CN110357393B

CN110357393B - Nano flocculant for sludge sedimentation and preparation method thereof

Info

Publication number: CN110357393B
Application number: CN201811040780.7A
Authority: CN
Inventors: 王凯军; 何文妍
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-09-07
Filing date: 2018-09-07
Publication date: 2021-11-30
Anticipated expiration: 2038-09-07
Also published as: CN110357393A

Abstract

The invention discloses a nano flocculant for sludge sedimentation and a preparation method thereof, belonging to the technical field of environment and chemistry. Firstly, the method comprises a nano flocculant and a preparation method, and the nano flocculant comprises the following components: the mass fraction of the poly-dimethyldiallylammonium chloride with the solid content of 20 percent is 9.88 percent, the mass fraction of the dimethyldiallylammonium chloride with the solid content of 60 percent is 0.82 percent, the mass fraction of the Fe is 0.85 percent, and the balance is water. The density is 1.1-1.2 at 20 deg.C, pH is 1.80-1.90, and particle size is 60-100 nm. And secondly, diluting the nano flocculant by 300 times, and using the nano flocculant for an activated sludge sedimentation experiment in municipal and industrial sewage plants on the same preparation day and after the nano flocculant is placed for 45 days. The results all show that: the medicine is added 2min before the aeration is finished, the concentration of the medicine is 20 mu L/L, and the sedimentation effect of the activated sludge in the aerobic tank is remarkably accelerated. Therefore, the nano flocculant has the advantages of small feeding amount, stable performance, quick sludge sedimentation, wide application range and the like, and is beneficial to municipal, industrial and other sewage treatment plants to improve the treatment water amount and reduce the floor area of a secondary sedimentation tank.

Description

Nano flocculant for sludge sedimentation and preparation method thereof

Technical Field

The invention belongs to the technical field of environment and chemistry, and particularly relates to a flocculant capable of remarkably improving the sedimentation performance of activated sludge, namely a preparation method of a polymeric ferric chloride-poly (dimethyl diallyl ammonium chloride) -dimethyl diallyl ammonium chloride nano-flocculant.

Background

Sludge bulking is a common problem in the sewage treatment technology by an activated sludge process, and can lead to the lightening of the quality of activated sludge and the deterioration of sedimentation performance, and the difficulty in normal sludge-water separation in a secondary sedimentation tank, thereby leading to the deterioration of the quality of effluent and directly influencing the sewage treatment effect. The development of the aerobic granular sludge technology provides a new idea for solving the problem of sludge bulking, but the problems of complexity of water quality, granule stability and the like exist, so that the technology still faces a plurality of challenges in engineering application. The addition of the inorganic ferric salt and aluminum salt flocculating agent can effectively control sludge expansion and improve sludge sedimentation performance, but has the problems of large dosage of medicament, accurate requirements on addition position and mixing mode and the like, so that the sludge sedimentation effect is not obvious, a large amount of excess sludge can be generated, and the realization of a sludge reduction target is not facilitated. And the organic polymeric flocculant is added independently, so that the sludge sedimentation rate can be effectively improved, but the treatment cost is too high.

In addition, compared with the sludge-water separation technologies such as a membrane technology with high energy consumption and high investment, a cloth filter technology, an ultra-high-speed sedimentation tank and the like, how to improve the self gravity action of the sludge and strengthen the sludge-water separation process is an important link in an activated sludge treatment system, and has an important effect on improving the overall efficiency of the treatment process.

Therefore, aiming at the defects of large dosage of inorganic iron salt and aluminum salt flocculating agents and inorganic-organic composite flocculating agents, insignificant sludge sedimentation effect and the like existing at present, the nano flocculating agent for sludge rapid sedimentation is innovative in that nano polymeric ferric chloride (with the particle size distributed between 30 and 60 nm) is compounded with dimethyl diallyl ammonium chloride and homopolymers thereof to obtain the nano flocculating agent with the particle size distributed between 60 and 100 nm. The nano flocculant not only keeps the advantages of wide application range and low price of ferric salt flocculant, but also has higher reaction activity because of small size and large specific surface area of nano particles. The nano poly ferric chloride is compounded with dimethyl diallyl ammonium chloride with high molecular weight and high density positive charge and a homopolymer thereof, so that the surface positive charge and the surface energy are effectively improved, and the adsorption charge neutralization and adsorption bridging capacity is obviously enhanced. Meanwhile, the addition of the poly dimethyl diallyl ammonium chloride can obviously improve the effective component Fe in the polyferric chloride_b(Fe³⁺Hydroxyl polymer, including primary polymer, oligomer and intermediate polymer) content, thereby further improving flocculation efficiency. The nano flocculant can remove the static state of suspended matters, promote the rapid aggregation of sludge, form large-cluster sludge flocs and accelerate the sedimentation under the action of self gravity by neutralizing the surface charge of the sludge and utilizing the self adsorption and bridging action of inorganic and organic macromolecules. Therefore, the nano flocculant has the advantages of small dosage, remarkable flocculation effect, low treatment cost and the like, thereby opening up a new way for solving the problems of sludge bulking and high-efficiency separation of sludge and water.

Disclosure of Invention

Aiming at the problems of long sludge settling time, high flocculant consumption, high economic cost and the like in the prior art, the invention aims to develop a nano flocculant aiming at sludge settling and a preparation method thereof, and aims to improve the sludge settling rate, realize high-efficiency and quick separation of sludge and water and improve the quality of effluent.

In order to achieve the purpose, the invention provides the following technical scheme:

a nanometer flocculating agent for sludge sedimentation and a preparation method thereof, the nanometer flocculating agent consists of poly dimethyl diallyl ammonium chloride with the solid content of 20 percent and the mass fraction of 9.88 percent, dimethyl diallyl ammonium chloride with the solid content of 60 percent and the mass fraction of 0.82 percent and Fe with the mass fraction of 0.85 percent, the density of the flocculating agent at 20 ℃ is 1.1 to 1.2, the pH value is 1.80 to 1.90, and the particle size distribution of nano particles is between 60 and 100 nm;

the preparation method of the nano flocculant comprises the following steps:

step one, preparing nano poly ferric chloride: FeCl is added₃·6H₂Fully mixing and dissolving O and distilled water according to the mass ratio of 1:10-14, and then slowly adding Na in the stirring process₂CO₃Solid powder with alkalization degree of 0.5-1.5, and adding Na₂HPO₄As a stabilizer, under the condition of the rotation speed of 900rpm, magnetically stirring for 12-16h, and then placing at 4 ℃ for cold storage and aging for 1-6 days to ensure that the particle size of the poly-ferric chloride in the obtained poly-ferric chloride solution is distributed between 30-60nm, wherein the mass fraction of Fe is 1.4-1.8%;

step two, preparing the nano flocculant: and (2) mixing the nano polyferric chloride with the Fe content of 1.4-1.8%, poly dimethyl diallyl ammonium chloride with the solid content of 20% and dimethyl diallyl ammonium chloride with the solid content of 60% according to the mass ratio of 32-38: 1 at the reaction temperature of 25-30 ℃, and magnetically stirring for 4-8h at the rotating speed of 900rpm to obtain the nano flocculant with the particle size of 60-100 nm.

The obtained nano flocculant is diluted by 300 times, is used for activated sludge sedimentation experiments on the preparation day and after being placed for 45 days, and is added with a medicament 30s-5min before the aeration is finished, wherein the dosage of the medicament is 5-50 mu L/L.

The mass fraction of the Fe is 1.46-1.72%.

The alkalization degree is 1.

The rotating speed of the magnetic stirrer is 900rpm, and the magnetic stirring time is 15 h.

The aging temperature is 4 ℃, and the aging time is 1-6 days.

The mass ratio of the polyferric chloride to the poly-dimethyl diallyl ammonium chloride to the dimethyl diallyl ammonium chloride is 35.87: 35.99: 1, and the reaction temperature is 25-30 ℃.

The aeration time is 2 min.

The dosage of the flocculant is 20 mu L/L.

The flocculant is used as a water treatment agent and has good application in the sludge settling process of municipal, textile printing and dyeing, chemical and other industrial sewage treatment plants.

Compared with the prior sludge settling and separating technology, the nano flocculant provided by the invention is used for a sludge settling experiment and has the following excellent effects:

firstly, by introducing the nanoscale polyferric chloride, on the basis of keeping the advantages of wide dosing range of the ferric salt flocculant and low treatment cost, the adsorption performance of the ferric salt flocculant is enhanced by improving the specific surface area and the specific surface energy of the ferric salt flocculant, so that the dosage of a medicament is effectively reduced, the economic cost is reduced, and the amount of excess sludge is reduced; secondly, on the basis of the adsorption charge neutralization and bridging performance of the polyferric chloride, by introducing a proper amount of dimethyldiallylammonium chloride with high-density positive charges and homopolymers thereof, the adsorption charge neutralization and bridging performance of the composite flocculant are further improved while the effective components of the polyferric chloride are improved, and sludge is promoted to rapidly aggregate to form larger flocs. The expanded flocs promote the coagulation of sludge flocs through the actions of adsorption, bridging, sweeping and the like, and simultaneously, fine particles, colloids and the like are rapidly settled under the action of gravity, so that the rapid separation of sludge and water is realized without other separation processes. The polyferric chloride-poly (dimethyldiallylammonium chloride) -dimethyldiallylammonium chloride nano flocculant has the synergistic advantages of nano particles, inorganic and organic polymeric flocculants, and has the characteristics of simple preparation process, small adding amount, high efficiency, economy, wide application range, good stability and the like. The flocculant can be used for treating emergencies caused by sludge bulking and upgrading and modifying an active sludge sewage treatment plant.

Detailed Description

One of the embodiments of the present invention is described in detail below.

A nano flocculant for sludge sedimentation and a preparation method thereof are disclosed, wherein the method comprises the following steps:

the method comprises the following steps: preparing nano poly ferric chloride:

5.53g FeCl₃·6H₂O was sufficiently dissolved in 61.13g of distilled water, and 2.173g of Na was slowly added thereto while stirring₂CO₃The powder is made to alkalinize degree of 1, and is used for 2h totally, then 0.1164g of Na are added₂HPO₄As a stabilizer, magnetically stirring at the rotation speed of 900rpm for 15h, and then refrigerating and aging at 4 ℃ for 1-6 days to obtain a tan nano poly-ferric chloride solution, wherein the mass fraction of Fe is 1.72%;

step two, preparing the nano flocculant: accurately weighing 5.6g of the polyferric chloride obtained in the step one, and slowly adding 5.6180g of poly-dimethyldiallylammonium chloride with the solid content of 20% and 0.1561g of dimethyldiallylammonium chloride with the solid content of 60% in the magnetic stirring process under the normal temperature condition to ensure that the mass ratio of the poly-dimethyldiallylammonium chloride to the dimethyldiallylammonium chloride is 35.87: 35.99: 1. And magnetically stirring for 5 hours at the rotating speed of 900rpm to obtain the nano flocculant.

The obtained nano flocculant is used for a sludge sedimentation experiment, and the specific implementation process comprises the following steps:

diluting the nano flocculant by 300 times, recording the flocculant on the dilution day as a medicament a and recording the flocculant after 45 days as a medicament b on the dilution day and after 45 days, adding the flocculant into 1L of aerobic tank activated sludge 2min before the aeration is finished, controlling the dosage of the medicament to be 20 mu L/L, comparing blank sludge without the medicament, and measuring the sedimentation performance and stability of the obtained nano flocculant to the sludge by measuring the SVI value.

Those of ordinary skill in the art will understand that: the discussion of any embodiment above is meant to be exemplary only, and is not intended to intimate that the scope of the disclosure, including the claims, is limited to these examples; within the idea of the invention, also technical features in the above embodiments or in different embodiments may be combined and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity. Therefore, any omissions, modifications, substitutions, improvements and the like that may be made without departing from the spirit and principles of the invention are intended to be included within the scope of the invention.

The nano flocculant of the invention is applied to sludge sedimentation as a water treatment agent, and specific application effects are illustrated by application examples below.

Application examples:

1) the nano flocculant is used for the sludge sedimentation treatment of an aerobic tank A of a certain municipal sewage treatment plant in Beijing, and is compared with the blank sludge without a medicament. Adding a medicament 30s-5min before the end of aeration, wherein the aeration time can be 2min, the medicament dosage is 5-50 mu L/L, calculating the sludge volume index SVI (mL/g) within 5min, and the result is shown in Table 1.

TABLE 1 effect of treating sludge from aerobic tank A of a municipal sewage plant in Beijing city with nano-flocculant (dosage of 20. mu.L/L)

From the above processing results, compared with the blank, the nano flocculant disclosed by the invention is diluted by 300 times, the sedimentation rate of the activated sludge of the municipal sewage plant can be rapidly increased on the preparation day and after the nano flocculant is placed for 45 days, and the SVI value of the sludge is less than 90mL/g at 5 min. And the prepared flocculant can be stored for a long time conventionally, has no requirement on storage conditions, and has strong stability.

2) The nano flocculant is used for the sludge sedimentation treatment of an aerobic tank B of a certain municipal sewage treatment plant in Beijing, and is compared with the blank sludge without a medicament. Adding a medicament 30s-5min before the end of aeration, wherein the aeration time can be 2min, the medicament dosage is 5-50 mu L/L, calculating the sludge volume index SVI (mL/g) within 5min, and the result is shown in Table 2.

TABLE 2 effect of treating sludge from aerobic tank B in a municipal sewage plant of Beijing city with nano-flocculant (dosage of 20. mu.L/L)

3) The nano flocculant is used for the sludge sedimentation treatment of an aerobic tank C of an industrial sewage treatment plant in Jiangsu province, and is compared with a blank sludge without a medicament. Adding a medicament 30s-5min before the end of aeration, wherein the aeration time can be 2min, the medicament dosage is 5-50 mu L/L, calculating the sludge volume index SVI (mL/g) within 5min, and the result is shown in Table 3.

TABLE 3 treatment of sludge from aerobic tank of Yixing industrial sewage treatment plant of Jiangsu province by nanometer flocculant (dosage of 20. mu.L/L)

The processing results show that compared with the blank, the nano flocculant disclosed by the invention is diluted by 300 times, the sedimentation rate of the activated sludge of an industrial sewage treatment plant such as printing and dyeing can be rapidly increased on the preparation day and after the nano flocculant is placed for 45 days, and the SVI value of the sludge is 101.87mL/g at 5 min. And the prepared flocculant can be stored for a long time conventionally, has no requirement on storage conditions, and has strong stability.

According to the results of the sludge sedimentation experiments, the SVI value of the sludge is less than 90-102mL/g at 5 min. Therefore, the flocculant has the advantages of extremely small using amount, short sludge settling time and strong economic practicability; the product can be preserved for a long time, has no requirement on preservation conditions, and has strong stability; can quickly improve the sedimentation rate of the sludge of municipal, textile printing and dyeing, papermaking, chemical, petroleum and other industrial sewage treatment plants, and has wide application range. Can achieve the purposes of efficiently and quickly separating mud and water and improving the quality of the effluent.

Claims

1. A preparation method of a nano flocculant for sludge sedimentation is characterized by comprising the following steps:

the method comprises the following steps: preparing nano poly ferric chloride:

2. The method for preparing a nano-flocculant for sludge sedimentation according to claim 1, characterized in that: the flocculant is used as a water treatment agent and has good application in the sludge settling process of municipal administration, textile printing and dyeing and chemical wastewater treatment plants.