CN114275995B - A combined sludge conditioner based on the theory of moderate flocculation and protein solidification, its conditioning method and the determination method of economic dosage - Google Patents

Abstract

The invention provides a sludge chemical combination conditioner based on the theories of proper flocculation and protein solidification, which comprises a protein solidifying agent accounting for 0.5-2.5 percent of the dry basis mass of sludge to be treated and a flocculating agent accounting for 0.5-2.5 percent of the dry basis mass of the sludge to be treated; the sludge chemical combination conditioner conditioning method based on the moderate flocculation and protein solidification theories is also provided, the method of solidification and flocculation is adopted, the dehydration capacity of the sludge is greatly improved, the water content of the prepared mud cake meets the requirement of less than 60%, the sludge is conditioned by using a mechanical medicament, the adding amount is less than 5%, the conductivity is increased by less than 10%, the dehydration efficiency is stable and controllable, and the defects of poor sludge dehydration performance, large medicament adding amount and more inorganic ion component residues in the prior art are overcome.

Description

A combined sludge conditioner based on the theory of moderate flocculation and protein solidification and its conditioner The rational method and the method of determining the economic dosage

technical field

The invention relates to the technical field of sludge treatment in municipal sewage plants, in particular to a sludge chemical joint conditioner based on the theory of moderate flocculation and protein solidification, a conditioning method and a method for determining economic dosage.

Background technique

Sludge is the main by-product of sewage biological purification treatment, enriching a large number of pathogenic bacteria, heavy metals, and organic pollutants. If it cannot be effectively treated and disposed of, it will produce extremely serious environmental secondary pollution. With the continuous improvement of economic development and urbanization, the rate of sewage collection and treatment in my country has increased year by year. By 2020, a total of 58.825 billion tons of sewage will be treated throughout the year, and 58.7939 million tons of sludge will be generated (with a moisture content of 80%). Such a huge volume of sludge must be safely treated, disposed of and utilized as a resource in order to truly achieve water pollution control rather than the transfer of pollution from liquid to solid.

Sludge treatment and disposal paths usually include deep dehydration-sanitary landfill, dry incineration-building material utilization, aerobic composting-land use, anaerobic fermentation-land use, etc. No matter which disposal route is adopted, strict technical limits are made on the moisture content of sludge. The long-term treatment process must include dehydration pretreatment or dehydration post-treatment process, which helps to reduce the volume of sludge, reduce fluidity, and increase calorific value. Therefore, how to efficiently reduce the moisture content of sludge has become an important technical requirement for the large-scale safe treatment and disposal of sludge in my country.

However, the sludge composition is extremely complex, with high hydrophilicity and charging characteristics, so that the sludge can exist in the form of stable colloidal flocs, and the dehydration performance is extremely poor. Under normal circumstances, direct suction filtration and dehydration of sludge can control the moisture content below 90%, while mechanical press filtration cannot be directly dehydrated due to problems such as sticky filter cloth and mud running. Therefore, necessary conditioning and pretreatment must be carried out on the sludge in order to achieve effective control of the moisture content. In recent years, a variety of dehydration conditioning agents including coagulants, flocculants, advanced oxidants, surfactants, filter aids, lysozymes, etc. have been widely used and reported. For example, the invention patent CN202110599343.4 relates to a compound agent for reducing the moisture content of sludge, including sludge deflocculation and destabilization agent, sludge flocculant, and filter aid; the sludge deflocculation and destabilization agent is KCl; the sludge flocculant is polyaluminum chloride (PAC) and/or polyacrylamide (PAM); the filter aid is biomass ash. Invention CN202110463024.0 relates to a sludge conditioning method for improving sludge dewatering ability, using bivalent iron stabilized by citric acid to activate peroxodisulfate to generate sulfate radicals, and using sulfate radicals to degrade sludge Extracellular polymers, thereby improving the dewatering ability of sludge.

However, the sludge dehydration conditioning technology has been in a "black box" state for a long time in terms of theoretical research and engineering application, and new theories and technologies are urgently needed to guide practical applications.

In terms of theoretical research, the coagulation/flocculation process mainly focuses on the effects of chemicals on the physicochemical properties of sludge such as Zeta potential and particle size distribution; the oxidation process mainly focuses on the non-selective cracking or dissolution of extracellular polymer EPS The impact on sludge dewatering performance; filter aid research is mostly limited to the direction of increasing the proportion of dry-based materials and reducing the compressibility of mud cake. However, the above studies did not clearly point out the key factors and direct causes affecting the sludge dewatering ability, and did not form a sludge conditioning technology with stable and controllable dewatering efficiency, resulting in often mismatched or even contradictory changes between the dewatering efficiency and the changes in various parameters. situation.

At the level of engineering application, sludge dewatering has long relied on inorganic salts (iron salts, aluminum salts), polyacrylamide, and lime (fly ash) alone or in combination, causing double pressure on the environment and economy. The dosage of ferric trichloride and polyaluminum chloride is huge (10-20% of the dry weight of the sludge), and the dosage of lime is even as high as 50%. The high dosage not only increases the cost, but also makes it easier to The phenomenon of "only dehydration without capacity reduction" appears due to excessive material dosing. In addition, iron salt residues can easily lead to soil compaction, aluminum salt residues will pollute nearby water bodies, polyacrylamide residues will form a surface "slime film" after rainfall, and chloride ion residues will aggravate the corrosion of drying and incineration equipment.

In response to the above problems, it is necessary to try a new direction and technical route, abandon the idea of pursuing to increase the molecular weight and ionicity of the flocculant, adding a large amount of oxidant to degrade EPS, and adding a large amount of inorganic salts and additives, and carry out moderate flocculation reaction and EPS. "Passivation" is expected to form an environmentally friendly conditioning technology that can stably meet the dehydration requirements, including stable effect, less dosage, less residue (iron, aluminum, chlorine), green safety and controllable cost.

Contents of the invention

In view of the above-mentioned problems existing in the prior art, this application provides a conditioning method of sludge chemical joint conditioner based on the theory of moderate flocculation and protein solidification, adopting the method of solidification first and then flocculation, which greatly improves the dewatering ability of sludge, and prepares The moisture content of the obtained mud cake meets the requirement of <60%, and the sludge is conditioned by using organic chemicals, the dosage is less than 5%, the increase in electrical conductivity is <10%, and the dehydration efficiency is stable and controllable, which solves the problems existing in the prior art The dehydration performance of sludge is poor, the dosage of chemicals is large, and the defects of residual inorganic ion components are more.

The purpose of the present invention can be achieved through the following technical solutions:

The invention provides a sludge joint conditioner based on moderate flocculation and protein solidification theory, the formula of the conditioner comprises:

A protein curing agent accounting for 0.5% to 2.5% of the dry weight of the sludge to be treated;

The flocculant accounts for 0.5% to 2.5% of the dry weight of the sludge to be treated.

The present invention also provides a conditioning method based on the moderate flocculation and protein solidification theory of sludge joint conditioner, comprising the following steps:

S1. Add the protein solidifying agent to the sludge to be treated, apply magnetic stirring at 200-500 rpm for 5-30 minutes, and obtain pretreated sludge;

S2. Add the flocculant to the pretreated sludge obtained in S1, apply magnetic stirring at 200-500 rpm for 3-15 minutes, and obtain conditioned sludge;

S3. Transfer the conditioned sludge obtained in S2 to a filter press equipment for a filter press treatment for 10-30 minutes to obtain a mud cake.

The protein curing agent described in S1 of the present invention is tannic acid, condensed tannin, novel tannin, one or a mixed compound of tannin extract;

The flocculant described in S2 of the present invention is cationic starch, chitosan, lignin, polydimethyldiallyl ammonium chloride, sodium polyacrylate, polyvinyl ether, polyvinyl alcohol, polysulfostyrene, poly Ethylene oxide, one of urea-formaldehyde resins or a mixed compound.

The filter press equipment described in S3 of the present invention is a plate and frame filter press, and its filter press pressure is 0.5-1.5Mpa.

The present invention also provides a method for determining the economic dosage of sludge joint conditioner based on moderate flocculation and protein solidification theory, comprising the following steps:

Step 1. Sludge Conditioning: Use a measuring cylinder to measure 500ml of raw sludge into a beaker, start the electric mixer, and set the speed of the mixer to 500r/min. After the sludge is evenly stirred, add flocculant to the raw sludge and keep stirring Stir at a speed of 500r/min for 15s to quickly mix the flocculant with the sludge, then reduce the speed to 300r/min, turn off the agitator after conditioning for 15min, and obtain the conditioned sludge;

Step 2, CST measurement: add the sludge conditioned in step 1 into the funnel of the capillary water absorption time tester, and record the indication;

Step 3. Determine the economic dosage of flocculant: CST gradually decays with the increase of flocculant. When CST reaches the minimum value, the corresponding dosage is the economic dosage;

Step 4. Determine the economical dosage of protein fixative: Add protein fixative to the conditioned sludge with flocculant added in economical dosage. When the apparent viscosity of the sludge reaches the maximum value, the corresponding The dosage is the dosage of curing agent.

The protein solidifying agent of the present invention is tannic acid, and the determined tannic acid accounts for 1.0% to 2.0% of the dry mass of the sludge to be treated, and the flocculant is polydimethyldiallylammonium chloride, The determined polydimethyldiallylammonium chloride accounts for 1.0% to 2.0% of the dry mass of the sludge to be treated.

The protein solidifying agent described in the present invention is condensed tannin, and the determined condensed tannin accounts for 0.8% to 2.2% of the dry weight of the sludge to be treated, and the flocculant is sodium polyacrylate, and the determined sodium polyacrylate It accounts for 0.8% to 2.2% of the dry weight of the sludge to be treated.

The protein curing agent described in the present invention is tannin extract, and the determined tannin extract accounts for 1.0% to 1.8% of the dry weight of the sludge to be treated, and the flocculant is polyvinyl ether, and the determined polyvinyl ether accounts for 1.0% to 1.8% of the dry mass of mud.

The protein solidifying agent described in the present invention is a novel tannin, and the novel tannin accounts for 1.0% to 2.2% of the dry weight of the sludge to be treated, and the flocculant is cationic starch and polydimethyldiallyl chloride A mixed compound of ammonium, the molar ratio of the cationic starch to the polydimethyldiallylammonium chloride is 1:0.1-10, and the determined mixed compound accounts for the dry weight of the sludge to be treated 1.0% to 2.0% of that.

Compared with the prior art, the present invention has the following characteristics:

1) In the conventional sludge dehydration method, the sludge specific resistance reduction rate is only 50-60%, and the final moisture content is 70-80%. However, the present invention provides a novel and efficient sludge dehydration conditioning method for the sludge treatment field The mud cake specific resistance reduction rate obtained by the conditioning method of the present invention can reach 95%, and the final water content can be reduced to 56%.

2) The conditioning agent used in the present invention does not use inorganic salts, and there is no risk of ion residues. The increase in electrical conductivity can be controlled within 10% by using the organic conditioning agent to condition the sludge, without affecting other equipment and sludge disposal schemes; in addition, the conditioning agent The dosage is controlled within 5% of the dry sludge, which will not increase the volume of dewatered sludge; the flocculant and curing agent are environmentally friendly, and the monomers are non-toxic and environmentally friendly. They only contain three elements of carbon, hydrogen and oxygen, and can Significantly increase the incineration calorific value of sludge.

3) The present invention optimizes the dosing sequence of the curing agent and the flocculant. Dosing the curing agent first can ensure that the active protein in the sludge reacts fully with the curing agent, and the hydrophilicity of the protein decreases significantly after the functional group is cross-linked and solidified. The bound water content also decreases; the protein insoluble matter formed after full reaction and solidification can also act as a filler to support the mud cake structure, reduce the compression deformation of the mud cake, and prevent the filter cake or filter membrane from clogging. Finally, the flocculant is used to coagulate into agglomerates to increase the particle size of flocs, which is helpful for solid-liquid separation and dehydration of mud cake. On the contrary, if the flocculation is carried out first, and then the protein curing reaction is carried out, the reaction between the protein and the curing agent will not be sufficient, which will affect the reaction efficiency and even cause the waste of pharmaceuticals.

4) The present invention adopts the test method of CST combined with sludge viscosity to accurately identify the economic dosage of conditioner, and optimize the rheological characteristic parameters such as thixotropy to control the degree of sludge conditioning, which can avoid the blindness of medicament conditioning The determined optimum dosage of flocculant and protein solidifier is the economic dosage of conditioner, which can not only reduce the cost of sludge dewatering chemicals, but also reduce transportation costs and landfill costs, and maximize economic benefits change.

Detailed ways

The technical solutions of the present invention will be further described below through specific embodiments.

Example 1

This embodiment provides a kind of conditioning method of the combined sludge conditioner based on moderate flocculation and protein solidification theory, and the conditioning method comprises the following steps:

S1. Add 1.0% tannic acid to the sludge to be treated on a dry basis, and apply magnetic stirring at 300 rpm for 15 minutes to obtain pretreated sludge;

S2. Adding 1.0% of polydimethyldiallylammonium chloride to the pretreated sludge obtained in S1, which accounts for 1.0% of the dry weight of the sludge to be treated, and applying 300 rpm magnetic stirring for 5 minutes to obtain conditioned sludge;

S3. Transfer the conditioned sludge obtained in S2 to a micro plate and frame filter press with a pressure of 0.9 MPa for 10 minutes to obtain a mud cake.

Experimental results:

In this embodiment, the sludge specific resistance reduction rate is 95%, the CST reduction rate is 86%, and the moisture content of the mud cake is 56%.

Example 2

This embodiment provides a kind of conditioning method of the combined sludge conditioner based on moderate flocculation and protein solidification theory, and the conditioning method comprises the following steps:

S1. Add condensed tannins accounting for 2.2% of the dry weight of the sludge to be treated to the sludge to be treated, and apply magnetic stirring at 500 rpm for 5 minutes to obtain pretreated sludge;

S2. Add sodium polyacrylate accounting for 1.0% of the dry weight of the sludge to be treated to the pretreated sludge obtained in S1, and apply magnetic stirring at 500 rpm for 3 minutes to obtain conditioned sludge;

S3. Transfer the conditioned sludge obtained in S2 to a micro plate and frame filter press with a pressure of 0.6 MPa for 30 minutes to obtain a mud cake.

Experimental results:

In this embodiment, the sludge specific resistance reduction rate is 94%, the CST reduction rate is 85%, and the moisture content of the mud cake is 56%.

Example 3

This embodiment provides a kind of conditioning method of the combined sludge conditioner based on moderate flocculation and protein solidification theory, and the conditioning method comprises the following steps:

S1. Adding 1.0% tannin extract to the sludge to be treated on a dry basis, and applying magnetic stirring at 400 rpm for 20 minutes to obtain pretreated sludge;

S2. Add polyvinyl ether accounting for 1.5% of the dry weight of the sludge to be treated to the pretreated sludge obtained in S1, and apply magnetic stirring at 400 rpm for 10 minutes to obtain conditioned sludge;

S3. Transfer the conditioned sludge obtained in S2 to a micro plate and frame filter press with a pressure of 1.0 MPa for 10 minutes to obtain a mud cake.

Experimental results:

In this embodiment, the sludge specific resistance reduction rate is 92%, the CST reduction rate is 88%, and the moisture content of the mud cake is 56%.

Example 4

This embodiment provides a kind of conditioning method of the combined sludge conditioner based on moderate flocculation and protein solidification theory, and the conditioning method comprises the following steps:

S1. Adding 1.0% new-type tannin to the sludge to be treated on a dry basis, and applying magnetic stirring at 350 rpm for 15 minutes to obtain pretreated sludge;

S2, add in the pretreatment sludge that S1 obtains and account for 1.0% mixed compound (the molar ratio is the cationic starch of 1:1 and polydimethyl diallyl ammonium chloride ) was subjected to 200rpm magnetic stirring reaction for 10min to obtain conditioned sludge;

S3. Transfer the conditioned sludge obtained in S2 to a micro plate and frame filter press with a pressure of 1.5 MPa for 10 minutes to obtain a mud cake.

Experimental results:

In this embodiment, the sludge specific resistance reduction rate is 96%, the CST reduction rate is 87%, and the moisture content of the mud cake is 57%.

Example 5

This embodiment provides a method for determining the economic dosage of sludge joint conditioner based on moderate flocculation and protein solidification theory, including the following steps:

Step 1. Sludge conditioning: Measure 500ml of raw sludge into a beaker with a measuring cylinder, start the electric stirrer, and set the speed of the stirrer to 500r/min. After the sludge is evenly stirred, add flocculant to the raw sludge and keep stirring Stir at a speed of 500r/min for 15s to quickly mix the flocculant with the sludge, then reduce the speed to 300r/min, turn off the agitator after conditioning for 15min, and obtain the conditioned sludge;

Step 2, CST measurement: add the sludge conditioned in step 1 into the funnel of the capillary water absorption time tester, and record the indication;

Step 3. Determine the economic dosage of flocculant: CST gradually decays with the increase of flocculant. When CST reaches the minimum value, the corresponding dosage is the economic dosage;

Step 4. Determine the economical dosage of protein fixative: Add protein fixative to the conditioned sludge with flocculant added in economical dosage for sludge conditioning. When the apparent viscosity of the sludge reaches the maximum value, the corresponding The dosage is the dosage of curing agent.

Comparative example:

The place where this comparative example is different from embodiment 1 is, adopt conventional sludge treatment method, specifically as follows:

S1. Add polydimethyldiallylammonium chloride accounting for 1.0% of the dry weight of the sludge to be treated to the sludge to be treated, and apply a magnetic stirring reaction at 300 rpm for 5 minutes to obtain pretreated sludge;

S2. Add 1.0% tannic acid to the pretreated sludge obtained in S1, and apply 300 rpm magnetic stirring for 15 minutes to obtain conditioned sludge;

S3. Transfer the conditioned sludge obtained in S2 to a micro plate and frame filter press with a pressure of 0.5 MPa for 10 minutes to obtain a mud cake.

Experimental results:

In this comparative example, the sludge specific resistance reduction rate is 53%, the CST reduction rate is 56%, and the moisture content of the mud cake is 76%.

The above descriptions of the embodiments are for those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described here to other embodiments without creative effort. Therefore, the present invention is not limited to the above-mentioned embodiments. Improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims (7)

1. a sludge combined conditioner based on moderate flocculation and protein solidification theory, is characterized in that, the formula of described conditioner comprises: Protein curing agent accounting for 0.5%~2.5% of the dry weight of the sludge to be treated; The flocculant accounts for 0.5%~2.5% of the dry weight of the sludge to be treated; The conditioning method of the sludge joint conditioner based on moderate flocculation and protein solidification theory, comprising the following steps: S1. Add the protein solidifying agent to the sludge to be treated, apply a magnetic stirring reaction at 200-500 rpm for 5-30 minutes, and obtain the pre-treated sludge; S2. Add the flocculant to the pretreated sludge obtained in S1, apply magnetic stirring at 200 to 500 rpm for 3 to 15 minutes, and obtain conditioned sludge; S3. Transfer the conditioned sludge obtained in S2 to a filter press equipment for 10-30 minutes of press filter treatment to obtain a mud cake; The method for determining the economic dosage of the sludge joint conditioner based on moderate flocculation and protein solidification theory comprises the following steps: Step 1. Sludge Conditioning: Use a measuring cylinder to measure 500ml of raw sludge into a beaker, start the electric mixer, and set the speed of the mixer to 500r/min. After the sludge is evenly stirred, add flocculant to the raw sludge and keep stirring Stir at a speed of 500r/min for 15s to quickly mix the flocculant with the sludge, then reduce the speed to 300r/min, turn off the agitator after conditioning for 15min, and obtain the conditioned sludge; Step 2, CST measurement: add the sludge conditioned in step 1 into the funnel of the capillary water absorption time tester, and record the indication; Step 3. Determine the economic dosage of flocculant: CST gradually decays with the increase of flocculant. When CST reaches the minimum value, the corresponding dosage is the economic dosage; Step 4. Determine the economical dosage of protein fixative: Add protein fixative to the conditioned sludge with flocculant added in economical dosage. When the apparent viscosity of the sludge reaches the maximum value, the corresponding The dosage is the dosage of curing agent. 2. the conditioning method of a kind of sludge joint conditioner based on moderate flocculation and protein solidification theory according to claim 1, it is characterized in that, protein solidifying agent described in S1 is tannic acid, condensed type tannin, castanoic acid One of the glues or a mixed compound. 3. the conditioning method of a kind of sludge joint conditioner based on moderate flocculation and protein solidification theory according to claim 1, it is characterized in that, the flocculant described in S2 is cationic starch, chitosan, lignin, poly One of dimethyl diallyl ammonium chloride, sodium polyacrylate, polyvinyl ether, polyvinyl alcohol, polysulfostyrene, polyethylene oxide, urea-formaldehyde resin or a mixed compound. 4. the conditioning method of a kind of sludge joint conditioner based on moderate flocculation and protein solidification theory according to claim 1, it is characterized in that, the press filter equipment described in S3 is a plate and frame filter press, and its press filter The pressure is 0.5~1.5Mpa. 5. a kind of method for determining the economic dosage of sludge joint conditioner based on moderate flocculation and protein solidification theory according to claim 1, is characterized in that, described protein solidifying agent is tannic acid, and described determination unit Nitric acid accounts for 1.0%~2.0% of the dry weight of the sludge to be treated, the flocculant is polydimethyldiallylammonium chloride, and the determined polydimethyldiallylammonium chloride accounts for Treat 1.0%~2.0% of the dry mass of sludge. 6. a kind of method for determining the economic dosage of sludge joint conditioner based on moderate flocculation and protein solidification theory according to claim 1, is characterized in that, described protein solidifying agent is condensed type tannin, and described determination The condensed tannin accounts for 0.8%-2.2% of the dry mass of the sludge to be treated, the flocculant is sodium polyacrylate, and the determined sodium polyacrylate accounts for 0.8%-2.2% of the dry mass of the sludge to be treated. 7. a kind of method for determining the economic dosage of sludge joint conditioner based on moderate flocculation and protein solidification theory according to claim 1, it is characterized in that, described protein solidifying agent is tannin extract, and described determination tannin extract Accounting for 1.0%-1.8% of the dry mass of the sludge to be treated, the flocculant is polyvinyl ether, and the determined polyvinyl ether accounts for 1.0%-1.8% of the dry mass of the sludge to be treated.