Background
At present, with the higher and higher requirements of China on the sewage collection rate, the sewage treatment capacity is increased, and then huge excess sludge is generated. The water content of the excess sludge discharged from sewage plants is 99% or more, and is about 98% even after concentration. The sludge has complex components and contains pathogenic microorganisms, parasites and toxic and harmful substances. If the treatment is not proper, the environment is polluted again. For the clear regulation of the national water pollution prevention and control action plan, the following are provided: sludge produced by sewage treatment facilities is subjected to stabilization, harmless and recycling treatment. The sludge of the sewage treatment plant is generally dewatered mechanically, the mechanical dewatering pressure is limited in actual production, and the water content of the untreated sludge is reduced to 75 percent after the sludge is dewatered. Mainly due to the poor compressibility of sludge and the high content of Extracellular Polymeric Substances (EPS) in sludge, intracellular bound water (interstitial water, capillary water, bound water) is difficult to remove from sludge even under very high pressure. Therefore, it is necessary to improve the compression performance and degradation performance in the dehydration process, improve the mechanical dehydration efficiency, and reduce the amount by deep dehydration with a machine by sludge conditioning. If the traditional conditioning method is used for conditioning the sludge, the compressibility of the sludge is low, and sludge cells and organic substances in the sludge block gaps of the filter cloth; meanwhile, the inorganic conditioner can reduce the organic matter content of the sludge, and is not beneficial to subsequent treatment processes such as incineration, carbonization and resource utilization.
Through the above analysis, the problems and defects of the prior art are as follows: the traditional conditioning method conditions the sludge, and the high compressibility and low compressibility of the sludge cause sludge cells and organic substances in the sludge to block gaps of filter cloth; meanwhile, the inorganic conditioner can reduce the organic matter content of the sludge, and is not beneficial to subsequent treatment processes such as incineration, carbonization and resource utilization.
The difficulty in solving the above problems and defects is: the extracellular polymeric substance content in the sludge is high, the surface of the sludge is easy to adhere with water, and meanwhile, more bound water exists among cells, under the state, the solid-liquid separation effect in the sludge is not ideal, if a gap between the filter cloth of the dewatering device and a mud cake is blocked, the sludge is in a state which is difficult to compress, and even if higher pressure is used, the water is still difficult to release. Meanwhile, a large amount of inorganic conditioner can increase the content of inorganic substances in the sludge and reduce the heat value. The significance of solving the problems and the defects is as follows: the extracellular polymeric substances in the sludge are damaged, bound water is released, the hydrophilicity of sludge cells is reduced, and the sludge-water separation effect is optimized. The water channels between the sludge and in the filter cloth are increased, and water can pass through the mud cake and the filter cloth under higher pressure to achieve good dehydration effect.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a conditioner based on sludge oxidation and skeleton construction and a sludge conditioning method. The invention solves the defects of poor sludge compressibility and difficulty in dehydration caused by the fact that organic matters in sludge easily block filter cloth, and provides the conditioner and the conditioning method for reducing the water content of sludge cakes after sludge dehydration, improving the sludge compressibility and increasing the sludge calorific value.
The invention is realized by the following steps that the conditioner based on sludge oxidation and skeleton construction consists of an oxidant, an activator and a skeleton construction material; the weight ratio of the oxidant is 10-15% of the absolute dry sludge; the weight ratio of the corn stalk powder is 30-40% of the absolute dry sludge.
Furthermore, the oxidant is potassium monopersulfate powder, and the framework construction material is corn straw powder.
Further, the grain diameter of the corn straw powder is 30-40 meshes.
Another object of the present invention is to provide a sludge conditioning method using the sludge oxidation and skeleton-building based conditioner, comprising:
step one, adding sludge into a pyrolysis stirring pool;
secondly, adding potassium monopersulfate into the sludge in the stirring pool; stirring simultaneously;
adding a skeleton building material, and stirring;
and step four, mechanically dehydrating the sludge which is uniformly stirred.
Further, the first step specifically includes: adding sludge with the water content of 96-97% into a sludge pyrolysis stirring tank, wherein the pyrolysis tank can be heated to a certain temperature by using industrial cooling water and is heated to 70-80 ℃ by using other modes.
In the second step, the stirring is carried out at a stirring speed of 150 rpm for 15 minutes.
Further, in the second step, the weight ratio of the added potassium monopersulfate is 10-15% of the amount of the oven-dried sludge.
Further, in the third step, the added framework construction material is corn straw powder with the weight ratio of 30-40% of the absolute dry sludge and the particle size of 30-40 meshes.
Further, in the third step, the stirring is performed at a stirring speed of 100 rpm for 15 minutes.
Further, in the fourth step, the sludge is sent to a plate-and-frame filter press with the pressing pressure of 1.6MPa by a sludge inlet pump with the feeding pressure of 0.5 MPa.
By combining all the technical schemes, the invention has the advantages and positive effects that: the invention is beneficial to activating the potassium monopersulfate in a heating mode, and is equivalent to a conditioning tank. The conditioner based on sludge oxidation and skeleton construction can destroy extracellular polymeric substance structures and cell walls of sludge and provide skeleton structures in the sludge dehydration process, thereby improving the settleability and compressibility of the sludge. The sludge conditioning method adopts a conditioner based on sludge oxidation and skeleton construction, improves the settleability and compressibility of the sludge, and reduces the water content of the dewatered sludge to below 58% by matching with mechanical dewatering; meanwhile, the heat value of the dewatered sludge is improved, and the sludge is favorably incinerated and the like.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Aiming at the problems in the prior art, the invention provides a conditioner based on sludge oxidation and skeleton construction and a sludge conditioning method, and the invention is described in detail below with reference to the accompanying drawings.
The conditioner based on sludge oxidation and skeleton construction provided by the embodiment of the invention comprises an oxidant, an activator and a skeleton construction material; wherein, the oxidant is potassium monopersulfate powder, and the weight ratio of the potassium monopersulfate powder is 10 to 15 percent of the oven-dried sludge; the construction framework material is corn straw powder, and the construction framework material is the corn straw powder with the weight ratio of 30-40% of absolute dry sludge and the particle size of 30-40 meshes.
The sludge conditioning method based on sludge oxidation and skeleton construction provided by the embodiment of the invention comprises the following steps:
s101: adding the sludge into a pyrolysis stirring pool, and heating to 80 ℃.
S102: adding potassium monopersulfate into the sludge in the stirring pool; while stirring is performed.
S103: adding the skeleton building material and stirring.
S104: and mechanically dehydrating the sludge which is uniformly stirred.
Preferably, step S101 specifically includes: adding sludge with the water content of 96-97% into a sludge stirring tank.
Preferably, the stirring in step S102 is performed at a stirring speed of 150 rpm for 15 minutes.
Preferably, the weight ratio of potassium monopersulfate added in step S102 is 10 to 15% of the amount of the oven-dried sludge.
Preferably, the building framework material added in the step S103 is corn straw powder with the weight ratio of 30-40% of the absolute dry sludge and the particle size of 30-40 meshes.
Preferably, the stirring in step S103 is performed at a stirring speed of 100 rpm for 15 minutes.
Preferably, step S104 comprises a sludge pump with a feeding pressure of 0.5MPa to send the sludge to a plate-and-frame filter press with a pressing pressure of 1.6 MPa.
Preferably, the water content of the sludge after mechanical dewatering in step S104 is 58% or less.
The technical solution of the present invention is further described with reference to the following specific examples.
Example 1
The conditioning method using the conditioner based on sludge oxidation and skeleton construction in the embodiment comprises the following steps:
(1) adding sludge with the water content of 96% into a sludge pyrolysis stirring pool, and heating to 80 ℃.
(2) Sodium peroxodisulfate powder, in an amount of 10% of the oven dried sludge, and ferric chloride solids, in an amount of 4% of the oven dried sludge, were added, followed by stirring at a stirring speed of 150 rpm for 15 minutes.
(3) Corn stalk powder with 30 percent of oven-dried sludge and 30 meshes of grain diameter is added and then stirred for 15 minutes at the stirring speed of 100 revolutions per minute.
(4) And mechanically dewatering the sludge which is uniformly stirred, wherein the filter chamber of the plate and frame filter press is 0.3m by 0.3m, the feeding pressure of a sludge inlet pump is 0.5MPa, and the pressing pressure of the plate and frame filter press is 1.6 MPa. The dehydration time was 20 minutes.
After mechanical dehydration, the water content of the dehydrated mud cake is 56.8 percent.
Example 2
The conditioning method using the conditioner based on sludge oxidation and skeleton construction in the embodiment comprises the following steps:
(1) adding the sludge with the water content of 97% into a sludge pyrolysis stirring pool, and heating to 80 ℃.
(2) Potassium monopersulfate powder was added in an amount of 12% of the oven-dried sludge, followed by stirring at a stirring speed of 150 rpm for 15 minutes.
(3) Corn stalk powder with the grain diameter of 40 meshes and the amount of 30 percent of the absolute dry sludge is added, and then the mixture is stirred for 15 minutes at the stirring speed of 100 revolutions per minute.
(4) And mechanically dewatering the sludge which is uniformly stirred, wherein the filter chamber of the plate and frame filter press is 0.3m by 0.3m, the feeding pressure of a sludge inlet pump is 0.5MPa, and the pressing pressure of the plate and frame filter press is 1.6 MPa. The dehydration time was 20 minutes.
After mechanical dehydration, the water content of the dehydrated mud cake is 57.2 percent.
Example 3
The conditioning method using the conditioner based on sludge oxidation and skeleton construction in the embodiment comprises the following steps:
(1) adding the sludge with the water content of 96% into a sludge pyrolysis stirring pool.
(2) Potassium monopersulfate powder in an amount of 15% by weight of the oven-dried sludge and ferrous sulfate powder in an amount of 5% by weight of the oven-dried sludge were added, followed by stirring at a stirring speed of 150 rpm for 15 minutes.
(3) Corn stalk powder with the grain diameter of 30 meshes and the absolute dry sludge amount of 40 percent is added, and then the mixture is stirred for 15 minutes at the stirring speed of 100 revolutions per minute.
(4) And mechanically dewatering the sludge which is uniformly stirred, wherein the filter chamber of the plate and frame filter press is 0.3m by 0.3m, the feeding pressure of a sludge inlet pump is 0.5MPa, and the pressing pressure of the plate and frame filter press is 1.6 MPa. The dehydration time was 20 minutes.
After mechanical dewatering, the water content of the dewatered mud cake is 55.5 percent.
Example 4
The conditioning method using the conditioner based on sludge oxidation and skeleton construction in the embodiment comprises the following steps:
(1) adding sludge with the water content of 97% into a sludge stirring tank, and heating to 80 ℃.
(2) Potassium monopersulfate powder was added in an amount of 15% of the oven-dried sludge, followed by stirring at a stirring speed of 150 rpm for 15 minutes.
(3) Corn stalk powder with the grain diameter of 40 meshes and the amount of the absolute dry sludge of 40 percent is added, and then the mixture is stirred for 15 minutes at the stirring speed of 100 revolutions per minute.
(4) And mechanically dewatering the sludge which is uniformly stirred, wherein the filter chamber of the plate and frame filter press is 0.3m by 0.3m, the feeding pressure of a sludge inlet pump is 0.5MPa, and the pressing pressure of the plate and frame filter press is 1.6 MPa. The dehydration time was 20 minutes.
After mechanical dehydration, the water content of the dehydrated mud cake is 54.9 percent.
The invention can also change the activation mode at 80 ℃ into ferrous sulfate accounting for 3-6% of the absolutely dry sludge and ferric chloride accounting for 2-4% of the absolutely dry sludge. The sludge temperature of 80 ℃ can be heated by partial cooling waste water. Sodium peroxodisulfate and potassium monopersulfate may be exchanged in equal amounts.
In conclusion, the conditioner based on sludge oxidation and skeleton construction is used for conditioning the sludge, the conditioner comprises an oxidant, an activator and a skeleton construction material, the conditioner based on sludge oxidation and skeleton construction can destroy extracellular polymeric substance structures and cell walls of the sludge, and meanwhile, the skeleton structure is provided in the sludge dehydration process, so that the settleability and compressibility of the sludge are improved. And finally, dehydrating by a plate-and-frame filter press, wherein the water content of the dehydrated mud cake can be reduced to below 58%, the heat value of the sludge can be improved, and the subsequent treatment is not influenced.
FIG. 2 is a variation of sludge Capillary Suction Time (CST) provided by the present invention; FIG. 3 is a graph of the change in sludge Specific Resistance (SRF) provided by the present invention; FIG. 4 shows the variation of the high heat value of the sludge according to the present invention.
The above description is only for the purpose of illustrating the present invention and the appended claims are not to be construed as limiting the scope of the invention, which is intended to cover all modifications, equivalents and improvements that are within the spirit and scope of the invention as defined by the appended claims.