CN110877938A

CN110877938A - Organic arsenic wastewater treatment and arsenic stabilization method

Info

Publication number: CN110877938A
Application number: CN201811029486.6A
Authority: CN
Inventors: 何小松; 虞敏达; 席北斗; 张慧; 毛旭辉; 李丹
Original assignee: Chinese Research Academy of Environmental Sciences
Current assignee: Chinese Research Academy of Environmental Sciences
Priority date: 2018-09-05
Filing date: 2018-09-05
Publication date: 2020-03-13
Anticipated expiration: 2038-09-05
Also published as: CN110877938B

Abstract

The invention discloses an organic arsenic wastewater treatment and arsenic stabilization method, specifically, under a neutral aerobic environment, zero-valent iron and a complex are added for stirring, and formed active oxygen species thoroughly oxidize organic arsenic in a water body into inorganic arsenic; after the oxidation stage is finished, stopping aeration, adding aluminum salt and continuously stirring to form a plurality of hydroxyl complexes and hydroxides so as to realize effective separation of inorganic arsenic; the stabilization of the arsenic-containing sludge is realized by controlling the proportion of the complex, zero-valent iron and aluminum salt in the system; the method can realize the thorough purification of the organic arsenic wastewater, and the formed arsenic-containing sludge has less amount, less arsenic leaching amount in the sludge and weak bioavailability; the method can be used for treating livestock and poultry breeding wastewater, industrial wastewater, surface water and underground water containing organic arsenic.

Description

Organic arsenic wastewater treatment and arsenic stabilization method

Technical Field

The invention relates to the technical field of wastewater treatment and disposal, in particular to a method for treating organic arsenic wastewater and stabilizing arsenic.

Background

Aromatic organic arsenic such as phenylarsinic acid and 3-nitro-4-hydroxyphenylarsonic acid has the functions of broad-spectrum sterilization, promotion of livestock growth, improvement of laying rate and the like, and is widely used in livestock and poultry breeding industry in China. The aromatic organic arsenic is difficult to be metabolized and decomposed in animals, and most of the aromatic organic arsenic is discharged out of the bodies along with excrement by drug prototypes. Because the organic arsenic has higher water solubility, the organic arsenic is easy to migrate and diffuse into surface water, soil and underground water and is converted into inorganic arsenic with stronger migration capability and higher toxicity through biological and non-biological mechanisms. As the largest livestock and poultry meat producing country in China, the annual consumption of feed additives such as amino phenylarsonic acid and the like exceeds 1000 tons, and meanwhile, the organic arsenic production industry also has the problem of wastewater treatment. Therefore, the development of technology for separating and removing organic arsenic effectively and fundamentally is a key point for reducing pollution of organic arsenic.

The currently effective aromatic organic arsenic treatment methods include chemical oxidation, adsorption and coagulation precipitation. The chemical oxidation method for treating the water body polluted by the organic arsenic mainly comprises ultraviolet light oxidation, ultraviolet light photocatalysis, ozone oxidation and the like, and the aromatic organic arsenic is quickly degraded under the photocatalytic oxidation condition to generate inorganic arsenic with higher toxicity and still exists in the water body. The adsorption method mainly focuses on iron-aluminum oxides, carbon materials, high molecular materials and the like. Adsorption technology, while relatively low cost, only transfers contaminants. In addition, the arsenic-containing regeneration liquid formed by the traditional adsorption method is an unsolved problem. Arsenic waste (such as waste adsorption materials, arsenic-containing sludge and the like) is inevitably generated finally regardless of adsorption, coagulation and precipitation or chemical oxidation, and the waste faces the problem of disposal. Therefore, the development of a low-cost and secondary-pollution-free organic arsenic wastewater treatment and disposal technology is needed.

In the environment of neutral oxygen exposure, the zero-valent iron and the complex are added and stirred, and the formed active oxygen species are utilized to thoroughly oxidize organic arsenic in the water body into inorganic arsenic; after the oxidation is finished, stopping aeration, adding aluminum salt and continuously stirring to form a plurality of hydroxyl complexes and hydroxides, thereby realizing the effective separation of inorganic arsenic. The stabilization of the arsenic-containing bottom mud is realized by controlling the proportion of the complex, zero-valent iron and aluminum salt in the system.

Disclosure of Invention

The present invention aims to provide a method for treating organic arsenic wastewater and stabilizing arsenic, so as to solve the problems in the background art.

In order to solve the technical problems, the invention provides the following technical scheme: an organic arsenic wastewater treatment and arsenic stabilization method comprises the following steps: step one, treating organic arsenic wastewater; stabilizing organic arsenic;

(1) on the premise of determining the content of organic arsenic in wastewater to be treated, adding a certain amount of complex, and adding zero-valent iron powder under a neutral aeration environment for stirring to realize complete mineralization and oxidation of the organic arsenic in the system;

(2) and stopping aeration after the oxidation process is finished, adding aluminum salt, stirring, standing, dehydrating and drying the inorganic arsenic-containing bottom sludge, and adding a calcium source to strengthen the stability of the sludge.

The content of organic arsenic in the wastewater comprises one or more of p-amino phenylarsonic acid, 4-hydroxy-3-nitrophenylarsonic acid and 4-hydroxy-3-aminophenylarsonic acid, and the concentration of the organic arsenic can be controlled to be 0.01-100 g/L in terms of arsenic.

The complex comprises one or more of silicate, ethylene diamine tetraacetic acid, N' -ethylenediamine disuccinic acid, polyphosphate and nitrilotriacetic acid, and the molar concentration of the complex is regulated by the organic arsenic content of wastewater and is controlled to be 1-100 mmol/L.

The neutral environment is that the pH value is controlled to be 5-10.

The aerobic environment is realized by introducing oxygen or air at a rate of 1-100 mL/s.

The zero-valent iron can be used independently or in combination with nano zero-valent iron and micron zero-valent iron, and the adding amount of the zero-valent iron is 1-15 times of the arsenic amount in the water body.

The aluminum salt can be one or a combination of more of aluminum chloride, aluminum sulfate, aluminum nitrate, aluminum silicate and aluminum sulfide, and the adding amount of the aluminum salt is 1-10 times of the arsenic amount in the water body.

The dehydration and drying of the bottom mud are realized by adopting a natural air drying, filter pressing or centrifuging mode to ensure that the water content of the bottom mud is lower than 80 percent, and adding calcium source powder accounting for 1 to 10 percent of the mass of the bottom mud for mixing.

The calcium salt comprises one or more of calcium hydroxide, calcium oxide, calcium chloride or industrial calcium slag.

Compared with the prior art, the invention has the following beneficial effects:

1. the invention can realize the mineralization of organic arsenic through the oxidation process of the earlier stage, and meanwhile, the floc formed at the later stage can better separate inorganic arsenic, and can thoroughly realize the purification of water containing arsenic pollution;

2. according to the invention, the mol ratio of zero-valent iron, ligand, calcium salt and arsenic is prepared, so that the re-release of the arsenic-containing bottom mud can be well inhibited, the leaching amount of the arsenic-containing bottom mud not only meets the landfill treatment requirement, but also the bioavailability of the arsenic-containing sludge is weakened;

3. the invention provides active oxygen free radicals with strong oxidation capacity by taking air as an oxygen source, thereby not only reducing the sewage treatment cost, but also being green and environment-friendly.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a state diagram of a process for treating a solution in accordance with the present invention;

FIG. 2 is a diagram showing the effect of 30min settling separation of sludge according to the present invention;

fig. 3 is a flow chart of the steps of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-3, the present invention provides a technical solution: a method for treating organic arsenic wastewater and stabilizing arsenic comprises collecting 200mL of simulated organic arsenic-polluted wastewater with an initial concentration of 30mg/L of phenylarsonic acid; after 3.5mmol/L sodium metasilicate and 1.5mmol/L ethylene diamine tetraacetic acid are added into the wastewater, the pH value of the system is controlled to be 6.5, then oxygen is introduced into the system at the flow rate of 60mL/s, and 20mg of nano zero-valent iron powder is added; stirring for 40min, and stopping aeration after the oxidative degradation process is finished; adding 10mg aluminum silicate into the system, stirring for 10min, standing (as shown in figures 1 and 2), collecting supernatant, and measuring the concentrations of organic arsenic and inorganic arsenic in the supernatant; after centrifugally dewatering the separated flocs, adding 50mg of calcium hydroxide, uniformly mixing, and after stabilizing for one week, leaching sludge to measure the arsenic leaching amount; the analysis result shows that the contents of the phenylarsinic acid, the trivalent arsenic and the pentavalent arsenic in the supernatant after standing are all less than 0.01 mg/L; the arsenic content in the standard toxic leach (TCLP) liquor is only 0.09mg/L, which is far below the national limit.

Compared with the traditional ferric salt sludge (added with the same content of ferrous chloride) (as shown in the table 1),

TABLE 1 sludge Leaching test results

The invention not only controls the arsenic leaching amount of the sludge well, but also obviously weakens the biological and plant availability of the arsenic-containing sludge.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for treating organic arsenic wastewater and stabilizing arsenic comprises the following steps of firstly, treating the organic arsenic wastewater; stabilizing organic arsenic; the method is characterized in that:

(1) on the premise of determining the content of organic arsenic in wastewater to be treated, adding a certain amount of complex, and adding zero-valent iron powder under a neutral aeration environment for stirring to realize complete oxidation of the organic arsenic in the system;

(2) stopping aeration after the oxidation is finished, adding aluminum salt, stirring, standing, dehydrating and drying the inorganic arsenic substrate sludge, and adding a calcium source to strengthen the sludge stability.

2. The wastewater organic arsenic in the step (1) of claim 1, which comprises one or more of p-nitroarsinic acid, 3-nitro-4-hydroxyphenylarsonic acid, p-aminophenylarsonic acid and 3-amino-4-hydroxyphenylarsonic acid, and the concentration of pollutants is controlled to be 0.01-100 g/L calculated by arsenic.

3. The complex in the step (1) of claim 1, which comprises one or more combinations of silicate, ethylene diamine tetraacetic acid, N' -ethylenediamine disuccinic acid, polyphosphate and nitrilotriacetic acid, wherein the molar concentration of the complex is regulated by the organic arsenic content of wastewater, and is optimally controlled to be 1-100 mmol/L.

4. The neutral environment according to the step (1) of claim 1, wherein the pH value is controlled to be between 5 and 10.

5. The aerobic environment in step (1) of claim 1, wherein the aerobic environment is achieved by introducing oxygen or air at a rate of 1-100 mL/s.

6. The zero-valent iron in the step (1) of claim 1 can be nano zero-valent iron, micro zero-valent iron and iron-based materials which are used singly or in combination, and the adding amount is 1-15 times of the arsenic content in the water body.

7. The aluminum salt according to claim 1, step (2), which is selected from the group consisting of aluminum chloride, aluminum sulfate, aluminum nitrate, aluminum silicate, and aluminum sulfide, and is added in an amount of 1-10 times the amount of arsenic in the water.

8. The dehydration and drying of the bottom mud according to the step (2) of claim 1, which is to mix the bottom mud with water content lower than 80% by natural air drying, filter pressing or centrifugation, and calcium source powder accounting for 1-10% of the weight of the bottom mud.

9. The calcium source of claim 1, step (2), comprising any one or a combination of more of calcium hydroxide, calcium oxide, calcium chloride, or industrial calcium slag.