating vane(32).

Description

The coagulating and dehydration method of sludge and apparatus

The present invention relates to a method for agglomeration and dehydration of sewage sludge having reduced cake moisture content using a multi-pore floc forming apparatus. The characteristics of the present invention are the prevention of a decrease in dehydration efficiency due to residual viscosity between flocks, which is a characteristic of a polymer flocculant, and a floc in flocculation. It is to improve the performance of the coagulation and dehydration process to reduce the moisture content by improving the dehydration efficiency through instantaneous high speed agitation together with the method of preventing the dehydration efficiency decrease due to the gap pore water generation and the multiple sludges and the multi flocculation agent again.

In the case of wastewater treatment, a study on the alumina by two-component flocculant of Yu and Somasundaran until recently [1] and the effect of pretreatment of iron salt or cationic surfactant by chitikela and dentel on flocculation of cationic polymer flocculant [ 2], Simultaneous Treatment of Cationic and Anionic Polymer Coagulants for Sedimentation Efficiency of Dredged Sludges of Bohm and Kulicke [3] and Evaluation of Effect on Sludge Dewatering Using Cationic and Nonionic Polymer Coagulants of CHLee and JCLiu [4] et al. Have been conducted. In addition, in the case of Kurita, various types of research have been made, including a patent (Japan Patent No.4-59100) for a granulating and concentrating device using an iron salt and an amphoteric polymer flocculant.

 [1] Xiang Yu and P. Somasundaran, "Enhanced flocculation with double flocculants" Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 81, 13 December 1993, Pages 17-23

 [2] Chitikela S. and Dentel S., "Dual chemical condition-ing and dewatering of anaerobically digested biosolids: laboratory evaluations." Wat. Environ. Res. 70, 1062- 1069, 1998

 [3] Bohm N. and Kulicke W. M., "Optimization of the use of polyelectrolytes for dewatering industrial sludge of various origins". Colloid Polym. Sci. 275, 73-81, 1997

 [4] C.H.Lee and J.C.Liu, "Enhanced sludge dewatering by dual polyelectrolytes conditioning", Water research, 34, 18, 4430-4436, 2000.

       As described above, the conventional techniques are not intended to improve the flocculation efficiency by a single flocculant and to improve the efficiency of change of the flocculating device. It is difficult to apply the generalized coagulation treatment in terms of improvement.

In addition, in the case of Kurita's patent, a technique using iron salt as an inorganic coagulant and an amphoteric coagulant as a coagulant, this technology also adds partial cationic and anionic properties in accordance with the combination ratio to cope with the size of the flocks. Since it is an application technology suitable for sludge, it is difficult to apply it universally, and it is difficult to put into practical use in consideration of the amount of sludge generated in the actual site because the input amount of the inorganic system is applied in excess of 2%.

In the case of the sludge dewatering capacity improving method (Patent Registration No. 10-0321061), it is a method of improving the dewatering capacity by adding FeCl ₃ , hydrated lime, fiber and polymer flocculant to each stage with several reactors, and the polymer flocculant 2 stage In this case, the amount of dehydration cake is excessive due to the method of condensation and flocculation by multi-drugs. In particular, the excessive amount of flocculant is 400-500 ppm. As the sludge is targeted for sludge, the actual dewatering efficiency decreases due to the influence of residual viscosity and the balance of charge, and at least 2300ppm (0.23%) and up to 4500 ppm of chemicals for reduction. (0.45%) is added, so it is simple to increase the amount of cake generated by increasing the solid content of about 16-32% compared to the 1.4% solid sludge to be removed. And causing a phenomenon, as opposed to only as the contamination reduction indicate moisture loss effect, a technology that can not be actually applied to the space constraints, such as installing the flocculation reaction tank as a four-stage.

In the case of high density sludge dewatering method (Patent Application No. 10-1999-0060888), high density sludge is introduced into the dehydrator through the instantaneous high speed and low speed agglomeration reaction by putting the polymer flocculant into the first and second reaction tanks using a two-stage reaction tank. It is a technology related to the dehydration method of sewage sludge, which is limited to high-density sludge, that is, sludge generated in the field of iron processing or stone processing, and limited the primary coagulation reaction rate to 60-200 rpm to prevent the dissolution of the flocs. This technology is difficult to apply to general sewage and industrial wastewater besides steel.

Accordingly, the inventors of the present invention have made efforts to solve the above problems, and as a result, the coagulant currently used in each treatment plant is used at a low coagulant dosage through the multi-injection method of the sludge and the multi-injection method of the coagulant without the addition of other drugs. In addition, it improves the cohesion efficiency and at the same time improves the compactness by forming the porous floc by forming the second coarse floc through the consolidation and dismantling of the first formed floc through instantaneous high speed stirring (700 ~ 1500 rpm). It has been found that the treatment cost can be reduced by reducing the moisture content of the dehydrated cake. In addition, the amount of coagulant is excessive in the case of highly organic food and sewage excess sludge, and when coagulant remains due to fluctuation of sludge load, it cannot be improved by physical treatment such as agitation. The present invention has been completed through the improvement of the cohesive efficiency in a way to improve the dehydration efficiency decrease due to the viscous effect of the residual coagulant.

Accordingly, an object of the present invention is to provide a technique for reducing moisture content of a dewatered cake and a method of applying the same by using a single sludge and a flocculant, a multi-moment high speed flocculation device and a porous floc formation using the device. When described in detail as follows.

The object of the present invention is to divide and add sludge and the flocculant is divided into the coagulation and dehydration, the sewage sludge characterized in that the instantaneous high speed stirring at the reaction rate of 700 rpm or more during the first coagulation reaction Is achieved by means of agglomeration and dehydration.

The flocculation and dewatering device for sewage sludge of the present invention comprises: a sludge ratio dividing regulating valve (11) for dividing sludge into two; Coagulant flow rate control valves 21, 22, and 23 for introducing sludge into threefold; The instantaneous multi-momentary high speed agglomeration device composed of the instantaneous high speed stirrer 30 having the stirring speed controller 31 and the stirring blades 32 and 32 and a belt press provided with a diaphragm are installed.

The stirring blade is composed of an upper baffle type stirring blade 32 and a lower circular stirring blade 33.

The instantaneous multiple instantaneous high speed flocculation apparatus of the present invention may include a regulator 40 to prevent backflow.

Through the present invention, the wastewater and the amount of flocculant are reduced by reducing the moisture content through the optimization of the flocculation reaction in the existing dehydration process, and the treatment cost of the environmental pollution is reduced by increasing the efficiency according to the secondary treatment of the dehydrated cake.

Hereinafter, the present invention will be described in detail.

The present invention is a method for maximizing the efficiency of the flocculation process by the cross-linking action between the suspended contaminant and the flocculant by the charging of the flocculant, each sludge treatment process characteristics such as influent waste water phase, pretreatment process, digestibility and concentration rate The composition and coagulation characteristics are different by each other.In each wastewater treatment process, the flocculation sedimentation and organic components of organic and inorganic components are decomposed and removed, resulting in a difference in the surface charge of the sludge. The proper charge of the flocculant used in the forming process is also a big difference, but the invention relates to a technique for increasing the efficiency of the multi-pore flocculation system through a multi-moment high-speed aggregation.

As a first detailed technology, a coagulation efficiency improvement technique by multiple injection of a single sludge and a single coagulant is described.

Most of the raw sludge is strongly cationic, and in the case of digested sludge, most of them are weakly cationic. The type of sludge that is applied to this patent is irrelevant to the type and source of sludge such as raw, surplus, digested and advanced treated surplus sludge, and the type of flocculant used is also classified into physical type such as powder type and emulsion type. It is characterized by agglomeration methods and apparatus related to agglomeration mechanisms applied irrespective of the classification of polymer forms such as molecular weight and molecular structure.

     As an example of the application, coagulation and dehydration experiments were carried out using a polyacrylamide emulsion type polymer coagulant on mixed sludge (total solids: 2.2%, pH: 6.89, VS: 73%, temperature: 28) of J sewage treatment plant. The contents of this patent will be described by using the results as an example. As a result of comparing the flocculation efficiency according to the charge of the flocculant to the sludge by inputting the same amount (220 ppm) of the emulsion type flocculent (average molecular weight: 20 million Dalton) with each charge, different charges are shown as shown in FIG. It shows different dehydration efficiency according to the efficiency of charge neutralization and crosslinking action between suspended flocculants with the flocculant. In case of this sludge, cationicity shows the optimum flocculation efficiency at 20 mol% and 60 mol%. It is considered that the proper charge necessary for the formation of the ring for the coarsening action is formed in this region.

Figure 3 shows the results of experiments on the correlation between the molecular weight and the flocculation efficiency by applying the product of different molecular weight of the cationic 20 mol% flocculant evaluated by the appropriate charge, the input amount at different molecular weights, unlike the effect of the charge It shows different cohesive behavior with change.

At this time, LMW has a molecular weight of 2 million to 10 million Dalton, MMW 10 million to 20 million Dalton, HMW is a coagulant having a molecular weight of 20 million Dalton or more.

The selection technology of the flocculant according to the charge and the molecular weight is a conventionally commercialized technology, but the multi-stage flocculation using a single flocculant is not a conventional technique. The approximate mechanism is the multiple of Tables 1 and 2 proposed by the present invention. The efficiency can be seen from the schematic diagram of the instantaneous fast aggregation mechanism.

Table 1. Multi-pore Flock Formation Mechanisms of Multiple Instant Fast Aggregates

Table 2. Flock formation mechanism of multi-momentary high speed aggregation

In the case of using a single flocculation device as shown in Table 1 and Table 2, in the case of using a multi-momentary high speed flocculation device or a mechanism in which the flocculation process is carried out by adding flocculant in the initial formation of the pin floc. In order to maximize the intensity while dismantling the first-formed floc, the gap number and free water between the flocs are maximized and the size of the floc is kept small. Induce the secondary reaction, and add a small amount of the same flocculant or sludge again to make the floc coarse through cross-linking between the flocs. Agglomeration method that improves consolidation by minimizing floc size and minimizes residual flocculant. By improving the dewatering efficiency is a technique for reducing the water content of the cake.

An important part of the present technology is that the application results of the coagulation performance of each of the typical input ratios by adjusting the input ratio of the first and second or higher in the multiple sludge and flocculant dosing method is shown in Figures 4a (sludge and flocculant) and 4a (coagulant). Alone).

4A and 4B are the results of experiments using the sludge through the centrifugal coagulant test method of maintaining the floc at a strong centrifugal force, and the coagulant used in FIG. 4A is a partially crosslinked emulsion coagulant. Approximately 8 million daltons of product were used, and the linear powder flocculant was used in the experiment of FIG. 4B.

In the present invention, the best dehydration in the preliminary experiment to compare the results of the single aggregation using the same flocculant to the single flocculation method and the result of applying the multiple flocculation method using the apparatus of the present invention and to determine the effect of molecular weight Comparative experiment was carried out using a high molecular weight flocculant showing efficiency.

As shown in the experimental results of Figure 4a, when the sludge and the flocculant is divided as a result of the first sludge input amount was 70%, the dehydration efficiency was the highest, and when adjusting the input amount less than the fluctuation of the coagulant input control was large. When the first sludge input amount was 90%, the improvement of dehydration efficiency was relatively low because the residual viscosity was not completely reduced due to the lack of the second sludge input amount.

Experiments with the first sludge input set at 70% and the first coagulant input at 30, 70 and 100% showed the lowest dehydration efficiency when the first input was set at 100%. The highest dehydration efficiency was shown by the smooth dispersion of sludge and flocculant and the coarsening process of sludge and flocculant in the second time.

In the experiment of FIG. 4b, which is an effect test according to the splitting ratio of the flocculant, the flocculant input at the first and second inputs was changed based on 25%, and the dosage was controlled. .

As a result, as shown in FIG. 4b, the best performance was obtained in the case of 75:25 ratio, and the dehydration efficiency was determined in the order of 25:75> 50:50> 100: 0> 0: 100.

This result is the result of the coarsening process for dehydration after increasing the consolidation and the strength of the floc during disassembly by generating the primary floc with the initial 75% dose as shown in the above mechanism. In this case, the initial floc is formed in a very fine form, but the separation effect of free water is excellent in this process, but in the case of floc pore water, it remains in some flocks during the coarsening process, which is the second input, and the efficiency is decreased.

In the case of inputting with the primary input amount of 100% by single input, after the coagulated flocculation is coarse, the floc is disassembled and the flocc is smaller than the size suitable for dehydration, and the efficiency is lowered. In the case of adding as%, the flocculated floc became coarse but the flocculation effect of the flocculant was not reduced and the dehydration efficiency was lowered.

Compared with the high molecular weight flocculant, it can be seen that the result of the two-stage addition resulted in a dehydration efficiency improvement of about 20%.

In this experiment, the first flocculation reaction was carried out for 30 seconds at 1000 rpm and the second flocculation reaction was carried out for 30 seconds at 500 rpm. However, for the practical application, the residence time required for the first reaction is within several seconds. Application is possible by mixing or the like. The reason for this is that as shown in FIG. 5, the dehydration efficiency is excellent at 45 seconds as a result of the coagulation reaction from 150 rpm to 120 seconds, which is a general coagulation condition.

As shown in the result of applying the instantaneous high speed flocculation reaction device to the flocculation reaction shown in FIG. 6, the dehydration efficiency of the reaction was 700% for 3 seconds, which was about 27% more than 38% of the single low flocculation reaction.

These results show the results of the evaluation of the floc strength by the additional reaction after the instantaneous fast reaction as shown in the state of the floc under each reaction condition shown in FIG. The floc strength was evaluated after 6 seconds at 600 rpm, indicating that the floc was the largest and strongest. For 45 seconds at 150 rpm, the floc was dismantled rather than consolidation. It can be seen that this is done, and the floc is continuously cracked upon further reaction.

Therefore, in the present invention, preferably, the primary coagulant input amount is 60 to 80%, the coagulation reaction rate is 700 rpm or more and 3 seconds or less, and the second coagulant input amount is 20 to 40%, and the most efficient. In general, it is a technique that separates into a first input amount and a second input amount and instantaneously rapidly aggregates them.

In addition to double dosing, when the triple dosing is applied, the primary input is 50-70%, and the secondary and tertiary inputs are added with the secondary flocculant input with 15% to 25%, or when the input is quadruple. The input amount is 50 ~ 70%, the input amount of each stage is about 10%, and the final input amount is 10 ~ 15%. It is a technique which coarsens a floc in the state containing pore, and makes dehydration easy.

In particular, in the case of centrifugal dehydration, unlike a belt press type dehydrator, there is no coagulation reaction tank in which flocculation agent is added to the front end to perform the coagulation reaction, which makes it difficult to control the reactivity between the coagulant and the sludge. Although there is a difficulty, by applying a small instantaneous high speed flocculation device of the present patent, it is possible to make very efficient dehydration by controlling the input method and the input amount of the coagulant according to the sludge change.

In general aggregation theory, when the molecular weight is large, the ring formation process for coarsening is slow, and the overall aggregation reaction rate is slow. Also, even in the case of slight overdosing, the residual viscosity due to the overlapping of the polymer as the coagulant on the surface of the suspended pollutant is multiplied. As a result, the dehydration efficiency is drastically lowered and, on the contrary, in the case of low molecular weight, in contrast to this phenomenon, it has a fast flocculation reaction rate and a wide range of appropriate flocculant input, but there is a small number of rings between the flocculant and the suspended contaminants which act as a coarsening between flocks. It is known to exhibit disadvantages in indicating floc strength.

In addition, the turbidity of the treated water is lower as the coagulation performance is excellent, and it is known that the fine floc adheres to all the flocs due to the residual viscosity in the excessive injection of the high molecular weight flocculant, thereby showing the optimum haze removal efficiency.

However, this experiment can be applied to the dehydration process of sludge that will contain most of the organic components regardless of the molecular weight and ionicity of the flocculant.

In the form of agitation blades of the instantaneous high speed flocculation device, the shape of a general wing may cause problems such as hairs being wound on the blades of sludge and need to be removed continuously after a certain period of time. The form is characterized in that the lower portion of the circular blade (similar to the lower circular wing of the washing machine 33) and the middle, the upper 32 is made of a gradient of the length horizontally with the stirring rod so that the hair is not wound.

The agitation of the instantaneous high speed flocculation device is characterized in that the coagulation reaction rate can be controlled at 300 to 1500 rpm to be adjusted according to the properties of the sludge. Preferably, it is characterized in that it is possible to stay at 3 or less seconds at 700 rpm.

Multiple injection method of sludge and flocculant is also possible to control individual valves (11, 21, 22, 23) to adjust artificially optimally according to sludge properties (type, total solids, etc.) of flocculant and sludge. Characterized by controlling the reactivity, preferably the sludge input is a two-stage input, the primary sludge input ratio is 60 ~ 80%, the secondary sludge input ratio is 40 ~ 20%, the flocculant input is 3 It is characterized in that the primary input amount is 50 to 70% and the input amount of each stage is 25 to 15%.

Example  One

In the dewatering process of the fresh sludge generated in the sewage treatment plant, the multi instantaneous high speed flocculation apparatus of FIG. 1 developed by the present patent was installed to perform other conditions in the same manner.

Under normal conditions, the sludge flow rate is 20 m ³ / hr while the coagulant is dissolved in 0.2% and supplied at 1.68 m ³ / hr. It was found that the free water was not enough for about 400 mm and stagnated, and the water content of the dehydrated cake was 76.59% under the conditions.

Simple instantaneous high speed agitation result shows that the flow rate of the coagulant is reduced by about 8% to 1.55 m ³ / hr in the existing control condition, and the initial free water is improved after instantaneous high speed aggregation at 1000 rpm. As a result, it was found that the initial freeness of about 50% was improved, and the water content was also reduced by 1.5% to 75.10%.

And while applying the device of the patent reduces the coagulant dose 15% 1.42 m ³ / hr of the primary coagulant dosage in the In experiments with 70% 1.0 m ³ / hr After In time high-speed aggregation and again the second coagulant 30% As a result of aggregating 0.42 m ³ / hr at the rear end of the instantaneous high speed flocculator, the initial free water was improved by 100%, and the water content was 75.02%, which was about 1.6% lower than that of the control group.

In order to further reduce the amount of flocculant used, the water content increased by about 0.5% to 77.11% at 1.3 m ³ / hr (23%), but the dehydration efficiency was stable, similar to the control.

As shown in the above results, when dewatering using a multi-moment high speed flocculator, the amount of flocculant used was reduced by about 15% and the water content was reduced by 1.5%.

The comparison results are posted in FIG. 8.

Example  2

In the dewatering process of the excess sludge generated in the sewage treatment plant, a multi instantaneous high speed flocculation device developed by the present patent was installed, and the other conditions were the same.

In the normal state, the sludge flow rate is 40 m ³ / hr while the flocculant is dissolved at 0.2% and fed at 2.5 m ³ / hr to perform centrifugal dehydration. The moisture content of the cake is about 80%. The detachment solution was excessively foamed by the residual flocculant.

To the sludge as a group to the first input 70% 28 m ³ / poured into hr supplying coagulants to 2.5 m ³ / hr to inject 12 m ³ / hr of sludge second drive after the high-speed aggregation device moment 2 As a result of the coagulation, the water content was about 78.5% and there was no residual viscosity and no foaming of the desorption solution.

As the experimental group, the sludge was divided into 70% and 30% as in the above conditions, and the flocculant was also divided into 70% and 30%. As a result, the water content increased slightly to 79%, but the bubbles in the desorption liquid were almost removed. The water content decreased by about 2.6% to 77.4% when the feed was divided into 50% and 50% of the flocculant.

As in the experimental results, the flocculation reaction for the surplus sludge of the slow-aggregation reaction rate was reduced by about 2.6% by multiple injection of the sludge and the flocculant.

Example  3

In the case of flocs produced by applying multiple instantaneous high speed flocculator to the sewage sludge belt press dewatering process in the sewage treatment plant, the initial free water is very good, so when the sludge flow rate is increased (from 8 to 10 m ³ / hr) when the belt press is dewatered Sludge is leaked out of the dehydrator due to sludge sludge during compression filtration, but when it is applied, it is decompressed even when operating by increasing the sludge flow rate (11 m ³ / hr or more) and belt speed after installing the diaphragm as shown in FIG. There was no swelling of the sludge, so smooth dehydration was possible.

1 is a schematic configuration diagram of a multi-moment high speed aggregation apparatus of the present invention.

Figure 2 is a graph showing the results of the flocculant titration experiment.

3 is a graph showing the relationship between molecular weight and aggregation efficiency.

Figure 4 is a graph showing the results of the coagulation performance comparison according to the adjustment of the input ratio, Figure 4a is a graph showing the comparison of the coagulation performance according to the adjustment of the input ratio of the sludge and Figure 4b is a comparison result of the coagulation performance according to the adjustment of the input ratio of the coagulant Graph shown.

Figure 5 is a graph showing the results of evaluating the dehydration efficiency in the general aggregation reaction conditions (150 rpm).

6 is a graph showing the dehydration efficiency evaluation results in the instantaneous fast aggregation reaction condition selection experiment (300 rpm or more).

7 is a comparison picture of the floc state and strength according to the aggregation reaction rate and time

8 is a photograph showing the water content reduction test results

Figure 9a is a photograph of the prior art device 9b is a photograph of the present patent device with a diaphragm installed

* Explanation of symbols for the main parts of the drawings *

11: Sludge Ratio Split Control Valve

21: primary input flocculant flow control valve

22: secondary input flocculant flow control valve

23: 3rd input flocculant flow control valve

30: instantaneous high speed stirrer

31: Stirring Speed Controller

32: upper baffle stirring blade

33: lower circular stirring blade

40: backflow prevention regulator

Claims (7)

A sludge agglomeration and dewatering method, characterized in that the sludge is divided into the input and the flocculant is added by agglomeration and agglomerated and dehydrated. The sludge flocculation and dewatering method according to claim 1, wherein the sludge is first introduced at 20 to 80% and the second at 20 to 80%. The sludge flocculation and dewatering method according to claim 1 or 2, wherein the first flocculant content is 60 to 80% and the second flocculant content is 20 to 40%. The primary flocculant content is 50 to 70%, the flocculation reaction rate is 700 rpm or more and 3 seconds or less, the secondary flocculant content is 15% to 25%, and the third Sludge flocculation and dewatering method characterized in that the amount of flocculant is added to 15% to 25%. A sludge ratio dividing regulating valve 11 for dividing and injecting sludge; Coagulant flow rate control valves 21, 22, and 23 for dividing and injecting a coagulant; And an instantaneous multiple instantaneous high speed agglomeration device composed of a stirring speed controller 31 and an instantaneous high speed stirrer 30 having a stirring blade, and a belt press provided with a diaphragm. The sludge flocculation and dewatering device according to claim 5, characterized in that the stirring blade is composed of an upper baffle type stirring blade (32) and a lower circular stirring blade (33). A sludge flocculation and dewatering device according to claim 5, characterized in that a regulator (40) for preventing backflow is provided at the end of said instantaneous multiple instantaneous high speed flocculation apparatus.

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