CN108640484B

CN108640484B - Preparation method of sludge dehydrating agent

Info

Publication number: CN108640484B
Application number: CN201810543614.2A
Authority: CN
Inventors: 胡次兵; 庄文琴; 刘红妹
Original assignee: Dongguan Dosheng Environmental Protection Technology Co ltd
Current assignee: DONGGUAN DOSHENG ENVIRONMENTAL PROTECTION TECHNOLOGY Co.,Ltd.
Priority date: 2018-05-31
Filing date: 2018-05-31
Publication date: 2020-12-22
Anticipated expiration: 2038-05-31
Also published as: CN108640484A

Abstract

The invention discloses a preparation method of a sludge dehydrating agent, belonging to the field of environmental protection. The invention utilizes ferric chloride hexahydrate and sodium borohydride to prepare zero-valent iron nanoparticles, the oxidation reaction of adding zero-valent iron in sulfuric acid to convert the zero-valent iron into ferrous iron is realized through a two-electron transfer reaction, oxygen molecules are activated into hydrogen peroxide, and after the electrons are transferred to an iron oxide nuclear shell layer, the electrons are adsorbed on electrophilic oxygen molecules on the surface and captured, so that the sludge has preoxidation effect, and can be degraded into substances with smaller molecular weight, thereby being beneficial to combining water release and converting into free water, accelerating the release of water, simultaneously generating hydroxyl free radicals, decomposing the sludge, accelerating the dehydration process and shortening the dehydration time. The invention solves the problems that the existing sludge dehydrating agent has long dehydrating time, generates a large amount of gas accompanied with odor in the process and has low dehydrating effect.

Description

Preparation method of sludge dehydrating agent

Technical Field

The invention belongs to the field of environmental protection, and particularly relates to a preparation method of a sludge dehydrating agent.

Background

The sludge is a final product of sewage treatment, and has high pollutant concentration, complex components, high organic matter content and strong hydrophilicity. It uses aerobic and anaerobic microorganisms as main body, and at the same time, it also mixes the sludge sand, fibre and animal and plant residues carried by the original sewage and various complex mixtures of organic matter, metal, germ, ova and colloid adsorbed on them. For sewage treatment plants in large cities, the heavy metal content in sewage sludge is higher due to the fact that a large amount of industrial wastewater is discharged into the system, wherein the copper and zinc content is often close to or exceeds the acceptance standard of the sludge as agricultural compost, the sludge discharged from the sewage treatment plants is generally a loose peptization paste with the water content of 95-99%, and the peptization paste has the physicochemical characteristics of light specific gravity, large volume, strong thixotropy (difficult dehydration) and extremely easy putrefaction and malodor, so that the treatment and the transportation are not very facilitated. The sludge dewatering is a very key link for reducing the subsequent treatment and disposal cost of the sludge as the most important pretreatment process, and can greatly reduce the accumulation field of the sludge, save the transportation cost, reduce the percolate of a landfill site and prevent the landfill from damaging the surface and underground water environment. When the sludge is subjected to composting treatment, the moisture content of the sludge can be greatly reduced by sludge dehydration, so that the requirement of the compost on the sludge with low moisture content can be met. The sludge usually contains a large amount of water, resulting in a very large volume of sludge, and therefore the sludge must be dewatered to reduce the volume of the sludge.

At present, one or more chemical agents are often used for conditioning the sludge, so that the properties of sludge particles are changed, and the moisture contained in the sludge is conveniently removed. The most commonly used sludge dewatering agents are Cationic Polyacrylamide (CPAM), polyacrylamide, iron salt, aluminum salt, hydrated lime and the like, but at present, the principle of the dewatering agent is mainly to destroy cell walls of microorganisms in the sludge, release a large amount of bound water contained in the cells, and remove water in the sludge by a natural air drying method, so that the dewatering time is long, and a large amount of gas accompanied with odor is generated in the air drying process. Therefore, it is important to produce a sludge-dewatering agent which can meet the use requirements.

Disclosure of Invention

The technical problems to be solved by the invention are as follows: aiming at the problems that the prior sludge dehydrating agent has long dehydrating time, generates a large amount of odor accompanied gas in the process and has low dehydrating effect, the preparation method of the sludge dehydrating agent is provided.

In order to solve the technical problems, the invention adopts the following technical scheme:

a preparation method of a sludge dehydrating agent is characterized by comprising the following steps:

(1) taking magnesium nitrate according to a mass ratio of 1-3: 1-4: 5-7, adding aluminum nitrate and deionized water, stirring and mixing for 20-30 min to obtain a stirring mixture, taking 5-7 parts of sodium carbonate: 2-4: 10-13, adding sodium hydroxide and deionized water, and mixing to obtain a stirring mixture a, wherein the stirring mixture a is prepared from the following components in a mass ratio of 5: 3, adding the stirred mixture, adding ammonia water with the concentration of 0.5mol/L to adjust the pH value to 9-9.5, stirring and mixing for 5-8 min, aging at 60-65 ℃ for 15-18 h, dialyzing, concentrating and drying to obtain a dried substance;

(2) taking acrylamide according to the mass ratio of 1-3: 2-4: 4-7, adding the dried substance and distilled water, mixing, adding acryloyloxyethyl dimethyl benzyl ammonium chloride with the mass being 10-20% of that of acrylamide, stirring and mixing at 30-40 ℃ for 30-40 min to obtain a mixture, and taking the mixture according to the mass ratio of 80-90: 1, adding urea, adjusting the pH value to 4-5, introducing nitrogen for protection, adding azodiisobutymidine hydrochloride accounting for 20-30% of the mass of the urea, irradiating for 50-60 min under ultraviolet light, and then preserving heat for 12-15 h at 30-40 ℃ to obtain a matrix substance;

(3) taking ferric chloride hexahydrate according to the mass ratio of 3-8: 80-100, adding deionized water, mixing to obtain a mixed solution, and taking sodium borohydride according to a mass ratio of 6-9: 60-80, adding deionized water, and mixing to obtain a mixed solution A, wherein the mixed solution A is prepared from the following raw materials in a mass ratio of 2: 3, adding the mixed solution, stirring and mixing for 2-3 h at 25-30 ℃, standing for 3-5 h, filtering, taking filter residues for drying to obtain a dried substance a, taking the dried substance a according to a mass ratio of 2: 5-7, adding a base material and mixing to obtain a sludge dehydrating agent base material;

(4) taking rosin according to a mass ratio of 1: 5-7, adding distilled water, performing microwave treatment at the temperature of 50-60 ℃ under the condition of 130W to obtain a microwave material, and mixing the microwave material according to the mass ratio of 1-3: adding petroleum ether 5-9, extracting at 40-50 ℃, distilling the supernatant under reduced pressure to obtain a reduced pressure distillate, and stirring and mixing 200-300 parts by weight of a sludge dehydrating agent base material, 40-60 parts by weight of the reduced pressure distillate, 2-5 parts by weight of 98% sulfuric acid, 30-50 parts by weight of polyethylene glycol, 12-15 parts by weight of oleylamine polyoxyethylene ether, 3-7 parts by weight of tween-20, 15-20 parts by weight of propylene glycol and 30-50 parts by weight of water at 30-40 ℃ to obtain the sludge dehydrating agent.

Compared with other methods, the method has the beneficial technical effects that:

(1) the intercalation additive is obtained by utilizing the coprecipitation of magnesium nitrate and aluminum nitrate, and can be stripped into a plurality of small lamellar clusters or lamellar sheets in the using process to form secondary polyampholyte molecules, so that the effective content of an active agent in unit volume can be increased, the further hydrolysis process of a framework is accelerated, and a large amount of the active agent is generated in the hydrolysis process Mg(OH)₂And Al (OH)₃Floc, which can adsorb organic impurity molecules while hydrolyzing to provide a large amount of Mg²⁺、Al³⁺The positive charges of the ions can neutralize the negatively charged ions or ion flocs in the sewage or the sludge, the effective distance of the double electric layers is shortened, and the flocculation effect can be obviously increased by the inherent structural characteristics;

(2) according to the invention, acrylamide monomers and acryloyloxyethyl dimethyl benzyl ammonium chloride monomers with amphiphilic structures are subjected to polymerization reaction under ultraviolet light initiation, and then a cationic hydrophobic association flocculant with ionic groups and hydrophobic groups is synthesized, and the hydrophobic groups in the hydrophobic association polyacrylamide interact with each other to enable macromolecular chains to generate intermolecular and intramolecular association so as to form a reversible three-dimensional physical crosslinking network structure, so that the interaction between polymers and small molecules in water can be enhanced, and the flocculation efficiency is improved;

(3) the invention utilizes ferric chloride hexahydrate and sodium borohydride to prepare zero-valent iron nanoparticles, the oxidation reaction of adding the zero-valent iron in sulfuric acid to convert the zero-valent iron into ferrous iron is realized through a two-electron transfer reaction, oxygen molecules are activated into hydrogen peroxide, and the oxygen molecules are captured by electrophilic oxygen molecules adsorbed on the surface after the electrons are transferred to an iron oxide nuclear shell layer, so that the oxygen molecules have preoxidation effect on sludge and can be degraded into substances with smaller molecular weight, thereby being beneficial to combining water release and converting the substances into free water, accelerating the release of water, simultaneously generating hydroxyl radicals to decompose the sludge, accelerating the dehydration process and shortening the dehydration time;

(4) the rosin is used as a raw material for extraction, the main components of the rosin are alpha-pinene and beta-pinene, the rosin is natural volatile aromatic oil, the plant extract can react with acidic odor molecules in sludge due to the alkaloid, while the salt generated by general acid-base reaction is toxic and can not be biodegraded, but the plant extract is non-toxic and biodegradable, and atomized liquid drops in the extract have large specific surface area and surface energy, so that chemical bonds in molecules of pollutants can be destroyed, the spatial configuration of the molecules is changed, and the effect of decomposing the odor molecules is achieved.

Detailed Description

A preparation method of a sludge dehydrating agent comprises the following steps:

(4) taking rosin according to a mass ratio of 1: 5-7, adding distilled water, and performing microwave treatment at the temperature of 50-60 ℃ for 20-30 min under the condition of 130W to obtain a microwave substance, wherein the mass ratio of the microwave substance to the water is 1-3: adding petroleum ether 5-9, extracting at 40-50 ℃ for 2-3 h, taking supernatant liquid, and distilling under reduced pressure to obtain a reduced pressure distillate, wherein 200-300 parts by weight of a sludge dehydrating agent base material, 40-60 parts by weight of the reduced pressure distillate, 2-5 parts by weight of 98% sulfuric acid, 30-50 parts by weight of polyethylene glycol, 12-15 parts by weight of oleylamine polyoxyethylene ether, 3-7 parts by weight of tween-20, 15-20 parts by weight of propylene glycol and 30-50 parts by weight of water are taken, and stirring and mixing at 30-40 ℃ for 1-2 h to obtain the sludge dehydrating agent.

Example 1

(1) taking magnesium nitrate according to a mass ratio of 1: 1: 5, adding aluminum nitrate and deionized water, stirring and mixing for 20min to obtain a stirring mixture, taking sodium carbonate 5: 2: 10, adding sodium hydroxide and deionized water, mixing to obtain a stirring mixture a, and taking the stirring mixture a according to the mass ratio of 5: 3 adding the stirred mixture, adding ammonia water with the concentration of 0.5mol/L to adjust the pH value to 9, stirring and mixing for 5min, aging at 60 ℃ for 15h, dialyzing, concentrating and drying to obtain a dried substance;

(2) taking acrylamide according to the mass ratio of 1: 2: 4, adding the dried substance and distilled water, mixing, adding acryloyloxyethyl dimethyl benzyl ammonium chloride with the mass of 10% of that of acrylamide, stirring and mixing for 30min at the temperature of 30 ℃ to obtain a mixture, and taking the mixture according to the mass ratio of 80: 1 adding urea, adjusting the pH value to 4, introducing nitrogen for protection, adding azodiisobutymidine hydrochloride accounting for 20 percent of the mass of the urea, irradiating for 50min under ultraviolet light, and then preserving heat at 30 ℃ for 12h to obtain a matrix substance;

(3) taking ferric chloride hexahydrate according to the mass ratio of 3: 80, adding deionized water, mixing to obtain a mixed solution, and taking sodium borohydride according to a mass ratio of 6: 60, adding deionized water, mixing to obtain a mixed solution A, and taking the mixed solution A according to a mass ratio of 2: 3, adding the mixed solution, stirring and mixing for 2h at 25 ℃, standing for 3h, filtering, taking filter residues and drying to obtain a dried substance a, taking the dried substance a according to the mass ratio of 2: 5 adding the base material and mixing to obtain a sludge dehydrating agent base material;

(4) taking rosin according to a mass ratio of 1: 5, adding distilled water, performing microwave treatment at the temperature of 50 ℃ for 20min under the condition of 130W to obtain a microwave material, and mixing the microwave material according to the mass ratio of 1: and 5, adding petroleum ether, extracting at 40 ℃ for 2h, distilling the supernatant under reduced pressure to obtain a reduced pressure distillate, and stirring and mixing 200 parts of sludge dehydrating agent base material, 40 parts of reduced pressure distillate, 2 parts of sulfuric acid with the mass fraction of 98%, 30 parts of polyethylene glycol, 12 parts of oleylamine polyoxyethylene ether, 3 parts of tween-20, 15 parts of propylene glycol and 30 parts of water at 30 ℃ for 1h to obtain the sludge dehydrating agent.

Example 2

(1) taking magnesium nitrate according to a mass ratio of 3: 4: 7, adding aluminum nitrate and deionized water, stirring and mixing for 30min to obtain a stirring mixture, taking sodium carbonate 7: 4: 13, adding sodium hydroxide and deionized water, mixing to obtain a stirring mixture a, and taking the stirring mixture a according to the mass ratio of 5: 3 adding the stirred mixture, adding ammonia water with the concentration of 0.5mol/L to adjust the pH value to 9.5, stirring and mixing for 8min, aging at 65 ℃ for 18h, dialyzing, concentrating and drying to obtain a dried substance;

(2) taking acrylamide according to the mass ratio of 3: 4: 7, adding the dried substance and distilled water, mixing, adding acryloyloxyethyl dimethyl benzyl ammonium chloride with the mass of 20% of acrylamide, stirring and mixing at 40 ℃ for 40min to obtain a mixture, and taking the mixture according to the mass ratio of 90: 1 adding urea, adjusting the pH value to 5, introducing nitrogen for protection, adding azodiisobutymidine hydrochloride accounting for 30 percent of the mass of the urea, irradiating for 60min under ultraviolet light, and then preserving heat for 15h at 40 ℃ to obtain a matrix substance;

(3) taking ferric chloride hexahydrate according to the mass ratio of 8: 100, adding deionized water, mixing to obtain a mixed solution, and taking sodium borohydride according to a mass ratio of 9: 80, adding deionized water, and mixing to obtain a mixed solution A, wherein the mixed solution A is prepared from the following raw materials in a mass ratio of 2: 3, adding the mixed solution, stirring and mixing for 3h at 30 ℃, standing for 5h, filtering, taking filter residues and drying to obtain a dried substance a, taking the dried substance a according to the mass ratio of 2: 7 adding the base material and mixing to obtain a sludge dehydrating agent base material;

(4) taking rosin according to a mass ratio of 1: 7, adding distilled water, performing microwave treatment at 130W and 60 ℃ for 30min to obtain a microwave material, and mixing the microwave material according to the mass ratio of 3: 9 adding petroleum ether, extracting at 50 ℃ for 3h, distilling the supernatant under reduced pressure to obtain a reduced pressure distillate, and stirring and mixing 300 parts of sludge dehydrating agent base material, 60 parts of reduced pressure distillate, 5 parts of sulfuric acid with the mass fraction of 98%, 50 parts of polyethylene glycol, 15 parts of oleylamine polyoxyethylene ether, 7 parts of tween-20, 20 parts of propylene glycol and 50 parts of water at 40 ℃ for 2h to obtain the sludge dehydrating agent.

Example 3

(1) taking magnesium nitrate according to a mass ratio of 2: 3: 6, adding aluminum nitrate and deionized water, stirring and mixing for 25min to obtain a stirring mixture, taking sodium carbonate 6: 3: 12, adding sodium hydroxide and deionized water, mixing to obtain a stirring mixture a, and taking the stirring mixture a according to the mass ratio of 5: 3 adding the stirred mixture, adding ammonia water with the concentration of 0.5mol/L to adjust the pH value to 9, stirring and mixing for 7min, aging at 63 ℃ for 17h, dialyzing, concentrating and drying to obtain a dried substance;

(2) taking acrylamide according to a mass ratio of 2: 3: and 5, adding the dried substance and distilled water, mixing, adding acryloyloxyethyl dimethyl benzyl ammonium chloride with the mass of 15% of that of acrylamide, stirring and mixing at 35 ℃ for 35min to obtain a mixture, and taking the mixture according to the mass ratio of 85: 1, adding urea, adjusting the pH value to 4, introducing nitrogen for protection, adding azodiisobutymidine hydrochloride accounting for 25 percent of the mass of the urea, irradiating for 55min under ultraviolet light, and then preserving heat at 35 ℃ for 13h to obtain a matrix substance;

(3) taking ferric chloride hexahydrate according to the mass ratio of 5: 90, adding deionized water, mixing to obtain a mixed solution, and taking sodium borohydride according to a mass ratio of 7: 70, adding deionized water, and mixing to obtain a mixed solution A, wherein the mixed solution A is prepared from the following raw materials in a mass ratio of 2: 3, adding the mixed solution, stirring and mixing for 2h at 27 ℃, standing for 4h, filtering, taking filter residues and drying to obtain a dried substance a, taking the dried substance a according to the mass ratio of 2: 6 adding the base material and mixing to obtain a sludge dehydrating agent base material;

(4) taking rosin according to a mass ratio of 1: 6, adding distilled water, performing microwave treatment at the temperature of 55 ℃ for 25min under the condition of 130W to obtain a microwave material, and mixing the microwave material according to the mass ratio of 2: adding petroleum ether into the mixture 7, extracting the mixture for 2 hours at the temperature of 45 ℃, distilling the supernatant under reduced pressure to obtain a reduced pressure distillate, and stirring and mixing 250 parts of sludge dehydrating agent base material, 50 parts of reduced pressure distillate, 7 parts of sulfuric acid with the mass fraction of 98%, 40 parts of polyethylene glycol, 16 parts of oleylamine polyoxyethylene ether, 5 parts of tween-20, 17 parts of propylene glycol and 40 parts of water at the temperature of 35 ℃ for 1 hour to obtain the sludge dehydrating agent.

Comparative example: a sludge-dewatering agent manufactured by a company of Suzhou city.

The sludge dehydrating agent prepared in the embodiment and the sludge dehydrating agent of the comparative example are respectively applied to sludge to be dehydrated (with the water content of 96-98% and the pH value of 6.8) of a certain municipal sewage treatment plant, the dosage is 50mg/L, the results are observed and recorded after 1 day, and the test results are shown in Table 1.

In conclusion, the sewage dehydrating agent disclosed by the invention has a better dehydrating effect and good environmental friendliness, and is worthy of popularization.

Claims

1. A preparation method of a sludge dehydrating agent is characterized by comprising the following steps: