CN108249564A - A kind of preparation method and application method of denitrification solid-state carbon source - Google Patents

Abstract

A kind of preparation method and application method of denitrification solid-state carbon source, belong to water-treatment technology field, the preparation method of denitrification solid-state carbon source is will to add in a certain proportion of sodium bicarbonate, anhydrous ferric chloride, anhydrous Manganese chloride in melting PHBV, modified PHBV materials are made in cooling, and pretreatment is shaken after filler is packed in 1 ~ 6% beta glucan aqueous solution, it is fitted into reactor and uses after drying.Sewage and the mixed water sample of anaerobic pond sludge, 36 ~ 48h of continuous service are prepared in injection in reactor, are reused preparation sewage and are continued to run with, after biofilm success, are discharged NO₃ ^‑N concentration can be less than 5mg/L.The invention has the advantages that increasing considerably microorganism attachment space, denitrifying bacterium quantity is promoted；Shorten the reactor start-up time；Improve material wetability；Accelerate microorganism to absorption of nutrient ingredients, enhancement microbiological breeding；Water outlet the concentration of nitrate nitrogen is stable and reaches sewage discharge requirement；It is easy to operate, it is easily controllable.

Description

A kind of preparation method and application method of denitrification solid carbon source

technical field

The invention belongs to the technical field of water treatment, and in particular relates to a preparation method and a use method of a denitrification solid carbon source. A modification of poly-3-hydroxybutyrate valeric acid copolyester (PHBV) by sodium bicarbonate, anhydrous ferric chloride, and anhydrous manganese chloride as a filler for a denitrification device and a specific use method.

Background technique

In recent years, due to the transformation of my country's economy and industry, a large amount of nitrogen-containing domestic sewage and agricultural sewage have been discharged into water bodies. The content of nitrate nitrogen in surface water systems and groundwater in some areas has risen sharply, which has become an area that needs to be developed in today's water treatment technology.

At present, the main means of removing nitrate nitrogen in urban sewage treatment is to rely on denitrifying bacteria to convert nitrate nitrogen into nitrogen gas and discharge it into the atmosphere. In order to ensure sufficient activity of denitrifying bacteria, it is necessary to have sufficient carbon sources as energy supply in their reaction environment.

In my country's current sewage treatment process, there is generally a shortage of carbon sources in the denitrification process. On the other hand, with the improvement of water treatment standards, the discharge standards of total nitrogen are increasing day by day. Therefore, under the condition of ensuring the effluent conditions, the study of new external carbon sources has become a more urgent key issue in the water treatment process.

The existing external carbon sources can usually be divided into two categories: traditional dissolved carbon sources and new solid carbon sources (Shao Liu, Xu Zuxin, Yin Hailong, Research progress of external carbon sources in denitrification process of polluted water bodies, Industrial Water Treatment 27( 12) (2007) 10-14).

Traditional dissolved carbon sources mainly include liquid organic matter such as methanol, acetic acid, and glucose. However, there are some common problems in this kind of dissolved organic matter, such as: the carbon-nitrogen ratio is difficult to control; the nitrate nitrogen in the water is difficult to control and other operational problems, and the excessive addition of carbon sources will increase the COD of the effluent water quality. Insufficient will lead to the accumulation of nitrite.

The above situations will lead to the deterioration of the effluent water quality and cause impact. The solid carbon source can only be used by denitrifying bacteria when the microorganisms are attached and the filler is decomposed by the enzymes in the microorganisms. On the one hand, it avoids the control problem of carbon source dosing, and on the other hand, it will not affect the quality of effluent water.

In recent years, many researchers at home and abroad have used many ways to find non-toxic, cheap slow-release carbon sources to replace traditional carbon sources, mostly natural solid organic matter rich in cellulose and some biodegradable artificial materials, such as cotton, Rice husk, paper, degradable lunch box, PCL, starch, etc. However, such substances usually have disadvantages such as hydrophobicity, easy crystallization, and long degradation time.

Poly-3-hydroxybutyrate-valeric acid copolyester (PHBV) is a kind of bio-polyester produced by using starch as raw material and using fermentation engineering technology. Its application in the field of water treatment technology has been proven to be effective, but the material itself has defects such as strong hydrophobicity, high particle density, and difficulty in providing a living place for microorganisms, which will affect its use in actual projects. Therefore, the PHBV raw material is modified to solve the above problems.

Contents of the invention

In order to solve the problems of traditional solid carbon sources such as long film-forming time, small number of microorganisms per unit volume, low biofilm strength, and poor impact resistance, a method for preparing and using a denitrifying solid carbon source is provided.

Concrete scheme of the present invention is as follows: a kind of preparation method of denitrification solid carbon source is characterized in that comprising the following content:

(1) Put poly-3-hydroxybutyrate-valerate copolyester (PHBV) powder into a beaker and heat at 160-175°C for 3-5 minutes; after poly-3-hydroxybutyrate-valerate copolyester is melted, Add the reagent with a mass ratio of poly-3-hydroxybutyrate valeric acid copolyester: sodium bicarbonate: anhydrous ferric chloride: anhydrous manganese chloride = 100: 5~10: 0.005~0.020: 0.001~0.010 into the beaker , stirring at a speed of 60~120rpm/min for 30~60s to make a solid carbon source for denitrification.

(2) Take out the denitrification solid carbon source after cooling, put it into a mesh packing bag with a pore size of 1.0~2.0mm, and measure the packing porosity of 55~65%; put the packing bag into a bag filled with 1~6%β -In the container of dextran aqueous solution, vibrate on a desktop shaker for 15~30s; take out the packing bag and dry it; put it into the reactor, and the filling rate of the reactor is 50%; the filler soaked in the β-glucan aqueous solution can Strengthen the ability to intercept microorganisms and increase the speed of film formation; after shaking, the amount of air in the modified PHBV material is reduced, which can reduce the impact on the anaerobic environment; the packing bag can be taken out at any time, which is convenient for cleaning, replacing and testing the reactor and packing , and prevent the stuffing bag from floating up;

(3) Mix the prepared sewage (the formula is shown in Table 1) and activated sludge at a volume ratio of 1:3, and stir at a rate of 60rpm/min to form a mixed liquid. In 50L of prepared sewage, the content of KH ₂ PO ₄ is 1.00g; the content of MgSO ₄ is 0.55g; the content of CaCl ₂ is 0.14g; the content of MnSO ₄ is 0.13g; the content of FeCl ₃ 6H ₂ O is _0.18g ; 0.11g; NaNO ₃ content is 12.14g.

(4) The mixed liquid enters from the bottom of the reactor through the peristaltic pump, flows out from the top, and continues to run for 36~48 hours; then the reactor is continuously operated with the prepared sewage, and the hydraulic retention time is maintained at 1.5 hours for rapid film formation; the reactor is taken every 24 hours The effluent is filtered and then measured for nitrate nitrogen, DOC content and pH value to maintain the operation of the reactor.

The activated sludge used comes from the anaerobic pool sludge of the sewage treatment plant.

The modified PHBV material was used not only as a solid carbon source for the reactor, but also as a microbial attachment carrier. Its advantages lie in greatly increasing the space for microbial attachment and increasing the number of denitrifying bacteria; shortening the start-up time of the reactor; improving the wettability of materials; accelerating the absorption of nutrients by microorganisms and strengthening microbial reproduction; the concentration of nitrate nitrogen in the effluent is stable and meets the sewage discharge requirements; Simple operation and easy control.

The beneficial effects of the present invention are:

(1) The porosity of modified PHBV is increased, the viscosity is enhanced, the amount of microbial adhesion is greatly increased, and the denitrification efficiency is improved;

(2) The modified PHBV is more suitable for the survival of denitrifying microorganisms and strengthens the reproduction of microorganisms;

(3) The modified PHBV greatly enhanced the denitrification capacity of PHBV and shortened the start-up time of the reactor;

(4) The modified PHBV filler did not significantly affect the pH environment in the reactor.

Description of drawings

Fig. 1 is a flow chart of the production process of the modified PHBV filler of the present invention.

Fig. 2 is a flow chart of the application method of the present invention.

Labels in the figure: 1-water inlet bucket; 2-peristaltic pump; 3-water inlet; 4-reactor; 5-filler mesh bag; 6-water outlet; 7-water outlet bucket; 8-filler;

specific implementation plan

The invention provides a method for modifying PHBV raw materials and using it as a reactor filler to remove nitrate nitrogen in water. Next, the invention will be further described in conjunction with the accompanying drawings and specific embodiments. Among them, commercially available PHBV, β-glucan and laboratory sodium bicarbonate, anhydrous ferric chloride and anhydrous manganese chloride reagents were selected, analytically pure.

In the present invention, 50L of prepared sewage contains _1.00g of _KH2PO4 ; 0.55g of _MgSO4 ; 0.14g of _CaCl2 ; 0.13g of _MnSO4 ; _0.18g of _{FeCl3.6H2O ;} ; NaNO ₃ is 12.14g.

The reactor of the present invention is a packed bed reaction column.

Example 1

(1) Put the PHBV powder into a beaker and heat it at 160~175°C for 5 minutes. After the PHBV is melted, add the reagent with a mass ratio of PHBV: sodium bicarbonate: anhydrous ferric chloride: anhydrous manganese chloride = 100:5:0.010:0.005 into the beaker, stir at 100rpm/min for 60s, and cool naturally. into filler;

(2) Take out the filler after cooling, put it into a mesh bag with a pore size of 1.0~2.0mm, put it into a container containing 1% β-glucan aqueous solution, and shake it on a table shaker for 30s; take out the filler bag Dry it, put it into the reactor, and the reactor filling rate is 50%;

(3) No organic carbon source is added to the prepared sewage. The prepared sewage and activated sludge are mixed at a volume ratio of 1:3; an additional stirring device is added to stir at 60rpm/min; the activated sludge comes from the anaerobic pool sludge of Taiyuan Sewage Treatment Plant;

(4) The material of the reactor is plexiglass, cylindrical, with an inner diameter of 5cm, a height of 45cm, and an effective volume of 0.88L, as shown in Figure 2; the mixed water sample is pumped in from the bottom and flows out from the top, and continues to run for 48 hours. The temperature is controlled at Between 15~17°C. Use a peristaltic pump to continuously inject the prepared sewage into the reactor, and the hydraulic retention time is 1.5h;

(5) After that, take the effluent every 24 hours, filter it through a 0.45 μm filter membrane, and test the nitrate nitrogen, DOC content and pH value; ensure that the prepared sewage is sufficient to maintain the operation of the reactor;

(6) After 3 days, the nitrate nitrogen content in the effluent of the reactor can be stably reduced from 40mg/L to less than 0.5mg/L, the DOC content is continuously maintained at 0.1-5mg/L, and the pH value varies between 6.89-7.21.

Example 2

(1) The mass ratio of PHBV: sodium bicarbonate: anhydrous ferric chloride: anhydrous manganese chloride = 100: 10: 0.020: 0.010 is used for modification.

(2) The shaking time is 15s, and the mixed water sample is continuously injected for 36 hours; the rest of the filler treatment, sewage preparation, reactor specifications, operating conditions, and test methods are the same as in Example 1.

(3) After 3 days, the nitrate nitrogen content in the effluent of the reactor can be stably reduced from 40mg/L to below 2.5mg/L, the DOC content is continuously maintained at 2.5-5.5mg/L, and the pH value varies between 6.71-7.33.

Example 3

(1) The mass ratio of PHBV: sodium bicarbonate: anhydrous ferric chloride: anhydrous manganese chloride = 100: 10: 0.015: 0.070 is used for modification.

(2) The shaking time is 15s, and the mixed water sample is continuously injected for 36 hours; the rest of the filler treatment, sewage preparation, reactor specifications, operating conditions, and test methods are the same as in Example 1.

(3) After 3 days, the nitrate nitrogen content in the effluent of the reactor can be stably reduced from 40mg/L to below 2.0mg/L, the DOC content is maintained at 5.0~7.0mg/L, and the pH value varies between 6.95~7.25.

The measured data and results of the examples can all meet the ideal requirements. The average NO ₃ ^- -N removal rate of the reactor is above 95%, the highest is 98%; the DOC concentration will not affect the COD of the effluent; the pH value is in the range suitable for the growth of denitrifying bacteria; the film formation speed is 1 day faster than that of the PHBV raw material reactor . Therefore, the modified PHBV can be used as a more excellent solid carbon source.

The description of the above examples is to facilitate those of ordinary skill in the art to understand and use the present invention. It will be apparent to those skilled in the art that modifications to the described examples of the invention can be made and the general principles of the techniques described can be applied to other examples. Therefore, the present invention is not limited to the above examples, and modifications and improvements made without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims (4)

1. A preparation method for denitrification solid carbon source, said denitrification solid carbon source is a modified PHBV material, characterized in that its preparation method is: heating poly 3-hydroxybutyrate valeric acid at 160 ~ 175 ° C The copolyester powder forms a molten state, and the input mass ratio is poly-3-hydroxybutyrate copolyester: sodium bicarbonate: anhydrous ferric chloride: anhydrous manganese chloride=100: 5~10: 0.005~0.020: 0.001~ 0.010, stirred at a speed of 60-120rpm/min for 30-60s, stopped heating, and cooled naturally to make a modified PHBV material. 2. the preparation method of a kind of denitrification solid carbon source according to claim 1 is characterized in that the using method of described denitrification solid carbon source comprises the steps: (1) Put the modified PHBV material into a mesh bag with a pore size of 1.0~2.0mm to form a stuffing bag; (2) Pretreatment of stuffing bags: put the stuffing bags in 1~6% β-glucan aqueous solution, and shake on the desktop shaker for 15~30s; take out the stuffing bags and put them into the reactor after drying. The filling rate is 50%; (3) Mix the prepared sewage and activated sludge according to the volume ratio = 1:3; stir at a rate of 60rpm/min to keep the sludge uniform and prepare mixed sewage; (4) Rapid film formation: inject the mixed sewage prepared in step (3) from the bottom of the reactor, and flow out from the top for 36~48 hours, at a rate of 2.5ml/min; use the prepared sewage to continuously feed the reactor to maintain hydraulic power The residence time is 1.5h. When the concentration of NO ₃ ^- -N in the effluent is lower than 5mg/L, the film formation is successful. 3. according to the preparation method of a kind of denitrification solid carbon source described in claim 1, it is characterized in that the porosity of the modified PHBV filler is 55～65%. 4. according to the preparation method of a kind of denitrification solid carbon source described in claim 1, it is characterized in that in 50L preparation sewage, KH ₂ PO ₄ content is 1.00g; MgSO ₄ content is 0.55g; CaCl ₂ content is 0.14g; The content of MnSO ₄ is 0.13g; the content of FeCl ₃ ·6H ₂ O is 0.18g; the content of ZnCl ₂ is 0.11g; and the content of NaNO ₃ is 12.14g.