Treatment method capable of achieving harmless treatment of all activated sludge and complete recycling of products thereof

Abstract

The present invention belongs to the technical field of the treatment of activated sludge, and provides a treatment method capable of achieving harmless treatment of all the activated sludge and complete recycling of the products thereof. The treatment method provided by the present invention comprises the steps of an ultrasonic treatment, a microwave and / or steam treatment, solid-liquid separation, a microbial mineralization treatment, an acidizing treatment, etc. In the present invention, all the steps are linked with one another, activated sludge can be successfully and completely converted into products such as organic fertilizers, ferrite materials and industrial silica sols, and full utilization of the activated sludge is achieved; moreover, the obtained products have a high quality and all meet the related quality standards. The present invention can solve the problems of the complete recycling of activated sludge being impossible to achieve, poor economic benefits, complex processes, etc., in the prior art, and is suitable for industrial development. In the present invention, the emission of greenhouse gases, especially malodorous gases, is avoided throughout the whole treatment process, thorough high-value-added recycling is achieved, and the method is much superior to treatment methods such as drying and incineration.

Description

A treatment method for completely harmless activated sludge and recycling its products Technical Field

[0001] The present invention relates to the technical field of activated sludge treatment, and in particular to a treatment method for completely rendering activated sludge harmless and completely utilizing its products as resources. Background Art

[0002] The activated sludge method for treating urban sewage using biochemical treatment is, in principle, a process of converting suspended, colloidal or dissolved substances in sewage into biochemical solids and separating them from the water body.

[0003] Activated sludge contains large amounts of organic matter and nutrients, pathogens, parasite eggs, heavy metals, and certain toxic, harmful, and difficult-to-degrade organic and inorganic flocculent substances. It is characterized by high moisture content, easy corruption, and foul odor. The sewage treatment process at municipal sewage treatment plants inevitably produces activated sludge. In a sense, the activated sludge process for treating municipal sewage sludge merely concentrates, converts, and separates toxic and harmful components in the wastewater, rather than providing a complete treatment process. Treating activated sludge according to the present invention safeguards and enhances the environmental performance of municipal sewage treatment plants.

[0004] Activated sludge treatment is an important part of water pollution control and water environment protection. It is also a major issue facing related sewage treatment plants and urban sanitary environment. Activated sludge treatment is also recognized as one of the most difficult pollutants to treat.

[0005] The prior art discloses a variety of activated sludge treatment methods, such as the one disclosed in Chinese Patent CN104230129A, which includes the following steps: 1. adding a heavy metal adsorbent to the sludge sedimentation tank of a sewage biological treatment unit; 2. sludge concentration; 3. anaerobic digestion of the sludge; 4. mechanical filter pressing and dehydration; 5. microbial remediation; 6. disinfection of the sludge cake; 7. feeding the sludge cake into an ultrasonic electric heating device; 8. feeding the sludge cake into a filter press again for mechanical filter pressing and dehydration; 9. feeding the sludge cake into a granulator for granulation, drying, and packaging. Using this method to treat sludge can completely remove heavy metal ions and volatile organic compounds from the sludge. However, in this solution, the difficult-to-decompose volatile organic compounds quickly escape from the sludge, and the heavy metal ions are only simply adsorbed. Hazardous waste is still generated during the process, increasing additional treatment costs. Furthermore, this solution cannot fully recycle the activated sludge, resulting in poor economic benefits.

[0006] Chinese patent CN101591130A discloses a method for treating activated sludge with complete resource utilization and zero emissions. The method uses ultrasonic cell wall disruption to dissolve the contents of the bacteria, removes heavy metals, and separates the organic and inorganic parts. The organic part is used to prepare microbial protein, and the inorganic part is used to prepare organic fertilizer. However, the step of preparing organic fertilizer in this solution requires the additional addition of a large amount of organic material, which is complex and costly, making it unsuitable for promotion and application in actual industry.

[0007] Summary of the Invention

[0008] The purpose of the present invention is to provide a treatment method for completely harmless activated sludge and completely resource-based its products, which can achieve efficient utilization of activated sludge and completely convert activated sludge into industrial products.

[0009] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0010] The present invention provides a method for treating activated sludge to render it completely harmless and to utilize its products as resources, comprising the following steps:

[0011] S1. adjusting the pH of the activated sludge to below 5 to obtain a mixture 1;

[0012] S2, subjecting the mixture 1 to ultrasonic treatment to obtain a mixture 2;

[0013] S3, subjecting the mixture 2 to microwave treatment or steam treatment to obtain a mixture 3;

[0014] S4, performing solid-liquid separation on the mixture 3 to obtain a liquid part 1 and a solid part 1;

[0015] S5, mixing the solid part 1 with the composite mineralizer and the mineralizing bacterial agent, performing a mineralization treatment to obtain a mineralized product;

[0016] S6. Mixing the mineralized product with an acidifying agent and performing acidification treatment to obtain an acidified product, thereby completing the complete resource recovery treatment of the activated sludge;

[0017] in,

[0018] The liquid portion 1 in S4 is used to prepare organic fertilizer and ferrite material;

[0019] The acidified product in S6 is used to prepare industrial silica sol.

[0020] Preferably, in S2, the frequency of the ultrasonic treatment is 5 to 40 kHz;

[0021] The intensity of the ultrasonic treatment is 1 to 30 W / cm 2 .

[0022] Preferably, in S2, the temperature of the ultrasonic treatment is 60-90°C;

[0023] The ultrasonic treatment time is 30 to 100 minutes.

[0024] Preferably, in S3, the frequency of the microwave treatment is 500 to 1000 MHz;

[0025] The power of the microwave treatment is 5 to 10 W / g;

[0026] The temperature of the steam treatment is 120-180°C;

[0027] The steam treatment time is 1 to 4 hours.

[0028] Preferably, in S3, the temperature of the microwave treatment is 120-180°C;

[0029] The microwave treatment time is 180 to 250 seconds.

[0030] Preferably, the composite mineralizer contains CaO and MgO, and the weight ratio of CaO to MgO in the composite mineralizer is 6 to 8:3;

[0031] When the solid part 1 is mixed with the composite mineralizer, the mass ratio of the solid part 1 to the composite mineralizer is 100:1-10;

[0032] The mineralizing bacterial agent contains jelly-like Bacillus;

[0033] The viable bacteria count of the jelly-like Bacillus is 1 to 5×10 8 / mL;

[0034] The mass ratio of the mineralizing bacterial agent to the solid part 1 is 1 to 10:100.

[0035] Preferably, the mineralization treatment adopts alkaline conditions;

[0036] The temperature of the mineralization treatment is 20-40°C;

[0037] The oxygen content is controlled to be 3 mg or above during the mineralization treatment.

[0038] Preferably, the acidifying agent is a sulfuric acid aqueous solution, and the volume fraction of the sulfuric acid aqueous solution is 20 to 40%;

[0039] The weight ratio of the mineralized product to the acidifier is 1:3-5.

[0040] Preferably, the temperature of the acidification treatment is 250-350°C;

[0041] The acidification treatment time is 2 to 6 hours.

[0042] Preferably, after obtaining the liquid part 1 in S4, heavy metals are removed to obtain ferrite containing heavy metals and the liquid part 2;

[0043] The liquid part 2 is used to prepare small molecule organic water-soluble fertilizer;

[0044] The heavy metal-containing ferrite is used to prepare iron ore powder.

[0045] Beneficial effects of the present invention:

[0046] The method for treating activated sludge to render it completely harmless and to utilize its products as resources includes ultrasonic treatment, microwave treatment or steam treatment, solid-liquid separation, microbial mineralization treatment, acidification treatment and other steps. Each step is closely linked to the other, and can successfully convert activated sludge into organic fertilizer, ferrite material and industrial silica sol and other products, thereby achieving full utilization of activated sludge. The obtained products are of high quality, meet relevant product quality standards and are suitable for industrial promotion. The method for treating activated sludge to render it completely harmless and to utilize its products as resources does not emit odorous gases or greenhouse gases during the entire process, thereby achieving full resource utilization while ensuring environmental friendliness and avoiding the generation of additional processing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] FIG1 is a process flow chart of the present invention. DETAILED DESCRIPTION

[0048] The present invention provides a method for treating activated sludge to render it completely harmless and to utilize its products as resources, comprising the following steps:

[0049] S1. adjusting the pH of the activated sludge to below 5 to obtain a mixture 1;

[0050] S2, subjecting the mixture 1 to ultrasonic treatment to obtain a mixture 2;

[0051] S3, subjecting the mixture 2 to microwave treatment or steam treatment to obtain a mixture 3;

[0052] S4, performing solid-liquid separation on the mixture 3 to obtain a liquid part 1 and a solid part 1;

[0053] S5, mixing the solid part 1 with the composite mineralizer and the mineralizing bacterial agent, performing a mineralization treatment to obtain a mineralized product;

[0054] S6. Mixing the mineralized product with an acidifying agent and performing acidification treatment to obtain an acidified product, thereby completing the complete resource recovery treatment of the activated sludge;

[0055] Wherein, the liquid part 1 in S4 is used to prepare organic fertilizer and ferrite material;

[0056] The acidified product in S6 is used to prepare industrial silica sol.

[0057] The activated sludge of the present invention can be activated sludge produced by biochemical treatment from a municipal sewage treatment plant or a food industry sewage treatment plant.

[0058] In the present invention, the pH of the activated sludge is adjusted to below 5 as described in S1, preferably the pH of the activated sludge is adjusted to 1-3, and more preferably 1.5-2.5; the pH adjustment preferably uses a strong acid aqueous solution as an acid-base regulator, and the strong acid aqueous solution is preferably a sulfuric acid aqueous solution, and the volume fraction of the sulfuric acid aqueous solution is preferably 20-40%, and more preferably 25-35%.

[0059] In the present invention, the frequency of the ultrasonic treatment in S2 is preferably 5 to 40 kHz, more preferably 10 to 20 kHz; the intensity of the ultrasonic treatment is preferably 1 to 30 W / cm 2 , more preferably 10 to 20 W / cm 2 The temperature of the ultrasonic treatment is preferably 60 to 90°C, more preferably 70 to 80°C, and the time of the ultrasonic treatment is preferably 50 to 80 minutes.

[0060] The pH adjustment step combined with the ultrasonic treatment step in the present invention can destroy the cell walls of the microorganisms in the sludge flocs, dissolve the cell contents, participate in subsequent treatment steps, and destroy the close combination of the microorganisms and the inorganic sludge, facilitating subsequent further treatment.

[0061] In the present invention, the frequency of the microwave treatment in S3 is preferably 500-1000 MHz, more preferably 700-900 MHz; the power of the microwave treatment is preferably 5-10 W / g, more preferably 6-8 W / g; the temperature of the microwave treatment is preferably 120-180°C, more preferably 140-160°C; the time of the microwave treatment is preferably 180-250s, more preferably 200-230s; the temperature of the steam treatment is 120-180°C; the time of the steam treatment is 1-4h. In the present invention, the steam treatment or the microwave treatment can be carried out alone or in synergy. When acting in synergy, equipment that satisfies automatic switching of the two processes can be used, and the total treatment time is 1-4h.

[0062] The microwave and / or steam step described in the present invention can kill biological contamination sources such as Escherichia coli, ascaris eggs, and viruses in activated sludge, and can also degrade mineral oil into small-molecule alkanols and alkanoic acid nutrients. The oxygen atoms connected to each other in persistent organic pollutants, polychlorinated biphenyls, and benzopyrenes are attacked by hydrogen ions released by acid hydrolysis to form a molecule of water and break them apart. The benzene rings and heterocycles are opened by microwave catalytic hydrolysis or steam heating to form harmless linear small-molecule organic acid nutrients. The polysaccharides, proteins, fats, and ribonucleic acids obtained in the microbial contents in the aforementioned steps are degraded into small-molecule amino acids, peptides, oligosaccharides, fatty acids, sugar alcohols, and nucleotides. This step can be combined with subsequent steps to achieve an effect in which the quality of the final output product exceeds the relevant standards. The optimal treatment effect can be achieved within the parameter range provided by the present invention.

[0063] In the present invention, the solid-liquid separation in S4 is preferably carried out by sedimentation, filtration, membrane filtration, filter press, vacuum, centrifugation, gravity concentration, mechanical dehydration, microfiltration, clarification or deep bed filtration. After solid-liquid separation, a liquid portion 1 and a solid portion 1 are obtained. The liquid portion 1 is used to prepare organic fertilizer and ferrite materials. After the liquid portion 1 is obtained in S4, heavy metal removal is preferably used to obtain heavy metal-containing ferrite and a liquid portion 2; the liquid portion 2 is used to prepare small molecule organic water-soluble fertilizer; the heavy metal-containing ferrite is used to prepare iron ore powder; the liquid portion 2 obtained by the present invention contains small molecule amino acids, peptides, oligosaccharides, fatty acids The invention relates to a small molecule organic water-soluble fertilizer or a solid product thereof, wherein the organic matter content is ≥10%, the total nutrient content (calculated as N+POr+K:O) is ≥5% (the content of a single nutrient is ≥1%), the trace element content (the sum of the content of six elements, namely, boron, zinc, manganese, iron, copper, and molybdenum, is ≥2%, the water-insoluble matter is ≤0.5%, and the pH value (1+250 times dilution) is 2.0-9.0 (cited from the Chinese national standard GB / T17419-2018). The product can meet the index thanks to the synergistic effect of all the above steps; the heavy metal-containing ferrite (silicon dioxide (SiO 2： w / %) 20-31, sodium oxide (NaO: w / %) ≤ 0.04-0.06, pH value 2.0-4.0, cited from China Chemical Industry Standard HG / T2521-2008), can be used as iron ore powder raw material.

[0064] In the present invention, the solid part 1 obtained by S4 is mixed with a composite mineralizer and subjected to mineralization treatment to obtain a mineralized product; the composite mineralizer preferably contains CaO and MgO, and the mass ratio of CaO and MgO in the composite mineralizer is preferably 6-8:3; when the solid part 1 is mixed with the composite mineralizer, the mass ratio of the solid part 1 to the composite mineralizer is preferably 100:1-10; the mineralization treatment preferably adopts alkaline conditions, and the pH value of the alkaline conditions is preferably 8-10; the temperature of the mineralization treatment is preferably 20-40°C, more preferably 25-35°C; the oxygen content in the mineralization treatment is controlled at 3 mg / kg or above, preferably 4-5 mg / kg; the oxygen content is preferably controlled by the turning method, and the turning speed is preferably 5-15 r / min; the mineralization treatment time is preferably 10-72 h, more preferably 30-50 h.

[0065] The mineralizing agent in S5 of the present invention preferably contains jelly-like Bacillus, and preferably, the number of viable bacteria of the jelly-like Bacillus is preferably 1 to 5×10 8 cells / mL, more preferably 2 to 4×10 8 The mineralizing agent is capable of consuming excess organic matter through growth and reacting with the inorganic sludge portion of the composite mineralizer to form mineralized sludge. This step builds upon all of the preceding steps, providing favorable material conditions for the mineralization process and enabling the successful production of a mineralized product.

[0066] In the present invention, the acidifying agent in S6 is preferably a sulfuric acid aqueous solution, and the volume fraction of the sulfuric acid aqueous solution is preferably 20-40%, more preferably 25-35%; the weight ratio of the mineralized product to the acidifying agent is preferably 1:3-5, more preferably 1:3.5-4.5; preferably, the temperature of the acidification treatment is preferably 250-350°C, more preferably 280-320°C; the time of the acidification treatment is preferably 2-6h, more preferably 2-3h; the acidification product of the present invention can be used to prepare industrial silica sol after cooling, and the main component of the product is active silica, wherein: silica (SiO 2： w / %) 20~31, sodium oxide (NaO: w / %) ≤ 0.04~0.06, pH value 2.0~4.0.

[0067] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0068] Example 1

[0069] (1) Take activated sludge, add 30% sulfuric acid to adjust pH = 1, and perform ultrasonic treatment. The ultrasonic frequency is controlled at 30kHz and the sound intensity is controlled at 25W / cm 2 , treated at 60℃ for 35min.

[0070] (2) The ultrasonic system was subjected to microwave treatment, the microwave frequency was controlled at 800 MHz, a high temperature of 150°C was generated, the microwave radiation power was 8 W / g, and the reaction time was 200 s.

[0071] (3) The solid-liquid separation of the microwave system is into two parts, wherein the liquid part is the organic part containing heavy metals, and the solid part is the inorganic part containing organic matter (the organic matter content is 4.7%).

[0072] (4) Add 800 mg / L of humic acid to the liquid part, react for 1 hour, and separate the humic acid precipitate containing heavy metals into a solid matter and a small molecule organic liquid without heavy metals through solid-liquid separation. The small molecule organic liquid is recorded as sludge product 1, which can be used to prepare a small molecule organic water-soluble fertilizer or its solid product with an organic matter content ≥10%, a total nutrient content (calculated as N+POr+K:O) ≥5% (single nutrient ≥1%), a trace element content (the sum of the six elements of boron, zinc, manganese, iron, copper, and molybdenum ≥2%, water-insoluble matter ≤0.5%, and a pH (1+250 times dilution) of 2.0 to 9.0 (cited from the Chinese national standard GB / T17419-2018);

[0073] (5) The humic acid precipitate containing heavy metals is subjected to a desorption reaction, the pH value is adjusted to 8.5, and ultrasonic treatment is performed at an operating frequency of 50 kHz and a temperature of 70°C for 5 minutes to separate the humic acid containing heavy metals. The humic acid can be dissolved and reused; the separated heavy metals are present as hydroxide precipitates, and the heavy metal hydroxides can be used to prepare ferrites. The preparation method is shown in Chinese patent CN101591130B.

[0074] (6) The solid fraction obtained in step (4) was subjected to mineralization treatment: a composite mineralizer (composed of 70% CaO and 30% MgO) was added to the total solid fraction until the system pH reached 8.5. The mineralizing microorganism Bacillus jelly-like ACCC01075 and culture medium 0065 (purchased from the China General Microbial Culture Collection) were simultaneously added to a liquid inoculum with an effective viable count of 1.5 billion / ml. The addition amount was 5% of the mineralized sludge. Aeration was provided by turning the material over at a speed of 10 r / min to maintain an oxygen content of approximately 4 mg / kg. The reaction was continued for 48 h to obtain mineralized sludge, which was recorded as sludge product 2.

[0075] (7) Add 40% sulfuric acid 3 times the weight of the material to the sludge product 2, heat to 250℃, react for 2h, stir at 30r / min, cool to room temperature 20℃, and obtain a liquid product mainly containing active SiO2, which meets the requirements of industrial silica sol silica (SiO 2： w / %) 20-31, sodium oxide (NaO: w / %) ≤ 0.04-0.06, pH value 2.0-4.0 (cited from China Chemical Industry Standard HG / T2521-2008) and related indicators, it can be used as cement, concrete additives, waterproof materials, anti-corrosion materials, adhesives and other products.

[0076] Example 2

[0077] This embodiment provides a method for treating activated sludge by first separating the organic part and the inorganic part, rendering them harmless and resource-based, and finally achieving complete harmlessness and resource-based treatment of the products, comprising the following steps:

[0078] S1. Adjusting the pH of the activated sludge to 1-3 to obtain a mixture 1;

[0079] S2, subjecting the mixture 1 to ultrasonic treatment to obtain a mixture 2;

[0080] S3, subjecting the mixture 2 to microwave treatment or steam treatment to obtain a mixture 3;

[0081] S4, performing solid-liquid separation on the mixture 3 to obtain an organic liquid portion and an inorganic solid portion;

[0082] S5. Add humic acid to the liquid part to remove heavy metals to obtain ferrite containing heavy metals. The ferrite is used as a composite to meet the requirements of (mass fraction) TFe ≥ 48.0 ~ 65%, SiO2 ≤ 3.5 ~ 15.0% 、 Al2O3≤1.5~4.0% 、Iron ore powder with P≤0.05~0.15%, S≤0.03~0.11% (cited from the 1~5 grade iron ore standards in China's ferrous metallurgy industry standard YB / T4267-2011). The remaining organic part is used as the standard for total cadmium (on dry basis) / (mg / kg)<3, total mercury (on dry basis) / (mg / kg)<3, total lead (on dry basis) / (mg / kg)<300, total chromium (on dry basis) / (mg / kg)<500, total arsenic (on dry basis) / (mg / kg)<30, total nickel (on dry basis) / (mg / kg)<100, total zinc (on dry basis) / (mg / kg)<200, total copper (on dry basis) / (mg / kg)<500, mineral oil (on dry basis) / (mg / kg)<500, benzo(a)pyrene (on dry basis) / (mg / kg)<2, polycyclic aromatic hydrocarbons (PCA) Sludge products meeting the pollutant control requirements of aromatic hydrocarbons (PAHs) (based on basis) / (mg / kg) < 5 (cited from China National Standard GB4284-2018 Agricultural Sludge Pollutant Control Standard), used for the production of small molecule organic water-soluble fertilizers or their solid products with an organic matter content ≥ 10%, a total nutrient content (calculated as N+POr+K:O) ≥ 5% (single nutrient ≥ 1%), a trace element content (the sum of the six elements of boron, zinc, manganese, iron, copper, and molybdenum ≥ 2%, a water-insoluble matter ≤ 0.5%, and a pH (1+250 times dilution) of 2.0-9.0 (cited from China National Standard GB / T17419-2018);

[0083] S6. After adding composite mineralizers calcium oxide and magnesium oxide to the inorganic solid part, and then adding mineralizing functional microbial agents and mixing, mineralization treatment is carried out to make the organic matter content of the sludge 3% to 5%, thereby obtaining sludge product 2.

[0084] S7, adding sulfuric acid to the sludge product 2 and performing acidification treatment to obtain silicon dioxide (SiO 2： w / %) 20-31, sodium oxide (NaO: w / %) ≤ 0.04-0.06, pH value 2.0-4.0 (cited from China Chemical Industry Standard HG / T2521-2008).

[0085] In S2, the frequency of the ultrasonic treatment is 5 to 40 kHz; the intensity of the ultrasonic treatment is 1 to 30 W / cm 2 ;

[0086] In S2, the temperature of the ultrasonic treatment is 60 to 90° C.; the time of the ultrasonic treatment is 30 to 100 minutes;

[0087] In S3, the frequency of the microwave treatment is 500-1000 MHz; the power of the microwave treatment is 5-10 W / g; the temperature of the auxiliary steam replacement treatment is 120-180° C.; and the time of the steam treatment is 1-4 hours;

[0088] In S3, the temperature of the microwave treatment is 120-180° C.; the time of the microwave treatment is 180-250 s;

[0089] The composite mineralizer contains CaO and MgO, wherein CaO accounts for 70% and MgO accounts for 30%, and the amount thereof is added to control the sludge pH to 8.5;

[0090] When the solid part is mixed with the composite mineralizer, the mass ratio of the solid part to the composite mineralizer is 100:1-10;

[0091] The mineralizing agent contains jelly-like Bacillus, which is selected from the Chinese bacterial species catalog ACCC10092 culture medium 0067 (purchased from the China General Microbiological Culture Collection Center);

[0092] The number of viable bacteria of the jelly-like Bacillus inoculum is 1 to 5×10 8 / mL;

[0093] The mass ratio of the mineralizing agent to the solid part 1 is 1 to 10:100;

[0094] The mineralization treatment adopts alkaline conditions pH 8.5;

[0095] The temperature of the mineralization treatment is 20-40°C;

[0096] During the mineralization treatment, the oxygen content is controlled at 1 mg / kg to 3 mg / kg, the microbial mineralization treatment time is 24 hours to 72 hours, and the organic matter content is controlled at 3% to 5%.

[0097] The acidifying agent is a sulfuric acid aqueous solution, and the concentration of the sulfuric acid aqueous solution is 20-40%;

[0098] The weight ratio of the mineralized sludge product to the sulfuric acid solution is 1:3 to 5;

[0099] The temperature of the acidification treatment is 250-350°C;

[0100] The acidification treatment time is 2 to 6 hours.

[0101] After the liquid portion is obtained from S4, the heavy metals are removed by humic acid treatment to prepare heavy metal-containing ferrite, which is used to produce iron ore powder that meets the standards.

[0102] The humic acid treatment method comprises the following steps:

[0103] S4.1, mixing the liquid portion with humic acid at a pH of 1-3, and performing adsorption treatment to obtain mixture 4;

[0104] S4.2, performing solid-liquid separation on the mixture 4 to obtain an organic liquid portion, i.e., a sludge product 1, and an inorganic solid portion 2;

[0105] S4.3. Adjust the pH value of the inorganic solid part 2 to 8-9, carry out desorption reaction, and separate the humic acid solution, which can be recycled, and heavy metal hydroxide; use the patent disclosed by the inventor to produce heavy metal ferrite materials as raw materials for producing iron ore powder.

[0106] The heavy metal hydroxide described in step S4.3 is used to prepare a ferrite material, and the liquid part of the heavy metal removal is the sludge product 1 as the inventor's public patent, to produce a small molecule organic water-soluble fertilizer or its solid product that meets the requirements of organic matter content ≥10%, total nutrient content (as N+POr+K:O) ≥5% (single nutrient ≥1%), trace element content (the sum of the contents of six elements: boron, zinc, manganese, iron, copper, and molybdenum ≥2%, pH (1+250 times dilution) 2.0~9.0 (cited from China National Standard GB / T17419-2018).

[0107] The detection index of sludge product 1 is as follows: total cadmium (on dry basis) / (mg / kg)<3, total mercury (on dry basis) / (mg / kg)<3, total lead (on dry basis) / (mg / kg)<300, total chromium (on dry basis) / (mg / kg)<500, total arsenic (on dry basis) / (mg / kg)<30, total nickel (on dry basis) / (mg / kg)<100, total zinc (on dry basis) / (mg / kg)<200, total copper (on dry basis) / (mg / kg)<500, mineral oil (on dry basis) / (mg / kg)<500, benzo(a)pyrene (on dry basis) / (mg / kg)<2, polycyclic aromatic hydrocarbons (PAHs) (on dry basis) / (mg / kg)<5 (cited from China National Standard GB4284-2018 Agricultural Sludge Pollutant Control Standard), among which: total cadmium (on dry basis) / (mg / kg)<3, the measured value of sludge product 1 is 1.2; total mercury (on dry basis) / (mg / kg)<3 , the measured value of sludge product is 0.3; total lead (on dry basis) / (mg / kg) <300, the measured value of sludge product is 78; total mercury and chromium (on dry basis) / (mg / kg) <500, the measured value of sludge product is 123; total nickel (on dry basis) / (mg / kg) <100, the measured value of sludge product is 26; total zinc (on dry basis) / (mg / kg) <1200, the measured value of sludge product is 800; total copper (on dry basis) / (mg / kg) <500, the measured value of sludge product is The measured value of the sludge product is 400; mineral oil (on a dry basis) / (mg / kg) is less than 500, and the measured value of the sludge product is 86; benzo(a)pyrene (on a dry basis) / (mg / kg) is less than 2, and the measured value of the sludge product is 0.1; polycyclic aromatic hydrocarbons (PAHs) (on a dry basis) / (mg / kg) is less than 5, and the measured value of the sludge product is 0.8; ascaris egg mortality rate / % is greater than or equal to 95, and the measured value of the sludge product is 100%; coliform bacteria value is greater than or equal to 0.01, and the measured value of the sludge product is not detected.

[0108] The sludge product 2 has 4.7% excess organic matter after solid-liquid separation, and 4.5% colloidal organic matter in the sludge product 2. After acidification, it is made into a cement concrete additive product containing active silica as the main component. According to SW-20 in Table 2 of the chemical industry standard HG / T2521-2018, the active silica content is ≥20%. The actual measured value of active silica in the cement concrete product formed by acidification of the sludge product 2 is 26%.

[0109] The small molecule organic water-soluble fertilizer prepared from sludge product 1 has an organic matter content of ≥10%, a total nutrient content (calculated as N+POr+K:O) of ≥5% (single nutrient content ≥1%), a trace element content (the sum of the contents of six elements: boron, zinc, manganese, iron, copper, and molybdenum ≥2%), a water-insoluble matter ≤0.5%, and a pH (1+250 times dilution) of 2.0-9.0 (cited from Chinese national standard GB / T17419-2018). Compared with the measured values ​​of the small molecule organic water-soluble fertilizer prepared from sludge product 1, the national standard value for organic matter is ≥10%, and the measured value of the product is 12%. The national standard value for the total amount of N+P2O5+K2O is ≥8%, and the measured value of the product is 9.8%. The national standard value for pH (1+250 times water dilution) is 2-9, and the measured value of the product is 4.5%. The national standard value for water-insoluble matter is ≤0.5%, and the measured value of the product is 0.3%.

[0110] Experimental example

[0111] The test standards and results of the product sludge product 1 in Example 1 are shown in Table 1 below:

[0112] Table 1 Sludge product 1 test results

[0113] The test standards and results of the product sludge product 2 are shown in Table 2 below:

[0114] Table 2 Sludge product 2 test results

[0115] The small molecule organic water-soluble fertilizer made from sludge product 1 was used as a sample and tested according to the method in the national standard GB / T17419-2018. The results are shown in Table 3 below:

[0116] Table 3 Test results of small molecule water-soluble fertilizer

[0117] The heavy metal ferrite made from sludge product 1 was used as an ironmaking material instead of iron ore powder. The test was carried out in accordance with the metallurgical industry iron ore powder standard YB / T4267-2011. The results are shown in Table 4:

[0118] Table 4 Ferrite test results

[0119] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for treating activated sludge to render it completely harmless and to utilize its products as resources, characterized in that: The following steps are involved: S1. adjusting the pH of the activated sludge to below 5 to obtain a mixture 1; S2, subjecting the mixture 1 to ultrasonic treatment to obtain a mixture 2; S3, subjecting the mixture 2 to microwave treatment and / or steam treatment to obtain a mixture 3; S4, performing solid-liquid separation on the mixture 3 to obtain a liquid part 1 and a solid part 1; S5, mixing the solid part 1 with the composite mineralizer and the mineralizing bacterial agent, performing a mineralization treatment to obtain a mineralized product; S6. Mixing the mineralized product with an acidifying agent and performing acidification treatment to obtain an acidified product, thereby completing the complete resource recovery treatment of the activated sludge; in, The liquid portion 1 in S4 is used to prepare organic fertilizer and / or ferrite material; The acidified product in S6 is used to prepare industrial silica sol.

2. The processing method according to claim 1, characterized in that In S2, the frequency of the ultrasonic treatment is 5 to 40 kHz; The intensity of the ultrasonic treatment is 1 to 30 W / cm 2 .

3. The processing method according to claim 2, characterized in that In S2, the temperature of the ultrasonic treatment is 60-90°C; The ultrasonic treatment time is 30 to 100 minutes.

4. The processing method according to claim 1, characterized in that In S3, the frequency of the microwave treatment is 500 to 1000 MHz; The power of the microwave treatment is 5 to 10 W / g; The temperature of the steam treatment is 120-180°C; The steam treatment time is 1 to 4 hours.

5. The processing method according to claim 4, characterized in that: In S3, the temperature of the microwave treatment is 120-180°C; The microwave treatment time is 180 to 250 seconds.

6. The processing method according to claim 1, characterized in that The composite mineralizer contains CaO and MgO, and the weight ratio of CaO to MgO in the composite mineralizer is 6 to 8:3; When the solid part 1 is mixed with the composite mineralizer, the mass ratio of the solid part 1 to the composite mineralizer is 100:1-10; The mineralizing bacterial agent contains jelly-like Bacillus; The viable bacteria count of the jelly-like Bacillus is 1 to 5×10 8 / mL; The mass ratio of the mineralizing bacterial agent to the solid part 1 is 1 to 10:

100.

7. The processing method according to claim 6, characterized in that The mineralization treatment adopts alkaline conditions; The temperature of the mineralization treatment is 20-40°C; The oxygen content is controlled to be 3 mg or above during the mineralization treatment.

8. The processing method according to claim 1, characterized in that The acidifying agent is a sulfuric acid aqueous solution, and the volume fraction of the sulfuric acid aqueous solution is 20-40%; The weight ratio of the mineralized product to the acidifier is 1:3-5.

9. The processing method according to claim 8, characterized in that: The temperature of the acidification treatment is 250-350°C; The acidification treatment time is 2 to 6 hours.

10. The processing method according to claim 1, characterized in that: After obtaining the liquid part 1 in S4, heavy metals are removed to obtain ferrite containing heavy metals and the liquid part 2; The liquid part 2 is used to prepare small molecule water-soluble organic fertilizer; The heavy metal-containing ferrite is used to prepare iron ore powder.

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