CN108975647B - Accelerator for accelerating anaerobic digestion of excess sludge, and preparation method and application thereof - Google Patents
Accelerator for accelerating anaerobic digestion of excess sludge, and preparation method and application thereof Download PDFInfo
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Abstract
The invention discloses an accelerator for accelerating anaerobic digestion of excess sludge, a preparation method and application thereof, and belongs to the field of resource utilization of solid wastes. Aiming at the problems of low iron dissolution speed, low efficiency, sludge reduction and low recycling degree in the existing iron treatment of excess sludge, the invention utilizes the excess sludge as a raw material to obtain highly activated sludge activated carbon through a series of steps, then the highly activated sludge activated carbon is mixed with iron powder, common activated carbon and a binding agent according to a specific proportion, pressed into balls, sintered, added with sodium ethylene diamine tetracetate, pressed into shapes and dried to obtain the accelerator for accelerating anaerobic digestion of the excess sludge. The invention utilizes the principle of iron-carbon micro-electrolysis, accelerates the dissolution of iron, and the existence of ethylene diamine tetraacetic acid and Mn, widens the pH range of the accelerator in sludge treatment, can directly use the accelerator obtained by the invention to treat sludge without adjusting the pH of the sludge, and reduces the cost.
Description
Technical Field
The invention belongs to the field of solid waste resource utilization, and particularly relates to an accelerator for accelerating anaerobic digestion of excess sludge, and a preparation method and application thereof.
Background
Along with the continuous improvement of the urbanization level of China, the sewage treatment technology is developed in a high way, and statistics shows that 3501 urban sewage treatment plants are built in China, and the sewage treatment capacity reaches 1.47 hundred million m3 per day (one method for improving the anaerobic digestion and supplementation of the residual activated sludge). With the increasing processing capacity and throughput, the problem that accompanies this is the large increase in excess sludge. According to statistics, the sludge is produced by over 3000 ten thousand tons (calculated by the water content of 80%) every year in China. The sludge contains a large amount of pollutants such as organic matters, bacteria, heavy metals and the like, and if the pollutants are directly discharged without treatment, secondary pollution to the environment is easily caused, the sewage treatment plant becomes an important pollution source. Therefore, sludge needs to be treated to be harmless, reduced and recycled. However, the investment and operation costs of sludge treatment are huge, and generally account for 30% -50% of the investment and operation costs of the whole sewage treatment plant, so that the sludge treatment is almost a burden of most sewage treatment plants, and the disposal problem becomes more and more prominent.
In recent years, research on excess sludge is gradually becoming a focus, and the anaerobic digestion technology has received great attention because of the advantages of harmlessness, reduction and recycling. Sludge digestion is a complex organic matter degradation and microorganism metabolism process, and the process is mainly divided into three stages, namely a hydrolysis acidification stage, a hydrogen-producing and acetic acid-producing stage and a methane-producing stage. The hydrolysis stage is to convert complex macromolecular organic matters into simple micromolecular or monomer soluble organic matters, and then ferment the organic matters into ethanol, fatty acids and the like through an acidification way, for example, proteins are firstly hydrolyzed into amino acids, and then fatty acids and the like are generated through deamination, and the hydrolysis stage is generally carried out slowly, so the hydrolysis stage is considered as a limiting stage in the anaerobic digestion process of excess sludge; in the hydrogen-producing and acetic acid-producing stage, under the action of hydrogen-producing and acetic acid-producing bacteria, water-soluble small molecule intermediate products such as fatty acid (propionic acid, butyric acid and the like) and alcohol (ethanol and the like) and the like produced in the first stage are converted into acetic acid, H2 and CO 2; the methanogenic stage refers to the methane bacteria converting formic acid, acetic acid, methanol, CO2, H2 and the like generated in the second stage into methane through different paths. However, the traditional anaerobic digestion technology has the defects of slow reaction speed, long retention time, low methane production efficiency, low organic matter degradation rate and the like, thereby limiting the popularization and application of the technology. In order to improve the traditional anaerobic digestion technology, researchers have researched various strengthening methods, which are commonly implemented by sludge strengthening pretreatment methods, such as physical and chemical methods like ultrasonic wave, heat treatment, ozone, acid and alkali, however, the pretreatment of sludge not only increases the steps of sludge treatment, but also has the disadvantages of high energy consumption and low efficiency.
Chinese patent, application No. 201310244932, published 2013, 6 and 19, discloses a method for accelerating anaerobic fermentation of excess sludge by utilizing a zero-valent iron technology, which comprises the following steps: mixing high-solid sludge with a solid content of less than 10% with scrap iron, loading into an anaerobic fermentation reactor, and inoculating anaerobic microorganisms. The reactor is subjected to anaerobic fermentation under a stirring state, and methane generated in the fermentation process is collected. The stirring speed, the pH value and the temperature in the reactor are required to be controlled in the stirring process. And after the fermentation is finished, discharging the sludge. The residual scrap iron is left in the anaerobic fermentation tank for the next batch of sludge fermentation. The technology promotes the reduction of high-solid sludge to a certain extent, simultaneously improves the generation amount of methane in the fermentation process to a certain extent, and is relatively simple in technical operation, but in the primary sludge digestion process, the dissolution rate of Fe2+ is low, the utilization rate of scrap iron is low, the scrap iron cannot be reused, the effect on microorganisms is limited, the reduction effect of methane yield and sludge is limited, and the method can achieve a certain effect by pretreating the residual sludge in the application process.
Chinese patent application No. 201510018525.2, published on 2015, 1 month and 14 days, discloses a method for improving anaerobic digestion methanogen activity and methanogenesis efficiency by using nano ferroferric oxide, which utilizes nano ferroferric oxide to improve anaerobic digestion methanogen activity and methanogenesis efficiency, the addition of nano ferroferric oxide promotes the degradation of short-chain fatty acid and improves the methane yield and the methane content in methane components, but the effect of the technology on the methanogenesis stage is obviously superior to that of the hydrolysis acidification stage, so that the technology needs to be matched with the use of a strengthening pretreatment technology, the operation of the method is relatively complex, and the nano ferroferric oxide is easy to cause problems of nano pollution and the like.
In the prior art, in the process of treating sludge by using iron, the iron dissolution speed is low, the efficiency is low, meanwhile, a better digestion effect can be realized only by matching with strengthening pretreatment, the iron cannot be recycled, the methane yield is low, the sludge reduction and recycling degree is low, and the application range is narrow.
Disclosure of Invention
1. Problems to be solved
The invention provides an accelerator for accelerating anaerobic digestion of excess sludge, a preparation method and application, aiming at the problems that in the existing treatment process of excess sludge by using iron, the iron dissolution speed is low, the efficiency is low, a better digestion effect can be realized only by matching with strengthening pretreatment, iron cannot be recycled, the methane yield is low, the sludge reduction and recycling degree is low, and the application range is narrow. The accelerant for accelerating anaerobic digestion of excess sludge provided by the invention can be used for carrying out reduction treatment on sludge without external strengthening pretreatment, can be repeatedly used, does not cause secondary pollution of iron, can adapt to sludge with different PH ranges, and has high methane yield in the treatment process.
2. Technical scheme
In order to solve the above problems, the present invention adopts the following technical solutions.
The invention uses excess sludge as raw material, adds polyaluminium chloride aqueous solution and sodium ethylene diamine tetracetate, then uses hydroxide solution and dilute hydrochloric acid to regulate pH value, pyrolyzes, uses dilute hydrochloric acid and zinc chloride to activate, loads magnesium chloride and potassium permanganate to obtain highly activated sludge activated carbon, then mixes with iron powder and common activated carbon according to a specific proportion, presses into balls, sinters to obtain sintered body rough blank, and then presses into shapes, heats and dries the obtained sintered body rough blank and the neutral sludge obtained after treatment in step (1) of the preparation method and adds sodium ethylene diamine tetracetate to obtain the accelerant for accelerating anaerobic digestion of excess sludge. The accelerator for accelerating anaerobic digestion of excess sludge obtained by the invention skillfully utilizes the principle of iron-carbon micro-electrolysis, accelerates the dissolution of iron, and carbon in the accelerator can provide attachment sites for methanogens and is more beneficial to the growth of the methanogens, thereby promoting the methanogenesis process.
A preparation method of an accelerant for accelerating anaerobic digestion of excess sludge is characterized by comprising the following steps: the method comprises the following steps:
(1) adding 20 mass percent of polyaluminum chloride aqueous solution and sodium ethylene diamine tetracetate into the residual sludge, stirring, dehydrating, adding sodium hydroxide solution to adjust the pH value to 10-11, and adjusting the pH value to 7-8 by using dilute hydrochloric acid to obtain neutral sludge; adding a sodium hydroxide solution to adjust the pH to 9-10, and adjusting the pH to 7-8 by using dilute hydrochloric acid to obtain neutral sludge, wherein the pH is adjusted to have the effect that the residual sludge contains inorganic components such as silicon dioxide and the like, and after the pH is adjusted, a binding agent such as sodium silicate and the like can be formed for use, the activated sludge has certain cohesiveness and is used as the binding agent, organic matters and silicate clay minerals in the sludge are completely utilized, the internal pore structure of the accelerant can be improved, and the carbon conversion rate and the reactivity of the accelerant are improved. In addition, the sludge contains iron and aluminum components and is a usable additive of the accelerator.
(2) Equally dividing the neutral sludge obtained in the step (1) into two parts, drying, crushing and carrying out vacuum pyrolysis on one part of neutral sludge to obtain a sludge activated carbon matrix raw material, and reserving the other part of neutral sludge for later use;
(3) soaking the activated carbon matrix raw material obtained in the step (2) in an activating agent, drying, and carbonizing under the protection of nitrogen to obtain a carbonized sludge activated carbon matrix raw material;
(4) soaking the carbonized sludge activated carbon matrix raw material obtained in the step (3) in a loading solution and performing ultrasonic treatment, wherein the loading solution is a mixed solution of a magnesium chloride solution and a potassium permanganate solution, the concentration of the magnesium chloride solution is 0.3-0.5 mol/L, and the concentration of the potassium permanganate solution is 0.1-0.3 mol/L, and drying to obtain sludge activated carbon; soaking the obtained carbonized sludge activated carbon matrix raw material in a loading solution and carrying out ultrasonic treatment, wherein the loading solution is a mixed solution of a magnesium chloride solution and a potassium permanganate solution, the concentration of the magnesium chloride solution is 0.3-0.5 mol/L, and the concentration of the potassium permanganate solution is 0.1-0.3 mol/L, and drying to obtain the sludge activated carbon. Under the condition, magnesium and manganese are loaded, and the accelerator obtained in the later stage can optimally promote anaerobic digestion. Because magnesium promotes sludge digestion to have an optimal concentration, if the concentration is large, the promotion effect is not obviously increased, anaerobic digestion is inhibited, and the concentration is also large to play a role in inhibiting manganese and waste reagents.
(5) Mixing the sludge activated carbon, the iron powder and the common activated carbon obtained in the step (4), wherein the weight ratio of the sludge activated carbon to the iron powder to the common activated carbon is (10-15): (10-30): (10-15) pelletizing and sintering to obtain a sintered body rough blank; the process of preparing the rough blank of the invention does not need an adhesive, only needs the sludge activated carbon, the iron powder and the common activated carbon to be mixed and pressed according to the proportion, and has the advantages that the sludge activated carbon is not only used as the raw material of the accelerant, but also used as the adhesive, the usage amount of the common activated carbon and the adhesive is reduced, and the performance of the accelerant is enhanced by adding the common activated carbon. The preparation method is simple, and the prepared rough blank has stable performance and is easy to perform secondary manufacturing and molding.
(6) And (3) pressing and forming the rough sintered body blank obtained in the step (5), the neutral sludge obtained in the step (1) and sodium ethylene diamine tetracetate, wherein the rough sintered body blank is prepared by the following steps: the neutral sludge: and (3) the weight ratio of the sodium ethylene diamine tetracetate is (5-10): 5-7): 1, the diameter of the pressed ball is 3-5 mm, and the ball is dried to obtain the accelerator for accelerating anaerobic digestion of the excess sludge. The accelerant obtained by the invention skillfully utilizes the principle of iron-carbon micro-electrolysis, accelerates the dissolution of iron, carbon in the accelerant can provide attachment sites for methanogenic bacteria, the iron and the carbon are skillfully combined, the hydrolytic acidification and methanogenesis in anaerobic digestion are effectively promoted, the existence of ethylene diamine tetraacetic acid and Mn widens the pH range of the accelerant in sludge treatment, so that the accelerant can be directly used for treating sludge without regulating the pH of the sludge, the complicated pH regulation steps are reduced, the cost is reduced, the residual sludge is changed into valuable, the useful accelerant and methane are changed, and the sludge digestion speed is accelerated.
Preferably, the volume ratio of the excess sludge in the step (1) to the polyaluminum chloride aqueous solution with the mass concentration of 20% is 1 (0.005-0.01), and the weight ratio of the excess sludge to the sodium ethylene diamine tetracetate is 1: (0.01-0.04), stirring for 1-2 hours at a stirring speed of 200-300 r/min, and dehydrating until the water content is 75-85%. The method comprises the steps of adding 20% of polyaluminum chloride aqueous solution and sodium ethylene diamine tetracetate into excess sludge to precipitate sludge and heavy metals in the sludge, wherein the volume ratio of the excess sludge to the 20% of polyaluminum chloride aqueous solution is (1), (0.005-0.01), and the weight ratio of the excess sludge to the sodium ethylene diamine tetracetate is (1): (0.01-0.04), so that most of sludge is precipitated and useful metal elements are chelated, the subsequent dehydration time is greatly reduced, the least amount of polyaluminum chloride and sodium ethylene diamine tetracetate is used, the secondary pollution to the environment is reduced, and the interference on the preparation of the accelerator is relieved most importantly.
Preferably, in the step (2), the drying temperature is 80-120 ℃, the drying time is 20-24 hours, the pyrolysis temperature is 400-500 ℃, and the pyrolysis time is 1-2 hours.
Preferably, the activator in the step (3) is obtained by mixing dilute hydrochloric acid and a zinc chloride aqueous solution, the concentration of the dilute hydrochloric acid is 1-2 mol/L, the concentration of the zinc chloride aqueous solution is 1-2 mol/L, the volume ratio of the dilute hydrochloric acid to the zinc chloride aqueous solution is 1:2, the weight of the activator added to each liter of carbonized sludge activated carbon matrix raw material is 20-40 g, the soaking time is 20-24 hours, the drying time is 10-15 hours, and the carbonization temperature is 400-600 ℃.
Preferably, the ultrasonic time in the step (4) is 1-2 hours, the drying time is 10-12 hours, and the drying temperature is 90-110 ℃. The drying temperature of the magnesium and manganese loaded accelerator is 90-110 ℃, the magnesium and manganese can be quickly released in the using process of the accelerator under the condition, and the energy can be saved and the accelerator is easy to control in the loading process.
Preferably, the diameter of the pressed ball in the step (5) is 1-2 mm, the sintering temperature is 1050-1300 ℃, and the sintering time is 3-5 hours.
Preferably, in the step (6), the drying time is 10-12 hours, and the drying temperature is 200-250 ℃.
An accelerator for accelerating anaerobic digestion of excess sludge, which is characterized in that: the accelerator obtained by the production method according to any one of claims 1 to 7.
Preferably, the accelerant for accelerating anaerobic digestion of the excess sludge and hydrogen peroxide are added into the excess sludge to be treated, the mixture is stirred, inoculated sludge is added for anaerobic digestion, the mass concentration of the hydrogen peroxide is 30%, and the mass ratio of the excess sludge to be treated is as follows: accelerator for accelerating anaerobic digestion of excess sludge: the weight ratio of hydrogen peroxide to water is 1000 (30-40): 1, the anaerobic digestion time is 15-20 days.
Preferably, the mass ratio of the excess sludge to the inoculated sludge is (7-9): 3-1, the stirring speed is 180rpm, and the stirring time is 48 hours.
In the application of the accelerant in the anaerobic digestion of the excess sludge, the ratio of the excess sludge to the inoculated sludge is 7-9: 3-1, and the ratio is found through the arduous exploration of the inventor, when the ratio of the excess sludge to the inoculated sludge is below 7:3, the speed of the anaerobic digestion process is not obviously increased, the quantity of the excess sludge which can be treated at one time is reduced, and when the ratio of the excess sludge to the inoculated sludge is more than 9:1, the anaerobic digestion rate is obviously reduced, so that the digestion is not facilitated; when the ratio is between the two, the rate of digestion increases significantly with increasing ratio.
3. Advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
(1) the obtained accelerant skillfully utilizes the principle of iron-carbon micro-electrolysis, accelerates the dissolution of iron, effectively promotes the hydrolytic acidification and methanogenesis in anaerobic digestion due to the ingenious combination of iron and carbon, widens the pH range of the accelerant in sludge treatment, enables the sludge to be directly treated by the accelerant without pH adjustment, reduces the complicated pH adjustment steps, reduces the cost, changes the residual sludge into valuable, becomes a useful accelerant and methane, and accelerates the sludge digestion speed;
(2) the method comprises the steps of adding 20% of polyaluminum chloride aqueous solution and sodium ethylene diamine tetracetate into excess sludge to precipitate sludge and heavy metals in the sludge, wherein the volume ratio of the excess sludge to the 20% of polyaluminum chloride aqueous solution is (1), (0.005-0.01), and the weight ratio of the excess sludge to the sodium ethylene diamine tetracetate is (1): (0.01-0.04), so that most of sludge can be precipitated and useful metal elements can be chelated, the subsequent dehydration time is greatly reduced, the least amount of polyaluminum chloride and sodium ethylene diamine tetracetate can be used, the secondary pollution to the environment is reduced, and the interference on the preparation of the accelerator is relieved;
(3) adding a sodium hydroxide solution to adjust the pH to 9-10, and adjusting the pH to 7-8 by using dilute hydrochloric acid to obtain neutral sludge, wherein the pH is adjusted to have the effect that the residual sludge contains inorganic components such as silicon dioxide and the like, and after the pH is adjusted, a binding agent such as sodium silicate and the like can be formed for use, the activated sludge has certain cohesiveness and is used as the binding agent, organic matters and silicate clay minerals in the sludge are completely utilized, the internal pore structure of the accelerant can be improved, and the carbon conversion rate and the reactivity of the accelerant are improved. In addition, the sludge contains iron and aluminum components, which are usable additives of the accelerator;
(4) soaking the obtained carbonized sludge activated carbon matrix raw material in a loading solution and carrying out ultrasonic treatment, wherein the loading solution is a mixed solution of a magnesium chloride solution and a potassium permanganate solution, the concentration of the magnesium chloride solution is 0.3-0.5 mol/L, and the concentration of the potassium permanganate solution is 0.1-0.3 mol/L, and drying to obtain the sludge activated carbon. Under the condition, magnesium and manganese are loaded, and the accelerator obtained in the later stage can optimally promote anaerobic digestion. Because magnesium promotes sludge digestion to have an optimal concentration, if the concentration is high, the promotion effect is not obviously increased, anaerobic digestion is inhibited, and reagents are wasted;
(5) the process of preparing the rough blank of the invention does not need an adhesive, only needs the sludge activated carbon, the iron powder and the common activated carbon to be mixed and pressed according to the proportion, and has the advantages that the sludge activated carbon is not only used as the raw material of the accelerant, but also used as the adhesive, the usage amount of the common activated carbon and the adhesive is reduced, and the performance of the accelerant is enhanced by adding the common activated carbon. The preparation method is simple, and the prepared rough blank has stable performance and is easy to perform secondary manufacturing and molding;
(6) the drying temperature of the magnesium and manganese loaded accelerator is 90-110 ℃, the magnesium and manganese can be quickly released in the using process of the accelerator under the condition, and the energy can be saved and the control is easy in the loading process;
Detailed Description
The invention is further described with reference to specific examples.
Example 1
Preparation of accelerator for accelerating anaerobic digestion of excess sludge
Weighing 20L of excess sludge in a secondary sedimentation tank, weighing 20kg, adding 100ml of 20 mass percent polyaluminum chloride aqueous solution into the 20L of excess sludge, then adding 200g of sodium ethylene diamine tetracetate, stirring for 1 hour at a stirring speed of 200r/min, dehydrating until the water content is 75%, adding a sodium hydroxide solution to adjust the pH to 10-11, adjusting the pH to 7-8 with dilute hydrochloric acid to obtain neutral sludge, dividing the obtained neutral sludge into two parts, drying one part of the neutral sludge at a drying temperature of 80 ℃ for 20 hours, crushing, performing vacuum pyrolysis at a pyrolysis temperature of 400 ℃ for 1 hour to obtain a sludge activated carbon matrix raw material, leaving the other part of the neutral sludge for later use, soaking the obtained activated carbon matrix raw material in an activating agent, drying for 10 hours, carbonizing under the protection of nitrogen at 400 ℃ to obtain a carbonized sludge activated carbon matrix raw material, mixing an activating agent with a dilute hydrochloric acid and a zinc chloride aqueous solution, wherein the concentration of the dilute hydrochloric acid is 1mol/L, the concentration of the zinc chloride aqueous solution is 1mol/L, the volume ratio of the dilute hydrochloric acid to the zinc chloride aqueous solution is 1:2, the weight of the activating agent added into each liter of carbonized sludge activated carbon matrix raw material is 20g, the soaking time is 20 hours, soaking the obtained carbonized sludge activated carbon matrix raw material in a loading solution and performing ultrasonic treatment, the ultrasonic treatment time is 1 hour, the negative carrier liquid is a mixed solution of a magnesium chloride solution and a potassium permanganate solution, the concentration of the magnesium chloride solution is 0.3mol/L, the concentration of the potassium permanganate solution is 0.1mol/L, drying is performed for 10 hours, the drying temperature is 90 ℃, sludge activated carbon is obtained, and the obtained sludge activated carbon is obtained, Mixing iron powder and common activated carbon, wherein the weight ratio of the sludge activated carbon to the iron powder to the common activated carbon is 10:10:15, preparing a ball, wherein the diameter of the pressed ball is 1-2 mm, sintering at 1050 ℃ for 3 hours to obtain a sintered body rough blank, putting the obtained sintered body rough blank, another part of neutral sludge and sodium ethylene diamine tetracetate, wherein the pH of the neutral sludge is adjusted to 7-8 by dilute hydrochloric acid, and the obtained sintered body rough blank is subjected to compression molding: the neutral sludge: and (3) the weight ratio of the sodium ethylene diamine tetracetate is 5:5:1, the diameter of the pressed ball is 3-5 mm, and the ball is dried for 10 hours at the drying temperature of 200 ℃ to obtain the accelerator for accelerating anaerobic digestion of the residual sludge.
Example 2
Preparation of accelerator for accelerating anaerobic digestion of excess sludge
Weighing 20L of excess sludge in a secondary sedimentation tank, weighing 20kg, adding 140ml of 20 mass percent polyaluminum chloride aqueous solution into the 20L of excess sludge, then adding 400g of sodium ethylene diamine tetracetate, stirring for 1.5 hours at a stirring speed of 250r/min, dehydrating until the water content is 80%, adding sodium hydroxide solution to adjust the pH value to 10-11, then adjusting the pH value to 7-8 with dilute hydrochloric acid to obtain neutral sludge, dividing the obtained neutral sludge into two parts, drying one part of the neutral sludge at a drying temperature of 100 ℃ for 22 hours, crushing, performing vacuum pyrolysis at a pyrolysis temperature of 450 ℃ for 1.5 hours to obtain a sludge activated carbon matrix raw material, reserving the other part of the neutral sludge for later use, soaking the obtained activated carbon matrix raw material in an activating agent, drying for 12.5 hours, carbonizing under the protection of nitrogen at 500 ℃ to obtain a carbonized sludge activated carbon matrix raw material, mixing an activating agent with dilute hydrochloric acid and a zinc chloride aqueous solution, wherein the concentration of the dilute hydrochloric acid is 1.5mol/L, the concentration of the zinc chloride aqueous solution is 1.5mol/L, the volume ratio of the dilute hydrochloric acid to the zinc chloride aqueous solution is 1:2, the weight of the activating agent added into each liter of carbonized sludge activated carbon matrix raw material is 30g, the soaking time is 22 hours, soaking the carbonized sludge activated carbon matrix raw material in a loading liquid and performing ultrasonic treatment, the ultrasonic treatment time is 1.5 hours, the loading liquid is a mixed liquid of a magnesium chloride solution and a potassium permanganate solution, the concentration of the magnesium chloride solution is 0.4mol/L, the concentration of the potassium permanganate solution is 0.2mol/L, drying is performed for 11 hours, the drying temperature is 100 ℃, so as to obtain sludge activated carbon, and drying the sludge activated carbon, Iron powder and common activated carbon are mixed to prepare balls, and the weight ratio of the sludge activated carbon to the iron powder to the common activated carbon can be 10-15: 10-30: 10-15, preferably 15:30:10 or preferably 10:10:15, the diameter of the pressed ball is 1-2 mm, sintering is carried out at 1200 ℃ for 3-5 hours to obtain a sintered body rough blank, the obtained sintered body rough blank, another part of neutral sludge after the pH is adjusted to 7-8 by dilute hydrochloric acid and sodium ethylene diamine tetracetate are put together for press forming, and the sintered body rough blank: the neutral sludge: the weight ratio of the sodium ethylene diamine tetracetate is 5-10: 5-7: 1, preferably 10:7:1 or 7.5:6:1, the diameter of a pressed ball is 3-5 mm, and the ball is dried for 11 hours at the drying temperature of 225 ℃ to obtain the accelerator for accelerating anaerobic digestion of excess sludge.
Example 3
Preparation of accelerator for accelerating anaerobic digestion of excess sludge
Weighing 20L of excess sludge in a secondary sedimentation tank, weighing 20kg, adding 200ml of 20 mass percent polyaluminum chloride aqueous solution into the 20L of excess sludge, then adding 800g of sodium ethylene diamine tetracetate, stirring for 2 hours at a stirring speed of 300r/min, dehydrating until the water content is 85%, adding sodium hydroxide solution to adjust the pH to 10-11, adjusting the pH to 7-8 with dilute hydrochloric acid to obtain neutral sludge, dividing the obtained neutral sludge into two parts, drying one part of the neutral sludge at a drying temperature of 120 ℃ for 24 hours, crushing, performing vacuum pyrolysis at a pyrolysis temperature of 500 ℃ for 2 hours to obtain a sludge activated carbon matrix raw material, leaving the other part of the neutral sludge for later use, soaking the obtained activated carbon matrix raw material in an activating agent, drying for 15 hours, carbonizing under the protection of nitrogen at 600 ℃ to obtain a carbonized sludge activated carbon matrix raw material, mixing an activating agent with dilute hydrochloric acid and a zinc chloride aqueous solution, wherein the concentration of the dilute hydrochloric acid is 2mol/L, the concentration of the zinc chloride aqueous solution is 2mol/L, the volume ratio of the dilute hydrochloric acid to the zinc chloride aqueous solution is 1:2, the weight of the activating agent added into each liter of carbonized sludge activated carbon matrix raw material is 40g, the soaking time is 24 hours, soaking the obtained carbonized sludge activated carbon matrix raw material in a loading solution and performing ultrasonic treatment for 2 hours, the negative carrier liquid is a mixed solution of a magnesium chloride solution and a potassium permanganate solution, the concentration of the magnesium chloride solution is 0.5mol/L, the concentration of the potassium permanganate solution is 0.3mol/L, drying is performed for 12 hours, the drying temperature is 110 ℃, so as to obtain sludge activated carbon, and drying the obtained sludge activated carbon, Mixing iron powder and common activated carbon, and pressing into balls, wherein the weight ratio of the sludge activated carbon to the iron powder to the common activated carbon can be 10-15: 10-30: 10-15, preferably 10:30:15 or preferably 10:20:13, the diameter of the pressed ball is 1-2 mm, sintering is carried out at 1300 ℃, the sintering time is 5 hours, a sintered body rough blank is obtained, the obtained sintered body rough blank, another part of neutral sludge after the pH is adjusted to 7-8 by dilute hydrochloric acid and sodium ethylene diamine tetracetate are put together, and the mixture is pressed and formed, wherein the weight ratio of the neutral sludge: the weight ratio of the sodium ethylene diamine tetracetate is 5-10: 5-7: 1, preferably 10:7:1 or 7.5:6:1, the diameter of a pressed ball is 3-5 mm, and the ball is dried for 12 hours at the drying temperature of 250 ℃ to obtain the accelerator for accelerating anaerobic digestion of excess sludge.
Example 4
Control group
Taking 1L of excess sludge in a secondary sedimentation tank, wherein the physicochemical properties of the sludge are shown in Table 1, adjusting the pH to 12 by using 4mol/LNaOH, mechanically stirring for 6h at 8rpm for pretreatment, then adjusting the pH to 7, inoculating 100ml of anaerobic sludge in an anaerobic reactor which runs stably in a laboratory, sealing the reactor, stirring by using an electric stirrer at the stirring speed of 80rpm, controlling the pH to 7 and carrying out anaerobic digestion at the temperature of 35 +/-1 ℃ for 20 days. The results after the reaction are shown in Table 2.
TABLE 1 physicochemical indices of excess sludge in secondary sedimentation tank
| TSS | 14.8 | Total protein | 8021 |
| VSS | 9.53 | Soluble protein | 201 |
| TCOD | 14707 | Total polysaccharides | 1845 |
| SCOD | 4010 | Soluble polysaccharides | 58 |
Note: the total protein, the soluble protein, the total polysaccharide and the soluble polysaccharide are all calculated by COD; except for TSS and VSS in g/L, the other units are mg/L.
TABLE 2 sludge anaerobic digestion treatment effect without addition of example agent
| Accumulated gas production | Methane content | Decrement rate (in VSS) |
| 1.4L | 59.6％ | 39.2％ |
Example 5
Taking 1L of excess sludge which is the same as that in a control group for fermentation, wherein the weight of the excess sludge is 1.0kg, directly placing the sludge in an anaerobic fermentation tank, adding 30g of the accelerator for accelerating the anaerobic digestion of the excess sludge obtained in the example 1 into the excess sludge to be treated, adding 1.0g of hydrogen peroxide with the mass concentration of 30%, stirring at 180rpm for 48h, then adding 385g of inoculated sludge, stirring and anaerobically digesting the inoculated sludge which is the anaerobic sludge in an anaerobic digester which runs stably in a laboratory, sealing the reactor, stirring by an electric stirrer at the stirring speed of 80rpm, controlling the pH to be 7, controlling the temperature to be 35 +/-1 ℃, and anaerobically digesting for 15 days. The results after the reaction are shown in Table 3.
TABLE 3 post-treatment effect of addition of the accelerators obtained in example 1
| Accumulated gas production | Methane content | Decrement rate (in VSS) |
| 1.8L | 68.8％ | 48％ |
Example 6
Taking 1L of excess sludge which is the same as that in a control group for fermentation, wherein the weight of the excess sludge is 1.0kg, directly placing the sludge in an anaerobic fermentation tank, adding 35g of the accelerator for accelerating the anaerobic digestion of the excess sludge obtained in the example 2 into the excess sludge to be treated, adding 1g of hydrogen peroxide with the mass concentration of 30%, stirring at 180rpm for 48h, adding 167g of inoculation sludge, wherein the inoculation sludge is anaerobic sludge in an anaerobic digester which runs stably in a laboratory, stirring, carrying out anaerobic digestion, sealing the reactor, stirring by an electric stirrer at the stirring speed of 80rpm, controlling the pH to be 7, controlling the temperature to be 35 +/-1 ℃, and carrying out anaerobic digestion for 18 days. The results after the reaction are shown in Table 4.
TABLE 4 post-treatment effect of addition of the accelerators obtained in example 2
| Accumulated gas production | Methane content | Decrement rate (in VSS) |
| 2.1L | 73.2％ | 56％ |
Example 7
Taking 1L of the same excess sludge in a control group for fermentation, wherein the weight of the excess sludge is 1.0kg, directly placing the sludge in an anaerobic fermentation tank, adding 40g of the accelerator for accelerating the anaerobic digestion of the excess sludge obtained in the example 1 into the excess sludge to be treated, adding 1g of hydrogen peroxide with the mass concentration of 30%, stirring at 180rpm for 48h, then adding 111g of inoculation sludge, wherein the inoculation sludge is anaerobic sludge in an anaerobic digester which runs stably in a laboratory, stirring, performing anaerobic digestion, sealing a reactor, stirring by an electric stirrer at the stirring speed of 80rpm, controlling the pH to be 7, controlling the temperature to be 35 +/-1 ℃, and performing anaerobic digestion for 15 days. The results after the reaction are shown in Table 5.
TABLE 5 post-treatment effect of addition of the accelerators obtained in example 3
| Accumulated gas production | Methane content | Decrement rate (in VSS) |
| 2.0L | 70.5％ | 52％ |
Claims (10)
1. A preparation method of an accelerant for accelerating anaerobic digestion of excess sludge is characterized by comprising the following steps: the method comprises the following steps:
(1) adding 20% of polyaluminum chloride aqueous solution and sodium ethylene diamine tetracetate into the residual sludge, wherein the volume ratio of the residual sludge to the 20% of polyaluminum chloride aqueous solution is 1 (0.005-0.01), and the weight ratio of the residual sludge to the sodium ethylene diamine tetracetate is 1: (0.01-0.04), stirring, dehydrating, adding a sodium hydroxide solution to adjust the pH to 10-11, and adjusting the pH to 7-8 by using dilute hydrochloric acid to obtain neutral sludge;
(2) equally dividing the neutral sludge obtained in the step (1) into two parts, drying, crushing and carrying out vacuum pyrolysis on one part of neutral sludge to obtain a sludge activated carbon matrix raw material, and reserving the other part of neutral sludge for later use;
(3) soaking the activated carbon matrix raw material obtained in the step (2) in an activating agent, drying, and carbonizing under the protection of nitrogen to obtain a carbonized sludge activated carbon matrix raw material;
(4) soaking the carbonized sludge activated carbon matrix raw material obtained in the step (3) in a loading solution and performing ultrasonic treatment, wherein the loading solution is a mixed solution of a magnesium chloride solution and a potassium permanganate solution, the concentration of the magnesium chloride solution is 0.3-0.5 mol/L, and the concentration of the potassium permanganate solution is 0.1-0.3 mol/L, and drying to obtain sludge activated carbon;
(5) mixing the sludge activated carbon, the iron powder and the common activated carbon obtained in the step (4), wherein the weight ratio of the sludge activated carbon to the iron powder to the common activated carbon is (10-15): (10-30): (10-15) pelletizing and sintering to obtain a sintered body rough blank;
(6) and (3) pressing and forming the rough sintered body blank obtained in the step (5), the neutral sludge obtained in the step (1) and sodium ethylene diamine tetracetate, wherein the rough sintered body blank is prepared by the following steps: the neutral sludge: and (3) the weight ratio of the sodium ethylene diamine tetracetate is (5-10): 5-7): 1, the diameter of the pressed ball is 3-5 mm, and the ball is dried to obtain the accelerator for accelerating anaerobic digestion of the excess sludge.
2. The method of producing an accelerator for accelerating anaerobic digestion of excess sludge according to claim 1, wherein: the stirring time in the step (1) is 1-2 hours, the stirring speed is 200-300 r/min, and the dehydration is carried out until the water content is 75-85%.
3. The method of producing an accelerator for accelerating anaerobic digestion of excess sludge according to claim 2, wherein: and (2) drying at the temperature of 80-120 ℃ for 20-24 hours, pyrolyzing at the temperature of 400-500 ℃ for 1-2 hours.
4. The method for producing an accelerator for accelerating anaerobic digestion of excess sludge according to any one of claims 1 to 3, wherein: the activating agent in the step (3) is obtained by mixing dilute hydrochloric acid and a zinc chloride aqueous solution, the concentration of the dilute hydrochloric acid is 1-2 mol/L, the concentration of the zinc chloride aqueous solution is 1-2 mol/L, the volume ratio of the dilute hydrochloric acid to the zinc chloride aqueous solution is 1:2, the weight of the activating agent added to each liter of carbonized sludge activated carbon matrix raw material is 20-40 g, the soaking time is 20-24 hours, the drying time is 10-15 hours, and the carbonization temperature is 400-600 ℃.
5. The method of producing an accelerator for accelerating anaerobic digestion of excess sludge according to claim 1, 2 or 3, wherein: the ultrasonic time in the step (4) is 1-2 hours, the drying time is 10-12 hours, and the drying temperature is 90-110 ℃.
6. The method of producing an accelerator for accelerating anaerobic digestion of excess sludge according to claim 2, wherein: the diameter of the pressed balls in the step (5) is 1-2 mm, the sintering temperature is 1050-1300 ℃, and the sintering time is 3-5 hours.
7. The method of producing an accelerator for accelerating anaerobic digestion of excess sludge according to claim 6, wherein: and (6) drying for 10-12 hours at the drying temperature of 200-250 ℃.
8. An accelerator for accelerating anaerobic digestion of excess sludge, which is characterized in that: the accelerator obtained by the production method according to any one of claims 1 to 7.
9. Use of an accelerator for accelerating anaerobic digestion of excess sludge according to claim 8 in anaerobic digestion of excess sludge, characterized in that: adding the accelerant for accelerating anaerobic digestion of the excess sludge and hydrogen peroxide into the excess sludge to be treated, stirring, adding inoculated sludge, and performing anaerobic digestion, wherein the mass concentration of the hydrogen peroxide is 30%, and the mass concentration of the excess sludge to be treated is as follows: accelerator for accelerating anaerobic digestion of excess sludge: the weight ratio of hydrogen peroxide to water is 1000 (30-40): 1, the anaerobic digestion time is 15-20 days.
10. The method of using an accelerator for accelerating anaerobic digestion of excess sludge according to claim 9, wherein: the mass ratio of the residual sludge to the inoculated sludge is (7-9) to (3-1), the stirring speed is 180rpm, and the stirring time is 48 hours.
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