Method for realizing sludge dewatering reduction through filamentous fungus Fenton conditioning and application of method

Abstract

The invention discloses a method for achieving sludge dewatering reduction through filamentous fungus Fenton conditioning and application of the method, and belongs to the technical field of sludge treatment. The method comprises the following steps: inoculating filamentous fungi, especially penicillium simplicissimum NAU-12, in sludge, inducing endogenous inert iron-containing compounds in the sludge to be converted into amorphous active nano-iron particles through the filamentous fungi, and inducing hypha to differentiate to produce H2O2 to initiate a Fenton-like reaction, so as to generate free radicals. OH and Fe (III) which are beneficial to sludge dehydration; therefore, deep dehydration (the water content is reduced from 95% to 60%) under the conditions that no Fenton chemical agent is added to an external source and the sludge is not pre-acidified is realized, the loss of organic matters of the generated dehydrated sludge cake is less, the pH value of the dehydrated filtrate is nearly neutral, the technical economy of sludge treatment is remarkably improved, and the method is green and environment-friendly.

Description

Technical Field

[0001] The present application belongs to the technical field of sludge treatment, and specifically relates to a method for achieving sludge dehydration and reduction by using filamentous fungi-type Fenton conditioning. Background Art

[0002] The sludge from sewage treatment plants has a high moisture content (generally >95%), which results in a large volume, which makes it very difficult to transport, dispose and recycle. How to achieve deep dehydration and reduction of sludge is of great significance to solving the problem of sludge disposal and ensuring the sustainable development of sewage treatment.

[0003] The main methods of sludge dehydration include: mechanical dehydration, using mechanical pressure or centrifugal force, such as plate and frame filter press, belt filter press, centrifugal dehydrator and other equipment to dehydrate sludge, which can reduce the sludge moisture content from more than 90% to about 70% to 85%; natural drying, placing the sludge in the drying field, removing water through natural evaporation, infiltration and drainage, etc., which can reduce the sludge moisture content to 60% to 75%, but it takes a long time and occupies a large area; adding chemicals to assist dehydration, adding flocculants, coagulants and other chemical agents to the sludge to improve the dehydration performance of the sludge, and then combining with mechanical dehydration, the sludge moisture content can be further reduced, and the sludge moisture content can be reduced from about 80% of simple mechanical dehydration to 60% to 70%. Based on Fe(II) catalytic H 2 O 2 The Fenton advanced oxidation technology, which produces strong oxidizing free radicals (·OH, etc.) and Fe(III) flocculation, can significantly reduce the water content of sludge from 95% to about 60%, with a very significant reduction effect. It is considered to be a sludge dehydration method with great engineering application prospects. For example, the applicant's previous application has a publication number of CN114920436A and an invention name of a method for chemically enhanced anaerobic digestion sludge bioleaching treatment.

[0004] In actual application, the main shortcomings that limit the wide-scale promotion and application of this method are: the large amount of Fenton reagent added and the high treatment cost. Usually, to achieve the goal of sludge moisture content <60%, acid (such as H 2 SO 4 The pH value of the sludge was acidified from 7.0 to about 4.0, and then 50-80 kg / t of Fe(II) and 60-100 kg / t of H were added. 2 O 2 (based on sludge dry matter) to initiate the Fenton chain radical reaction. 2 O 2 As they are hazardous chemicals, there are many inconveniences in purchasing, transporting and storing them.

[0005] Therefore, there is an urgent need to develop a new green and efficient method that can achieve deep dehydration and reduction of sludge. Summary of the invention

[0006] 1. Problem to be solved

[0007] This application aims at the exogenous Fe(II) / H 2 O 2 In order to solve the problem of large reagent dosage and high cost, a method and application of filamentous fungus Fenton conditioning to achieve sludge dehydration and reduction is provided. The method uses filamentous fungi, especially Penicillium simplicissimum NAU-12 to condition sludge, and produces H through mycelium differentiation. 2 O 2 The bio-induced conversion of endogenous inert iron-containing substances in sludge into amorphous active nano-iron particles, which in turn triggered a Fenton-like reaction (generating free radicals ·OH and Fe(III)), achieving zero addition of exogenous Fenton chemicals (inorganic acids, organic acids and Fe(II) / H 2 O 2 Under the conditions of reagents, the sludge water is quickly released and dehydrated.

[0008] 2. Technical solution

[0009] In order to solve the above problems, the technical solutions adopted in this application are as follows:

[0010] The present application provides a method for achieving sludge dehydration and reduction by using filamentous fungus Fenton conditioning, the method comprising:

[0011] S1, inoculating filamentous fungi into sludge and adding nutrients; the filamentous fungi have the ability to differentiate and produce H 2 O 2 and the function of inducing the transformation of inert iron-containing compounds into amorphous active nano-iron particles;

[0012] S2, the sludge is placed under stirring, mixing, aeration and oxygenation conditions to carry out a Fenton-like reaction. Under stirring, mixing, aeration and oxygenation conditions, on the one hand, the hyphae of filamentous fungi differentiate and produce H 2 O 2 On the other hand, the inert iron-containing substances in the sludge are induced to transform into amorphous active nano-iron particles, and a Fenton-like reaction occurs between the two, and free radicals ·OH and Fe(III) are produced in the system, thereby triggering the release of water held in the sludge.

[0013] S3, mechanically dewatering the treated sludge to obtain dewatered sludge cake and filtrate, thereby achieving sludge dehydration and reduction.

[0014] Furthermore, the above-mentioned filamentous fungi include Penicillium simplicifolium.

[0015] Furthermore, the above-mentioned Penicillium simplicissimum is Penicillium simplicissimum NAU-12, which is classified and named Penicillium simplicissimum and deposited in the General Microbiological Center of China Microorganism Culture Collection Committee on July 6, 2015, with a deposit number of CGMCC NO.10990. The microorganism is a microorganism screened and deposited by the inventor in the early stage, as shown in the Chinese invention patent with publication number CN106190871A; the applicant found in the research process that the microorganism has the ability to differentiate and produce H 2 O 2 and the function of inducing the transformation of inert iron-containing compounds into amorphous active nano-iron particles.

[0016] Furthermore, the inoculation density of the above Penicillium simplex NAU-12 is 1×10 8 ~1×10 9 Spores / mL.

[0017] Furthermore, the above-mentioned nutrients include phosphorus, calcium, sugar and acid.

[0018] Furthermore, the above-mentioned nutrient includes K 2 HPO 4 , CaCl 2 ·2H 2 O, oxalic acid and sucrose.

[0019] Furthermore, the concentrations of the above nutrients after addition are:

[0020] K 2 HPO 4 0.01~0.04g / L,

[0021] CaCl 2 ·2H 2 O 0.01~0.036g / L,

[0022] Oxalic acid 0.01~0.02g / L,

[0023] Sucrose 0.001~0.01g / L.

[0024] Furthermore, the concentrations of the above nutrients after addition are:

[0025] K 2 HPO 4 0.01g / L,

[0026] CaCl 2 ·2H 2 O 0.036 g / L,

[0027] Oxalic acid 0.01g / L,

[0028] Sucrose 0.001g / L.

[0029] Furthermore, the solid concentration of the sludge is 1-5%.

[0030] Furthermore, the above-mentioned stirring, mixing, aeration and oxygenation conditions include: 20-35° C., ventilation and stirring for 2-4 days, and controlling the dissolved oxygen content to 1-2 mg / L.

[0031] Furthermore, the above stirring, mixing, aeration and oxygenation conditions include: 25° C., ventilation and stirring for 3 days.

[0032] Furthermore, the mechanical dehydration includes dehydration using mechanical pressure or centrifugal force.

[0033] Furthermore, the above-mentioned mechanical dehydration includes dehydrating the sludge using equipment such as a plate and frame filter press, a belt filter press, and a centrifugal dehydrator.

[0034] The present application also provides the application of the above-mentioned method of achieving sludge dewatering and reduction by filamentous fungus Fenton conditioning in sludge dewatering and reduction.

[0035] A process for sludge dehydration and reduction, comprising the method of achieving sludge dehydration and reduction by using the above-mentioned filamentous fungus Fenton conditioning.

[0036] 3. Beneficial effects

[0037] Compared with the prior art, the present application has the following beneficial effects:

[0038] (1) The present application provides a method and application of filamentous fungus Fenton conditioning to achieve sludge dehydration and reduction, wherein filamentous fungi, especially Penicillium simplicissimum NAU-12, are inoculated into the sludge. Penicillium simplicissimum NAU-12 can induce the conversion of endogenous inert iron-containing compounds in the sludge into amorphous active nano-iron particles, and at the same time, the mycelium of Penicillium simplicissimum NAU-12 differentiates to produce H 2 O 2 This dual characteristic triggers a Fenton-like oxidation reaction, producing free radicals OH and Fe(III) that are beneficial to sludge dehydration, thereby significantly reducing the treatment cost of sludge dehydration. 2 O 2 As for the sludge dewatering technology using chemical reagents and chemical acids, this method achieves deep sludge dehydration without adding exogenous Fenton chemicals, significantly improving the economic efficiency.

[0039] (2) The present application provides a method and application of filamentous fungus Fenton conditioning to achieve sludge dehydration and reduction. Penicillium simplex is widely present in sludge and is an indigenous microorganism with strong environmental adaptability. The nutrients required for its growth include K 2 HPO 4 , CaCl 2 ·2H 2 O. Oxalic acid and sucrose are cheap and readily available.

[0040] (3) The present application provides a method for achieving sludge dehydration and reduction by using filamentous fungus-based Fenton conditioning and its application. The entire treatment process is simple, easy to operate, green and efficient, and economical and practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is the result of the laser particle size analyzer detecting the change in particle size of Fe compounds.

[0042] Figure 2 It is the result of X-ray diffraction detection and analysis of the mineral phase changes of Fe compounds.

[0043] Figure 3 In situ staining detection of H 2 O 2 and O 2 ·- The results of production.

[0044] Figure 4 This is the appearance of sludge before (left) and after (right) Fenton-like conditioning. DETAILED DESCRIPTION

[0045] The present application is further described below in conjunction with specific embodiments.

[0046] It should be noted that the terms such as "upper", "lower", "left", "right", "middle", etc. cited in this specification are only for the convenience of description and are not used to limit the scope of implementation. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of this application without substantially changing the technical content.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the term "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0048] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0049] As used herein, the term "about" is used to provide flexibility and imprecision associated with a given term, measurement or value. The degree of flexibility for a particular variable can be easily determined by one skilled in the art.

[0050] As used herein, the term "at least one of" is intended to be synonymous with "one or more of." For example, "at least one of A, B, and C" expressly includes only A, only B, only C, and combinations of each thereof.

[0051] Concentration, amount and other numerical data can be presented in range format herein.It should be understood that such range format is only used for convenience and simplicity, and should be flexibly interpreted as not only including the numerical value clearly described as range limit, but also including all single numerical values ​​or sub-ranges contained in the range, just as each numerical value and sub-range are clearly described.For example, the numerical range of about 1 to about 4.5 should be interpreted as not only including the limit value of 1 to about 4.5 clearly described, but also including single numerals (such as 2,3,4) and sub-ranges (such as 1 to 3,2 to 4, etc.).The same principle is applicable to the scope of only narrating a numerical value, such as "less than about 4.5", which should be interpreted as including all the above-mentioned values ​​and ranges.In addition, no matter how the breadth of the described range or feature is, this explanation should be applicable.

[0052] As used herein, "inert iron-containing compounds" refer to iron-containing compounds that are relatively inactive and not easily involved in chemical reactions under certain conditions, such as hematite, the main component of which is ferric oxide (Fe 2 O 3 ); magnetite, the main component of which is ferroferric oxide (Fe 3 O 4 ); Potassium ferrosite: chemical formula is KFe 3 (SO 4 ) 2 (OH) 6, which is a sulfate mineral containing potassium and iron. Sludge usually contains inert iron-containing compounds, including those brought in by industrial wastewater. For example, many industrial production processes such as electroplating, steel processing, and electronic manufacturing will produce wastewater containing a large amount of iron ions. The iron ions in these wastewaters will combine with hydroxide ions, sulfides, etc. during the wastewater treatment process to form various iron-containing compounds. Some iron compounds will be converted into inert iron-containing compounds such as hematite and magnetite during the subsequent sludge formation and treatment process; brought in by domestic sewage. Domestic sewage also contains a certain amount of iron, which mainly comes from waste generated by human activities, additives in detergents, etc. Some iron elements will participate in the metabolic process of microorganisms during the biochemical reaction stage of sewage treatment. Microorganisms will convert part of the iron elements into iron-containing substances in the cells. During the sedimentation and compaction of sludge, these iron-containing substances may be further converted into inert iron-containing compounds; as well as mixing with the natural environment. During the operation of the sewage treatment plant, the sludge will have a certain contact with the surrounding natural environment. Soil particles, dust, etc. may be mixed into the sludge. The soil itself contains various inert iron-containing compounds, such as hematite, potassium ferroaluminate, etc., which will also cause the sludge to contain a certain amount of inert iron-containing compounds.

[0053] As used herein, "solid concentration" is an important indicator for measuring the content of solid matter in sludge. When sludge solid concentration is expressed as a percentage (%), it refers to the proportion of the mass of solid matter in the sludge to the total mass of the sludge.

[0054] As used in this article, "CST", or capillary suction time, refers to the time required for water in sludge to penetrate from the sludge to the filter paper under capillary action and diffuse a certain distance on the filter paper, measured in seconds (s). It reflects the ease with which water in the sludge passes through porous media such as filter paper. The larger the CST value, the more difficult it is to dehydrate the sludge.

[0055] As used herein, "SRF", or Specific Resistance to Filtration, refers to the resistance of dry sludge per unit mass per unit filtration area, in m / kg. It indicates the resistance of sludge to the filter medium (such as filter cloth) during the sludge filtration and dehydration process. The higher the SRF value, the more difficult it is to filter and dehydrate the sludge.

[0056] Example 1

[0057] This embodiment provides a method for achieving sludge dehydration and reduction by using filamentous fungus-based Fenton conditioning.

[0058] In this example, the sludge was collected from a domestic sewage plant in Jiangbei New District, Nanjing, and its basic properties are shown in Table 1.

[0059] Table 1 Basic physical and chemical properties of sludge

[0060]

[0061] In this embodiment, the filamentous fungus is Penicillium simplicissimum NAU-12, which is classified and named Penicillium simplicissimum, and is deposited in the General Microbiological Center of China Microorganism Culture Collection Administration. The deposit date is July 6, 2015, and the deposit number is CGMCC NO.10990. The microorganism is a microorganism screened and deposited by the inventor in the early stage. For details, see the Chinese invention patent with publication number CN106190871A.

[0062] In this embodiment, a method for achieving sludge dehydration and reduction by filamentous fungus Fenton conditioning includes:

[0063] S1, prepare Penicillium simplicissimum NAU-12 spore suspension, inoculate Penicillium simplicissimum into the sludge to make the bacterial density reach 3×10 8 Spores / mL; and added nutrients (g / L): K 2 HPO 4 0.01, CaCl 2 ·2H 2 O0.036, oxalic acid 0.01, sucrose 0.001;

[0064] S2, the sludge was placed in a stirred aeration at 25°C, the dissolved oxygen content was controlled at 1-2 mg / L, and Fenton-like conditioning was performed for 3 days; at the beginning (0h) and after conditioning (72h), the changes in the particle size and mineral phase of Fe compounds were detected using a laser particle size analyzer and X-ray diffraction, and H 2 O 2 and O 2 ·- The production of Fe compounds; laser particle size analyzer and X-ray diffraction detection of Fe compound particle size and mineral phase changes such as Figure 1 and Figure 2 As shown, it can be seen that new amorphous Fe compounds are generated in the system, and the particle size of the Fe compounds becomes smaller and more uniform (average particle size 350nm), and the total soluble Fe content in the system is 36mg / L; the in-situ staining test results are shown Figure 3 As shown, a large amount of H 2 O 2 and O 2 ·- , a strong peak signal of ·OH free radical was detected; before Fenton-like conditioning ( Figure 4 Middle left), after ( Figure 4 The sludge in the middle right picture is as follows Figure 4As shown in the figure, after testing, the sludge CST value dropped to 39s and the SRF dropped to 1.3×10 11 m / kg;

[0065] S3, the treated sludge is subjected to plate and frame filter pressing and dehydration to obtain a dry dehydrated sludge cake (water content 58%) and a clear dehydrated filtrate, thereby achieving sludge dehydration and reduction.

[0066] Comparative Example 1

[0067] This comparative example adopts the traditional chemical exogenous addition of Fenton reagent (Fe(II) / H 2 O 2 ) was used as a control for sludge dewatering.

[0068] The sample is the same as the sample in Example 1, and the processing steps of this comparative example are as follows:

[0069] (1) Pre-acidified sludge: 50 kg H 2 SO 4 / ton dosage H 2 SO 4 Acidify the sludge pH from 7.2 to 3.7;

[0070] (2) Fenton chemical oxidation treatment of sludge: FeSO was added at a dosage of 50 kg / t and 80 kg / t respectively. 4 and H 2 O 2 The two reagents were stirred at 25 °C and Fenton chemical conditioning was performed for 2 h. After testing, the total soluble Fe content in the treatment system was 88 mg / L, with an obvious free radical OH peak signal, the sludge CST value dropped to 37 s, and the SRF dropped to 2.2 × 10 11 m / kg;

[0071] (3) Mechanical dehydration: The treated sludge is dehydrated by plate and frame filter pressing to obtain dehydrated sludge cake (water content 56%) and dehydrated filtrate.

[0072] The dehydration effects of Example 1 and Comparative Example 1 are shown in Table 2. Under the condition of zero exogenous addition of Fenton chemical reagents, basically the same dehydration effect is achieved, and the pH values ​​of the dehydrated sludge and the dehydrated filtrate finally produced are close to neutral, which is safer, and the organic matter loss in the sludge is also less, which is easy for subsequent resource utilization.

[0073] Table 2 Comparison of sludge dehydration effects between Example 1 and Comparative Example 1

[0074]

[0075] Comparative Example 2

[0076] This comparative example uses only chemical addition of H2 O 2 However, Penicillium simplicissimum NAU-12 was not inoculated for sludge dewatering.

[0077] The sample is the same as that in Example 1, and the processing steps of this comparative example are as follows:

[0078] (1) Pre-acidified sludge: 50 kg H 2 SO 4 / ton dosage H 2 SO 4 Acidify the sludge pH from 7.2 to 3.7;

[0079] (2) Chemical addition of H 2 O 2 Sludge treatment: Add H at a dosage of 80 kg / t 2 O 2 The reagent was placed at 25 °C and stirred for 2 h. After testing, the total soluble Fe content in the treatment system was only 1.2 mg / L, and there was no obvious free radical OH peak signal, indicating that the Fenton reaction did not occur significantly; the sludge CST value was 197 s, and the SRF was 2.8 × 10 13 m / kg;

[0080] (3) Mechanical dehydration: The treated sludge was subjected to plate and frame filter pressing to obtain a dehydrated sludge cake with a relatively high moisture content (82% moisture content) and a dehydrated filtrate with a very turbid appearance, indicating that the dehydration property of the treated sludge was still relatively poor.

[0081] Comparative Example 3

[0082] This comparative example adopts the method with publication number CN114920436A and invention name "A method for chemically enhanced anaerobic digestion sludge bioleaching treatment" to perform sludge dehydration control.

[0083] The sample is the same as that in Example 1, and the processing steps of this comparative example are as follows:

[0084] (1) Penicillium simplicissimum NAU-12 culture;

[0085] (2) Bioleaching treatment: Penicillium simplex NAU-12 bacterial solution (10%, v / v) was inoculated into the sludge and cultured in a constant temperature shaking incubator at 28°C and 180 rpm for 1 day. The water loss was supplemented by weighing and replenishing water to maintain the water content at about 97%. The bioleaching modified sludge was obtained and the sludge pH was measured to be 4.2;

[0086] (3) Chemically enhanced bioleaching conditioning: 60 mg / g sludge dry solids (DS) Fe 2+ and 30mg / g DS H 2 O 2 , placed in a constant temperature shaking incubator at 28°C and 180 r / min for 1 h, and the sludge pH was measured to be 3.0;

[0087] (4) Mechanical dehydration: The treated sludge was subjected to plate and frame filter pressing, with a feed time of 30 min, high-pressure water pressing and pressure maintenance of 30 min, a feed pressure of 0.7 MPa, and a diaphragm pressing pressure of 1.5 MPa to obtain a yellowish dehydrated water cake (water content 58%) and a clear dehydrated filtrate.

[0088] It can be seen from the embodiments and comparative examples that the method and application of the present application for achieving sludge dehydration and reduction by using a filamentous fungus-type Fenton conditioning method can reduce the moisture content of the sludge from 97% to 58%, and the dehydration rate is about 45%. The effect is basically the same as that of the existing Fenton reagent chemical oxidation method and the chemical enhanced sludge bioleaching method with publication number CN114920436A, and both can meet the national standard requirement of a mud cake moisture content of <60%. More importantly, the filamentous fungus-type Fenton treatment method of the present application is achieved under the condition of zero exogenous addition of Fenton chemical reagents, and the pH values ​​of the dehydrated mud cake and dehydrated filtrate produced in the end are close to neutral, which is safer, and the organic matter loss in the sludge is also less, which is easy for subsequent resource utilization.

Claims

1. A method for achieving sludge dehydration and reduction by using filamentous fungi Fenton conditioning, characterized in that: The method comprises: S1, inoculating filamentous fungi into sludge and adding nutrients; the filamentous fungi have the function of differentiating to produce H2O2 and inducing inert iron-containing compounds to transform into amorphous active nano-iron particles; S2, placing the sludge under stirring, mixing, aeration and oxygenation conditions to carry out a Fenton-like reaction; S3, mechanically dewatering the treated sludge to achieve sludge dehydration and reduction.

2. The method for achieving sludge dehydration and reduction by filamentous fungus Fenton conditioning according to claim 1, characterized in that: The filamentous fungi include Penicillium simplicifolium.

3. The method for achieving sludge dehydration and reduction by filamentous fungus Fenton conditioning according to claim 2, characterized in that: The Penicillium simplicissimum is Penicillium simplicissimum NAU-12, which is classified and named Penicillium simplicissimum and deposited in the General Microbiological Center of China National Microbiological Culture Collection Administration on July 6, 2015, with a deposit number of CGMCCNO.10990.

4. The method for achieving sludge dehydration and reduction by filamentous fungus Fenton conditioning according to claim 3, characterized in that: The inoculation density of the Penicillium simplex NAU-12 was 1×10 8 ~1×10 9 Spores / mL.

5. The method for achieving sludge dehydration and reduction by filamentous fungus Fenton conditioning according to any one of claims 1 to 4, characterized in that: The nutrients include phosphorus, calcium, sugar and acid.

6. The method for achieving sludge dehydration and reduction by filamentous fungus Fenton conditioning according to claim 5, characterized in that: The nutrient comprises K2HPO4, CaCl2·2H2O, oxalic acid and sucrose.

7. The method for achieving sludge dehydration and reduction by filamentous fungus Fenton conditioning according to claim 5, characterized in that: The concentrations of the nutrients after addition are: K2HPO4 0.01-0.04 g / L; CaCl2·2H2O 0.01-0.036 g / L; oxalic acid 0.01-0.02 g / L; sucrose 0.001-0.01 g / L.

8. The method for achieving sludge dehydration and reduction by filamentous fungus Fenton conditioning according to claim 6 or 7, characterized in that: The stirring, mixing, aeration and oxygenation conditions include: 20-35° C., ventilation and stirring for 2-4 days, and controlling the dissolved oxygen content to 1-2 mg / L.

9. Use of the method for achieving sludge dehydration and reduction by filamentous fungus Fenton conditioning as described in any one of claims 1 to 8 in sludge dehydration and reduction.

10. A process for dehydrating and reducing sludge, characterized in that: The process includes the method for achieving sludge dehydration and reduction by filamentous fungus Fenton conditioning as described in any one of claims 1-8.

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