Process for the treatment of printing and dyeing mill sludge to increase the calorific value

Abstract

The present application relates to the field of printing and dyeing plant sludge treatment, and particularly relates to a printing and dyeing plant sludge treatment method for increasing combustion value, comprising the following steps: S1, sludge gravity concentration: the sludge is introduced into a concentration tank; the sludge enriched by bottom settlement is pumped out by a sludge pump; S2, sawdust is first added, then an inorganic coagulant is added; a high-molecular flocculant of anionic polyacrylamide PAM is added; finally, special sludge fermentation bacteria are added; the medicaments are fully mixed with the concentrated sludge by a stirring tank; S3, mechanical deep dewatering: the sludge is continuously punched into a filter plate filter chamber, the filter cloth retains the solid sludge, the water is discharged through the filter cloth, and the filter chamber is gradually filled with the sludge to form a sludge cake; S4, sludge temporary storage and transportation: the dewatered sludge cake is transported to a closed sludge storage shed for stacking and storage, and a foul gas collecting air pipe is arranged at the closed sludge storage shed. The present application provides a printing and dyeing plant sludge treatment method for increasing combustion value, and the sludge cake with increased combustion value can be used as fuel.

Description

Technical Field

[0001] This invention relates to the field of sludge treatment in printing and dyeing plants, and more specifically to a method for treating sludge in printing and dyeing plants to increase its calorific value. Background Technology

[0002] The sludge from the printing and dyeing plant needs to be squeezed to remove the water and reduce its volume.

[0003] The treated sludge has a low calorific value and cannot be used directly as fuel. It can only be used for road paving or as building materials. There is a technical problem with the low calorific value of sludge from printing and dyeing plants, and there is an urgent need to design a treatment method for sludge from printing and dyeing plants that can increase the calorific value.

[0004] It should be noted that the information disclosed in this background section is only for understanding the background technology of this application concept, and therefore may include information that does not constitute prior art. Summary of the Invention

[0005] The purpose of this invention is to provide a method for treating sludge from printing and dyeing plants that increases calorific value, thereby solving the above-mentioned problems.

[0006] To achieve the above objectives, the present invention provides the following technical solution: Methods for treating sludge from dyeing and printing plants to increase its calorific value include: Step S1, Sludge Gravity Thickening: Sludge is fed into a thickening tank; the sludge settles naturally in the tank, and the solid particles in the sludge settle to the bottom of the tank by their own weight, while low-concentration supernatant wastewater is separated from the upper layer; the sludge enriched by settling at the bottom is pumped out by a sludge pump. Step S2: First, add sawdust, then add inorganic coagulant; next, add anionic polyacrylamide (PAM) polymeric flocculant; finally, add sludge-specific fermentation bacteria; the agents are thoroughly mixed with the concentrated sludge in a mixing tank. Step S3, Mechanical Deep Dewatering: Sludge is continuously fed into the filter plate chamber, the filter cloth traps solid sludge, water passes through the filter cloth and is discharged, and the filter chamber is gradually filled with sludge to form a sludge cake; after feeding, low-pressure compressed air is introduced to initially squeeze the sludge cake and discharge free water; high-pressure water or high-pressure gas is introduced into the diaphragm inside the filter plate, the diaphragm expands and strongly squeezes the sludge cake; after pressing, the equipment pulls open the filter plate, and the sludge cake falls to the sludge storage area below by its own weight; Step S4, sludge temporary storage and transfer: The dewatered sludge cake is transported to a closed sludge storage shed for storage. The closed sludge storage shed is equipped with an odor collection duct.

[0007] In one alternative implementation, in step S1, the sludge is fed into a thickening tank by gravity through a pipe. The sawdust in step S2 is generated during wood processing.

[0008] In one optional implementation, a sludge scraper is provided at the bottom of the thickening tank in step S1; The sludge that settles and accumulates at the bottom of the thickening tank is collected by a sludge scraper into the sludge hopper in the center of the tank. The inorganic coagulant in step S2 is polyaluminum chloride.

[0009] In one optional embodiment, the supernatant from the thickener in step S1 overflows and is returned to the front-end integrated wastewater equalization tank for reprocessing. In step S2, polyferric sulfate is added as a supplement.

[0010] In one optional implementation, the thickening tank in step S1 is equipped with a sealed gas collection hood to collect the odorous waste gas generated by anaerobic sludge and send it into the deodorization system. The sludge-specific fermentation bacteria in step S2 include bacteria and fungi.

[0011] In one optional embodiment, the bacteria in step S2 include Bacillus subtilis, Bacillus licheniformis, Bacillus laterosporus, and Bacillus thermophilus.

[0012] In one alternative implementation, the fungi in step S2 include Trichoderma longifolia, Aspergillus oryzae, and thermophilic actinomycetes.

[0013] In one optional embodiment, the stirring speed in step S2 is initially fast and then slows down, so that rapid mixing ensures uniform dispersion of the agent, while slow stirring promotes the growth of flocs without breaking them. In step S3, the pressing time is controlled between 20 and 60 minutes.

[0014] In one optional embodiment, the filter press filtrate generated during dehydration in step S3 is recycled to the wastewater treatment process for further treatment.

[0015] The beneficial effects of this invention are as follows: It provides a method for treating sludge in printing and dyeing plants that increases its calorific value. This method involves the combined use of gravity thickening of sludge, addition of sawdust, addition of inorganic coagulants, addition of anionic compounds, addition of sludge-specific fermentation bacteria, and mechanical deep dewatering. By adding sawdust and fermentation bacteria to the sludge, the calorific value of the sludge is increased during the treatment process. The calorific value of the sludge cake increases from 1500-2000 to 4000. Sludge cake with low calorific value cannot be used as fuel; sludge cake with increased calorific value can be used as fuel. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] As used herein, the phrases “in one embodiment,” “according to one embodiment,” “in some embodiments,” etc., generally refer to the fact that a particular feature, structure, or characteristic following the phrase can be included in at least one embodiment of this disclosure. Therefore, a particular feature, structure, or characteristic can be included in more than one embodiment of this disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, the terms “example,” “exemplary,” etc., are used to “serve as an example, instance, or illustration.” Any implementation, aspect, or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or superior to other implementations, aspects, or designs. Rather, the use of the terms “example,” “exemplary,” etc., is intended to present concepts in a specific manner.

[0018] At least one embodiment provides a method for treating sludge from a dyeing and printing plant to increase its calorific value, comprising: all of which are connected to an external control system for controlling the operation and shutdown of the system and for transmitting signals.

[0019] In some embodiments, the process includes: Step S1, sludge gravity thickening: Sludge is fed into a thickening tank via a pipeline, and a sludge scraper is installed at the bottom of the thickening tank; the sludge settles naturally in the tank, and the solid particles in the sludge settle to the bottom of the tank by their own weight, while low-concentration supernatant wastewater is separated from the upper layer; the supernatant overflows and is returned to the upstream integrated wastewater equalization tank for reprocessing; the sludge enriched by the bottom settling is collected by the sludge scraper to the sludge hopper in the center of the tank and pumped out by a sludge pump; the thickening tank is equipped with a sealed gas collection hood to collect the odorous exhaust gas generated by the anaerobic treatment of the sludge and send it to the deodorization system; Step S2, sludge chemical conditioning: After thickening, the colloidal particles inside the dyeing and printing sludge are negatively charged, and the particles repel each other and disperse. The water is wrapped in the colloid and is difficult to separate, so chemical agents must be added. The process involves breaking down the colloidal structure to complete the conditioning. Sawdust is added first, followed by inorganic coagulants, primarily polyaluminum chloride. For dyeing and printing sludge with high dye and slurry content, polyferric sulfate is added as a supplement. The agents neutralize the negative charge on the sludge colloidal surface, causing tiny sludge particles to destabilize and aggregate into fine flocs. Further, anionic polyacrylamide (PAM) is added as a high-molecular-weight flocculant. Its long molecular chains adsorb and cascade the fine flocs, forming large, dense, and highly permeable flocs. Finally, sludge-specific fermentation bacteria are added. The agents are rapidly and thoroughly mixed with the concentrated sludge in a mixing tank. The mixing speed is initially fast and then slows down. Rapid mixing ensures uniform dispersion of the agents, while slow mixing promotes floc growth without breakage. The fermentation bacteria include Bacillus subtilis, Bacillus licheniformis, and laterophytic spores. Bacillus subtilis, thermophilic Bacillus, a small amount of fungi and actinomycetes in non-rotten sawdust, Trichoderma longifolia, Aspergillus oryzae, and a small amount of thermophilic actinomycetes; the Bacillus subtilis is suitable for decomposing sludge organic matter and pulp, and slightly softening the surface of sawdust; the Bacillus licheniformis is suitable for continuous heat generation for dehydration and deodorization at 55–70℃; the Bacillus laterosporus, i.e., thermophilic laterosporus, is the main force of high-temperature drying, producing low ligninase and not deeply decomposing sawdust; the thermophilic Bacillus generates heat at 60–70℃, evaporates moisture, and retains the sawdust skeleton; the Trichoderma longifolia and Aspergillus oryzae produce only a small amount of cellulase, soften the surface, and do not contain highly active white-rot fungi; the small amount of thermophilic actinomycetes assists in heating and does not deeply degrade lignin; Step S3. Mechanical deep dewatering: The conditioned flocculent sludge is pumped into a diaphragm plate and frame filter press; Feeding stage: Sludge is continuously pumped into the filter chambers of the filter plates, the filter cloth traps the solid sludge, and water passes through the filter cloth and is discharged, and the filter chambers are gradually filled with sludge to form a sludge cake; Low-pressure pre-compression stage: After feeding, low-pressure compressed air is introduced to initially squeeze the sludge cake and discharge free water; High-pressure diaphragm pressing stage: High-pressure water or high-pressure gas is introduced into the diaphragm inside the filter plates, the diaphragm expands and strongly squeezes the sludge cake, the pressing time is controlled according to the characteristics of the sludge, 20-60 minutes, to squeeze out the capillary water inside the sludge cake to the maximum extent; After pressing, the equipment pulls open the filter plates, and the sludge cake falls to the sludge storage area below by its own weight; The filter press filtrate produced by dewatering is uniformly returned to the front end of the wastewater treatment for reprocessing;Step S4, Sludge Temporary Storage and Transfer: The sludge cakes removed by filter pressing are transported to a sealed sludge storage shed for storage. The shed is fully enclosed and equipped with odor collection ducts to collect hydrogen sulfide and organic odors emitted by the sludge and treat them in a biological deodorization tower.

[0020] In the description of the embodiments of the present invention, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. While this patent document contains numerous details, it should not be construed as limiting the scope of any invention or claim, but rather as a description of features of specific embodiments of a particular invention. Certain features described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various functions described in the context of a single embodiment may also be implemented individually in multiple embodiments, or in any suitable sub-combination. Furthermore, although the foregoing features may be described as functioning in certain combinations, or even initially claimed to be so, in certain circumstances, one or more features from a combination of claims may be removed from the combination, and a combination of claims may refer to a sub-combination or a variation of a sub-combination.

[0021] Only some implementations and examples are described; other implementations, enhancements, and variations can be made based on the content described and illustrated in this patent document.

[0022] While several embodiments are provided in this disclosure, it should be understood that the disclosed systems and methods may be embodied in many other specific forms without departing from the spirit or scope of this disclosure. The present examples are intended to be illustrative rather than restrictive and are not limited to the details given. For example, various elements or components may be combined or integrated into another system, or certain features may be omitted or not implemented.

Claims

1. A method for treating sludge from a dyeing and printing plant to increase its calorific value, characterized in that, include: Step S1, Sludge Gravity Thickening: The sludge is fed into the thickening tank; The sludge settles naturally in the pool, and the solid particles in the sludge sink to the bottom of the pool by their own weight. Low-concentration supernatant wastewater is separated from the upper layer. The sludge that has settled and accumulated at the bottom is pumped out by a sludge pump. Step S2: First, add sawdust, then add inorganic coagulant; next, add anionic polyacrylamide (PAM) polymeric flocculant; finally, add sludge-specific fermentation bacteria; the agents are thoroughly mixed with the concentrated sludge in a mixing tank. Step S3, Mechanical Deep Dewatering: Sludge is continuously fed into the filter plate chamber, the filter cloth traps solid sludge, water passes through the filter cloth and is discharged, and the filter chamber is gradually filled with sludge to form a sludge cake; after feeding, low-pressure compressed air is introduced to initially squeeze the sludge cake and discharge free water; high-pressure water or high-pressure gas is introduced into the diaphragm inside the filter plate, the diaphragm expands and strongly squeezes the sludge cake; after pressing, the equipment pulls open the filter plate, and the sludge cake falls to the sludge storage area below by its own weight; Step S4, sludge temporary storage and transfer: The dewatered sludge cake is transported to a closed sludge storage shed for storage. The closed sludge storage shed is equipped with an odor collection duct.

2. The method for treating sludge from dyeing and printing plants to increase its calorific value according to claim 1, characterized in that: In step S1, the sludge is fed into the thickening tank by gravity through a pipeline. The sawdust in step S2 is generated during wood processing.

3. The method for treating sludge from dyeing and printing plants to increase its calorific value according to claim 2, characterized in that: A sludge scraper is installed at the bottom of the thickening tank in step S1. The sludge that settles and accumulates at the bottom of the thickening tank is collected by a sludge scraper into the sludge hopper in the center of the tank. The inorganic coagulant in step S2 is polyaluminum chloride.

4. The method for treating sludge from dyeing and printing plants to increase its calorific value according to claim 1, characterized in that: In step S1, the supernatant from the thickener overflows and is returned to the front-end integrated wastewater equalization tank for reprocessing. In step S2, polyferric sulfate is added as a supplement.

5. The method for treating sludge from dyeing and printing plants to increase its calorific value according to claim 1, characterized in that: In step S1, the thickening tank is equipped with a sealed gas collection hood to collect the odorous waste gas generated by anaerobic sludge and send it into the deodorization system. The sludge-specific fermentation bacteria in step S2 include bacteria and fungi.

6. The method for treating sludge from dyeing and printing plants to increase its calorific value according to claim 5, characterized in that: The bacteria in step S2 include Bacillus subtilis, Bacillus licheniformis, Bacillus laterosporus, and Bacillus thermophilus.

7. The method for treating sludge from dyeing and printing plants to increase its calorific value according to claim 5, characterized in that: The fungi in step S2 include Trichoderma longifolia, Aspergillus oryzae, and thermophilic actinomycetes.

8. The method for treating sludge from dyeing and printing plants to increase its calorific value according to claim 1, characterized in that: In step S2, the stirring speed is first fast and then slow, so that rapid mixing ensures uniform dispersion of the agent, and slow stirring promotes the growth of flocs without breaking them. In step S3, the pressing time is controlled between 20 and 60 minutes.

9. The method for treating sludge from dyeing and printing plants with increased calorific value according to claim 8, characterized in that: The filter filtrate produced during dehydration in step S3 is returned to the wastewater treatment process for further treatment.