CN110482835A - A method of quickly preparing aerobic particle mud - Google Patents

Abstract

The invention discloses a method for rapidly preparing aerobic granular sludge. The method comprises the following steps: (1) extracting sludge with high biological activity; (2) performing ultrasonic pretreatment on the sludge; (3) Add flocculant to the sludge in an amount of 1.5‰ to 3‰ of the dry solids of the sludge; (4) add lignocellulose to the sludge in an amount of 5% to 15% of the dry solids of the sludge %; (5) Add microbial exopolysaccharides to the sludge in an amount of 1.5‰ to 3‰ of the dry solids of the sludge; (6) Centrifuge, dehydrate and granulate the sludge to obtain aerobic granular sewage mud. The aerobic granular sludge obtained by the present invention is put into the aeration tank as the nuclear substance for inoculating the granular sludge, the cultivation period is short and the system is stable, and it can be quickly used and used in engineering practice. Compared with traditional activated sludge, it has good settling performance and short settling time. At the same time, the added chemicals will not affect the activity of microorganisms in the sludge, which improves the efficiency of the wastewater treatment system.

Description

A method for rapidly preparing aerobic granular sludge

technical field

The invention belongs to the technical field of water treatment, in particular to a method for rapidly preparing aerobic granular sludge applied to wastewater treatment.

Background technique

With the rapid development of economy and society, and the acceleration of industrialization and urbanization, a large amount of toxic and harmful substances are accumulated in natural water bodies, and the fresh water resources that human beings depend on for survival are seriously polluted. This has led to a series of water ecological environment problems that need to be solved urgently. Among them, the eutrophication of water body has become the main water environment problem that seriously threatens the aquatic animals and plants, human health and the development of industry and agriculture, and the main cause of water eutrophication is the excessive discharge of nitrogen and phosphorus in domestic sewage.

There are many problems in the water treatment methods in the prior art, and most of them have certain limitations, such as long process flow, complicated treatment process, large floor area, low treatment efficiency, and high operating cost. Aiming at the poor effect of simultaneous nitrogen and phosphorus removal by most biological treatments in sewage treatment plants, the aerobic granular sludge process is considered to be a promising sewage biological advanced treatment technology because of its economical and high-efficiency characteristics. Aerobic granular sludge is a group of mutually aggregated, multi-species microorganisms, which is considered to be a special kind of self-immobilized special biofilm. Aerobic granular sludge has a large specificity and bio-dense characteristics make it have a fast settling speed, which is beneficial to the separation of sludge and water, reducing or eliminating the sludge secondary sedimentation tank, simplifying the process flow, and reducing the footprint and investment cost of the sewage treatment system . Moreover, the high sludge concentration and volume load of aerobic granular sludge can withstand the impact of water quality fluctuations and high organic loads, ensuring good effluent water quality. In addition, the granular structure of aerobic granular sludge makes _O2 suffer from mass transfer resistance during the transmission process, and it is divided into aerobic layer, anoxic layer and anaerobic layer from outside to inside, providing suitable living space for different microorganisms , this unique hierarchical structure endows it with high biodiversity and the potential to simultaneously degrade organic carbon, nitrogen, and phosphorus.

Since 1992, dozens of papers have reported that the use of ultrasonic effects can improve the dewatering efficiency and biological treatment effect of sludge. Ultrasonic pretreatment destroys the good water retention of bacteria micelles and the bound water in cells, while maintaining larger sludge particles, which improves the sludge settling performance. The destroyed sludge can be used as endogenous carbon, saving or even replacing external carbon sources, and accelerating the formation of aerobic granular sludge nutrient channels.

In 1991, Mishima and Nakamura obtained aerobic granular sludge for the first time in a continuous flow aerobic sludge bioreactor. Morgenroth et al. used SBR reactors to cultivate aerobic granular sludge for the first time in 1997. By gradually shortening the hydraulic retention time and increasing the water exchange rate, and using a very short settling time (0-1min), it took 70 days to successfully achieve Aerobic sludge granulation. It shows that the formation time of aerobic granular sludge is too long, and most practices show that the formation of stable aerobic granular sludge takes 60 to 90 days, which is difficult to meet the start-up requirements of practical engineering applications.

Liu et al. confirmed that adding 500mg/L polyaluminum chloride can accelerate the formation process of aerobic granular sludge (from 17 days to 7 days). The average particle size of aerobic granular sludge is 3.2mm. The aluminum chloride particles formed in the reactor were smaller (2.7mm). Moreover, polyaluminum chloride can significantly improve the settling property, compactness, mechanical strength and EPS secretion of aerobic granular sludge. However, adding polyaluminum chloride has little effect on the treatment effect of COD and NH4 ⁺ -N. It shows that although the addition of high molecular polymer accelerates the cultivation time of aerobic granular sludge, it has no obvious change in the effect of sewage treatment, which increases the cost of the project.

Wan et al. perfected the mechanism of aerobic granular sludge formation from the perspective of calcium precipitation as the particle core: a variety of crystals form inorganic cores in alkaline environments for microorganisms to attach to, and then these microorganisms secrete PS to gradually form the framework of aerobic granular sludge . Among them, the functional bacteria attached to the inner core mainly include Sphingomonas sp., Paracoccus sp. Sinorhizobium americanum strain and Flavobacterium sp., these bacteria will promote the synthesis of extracellular circulation diguanylate cyclase, and then accelerate the aerobic granular sludge formation and maturation. The formation process of aerobic granular sludge can be accelerated by changing the components of aerobic granular sludge, but the process is complicated and difficult to realize in practical application.

One of the bottlenecks that limits the application and optimization of aerobic granular sludge is the unstable start-up time of aerobic granular sludge. Restricted by certain factors, aerobic granular sludge has not been applied on a large scale worldwide. In response to this problem, the inoculated sludge that granulates fresh aerobic dewatered sludge into spherical granules is developed to promote the granulation of aerobic sludge and further promote the formation of aerobic granular sludge, which is beneficial to the cultivation conditions of aerobic granular sludge. Optimization.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for rapidly preparing aerobic granular sludge with rapid granulation, short cultivation period and stable system.

The present invention solves the above technical problems with the following technical solutions:

A method for rapidly preparing aerobic granular sludge of the present invention comprises the following steps:

(1) extract sludge with high biological activity;

(2) Ultrasonic pretreatment is carried out to the sludge of step (1);

(3) Add flocculant to the sludge in step (2), stir to make it fully mixed, the addition of flocculant is 1.5‰-3‰ of the dry solids of sludge;

(4) adding lignocellulose to the sludge of step (3), stirring to make it fully mixed, the addition of lignocellulose is 5%-15% of the dry solids of the sludge;

(5) adding microbial exopolysaccharide to the sludge in step (4), stirring to make it fully mixed, the amount of microbial exopolysaccharide added is 1.5‰-3‰ of the dry solid content of the sludge;

(6) The sludge in step (5) is centrifugally dehydrated and granulated to obtain aerobic granular sludge.

The sludge in step (1) is secondary sedimentation tank sludge, excess sludge or sugar food industry sludge, and is sieved to remove filamentous and large particle substances, and the MLVSS/MLSS in the sludge is 0.75-0.8.

For the ultrasonic pretreatment described in step (2), the ultrasonic power used is 20-25 Hz, and the pretreatment time is 30-50 s.

The flocculant in step (3) is one or more of polyferric sulfate, polyaluminum chloride and polyacrylamide.

The lignocellulose described in step (4) is one or more of bagasse cellulose, straw cellulose, wood cellulose, bamboo cellulose, and the cellulose is dried and crushed to a particle size of 0.425mm- 0.5mm.

The microbial exopolysaccharide described in step (5) is one of gellan gum, Welan gum and xanthan gum.

The centrifugal dehydration treatment described in step (6) uses a rotating speed of 3000-4000r/min and a time of 15-25min, and the moisture content of the sludge after dehydration treatment is 75%-80%.

The granulation treatment described in step (6) is realized by an extrusion granulator, and the dewatered sludge is extruded through a sieve plate with an aperture of 1.5mm-3mm, cut into columnar particles, and then rotated for 5-15min Granulation, that is, to obtain spherical aerobic granular sludge.

The method of the present invention combines the physical method and the chemical method to make the sludge granulate, and compared with the prior art, it has the following beneficial effects:

(1) The present invention selects the sludge with higher biological activity after sieving to ensure the diversity of microbial quantity and type in the sludge; the sludge destroys the sludge bacteria micelles after ultrasonic pretreatment, so that the sludge has Better aggregation and settling properties;

(2) The method of the present invention is by suitably mixing lignocellulose after pulverizing, as bagasse, sawdust, straw and bamboo fiber etc., because cellulose is biochemically degradable composition, the pore channel in the granular sludge after the degradation is conducive to oxygen In order to increase the internal porosity of the sludge and improve the oxygen mass transfer efficiency, increase the activity of the sludge, and accelerate the formation of aerobic granular sludge.

(3) The method of the present invention is by appropriately adding chemical flocculants, such as polyferric sulfate, polyaluminum chloride and cationic, anionic or nonionic polyacrylamide, so that the formed sludge is compared with traditional activated sludge It has good settling performance and saves settling time. At the same time, the addition of chemical agents not only does not affect the biological activity of activated sludge, but also improves the efficiency of the wastewater treatment system.

(4) The method of the present invention suitably adds microbial extracellular polysaccharides, such as cold gelatin, Welan gum and xanthan gum, which can be used as a degradable bioadhesive to bond activated sludge into agglomerates and can be used as a microbial culture medium The adsorbed microorganisms secrete a large amount of extracellular polymers, and quickly form aerobic granular sludge bacteria micelles.

(5) The inventive method processes the dewatered sludge into spherical aerobic granular sludge through granulation, and the granular sludge formed by physical granulation is more evenly stressed and can withstand greater surface tension. The air pool can withstand stronger high-pressure water flushing, aeration scour, collision and cutting between sludge, etc.

Detailed ways

The technical solutions of the present invention are further described below in conjunction with specific examples, but are not limited to the following examples.

Example 1

(1) Activated sludge dehydration: extract 20g of sludge from the secondary settling tank of the sewage treatment plant, and remove filamentous and large particles through sieving. Add anionic polyacrylamide with a sludge dry solid content of 3‰, stir to fully flocculate the sludge; then add bagasse cellulose with a sludge dry solid content of 10%, dry the bagasse cellulose at 105°C for 4 hours in the early stage, and then After pulverization and pretreatment until the particle size is 0.425mm-0.5mm, then fully mix the cellulose and sludge by stirring; then add cold gelatin with a dry solid content of sludge of 2‰, and stir to make the sludge fully glued; then Centrifuge and dewater 20min at a rotating speed of 3500r/min as the sludge used in the test, and the moisture content of the sludge is 80%.

(2) Spherical granulation: Use a granulator to extrude the sludge dehydrated in step (1) from a sieve plate with an aperture of 1.5 mm, and then place the obtained cylindrical sludge in a drum for 5 minutes of rotation After granulation, aerobic granular sludge with a particle size of 1.5 mm was produced.

The application shows that using the physical granular sludge formed by dehydration and granulation as inoculated sludge can significantly increase the granulation speed of aerobic sludge. On the 25th day, more than 90% of the sludge inoculated with physical granular sludge had a particle size greater than 0.2mm, the removal rates of COD and ammonia nitrogen were greater than 90% during the cultivation period, and the removal rate of TN was about 70% in the later period of cultivation.

Example 2

(1) Activated sludge dehydration: extract 20g of industrial sludge produced in the process of sugar industry wastewater treatment, and remove filamentous and large particles through sieving, MLVSS/MLSS in the sludge = 0.78; ultrasonic power 23kHz, ultrasonic time 40s After ultrasonic pretreatment, add polyaluminum chloride with a dry solid content of 2‰ of the sludge, and stir to fully flocculate the sludge; then add straw cellulose with a dry solid content of 15% of the sludge, and dry the straw cellulose at 105°C in the early stage Dry for 4 hours, and then crush and pretreat until the particle size is 0.425mm-0.5mm, stir to fully mix the cellulose and sludge; then add Welan gum with a dry solid content of sludge of 3‰, and stir to make the sludge fully glued ; Then centrifuge and dewater 15min as the sludge used in the test at a rotating speed of 4000r/min, and the moisture content of the sludge is 78%.

(2) Spherical granulation: Use a granulator to extrude the sludge dehydrated in step (1) from a sieve plate with an aperture of 2 mm, and then place the obtained cylindrical sludge particles in a drum for 10 minutes of rotation After granulation, aerobic granular sludge with a particle size of 2 mm was produced.

The application shows that using the physical granular sludge formed by dehydration and granulation as inoculated sludge can significantly increase the granulation speed of aerobic sludge. On the 20th day, more than 90% of the sludge inoculated with physical granular sludge had a particle size greater than 0.2mm, the removal rates of COD and ammonia nitrogen were greater than 90% during the cultivation period, and the removal rate of TN was about 70% in the later period of cultivation.

Example 3

(1) Activated sludge dehydration: extract 20g of residual sludge from sewage treatment plant, remove filamentous and large particles through sieving, MLVSS/MLSS in the sludge=0.75; after ultrasonic pretreatment with ultrasonic power of 25kHz and ultrasonic time of 30s, Add polyferric sulfate with sludge dry solid content of 1.5‰, stir to fully flocculate the sludge; then add bamboo cellulose with sludge dry solid content of 5%, bamboo cellulose is dried at 105°C for 4 hours in the early stage, and then pulverized Pretreatment until the particle size is 0.425mm-0.5mm, stirring to fully mix the cellulose and sludge; then adding xanthan gum with a dry solid content of the sludge of 1.5‰, stirring to make the sludge fully glued; then at 3000r/min Centrifuge and dehydrate for 25 minutes as the sludge used in the test, and the moisture content of the sludge is 75%.

(2) Spherical granulation: Use a granulator to extrude the sludge dehydrated in step (1) from a sieve plate with an aperture of 3 mm, and then place the obtained cylindrical sludge particles in the drum for 15 minutes of rotation After granulation, aerobic granular sludge with a particle size of 3 mm was produced.

The application shows that using the physical granular sludge formed by dehydration and granulation as inoculated sludge can significantly increase the granulation speed of aerobic sludge. On the 16th day, more than 90% of the sludge inoculated with physical granular sludge had a particle size greater than 0.2mm, the removal rates of COD and ammonia nitrogen were greater than 90% during the cultivation period, and the removal rate of TN was about 70% in the later period of cultivation.

Claims (8)

1. A method for preparing aerobic granular sludge rapidly, is characterized in that, comprises following operating steps: (1) extract sludge with high biological activity; (2) Ultrasonic pretreatment is carried out to the sludge of step (1); (3) Add flocculant to the sludge in step (2), stir to make it fully mixed, the addition of flocculant is 1.5‰-3‰ of the dry solids of sludge; (4) adding lignocellulose to the sludge of step (3), stirring to make it fully mixed, the addition of lignocellulose is 5%-15% of the dry solids of the sludge; (5) adding microbial exopolysaccharide to the sludge in step (4), stirring to make it fully mixed, the amount of microbial exopolysaccharide added is 1.5‰-3‰ of the dry solid content of the sludge; (6) The sludge in step (5) is centrifugally dehydrated and granulated to obtain aerobic granular sludge. 2. according to the method for preparing aerobic granular sludge rapidly according to claim 1, it is characterized in that, the sludge described in step (1) is secondary sedimentation tank sludge, excess sludge or sugar food industry sludge, and After sieving to remove filamentous and large particle substances, the MLVSS/MLSS in the sludge is 0.75-0.8. 3. according to the method for preparing aerobic granular sludge described in claim 1 and 2 fast, it is characterized in that, the ultrasonic pretreatment described in step (2), the ultrasonic power that adopts is 20-25Hz, and the pretreatment time is 30-25Hz. 50s. 4. according to the method for rapidly preparing aerobic granular sludge according to claim 1 and 2, it is characterized in that, the flocculant described in step (3) is a kind of in polyferric sulfate, polyaluminum chloride, polyacrylamide or several. 5. according to the method for rapidly preparing aerobic granular sludge described in claim 1 and 2, it is characterized in that, the lignocellulose described in step (4) is bagasse cellulose, straw cellulose, wood cellulose, bamboo fiber One or several types of cellulose, and the cellulose is dried and crushed to a particle size of 0.425mm-0.5mm. 6. according to the method for rapidly preparing aerobic granular sludge described in claim 1 and 2, it is characterized in that, the microbial exopolysaccharide described in step (5) is one of gellan gum, Welan gum and xanthan gum kind. 7. according to the method for preparing aerobic granular sludge described in claim 1 and 2 rapidly, it is characterized in that, the rotating speed that the centrifugal dehydration treatment described in step (6) adopts is 3000-4000r/min, and the time is 15-25min, The moisture content of the sludge after dehydration treatment is 75%-80%. 8. according to the method for fast preparation of aerobic granular sludge described in claim 1 and 2, it is characterized in that, the granulation treatment described in step (6) is to realize by extruding granulator, dewatered sludge is passed through aperture is Extrude from a 1.5mm-3mm sieve plate, cut into columnar particles, and then rotate and granulate for 5-15min to obtain spherical aerobic granular sludge.