阅读说明：本技术 一种促进剩余污泥脱水同时生产脂肪酸的方法 (Method for promoting dehydration of excess sludge and simultaneously producing fatty acid ) 是由 杨静楠 符气梓 王冬波 于 2019-11-14 设计创作，主要内容包括：本发明涉及一种热激活过一硫酸氢钾复合盐促进剩余污泥脱水同时生产脂肪酸的方法。具体方法包括：(1)以城市污水处理厂二沉池产生的剩余活性污泥为发酵原料,经自然沉降去除上清液进行浓缩处理后得到污泥样品；(2)将所述污泥样品与过一硫酸氢钾复合盐混合后在温度为60℃的水浴下预处理一个小时,在厌氧环境下发酵,产生脂肪酸并得到脱水污泥。本发明基于过一硫酸氢钾复合盐在热处理条件下产生自由基,减少了药剂的消耗,加快污泥中有机物的溶出,极大提高了产酸效率,缩短了污泥厌氧发酵的时间,污泥的脱水性能也有所改善,对于实现污泥的减量化和资源化具有重要的环保生态意义。(The invention relates to a method for promoting dehydration of excess sludge and producing fatty acid by thermally activating potassium peroxymonosulfate composite salt. The specific method comprises the following steps: (1) taking residual activated sludge generated by a secondary sedimentation tank of an urban sewage treatment plant as a fermentation raw material, removing supernatant through natural sedimentation, and concentrating to obtain a sludge sample; (2) and mixing the sludge sample with potassium peroxymonosulfate composite salt, pretreating for one hour in a water bath at the temperature of 60 ℃, and fermenting in an anaerobic environment to generate fatty acid and obtain dewatered sludge. The invention generates free radicals based on potassium hydrogen peroxymonosulfate composite salt under the heat treatment condition, reduces the consumption of medicaments, accelerates the dissolution of organic matters in the sludge, greatly improves the acid production efficiency, shortens the anaerobic fermentation time of the sludge, improves the dehydration performance of the sludge, and has important environmental protection ecological significance for realizing the reduction and the recycling of the sludge.)

1. A method for facilitating dewatering of excess sludge while producing fatty acids, comprising the steps of:

taking residual activated sludge generated by a secondary sedimentation tank of an urban sewage treatment plant, removing supernatant through natural sedimentation, concentrating to obtain a sludge sample, mixing the sludge sample with potassium peroxymonosulfate composite salt, pretreating for one hour in a water bath at 60 ℃, fermenting in an anaerobic environment to generate fatty acid and obtain dewatered sludge.

2. The method for promoting dewatering of excess sludge while producing fatty acids according to claim 1, wherein: the sludge is the residual sludge in a secondary sedimentation tank of an urban sewage plant, the static sedimentation temperature is 4 ℃, and the sedimentation time is 24 hours.

3. The method for promoting dewatering of excess sludge while producing fatty acids according to claim 1, wherein: the adding dosage of the potassium hydrogen peroxymonosulfate composite salt is 0.03-0.09 g of PMS/g of TSS, and preferably 0.05g of PMS/g of TSS.

4. The method for promoting dewatering of excess sludge while producing fatty acids according to claim 1, wherein: after the potassium hydrogen peroxymonosulfate composite salt is added into the sludge, the sludge is rapidly stirred for 5min at 300rpm and then is stirred for 90min at 150rpm, so that the medicament is fully mixed with the sludge.

5. The method for promoting dewatering of excess sludge while producing fatty acids according to claim 1, wherein: after the sludge and the medicament are uniformly mixed, the mixture is treated for one hour in a water bath at the temperature of 50-80 ℃, the oscillation intensity is 150rpm, and the preferred temperature is 60 ℃.

6. The method for promoting dewatering of excess sludge while producing fatty acids according to claim 1, wherein: introducing nitrogen into the pretreated sludge at the speed of 0.5L/min for 1.5min until no oxygen exists in the reactor, sealing the reactor, and placing the reactor into a shaking table with the temperature of 35 +/-1 ℃ and the stirring speed of 120rpm/min for anaerobic fermentation.

7. The method for promoting dewatering of excess sludge while producing fatty acids according to claim 1, wherein: the pH value of the sludge in the reactor is not required to be adjusted in the whole process.

8. The method for promoting dewatering of excess sludge while producing fatty acids according to claim 1, wherein: the sludge fermentation time is 3-8 days.

Technical Field

The invention relates to the technical field of sludge treatment and recycling, in particular to a method for promoting dehydration of excess sludge and producing short-chain fatty acid.

Technical Field

In the past decades, with the rapid development of industrialization and urbanization, the amount of municipal sewage and industrial wastewater has sharply increased worldwide. The activated sludge process has been widely used in various types of wastewater treatment as the most widely used method worldwide. However, as the amount of sewage treatment increases, a large amount of excess sludge is produced, with china producing approximately 11.2 million tons of dry sludge per year. The residual sludge is difficult to treat due to high organic matters and water content, and if the water content of the sludge can be reduced and part of usable substances in the sludge can be recycled, the cost can be saved, and the purposes of sludge reduction and recycling can be achieved.

Anaerobic fermentation of sludge generally consists of three steps: hydrolysis, acidogenesis and methanogenesis. Therefore, if the hydrolysis process, which is the rate-limiting step of the acidification reaction, can be accelerated, the acid production efficiency of the sludge can be greatly improved. Studies have shown that high temperature heat treatment in combination with alkaline substances can increase the rate of sludge hydrolysis (Yuan et al environ. sci. technol.2006,40, 2025-. The heating pretreatment can promote the sludge cell breaking, so that a large amount of organic matters such as protein, polysaccharide and the like are released, and sufficient substrates are provided for the subsequent generation of fatty acid. If a large amount of excess sludge generated in the sewage treatment process is subjected to anaerobic fermentation to produce short-chain fatty acid, the short-chain fatty acid can be used as endogenous carbon to be utilized by denitrifying and dephosphorizing bacteria to remove nitrogen and phosphorus in eutrophic sewage, and can also be used as an external carbon source for other fermentations to be reused.

In recent years, advanced oxidation technologies based on sulfate radicals have been increasingly applied to sludge treatment. Potassium hydrogen Peroxymonosulfate (PMS) is a stable, convenient and widely-used excellent acidic oxidant, and is often used as a disinfectant in the field of sewage treatment. But because potassium hydrogen peroxymonosulfate composite salt is relatively stable, the reaction rate is relatively slow at normal temperature, but the potassium hydrogen peroxymonosulfate composite salt can be activated and decomposed into sulfate radicals (SO) under the conditions of light, heat, transition metal ions and the like₄ ^-.) And a hydroxyl radical (C^.OH). Therefore, it is strongly oxidizing and theoretically degrades most organic pollutants. One of the methods for obtaining free radicals is to activate the PMS in a variety of ways, such as ultrasound, heat, photolysis, transition metals, etc. Compared with other methods, the heating method is simple to operate and reduces energy consumption.

The free sulfuric acid radical has strong oxidizing property, can promote cell dissolution, destroy cell walls of microorganisms, release organic matters in the microorganisms and achieve the effect of killing the microorganisms in water. Therefore, the invention introduces the method of thermally activating the potassium peroxymonosulfate composite salt into the anaerobic sludge digestion system, improves the acid production efficiency and simultaneously improves the dehydration performance of the residual sludge.

Disclosure of Invention

The invention aims to provide a pretreatment method for promoting dehydration of excess sludge and acid production, which improves the acid production efficiency and improves the dehydration performance of the excess sludge.

In order to achieve the above purpose, the solution of the invention is:

a method for promoting dehydration of excess sludge and production of acid by using thermally activated potassium peroxymonosulfate complex salt (PMS) as a pretreatment means comprises the following steps:

(1) taking residual activated sludge generated by a secondary sedimentation tank of an urban sewage treatment plant as a fermentation raw material, removing supernatant through natural sedimentation, and concentrating to obtain a sludge sample;

(2) and mixing the sludge sample with potassium hydrogen Peroxymonosulfate (PMS), pretreating for one hour in a water bath at the temperature of 60 ℃, and fermenting in an anaerobic environment to generate fatty acid and obtain dewatered sludge.

In the step (1), the sludge is the residual sludge in a secondary sedimentation tank of an urban sewage plant, the static sedimentation temperature is 4 ℃, and the sedimentation time is 24 hours.

In the step (2), the dosage of PMS is 0.03-0.09 g PMS/gTSS, preferably 0.05g PMS/gTSS.

In the step (2), after the sludge is added into the PMS, the sludge is rapidly stirred at 300rpm for 5min and then at 150rpm for 90min, so that the medicament is fully mixed with the sludge.

In the step (2), the sludge and the medicament are uniformly mixed and then treated in a water bath at 50-80 ℃ for one hour, wherein the oscillation intensity is 150rpm, and the preferred temperature is 60 ℃.

In the step (2), the anaerobic environment is a nitrogen environment, nitrogen is introduced into the pretreated sludge at the speed of 0.5L/min for 1.5min until no oxygen exists in the reactor, and the reactor is sealed and put into a shaking table with the temperature of 35 +/-1 ℃ and the stirring speed of 120rpm/min for anaerobic fermentation.

In the step (2), the pH value of the sludge in the reactor is not required to be adjusted in the whole process.

In the step (2), the anaerobic fermentation time of the sludge is 3-8 days.

In a preferred embodiment, the dosage of PMS is 0.03-0.09 gPMS/gTSS. Although the dosage of the PMS can promote the organic matters in the sludge to be converted into the target fatty acid (0.03-0.07 g of PMS/g of TSS) within a certain range, the promotion effect on the anaerobic fermentation acid production of the sludge is more obvious along with the increase of the PMS within a certain range. However, the relationship between the raw material cost and the yield of the short-chain fatty acid is comprehensively considered, and the ideal dosage range of PMS adopted by the invention is 0.03-0.05 g of PMS/g of TSS.

Due to the adoption of the technical scheme, the invention has the following beneficial effects:

1. the invention adopts potassium hydrogen peroxymonosulfate composite salt (PMS) as an oxidant for anaerobic fermentation of sludge, has strong oxidizing capability, destroys sludge cell walls, obviously improves the degree of dissolving organic matters such as protein, polysaccharide and the like in the sludge into water, greatly reduces the use cost of medicaments by combining low-temperature heating pretreatment with the reaction condition of the potassium hydrogen peroxymonosulfate composite salt, improves the acid production fermentation efficiency to a certain extent, shortens the anaerobic fermentation time of the sludge, and has important significance for realizing the reclamation, harmlessness and reduction of the residual sludge.

2. The sludge treated by the method has improved dehydration performance, is rich in short-chain fatty acid, can be used as a carbon source for supplementing the deficiency of the carbon source at the last stage of anaerobic fermentation of the sludge or used for producing clean energy such as hydrogen and the like, thereby degrading organic substances in the residual sludge to the maximum extent and achieving the purposes of reducing the sludge volume and reducing the pollution of sludge organic substances to the environment.

Drawings

FIG. 1 is a schematic process flow diagram of the present invention.

Detailed Description

The invention is further described with reference to specific examples, but the scope of the invention is not limited thereby.