Innocent treatment method of excess sludge

Abstract

The invention provides a harmless treatment method of excess sludge, and belongs to the technical field of sludge treatment. The harmless treatment method of the excess sludge comprises the following steps: crushing the excess sludge, and screening; adding fermentation auxiliary materials into the pretreated sludge to obtain a mixed material; carrying out inactivation treatment on the mixed material; adding nutrient substances into the inactivated mixed material, and adjusting the carbon nitrogen ratio and the pH value of the mixture to obtain excess sludge to be fermented; feeding into an aerobic digestion tank, and carrying out aerobic digestion; and carrying out solid-liquid separation on the residual sludge subjected to harmless treatment to realize reduction and resource utilization of the sludge. According to the harmless treatment method, the biodegradability of the excess sludge and the activity of microorganisms are improved by means of pretreatment, pH adjustment, control of conditions in the aerobic digestion tank and the like, the digestion efficiency is further improved, meanwhile, solid-liquid separation is conducted on the excess sludge, and reduction and resource utilization of the sludge are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of sludge treatment, and in particular to a method for harmlessly treating excess sludge. Background Art

[0002] Sewage treatment plants produce more than 40 million tons of sludge every year, with a water content of 80%, but the sludge treatment efficiency is only 20%. As a byproduct of biological treatment in sewage treatment plants, residual sludge is a complex solid-liquid mixture. Its solid phase is mainly composed of active microorganisms (such as bacteria, fungi, parasites, etc.), microbial oxidation residues, organic matter adsorbed on the surface of sludge that has not been degraded or is difficult to degrade (such as nitrogen-containing compounds such as proteins and humus, polysaccharides, polychlorinated biphenyls and dioxins, etc., which are difficult to degrade and toxic and harmful substances) and inorganic matter (such as heavy metals and inorganic salts such as copper, zinc, chromium, etc.). Improper treatment will cause great environmental sanitation problems. Therefore, sludge treatment has become an issue that needs attention.

[0003] Traditional sludge treatment methods include physical treatment, biological treatment, chemical treatment, thermal treatment and other treatment methods. Biological treatment includes anaerobic digestion, aerobic digestion and composting. Aerobic digestion has attracted widespread attention due to its low operating cost and good treatment effect. Aerobic digestion does not produce harmful substances. However, the traditional aerobic digestion method of excess sludge has problems such as low digestion efficiency and poor sludge reduction effect.

[0004] Therefore, it is necessary to develop an efficient aerobic digestion treatment method for excess sludge to improve the treatment effect and resource utilization rate of sludge. Summary of the invention

[0005] The purpose of the present invention is to provide a method for harmlessly treating excess sludge, aiming to solve the technical problems of low aerobic treatment efficiency and poor sludge reduction effect in the prior art.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for harmlessly treating excess sludge, comprising the following steps:

[0008] The remaining sludge is crushed and then screened to obtain pretreated sludge;

[0009] Adding fermentation auxiliary materials to the pretreated sludge and mixing them evenly to obtain a mixed material;

[0010] The mixed material is subjected to an inactivation treatment to obtain an inactivated mixed material;

[0011] Adding nutrients to the inactivated mixed material, adjusting the carbon-nitrogen ratio and pH value of the mixture, and obtaining excess sludge to be fermented;

[0012] The remaining sludge to be fermented is sent to an aerobic digestion tank for aerobic digestion to obtain harmlessly treated remaining sludge;

[0013] The residual sludge after harmless treatment is separated into solid and liquid, the solid part is composted or land utilized, and the liquid part is returned to the aerobic digestion tank for further aerobic digestion.

[0014] Furthermore, the remaining sludge is allowed to stand before the crushing, and the supernatant and floating impurities are discarded; the particle size of the remaining sludge after the crushing is 8 to 10 mm.

[0015] Furthermore, the carbon-nitrogen ratio of the residual sludge to be fermented is 15-20:1, and the pH is 7.0-7.2.

[0016] Furthermore, the fermentation auxiliary material includes one or more of livestock manure, Chinese medicine residue, peanut shells, rice bran, wood chips and straw; and the particle size of the fermentation auxiliary material is 10 to 12 mm.

[0017] Furthermore, the dosage ratio of the pretreated sludge to the fermentation auxiliary material is 10-8:2-3.

[0018] Furthermore, the inactivation treatment is to heat treat the mixed material, the temperature of the heat treatment is 130-150° C., and the time of the heat treatment is 30-40 minutes.

[0019] Furthermore, the dissolved oxygen concentration of the aerobic digester is 2-4 mg / L and the temperature is 20-35°C.

[0020] Furthermore, the aerobic digestion time is 15 to 20 days.

[0021] Furthermore, the nutrients include a nitrogen source and a phosphorus source.

[0022] The present invention also provides the application of the harmless treatment method for excess sludge described in the above technical solution in sludge treatment.

[0023] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0024] The present invention improves the biodegradability of the residual sludge and enhances the activity of microorganisms through pretreatment and adjustment of pH value, thereby improving the efficiency of aerobic digestion; secondly, the present invention performs an inactivation treatment on the mixed material after adding the fermentation auxiliary material, which can effectively eliminate most of the harmful microorganisms and improve the activity of the fermentation microorganisms; furthermore, the present invention improves the digestion efficiency of the microorganisms by adjusting the conditions such as dissolved oxygen and temperature in the aerobic digestion tank; finally, the present invention also performs solid-liquid separation on the treated residual sludge, realizes the resource utilization of sludge reduction, and reduces secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the process of the harmless treatment method of excess sludge of the present invention. DETAILED DESCRIPTION

[0026] The present invention provides a method for harmlessly treating excess sludge, comprising the following steps:

[0027] The remaining sludge is crushed and then screened to obtain pretreated sludge;

[0028] Adding fermentation auxiliary materials to the pretreated sludge and mixing them evenly to obtain a mixed material;

[0029] The mixed material is subjected to an inactivation treatment to obtain an inactivated mixed material;

[0030] Adding nutrients to the inactivated mixed material, adjusting the carbon-nitrogen ratio and pH value of the mixture, and obtaining excess sludge to be fermented;

[0031] The remaining sludge to be fermented is sent to an aerobic digestion tank for aerobic digestion to obtain harmlessly treated remaining sludge;

[0032] The residual sludge after harmless treatment is separated into solid and liquid, the solid part is composted or land utilized, and the liquid part is returned to the aerobic digestion tank for further aerobic digestion.

[0033] The remaining sludge is crushed and then screened to obtain pretreated sludge;

[0034] In the present invention, the residual sludge is preferably allowed to stand before crushing, and the supernatant and floating impurities are discarded, and then crushing and screening are performed after standing.

[0035] In the present invention, the particle size of the residual sludge after crushing is preferably 8 to 10 mm, and more preferably 8 to 9 mm.

[0036] Adding fermentation auxiliary materials to the pretreated sludge and mixing them evenly to obtain a mixed material;

[0037] In the present invention, the fermentation auxiliary material preferably includes one or more of livestock manure, Chinese medicine residue, peanut shells, rice bran, wood chips and straw; the particle size of the fermentation auxiliary material is preferably 10 to 12 mm, and more preferably 10 to 11 mm.

[0038] When the present invention uses a variety of fermentation auxiliary materials, there is no special limitation on the usage ratio between the different types of auxiliary materials, and any ratio can be used as needed.

[0039] In the present invention, the dosage ratio of the pretreated sludge to the fermentation auxiliary material is preferably 8-10:2-3, and more preferably 9-10:2-3.

[0040] The mixed material is subjected to an inactivation treatment to obtain an inactivated mixed material;

[0041] In the present invention, the inactivation treatment is preferably heat treatment of the mixed material, the heat treatment temperature is preferably 130-150°C, more preferably 130-140°C; the heat treatment time is preferably 30-40 minutes, more preferably 30-35 minutes.

[0042] Adding nutrients to the inactivated mixed material, adjusting the carbon-nitrogen ratio and pH value of the mixture, and obtaining excess sludge to be fermented;

[0043] In the present invention, the nutrients preferably include a nitrogen source and a phosphorus source. The present invention does not specifically limit the types of the phosphorus source and the nitrogen source, and phosphorus sources and nitrogen sources well known to those skilled in the art can be used.

[0044] In the present invention, the carbon-nitrogen ratio of the excess sludge to be fermented is preferably 15 to 20:1, more preferably 15 to 18:1; the pH is preferably 7.0 to 7.2, more preferably 7.0 to 7.1.

[0045] The residual sludge after harmless treatment is separated into solid and liquid, the solid part is composted or land utilized, and the liquid part is returned to the aerobic digestion tank to continue aerobic digestion;

[0046] In the present invention, the dissolved oxygen concentration of the aerobic digester is preferably 2-4 mg / L, more preferably 2-3 mg / L; the temperature is preferably 20-35°C, more preferably 20-30°C.

[0047] In the present invention, the aerobic digestion time is preferably 15 to 20 days, more preferably 15 to 18 days.

[0048] The present invention also provides the application of the harmless treatment method for excess sludge described in the above technical solution in sludge treatment.

[0049] In the present invention, unless otherwise specified, the required raw materials for preparation are all commercially available products well known to those skilled in the art.

[0050] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0051] Example 1

[0052] (1) 100 kg of excess sludge is allowed to stand for a period of time, and then the supernatant and floating impurities are removed. The excess sludge is then crushed and sieved to obtain sludge with a particle size of 8 to 10 mm. The pretreated excess sludge is stored for later use;

[0053] (2) Mixing Chinese medicinal residue, peanut shells and livestock manure in a ratio of 1:1:1 to obtain a fermentation auxiliary material, crushing the mixture into fermentation auxiliary materials with a particle size of 10 to 12 mm, mixing the mixture in a ratio of sludge to fermentation auxiliary materials of 5:1, and mixing the mixture evenly to obtain a mixed material;

[0054] (3) The mixed material is then inactivated at a temperature of 130° C. for 30 minutes;

[0055] (4) adding urea and potassium dihydrogen phosphate in a mass ratio of 1:1 to the inactivated mixed material until the carbon-nitrogen ratio of the mixed material is 20:1 and the pH is 7.0, and then stopping the addition of urea and potassium dihydrogen phosphate to obtain excess sludge to be fermented;

[0056] (5) The above-mentioned residual sludge to be fermented is sent to the SBR reactor for aerobic digestion. The dissolved oxygen concentration in the SBR reactor is set to 2 mg / L and the temperature is set to 20°C. The treated sludge is taken out after 15 days of reaction. The treated sludge is separated into solid and liquid. The solid part is put into land use, and the liquid part is returned to the aerobic digester for further aerobic digestion.

[0057] Example 2

[0058] (1) 100 kg of excess sludge is allowed to stand for a period of time, and then the supernatant and floating impurities are removed. The excess sludge is then crushed and sieved to obtain sludge with a particle size of 8 to 10 mm. The pretreated excess sludge is stored for later use;

[0059] (2) mixing Chinese medicinal residue, rice bran and livestock manure in a ratio of 1:1:1 to obtain a fermentation auxiliary material, crushing the mixture into fermentation auxiliary materials with a particle size of 10 to 11 mm, mixing the mixture in a ratio of sludge to fermentation auxiliary materials of 4:1, and uniformly mixing to obtain a mixed material;

[0060] (3) The mixed material is then inactivated at a temperature of 140° C. for 35 minutes;

[0061] (4) adding urea and potassium dihydrogen phosphate in a mass ratio of 1:1 to the inactivated mixed material until the carbon-nitrogen ratio of the mixed material is 15:1 and the pH is 7.1, and then stopping the addition of urea and potassium dihydrogen phosphate to obtain excess sludge to be fermented;

[0062] (5) The above-mentioned residual sludge to be fermented is sent to the SBR reactor for aerobic digestion. The dissolved oxygen concentration in the SBR reactor is set to 3 mg / L and the temperature is set to 30°C. The treated sludge is taken out after 18 days of reaction, and the treated sludge is separated into solid and liquid. The solid part is put into land use, and the liquid part is returned to the aerobic digester for further aerobic digestion.

[0063] Example 3

[0064] (1) 100 kg of excess sludge is allowed to stand for a period of time, and then the supernatant and floating impurities are removed. The excess sludge is then crushed and sieved to obtain sludge with a particle size of 8 to 10 mm. The pretreated excess sludge is stored for later use;

[0065] (2) Mixing Chinese medicinal residue, peanut shells and livestock manure in a ratio of 1:1:1 to obtain a fermentation auxiliary material, crushing the mixture into fermentation auxiliary materials with a particle size of 10 to 12 mm, mixing the mixture in a ratio of sludge to fermentation auxiliary materials of 10:3, and mixing the mixture evenly to obtain a mixed material;

[0066] (3) The mixed material is then inactivated at a temperature of 150° C. for 40 minutes;

[0067] (4) adding urea and potassium dihydrogen phosphate in a mass ratio of 1:1 to the inactivated mixed material until the carbon-nitrogen ratio of the mixed material is 18:1 and the pH is 7.2, and then stopping the addition of urea and potassium dihydrogen phosphate to obtain excess sludge to be fermented;

[0068] (5) The above-mentioned residual sludge to be fermented is sent to the SBR reactor for aerobic digestion. The dissolved oxygen concentration in the SBR reactor is set to 4 mg / L and the temperature is set to 35°C. The treated sludge is taken out after 20 days of reaction. The treated sludge is separated into solid and liquid. The solid part is put into land use, and the liquid part is returned to the aerobic digester for further aerobic digestion.

[0069] 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 principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for harmless treatment of excess sludge, characterized in that: The following steps are involved: The remaining sludge is crushed and then screened to obtain pretreated sludge; Adding fermentation auxiliary materials to the pretreated sludge and mixing them evenly to obtain a mixed material; The mixed material is subjected to an inactivation treatment to obtain an inactivated mixed material; Adding nutrients to the inactivated mixed material, adjusting the carbon-nitrogen ratio and pH value of the mixture, and obtaining excess sludge to be fermented; The remaining sludge to be fermented is sent to an aerobic digestion tank for aerobic digestion to obtain harmlessly treated remaining sludge; The residual sludge after harmless treatment is separated into solid and liquid, the solid part is composted or land utilized, and the liquid part is returned to the aerobic digestion tank for further aerobic digestion.

2. The method for harmless treatment of excess sludge according to claim 1, characterized in that: Before the crushing, the remaining sludge is left to stand, and the supernatant and floating impurities are discarded; the particle size of the remaining sludge after the crushing is 8 to 10 mm.

3. The method for harmless treatment of excess sludge according to claim 1, characterized in that: The carbon-nitrogen ratio of the residual sludge to be fermented is 15-20:1, and the pH is 7.0-7.

2.

4. The method for harmless treatment of excess sludge according to claim 1, characterized in that: The fermentation auxiliary material comprises one or more of animal manure, Chinese medicine residue, peanut shell, rice bran, wood chips and straw; the particle size of the fermentation auxiliary material is 10-12 mm.

5. The method for harmless treatment of excess sludge according to claim 1, characterized in that: The dosage ratio of the pretreated sludge to the fermentation auxiliary material is 8-10:2-3.

6. The method for harmless treatment of excess sludge according to claim 1, characterized in that: The inactivation treatment is to heat treat the mixed material, the temperature of the heat treatment is 130-150° C., and the time of the heat treatment is 30-40 minutes.

7. The method for harmless treatment of excess sludge according to claim 1, characterized in that: The dissolved oxygen concentration of the aerobic digestion tank is 2-4 mg / L, and the temperature is 20-35°C.

8. The method for harmless treatment of excess sludge according to claim 1, characterized in that: The aerobic digestion time is 15 to 20 days.

9. The method for harmless treatment of excess sludge according to claim 1, characterized in that: The nutrients include nitrogen source and phosphorus source.

10. Use of the method for harmless treatment of excess sludge according to any one of claims 1 to 9 in sludge treatment.

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