Sludge treatment method

Abstract

The invention provides a sludge treatment method which comprises the following steps: step 1, adding a prefabricated acid solution into sludge, and stirring the sludge; step 2, performing gravity concentration on the sludge, discharging supernate, recovering the prefabricated acid solution in the supernate through evaporation, and applying the recovered prefabricated acid to the step 1; 3, adding a Fe < 3 + > solution and lime particles into the sludge subjected to gravity concentration, and stirring the sludge; 4, pressurizing the sludge in the step 3, conveying the sludge into a plate-and-frame filter pressing dehydrator for dehydration, and discharging separated liquid; step 5, inputting the dewatered sludge into crushing and dispersing equipment so as to crush and disperse the sludge; and step 6, heating the crushed and dispersed sludge blocks by using hot air, washing waste gas generated after heating by using a washing device, and then discharging the waste gas. According to the sludge treatment method, the sludge treatment cost is reduced to a certain extent.

Description

Technical Field

[0001] The present disclosure relates to the technical field of sewage sludge treatment, and in particular to a sludge treatment method. Background Art

[0002] Chinese patent CN101691273B discloses a method for integrating sewage sludge concentration, dehydration and aerobic air drying, which has the characteristics of high sludge concentration and dehydration efficiency, low drying energy consumption, less tail gas pollution, low equipment investment and operating costs, and high safety performance.

[0003] However, in the prior art integrated method of sewage sludge concentration, dehydration and aerobic air drying, the organic and inorganic agents added to the sludge are not recycled, which makes the cost of sludge treatment high. Summary of the invention

[0004] A technical problem to be solved by the present disclosure is to reduce the cost of treating sludge.

[0005] In order to solve the above technical problems, the present disclosure provides a sludge treatment method, comprising:

[0006] Step 1: adding a pre-made acid solution into the sludge and stirring the sludge;

[0007] Step 2: gravity concentrating the sludge, discharging the supernatant, and recovering the pre-acid solution in the supernatant by evaporation, and applying the recovered pre-acid to step 1;

[0008] Step 3: Adding Fe to the sludge after gravity concentration 3+ solution and lime particles, and stir the sludge;

[0009] Step 4: pressurizing the sludge in step 3 and conveying it to a plate and frame filter press dehydrator for dehydration, and discharging the separated liquid;

[0010] Step 5: inputting the dehydrated sludge into a crushing and dispersing device to crush and disperse the sludge; and,

[0011] Step 6: The crushed and dispersed sludge blocks are heated by hot air, and the waste gas generated after heating is washed with water by a water washing device and then discharged.

[0012] In some embodiments, the step 1 further comprises: adding the pre-made acid solution so that the pH value of the sludge satisfies the relationship: 5≤pH≤6.

[0013] In some embodiments, in step 1, the step of stirring the sludge comprises:

[0014] The sludge is stirred by a homogenizer, and the rotation speed r of the homogenizer satisfies the relationship: 2rpm≤r≤20rpm.

[0015] In some embodiments, the step 1 further comprises: after evaporating the supernatant, conveying the generated impurities to the crushing and dispersing equipment.

[0016] In some embodiments, the preformed acid comprises at least one of nitric acid or hydrochloric acid.

[0017] In some embodiments, step 4 further includes:

[0018] The separated liquid is filtered and the Fe in the filtrate is recovered. 3+ solution and the pre-made acid solution, applying the pre-made acid solution to the step 1, 3+ The solution is applied to the step 3, and the filtered solid impurities are simultaneously conveyed to the crushing and dispersing equipment.

[0019] In some embodiments, the step of recovering the pre-acid solution in the filtrate comprises:

[0020] The filtrate is heated to above 85° C. to evaporate and condense the pre-acid solution, and the condensed pre-acid solution is collected.

[0021] In some embodiments, the Fe in the filtrate is recovered 3+ The solution steps include:

[0022] Heating the filtrate to evaporate the pre-acid solution, and heating again to concentrate the remaining Fe3+ solution; or,

[0023] Adjust the pH value of the filtrate to satisfy the relationship: 7≤pH≤8, so that Fe 3+ Ion precipitation, filtering the filtrate, taking the precipitate and dissolving it in an appropriate amount of acid, thereby preparing Fe 3+ Solution.

[0024] In some embodiments, the step of heating the crushed and dispersed sludge cakes with hot air comprises:

[0025] Air is sucked into a cold exchanger, moisture in the air is condensed by the cold exchanger, the condensed water is transported to the water washing device, and the condensed air is transported to a heat exchanger;

[0026] The air entering the heat exchanger is heated by a compressor, and the hot air in the heat exchanger is blown onto the sludge cake.

[0027] In some embodiments, step 6 further includes:

[0028] The solution flowing out of the water washing device is recovered and filtered, and the filtered solution is input into the water washing device, and the filtered impurities are transported to the crushing and dispersing equipment.

[0029] Through the above technical scheme, the present application discloses a method for treating sludge. Different from the prior art, the present application adds a preformed acid solution to the sludge, so that the bacterial flora in the sludge is in an acidic environment, which improves the decomposition of organic matter by the bacterial flora, thereby avoiding the high content of toxic organic matter in the sludge, and then causing environmental damage after the use of sludge products. In addition, in the present application, after the sludge is concentrated by gravity, the precipitated supernatant is recovered and the preformed acid in the supernatant is extracted, thereby reducing the amount of preformed acid used in the sludge treatment process to reduce the cost of sludge treatment. In addition, the present application collects the solution separated from the sludge during the mechanical dehydration process, and dehydrates the preformed acid and Fe in the solution. 3+ The solution is recycled, further reducing the cost of sludge treatment. On the other hand, during the aerobic reaction process, the present application filters and reuses the water discharged from the water washing device to reduce the water consumption of the water washing device. Finally, the present application recovers the pre-made acid solution, Fe 3+ When the solution and water washing device discharge water, the impurities generated are transported to the crushing and dispersion equipment, thereby increasing the final sludge output. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 It is the process intention of the sludge treatment method disclosed in the embodiment of the present disclosure;

[0032] Figure 2 It is a schematic diagram of the steps of the sewage treatment method disclosed in the embodiment of the present disclosure; DETAILED DESCRIPTION

[0033] The following is a further detailed description of the embodiments of the present disclosure in conjunction with the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to exemplarily illustrate the principles of the present disclosure, but cannot be used to limit the scope of the present disclosure. The present disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

[0034] The present disclosure provides these embodiments to make the present disclosure thorough and complete, and to fully express the scope of the present disclosure to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of the parts and steps, the composition of the materials, the numerical expressions and the numerical values ​​set forth in these embodiments should be interpreted as being merely exemplary, and not as limiting.

[0035] It should be noted that, in the description of the present disclosure, unless otherwise specified, the meaning of "multiple" is greater than or equal to two; the terms "upper", "lower", "left", "right", "inner", "outer", etc., indicating the orientation or positional relationship, are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present disclosure. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0036] In addition, the words "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different parts. "Vertical" does not mean vertical in the strict sense, but is within the tolerance range. "Parallel" does not mean parallel in the strict sense, but is within the tolerance range. "Include" or "comprising" and similar words mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of including other elements.

[0037] It should also be noted that in the description of the present disclosure, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present disclosure can be understood according to the specific circumstances. When a specific device is described as being located between a first device and a second device, there may or may not be an intermediate device between the specific device and the first device or the second device.

[0038] All terms used in the present disclosure have the same meanings as those understood by those of ordinary skill in the art to which the present disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries, for example, should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an idealized or extremely formal sense, unless explicitly defined as such herein.

[0039] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0040] The present application discloses a sludge treatment method, which comprises:

[0041] Step 1: Add pre-made acid solution into the sludge and stir the sludge;

[0042] Step 2: gravity concentrate the sludge, discharge the supernatant, and recover the pre-acid solution in the supernatant by evaporation, and the recovered pre-acid is applied to step 1;

[0043] Step 3: Adding Fe to Gravity Thickened Sludge 3+ solution and lime particles, and stir the sludge;

[0044] Step 4: pressurizing the sludge in step 3 and conveying it to a plate and frame filter press dehydrator for dehydration, and discharging the separated liquid;

[0045] Step 5: inputting the dehydrated sludge into a crushing and dispersing device to crush and disperse the sludge; and,

[0046] Step 6: Use hot air to heat the crushed and dispersed sludge blocks, and the waste gas generated after heating is washed with water by a water washing device and then discharged.

[0047] Specifically, in sludge treatment, since the sludge contains a variety of bacterial communities, in order to enable some bacterial communities to decompose organic matter in the sludge faster, a preformed acid solution is added to the sludge in step 1, so that bacterial communities such as anaerobic bacteria and acid fermentation bacteria are more active in an acidic environment, thereby quickly decomposing toxic substances in the sludge and preventing toxic substances in subsequent sludge products from affecting the environment. In addition, after the preformed acid solution is added to the sludge, the sludge needs to be fully stirred so that the bacterial communities in the sludge are all in an acidic environment. In this embodiment, the gravity concentration of step 2 is natural precipitation, and the time of natural precipitation is set to 2 hours to ensure that the sludge is fully precipitated. After precipitation, the precipitated supernatant is recovered, and the preformed acid in the supernatant is purified, and the preformed acid is applied to step 1, so that in the sludge treatment process, the use of preformed acid can be reduced, thereby reducing the cost of treating sludge. It can be understood that in this embodiment, evaporation is used to recover the preformed acid, that is, the preformed acid solution in the supernatant is evaporated after heating, and the evaporated preformed acid is then condensed and gathered to form a preformed acid solution. The advantage of using evaporation recovery is that the preformed acid can be separated from other substances according to the boiling point of the preformed acid, and the operation steps are few and the recovery cost is low.

[0048] Step 3 is the inorganic agent preparation step, in which Fe is added to the precipitated sludge. 3+ Solution, Fe 3+ The solution can improve the hydrophobicity of the sludge, thereby improving the dewatering performance of the sludge. 3+After the solution, the sludge needs to be fully stirred, and the stirring time is set between 10 seconds and 180 seconds. Afterwards, lime particles are added to the sludge and stirred for 30 seconds to 300 seconds. The lime particles can improve the compressibility of the sludge. In step 4, the sludge is compressed and dehydrated by a plate and frame filter press dehydrator to reduce the water content of the sludge. The process of step 4 is mechanical dehydration. Afterwards, the compressed sludge is transported to a crushing and dispersion device for crushing and dispersion, so that the sludge is dispersed into multiple small pieces, which is convenient for further dehydration of the sludge. The process of step 5 is crushing and dispersion. In step 6, hot air is introduced to heat the sludge. After heating, the aerobic bacteria in the sludge will further improve the efficiency of decomposing organic matter, thereby releasing a certain amount of heat. Under the environment of external heat and internal heat generation of the sludge, the water in the sludge further evaporates, thereby reducing the water content in the sludge. The process of step 6 is aerobic air drying. In addition, in step 6, a rolling device can be provided at the bottom of the sludge block, so that the sludge block is constantly rolled under the action of the rolling device, so that all sides of the sludge block are heated evenly. After the sludge is heated, part of the sludge may become dust, and at the same time, the degradation of organic matter by the bacterial flora after heating may produce gases such as ammonia, which are discharged with the waste gas, thereby affecting the environment. Therefore, a water washing device is provided in this embodiment, and the waste gas needs to be washed by the water washing device before it can be discharged. The waste gas after washing can avoid the sludge dust or the generated gas from being directly discharged into the atmosphere to a certain extent. On the other hand, after the aerobic air-drying process, the sludge block can be further crushed and dried by a spiral crusher, so that the sludge block becomes sludge powder, and then the sludge powder is recycled as needed, such as sintering into bricks, making cement, etc.

[0049] Compared with the prior art, on the one hand, the pre-made acid solution is added in this embodiment, so that the bacterial flora in the sludge is in an acidic environment, thereby making some of the bacterial flora more active, which can quickly decompose the toxic organic matter in the sludge, reduce the content of toxic substances in the sludge, and reduce the impact of toxic substances on the environment to a certain extent when using sludge products. On the other hand, after the sludge is concentrated by gravity, the pre-made acid solution in the supernatant is recycled in this embodiment, thereby reducing the cost of sludge treatment to a certain extent.

[0050] In some embodiments, step 1 further comprises: adding a pre-made acid solution so that the pH value of the sludge satisfies the relationship: 5≤pH≤6.

[0051] Specifically, when the pH value of the sludge satisfies the above relationship, the bacterial flora such as yeast or mold in the sludge is relatively active, and can quickly decompose the organic matter in the sludge, so that the organic matter is degraded into carbon dioxide and water or other metabolites. In addition, some bacterial flora, such as acidifying bacteria, can convert organic matter into organic acids in an acidic environment, thereby reducing the toxicity of the sludge. If the pH value is less than 5, the acidic environment is too strong, resulting in, for example, a decrease in the activity of nitrifying bacteria, which reduces the efficiency of nitrifying bacteria in converting organic matter into ammonia. When the pH value is greater than 6, the efficiency of yeast or mold in decomposing organic matter is reduced, resulting in a higher content of toxic organic matter in the final product sludge, which may cause pollution to the environment after the sludge is used.

[0052] In some embodiments, in step 1, the step of stirring the sludge includes: stirring the sludge using a homogenizer, and the rotation speed r of the homogenizer satisfies the relationship: 2rpm≤r≤20rpm.

[0053] In this embodiment, during the sludge treatment process, the bacterial community on the sludge will grow more microbial flocs, and the microbial flocs can degrade organic matter in the sludge. In addition, more bubbles will be produced in the sludge, and the bubbles can provide oxygen to the aerobic bacterial community, thereby improving the efficiency of the aerobic bacterial community in degrading organic matter. When the speed of the homogenizer meets the above range, due to the low speed, the homogenizer can avoid destroying the microbial flocs and bubbles in the sludge. If the speed r of the homogenizer is lower than 2rpm, the speed is slow, it is difficult to mix the sludge evenly, and part of the sludge is not in an acidic environment. When r is higher than 20rpm, the speed is too fast, resulting in the destruction of the microbial flocs and bubbles in the sludge, thereby reducing the efficiency of the bacterial community in degrading organic matter. The speed r of the homogenizer can be set to 2rpm, 4rpm, 6rpm, 8rpm, 10rpm, 12rpm, 14rpm, 16rpm, 18rpm and 20rpm.

[0054] In some embodiments, step 1 further comprises: after evaporating the supernatant, conveying the generated impurities to a crushing and dispersion device.

[0055] Specifically, after the supernatant is heated, the water in the supernatant and the preformed acid will completely evaporate, and some solid impurities will be produced. In order to fully recycle the sludge, the solid impurities are transported to the crushing and dispersion equipment.

[0056] In some embodiments, the preformed acid includes at least one of nitric acid or hydrochloric acid.

[0057] It is understandable that nitric acid and hydrochloric acid have low boiling points and certain volatility, which is convenient for recovery after heating the supernatant. Of course, preformed acid can also use acetic acid or sulfuric acid. When preformed acid uses sulfuric acid, the purification process of preformed acid can use filtering to separate the solid and liquid of the supernatant, and the separated liquid can be concentrated again and used as sulfuric acid. Optionally, the preformed acid can also be a mixture of hydrochloric acid and nitric acid, or a mixture of sulfuric acid and nitric acid. It is worth mentioning that since some bacterial communities will be inactivated in the environment of nitric acid, hydrochloric acid or other acids, resulting in the inability of the bacterial community to degrade organic matter, a specific preformed acid solution can be configured according to the situation of the bacterial community contained in the sludge.

[0058] In some embodiments, step 4 further comprises: filtering the separated liquid and recovering Fe 3+ solution and pre-made acid solution, the pre-made acid solution is applied to step 1, Fe 3+ The solution is applied in step 3, and the filtered solid impurities are simultaneously conveyed to the crushing and dispersing equipment.

[0059] It is worth mentioning that since a certain amount of lime particles, namely calcium oxide, needs to be added to the sludge, calcium oxide will react with the preformed acid. Therefore, after the addition of lime particles, the content of preformed acid in the sludge is reduced. In order to reduce the cost of sludge treatment, the preformed acid still needs to be recovered. Specifically, since there is a certain amount of Fe 3+ solution and pre-made acid solution, after mechanical dehydration of sludge, part of Fe 3+ The solution and the pre-made acid solution are discharged. In this embodiment, the Fe 3+ The solution and pre-made acid solution are recovered, so that Fe 3+ The total usage of the solution and pre-made acid solution can be reduced, thereby reducing the cost of sludge treatment. In addition, after filtering the liquid separated from the sludge, the solid impurities produced are transported to the crushing and dispersion equipment, and the subsequent steps are performed to fully utilize the treated sludge.

[0060] In some embodiments, the step of recovering the pre-acid solution in the filtrate includes: heating the filtrate to above 85° C. to evaporate and condense the pre-acid solution, and collecting the condensed pre-acid solution.

[0061] In a specific embodiment, the pre-made acid solution is a nitric acid solution, and the heating temperature is 85°C. When the temperature of the filtrate is 85°C, the nitric acid solution in the filtrate evaporates, and the evaporated nitric acid condenses and converges into a nitric acid solution, which can be used in step 1.

[0062] In some embodiments, Fe in the filtrate is recovered 3+The steps of the solution include: heating the filtrate to evaporate the pre-made acid solution, heating it again to evaporate the remaining Fe 3+ The solution was concentrated.

[0063] That is, after evaporating and recovering the pre-acid solution, the filtrate is heated again to evaporate the water in the filtrate, thereby concentrating the Fe 3+ The solution is heated again to a temperature of 100° C. The advantages of recovering iron ions in this embodiment are low cost and high efficiency. Of course, a disadvantage of this method is that the solution contains more other elements.

[0064] In other embodiments, Fe in the filtrate is recovered 3+ The steps of the solution include: adjusting the pH value of the filtrate to satisfy the relationship: 7≤pH≤8, so that Fe 3+ Ion precipitation, filtering the filtrate, taking the precipitate and dissolving it in an appropriate amount of acid, thereby preparing Fe 3+ Solution.

[0065] That is to say, after the pre-made acid is recovered, an appropriate amount of NaOH solution can be added to the filtrate to adjust the pH value of the filtrate so that the pH value satisfies: 7≤pH≤8, thereby making Fe 3+ The ions are precipitated as Fe, and then an appropriate amount of acid solution is added to convert Fe(OH) 3 Dissolve and apply the solution to step 3. One advantage of this method is that it can reduce the precipitation of other impurities in the precipitate and increase the content of Fe element in the precipitate. The disadvantage of this method is that the recovery cost is relatively high.

[0066] In addition, Fe 3+ The solution can be FeCl 3 solution, or Fe 2 O 3 Specifically, FeCl 3 The solution will introduce chloride ions. When the chloride ion concentration is too high, it will cause the death of filamentous bacteria and protozoa in the sludge, and the bacterial flocs will become denser. At this time, the microbial flocs will become small and compact, which will cause the bacterial community in the sludge to reduce the ability to degrade organic matter. 2 O 3 If the sludge is dissolved in an acid solution, chloride ions will not be introduced into the sludge. 2 O 3 Dissolved in nitric acid.

[0067] In some embodiments, the step of using hot air to heat the crushed and dispersed sludge blocks includes: sucking air into a cold exchanger, using the cold exchanger to condense moisture in the air, conveying the condensed water to a water washing device, and conveying the condensed air to a heat exchanger; using a compressor to heat the air entering the heat exchanger, and blowing the hot air in the heat exchanger onto the sludge blocks.

[0068] Specifically, air is sucked into the cold exchanger through the first fan. At this time, the compressor absorbs heat from the cold exchanger and releases heat to the heat exchanger. The temperature inside the cold exchanger is relatively low, and the moisture in the air condenses into condensed water after being cooled. The condensed water gathers and flows into the water cooling device. The air then enters the heat exchanger, which heats the air. After that, the gas in the heat exchanger is blown onto the sludge block through the second fan. It can be understood that by introducing condensed water into the water washing device, the water consumption of the water washing device can be reduced to a certain extent. Through the above steps, the water content of the air blown to the sludge block can be effectively reduced, thereby preventing the sludge block from having too high a water content after aerobic air drying.

[0069] In some embodiments, step 6 also includes: recovering and filtering the solution flowing out of the water washing device, inputting the filtered solution into the water washing device, and conveying the filtered impurities to the crushing and dispersion equipment.

[0070] Specifically, during sewage treatment, the water in the water washing device needs to be continuously replenished. When there is too much water in the water washing device, the water washing device will discharge some of the water. In this embodiment, the water discharged from the water washing device is recycled. Since the water contains sludge and dust, the water is filtered. Usually, two filtrations are used. The first filtration is performed using a sand filter to filter out larger particulate impurities in the water. The second filtration is performed using a membrane filter to filter out smaller impurities in the water. The filtered water can be transported to the water washing device again to reduce the water consumption of the water washing device. The impurities generated after filtration are transported to the crushing and dispersion equipment to increase the usable amount of sludge.

[0071] In a specific embodiment, sludge with a water content of 99.8% and a volume of V1 / L is transported to a stirring tank. At this time, the mass of the sludge is 0.002V1·ρ, where V1 represents the volume and ρ represents the average density of the sludge. Subsequently, a nitric acid solution with a concentration of 70% is added to the sludge. The volume of the nitric acid solution added is 4.13V1·10 -3 / L, and then the sludge is stirred with a homogenizer for 60 seconds at a speed of 10rpm. After stirring, the sludge is left to stand for 2 hours to allow the sludge to settle under the action of gravity. At this time, part of the liquid is separated from the sludge, and the separated supernatant is evaporated through an evaporator to recover the nitric acid solution in the supernatant. The nitric acid solution after evaporation and condensation can be heated again to reduce the water content in the nitric acid solution, thereby concentrating the nitric acid solution. The water content of the lower layer of sludge is 95% at this time. A 40% ferric chloride solution is added to the sludge. The volume of the added ferric chloride solution is 4.22V1·10 -4 / L, and then stir the sludge for 60 seconds. Then, add lime particles, the content of calcium oxide in the lime particles is 70%, and the mass of calcium oxide is 4.2V1·10 -4 / kg, and stir the sludge for 60 seconds. After the stirring is completed, the sludge is transported to the plate and frame filter press by a screw pump for compression and dehydration, and the injection pressure of the screw pump is 1Mpa. The solution discharged from the plate and frame filter press is collected, and the nitric acid solution and the ferric chloride solution are recovered by heating the evaporator at different temperatures. Similarly, the recovered ferric chloride solution is heated again to concentrate the concentration of the ferric chloride solution to about 38%, so that the ferric chloride solution can be used in step 3. After mechanical dehydration, the water content of the sludge is 61%. At this time, the sludge is transported to the crushing and dispersion equipment to disperse the sludge into a sludge particle layer. Subsequently, the sludge particle layer is transported to the first conveyor belt, and 85°C dry air is input into the sludge particle layer to increase the oxygen content of the sludge particles so that the bacterial flora in the sludge particles produce an aerobic reaction. The first conveyor belt is provided with a particle layer thickness regulator to adjust the thickness of the sludge particles. After the sludge particles pass through the particle layer thickness regulator on the first conveyor belt, the thickness of the sludge particles is adjusted to 200mm. When the sludge particles reach the end of the first conveyor belt, the sludge particles fall under the action of gravity and fall onto the second conveyor belt at the lower end of the first conveyor belt. The sludge particles can be turned over when falling. The sludge particles are conveyed to the screw machine under the action of the second conveyor belt to further crush the sludge. At this time, the water content of the sludge particles is 36%. In this embodiment, the transmission speed of the first conveyor belt and the second conveyor belt is 2mm / s, and the transmission time of the sludge particles on the first conveyor belt and the second conveyor belt is 20h. The first conveyor belt and the second conveyor belt are both passed with 85℃ dry hot air. The hot air blowing through the sludge particles is sucked by the exhaust fan and discharged after being washed by the water washing device. In addition, after the sludge particles are crushed by the screw machine, the sludge can be dried again, which is convenient for the subsequent processing and reuse of the sludge.

[0072] In summary, the present application provides a method for treating sludge. Unlike the prior art, the present application adds a preformed acid solution to the sludge, so that the bacterial flora in the sludge is in an acidic environment, thereby improving the decomposition of organic matter by the bacterial flora, thereby avoiding a high content of toxic organic matter in the sludge, which in turn causes environmental damage after the sludge products are used. In addition, after the sludge is concentrated by gravity, the precipitated supernatant is recovered and the preformed acid in the supernatant is extracted, thereby reducing the amount of preformed acid used in the sludge treatment process to reduce the cost of sludge treatment. In addition, the present application collects the solution separated from the sludge during the mechanical dehydration process, and dehydrates the preformed acid and Fe 3+ The solution is recycled, further reducing the cost of sludge treatment. On the other hand, during the aerobic reaction process, the present application filters and reuses the water discharged from the water washing device to reduce the water consumption of the water washing device. Finally, the present application recovers the pre-made acid solution, Fe 3+ When the solution and water washing device discharge water, the impurities generated are transported to the crushing and dispersion equipment, thereby increasing the final sludge output.

[0073] So far, various embodiments of the present disclosure have been described in detail. In order to avoid obscuring the concept of the present disclosure, some details known in the art are not described. Based on the above description, those skilled in the art can fully understand how to implement the technical solution disclosed here.

[0074] Although some specific embodiments of the present disclosure have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. It should be understood by those skilled in the art that the above embodiments may be modified or some technical features may be replaced by equivalents without departing from the scope and spirit of the present disclosure. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict.

Claims

1. A sludge treatment method, characterized in that: include: Step 1: adding a pre-made acid solution into the sludge and stirring the sludge; Step 2: gravity concentrating the sludge, discharging the supernatant, and recovering the pre-acid solution in the supernatant by evaporation, and applying the recovered pre-acid to step 1; Step 3: Adding Fe to the sludge after gravity concentration 3+ solution and lime particles, and stir the sludge; Step 4: pressurizing the sludge in step 3 and conveying it to a plate and frame filter press dehydrator for dehydration, and discharging the separated liquid; Step 5: inputting the dehydrated sludge into a crushing and dispersing device to crush and disperse the sludge; and, Step 6: The crushed and dispersed sludge blocks are heated by hot air, and the waste gas generated after heating is washed with water by a water washing device and then discharged.

2. The sludge treatment method according to claim 1, characterized in that: The step 1 further comprises: adding the pre-made acid solution so that the pH value of the sludge satisfies the relationship: 5≤pH≤6.

3. The sludge treatment method according to claim 1, characterized in that: In step 1, the step of stirring the sludge comprises: The sludge is stirred by a homogenizer, and the rotation speed r of the homogenizer satisfies the relationship: 2rpm≤r≤20rpm.

4. The sludge treatment method according to claim 1, characterized in that: The step 1 further comprises: after evaporating the supernatant, conveying the generated impurities to the crushing and dispersing equipment.

5. The sludge treatment method according to claim 1, characterized in that: The prefabricated acid at least includes: at least one of nitric acid and hydrochloric acid.

6. The sludge treatment method according to claim 1, characterized in that: The step 4 also includes: The separated liquid is filtered and the Fe in the filtrate is recovered. 3+ solution and the pre-made acid solution, applying the pre-made acid solution to the step 1, 3+ The solution is applied to the step 3, and the filtered solid impurities are simultaneously conveyed to the crushing and dispersing equipment.

7. The sludge treatment method according to claim 6, characterized in that: The step of recovering the pre-acid solution in the filtrate comprises: The filtrate is heated to above 85° C. to evaporate and condense the pre-acid solution, and the condensed pre-acid solution is collected.

8. The sludge treatment method according to claim 6, characterized in that: Recover the Fe in the filtrate 3+ The solution steps include: The filtrate is heated to evaporate the pre-acid solution and then heated again to evaporate the remaining Fe 3+ The solution is concentrated; or, Adjust the pH value of the filtrate to satisfy the relationship: 7≤pH≤8, so that Fe 3+ Ion precipitation, filtering the filtrate, taking the precipitate and dissolving it in an appropriate amount of acid, thereby preparing Fe 3+ Solution.

9. The sludge treatment method according to any one of claims 1 to 8, characterized in that: The step of heating the crushed and dispersed sludge blocks by hot air comprises: Air is sucked into a cold exchanger, moisture in the air is condensed by the cold exchanger, the condensed water is transported to the water washing device, and the condensed air is transported to a heat exchanger; The air entering the heat exchanger is heated by a compressor, and the hot air in the heat exchanger is blown onto the sludge cake.

10. The sludge treatment method according to any one of claims 1 to 8, characterized in that: The step 6 also includes: The solution flowing out of the water washing device is recovered and filtered, and the filtered solution is input into the water washing device, and the filtered impurities are transported to the crushing and dispersing equipment.

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