CN111186882A

CN111186882A - Electrochemical method for synchronously realizing organophosphorus wastewater treatment and resource utilization

Info

Publication number: CN111186882A
Application number: CN202010023098.8A
Authority: CN
Inventors: 江波; 宁亚男; 苏晴; 关雨欣; 王婧茹; 刘奕捷; 毕学军; 唐沂珍; 罗思义
Original assignee: Qingdao University of Technology
Current assignee: Qingdao University of Technology
Priority date: 2020-01-09
Filing date: 2020-01-09
Publication date: 2020-05-22
Also published as: WO2021138960A1

Abstract

The invention relates to the field of organic phosphorus wastewater treatment, and provides a new method for degrading organic phosphorus pollutants by using an electrochemical anode and realizing the recycling of inorganic phosphorus by utilizing the local strong alkalinity of the cathode at the same time. This patent establishes an electrochemical reaction system of "anodic oxidation-cathode enrichment", in which a large number of strongly oxidizing hydroxyl radicals are generated on the anode surface to rapidly degrade organic phosphorus pollutants into inorganic phosphate ions. The cathode surface can generate a local strong alkaline atmosphere due to the electrolysis of water, which induces and strengthens the enrichment of phosphate ions and calcium hardness ions on the cathode surface, forming phosphate minerals that can be recycled. The present invention can realize the efficient and thorough removal of organic phosphorus pollutants in the water body, and also realize the resource utilization of wastewater containing organic phosphorus, and has higher social and economic benefits.

Description

Electrochemical method for synchronously realizing organophosphorus wastewater treatment and resource utilization

Technical Field

The invention relates to the field of wastewater treatment, in particular to an electrochemical method for synchronously realizing organophosphorus wastewater treatment and resource utilization.

Background

With the wide use of organophosphorus pesticides in agriculture and forestry, the problem of environmental pollution caused by organophosphorus pesticides is increasingly serious, and how to eliminate residual organophosphorus pesticides in the environment becomes a research hotspot of countries in the world, so that the organophosphorus pesticides have wide application prospects and great application values. At present, common methods for degrading organic phosphorus comprise photodegradation, microbial degradation and chemical degradation, but because of high treatment difficulty of organic phosphorus wastewater, heavy load of a biochemical treatment device and high treatment energy consumption, in recent years, electrochemical advanced oxidation technology is widely concerned in the field of water treatment by virtue of the advantages of high efficiency, universality, thoroughness and the like of organic matter degradation. However, although some researches focusing on the treatment of organic phosphorus wastewater by electrochemical advanced oxidation technology are available, the researches only realize the oxidative conversion of organic phosphorus into inorganic phosphorus, and do not realize the complete removal and resource utilization of phosphorus in water.

As an irrenewable resource which is wide in application, indispensable and has no substitute variety temporarily, the global reserve of the phosphate ore is greatly reduced year by year, and the potential shortage crisis of phosphorus resources is possibly caused in the future, so that how to realize the resource utilization of phosphorus in the organophosphorus wastewater becomes important. In most cases, inorganic phosphate ions can be removed by generating a poorly soluble or insoluble phosphate precipitate. The calcium hydroxy phosphate can be used as a high-quality raw material in the fertilizer industry, and most of water bodies usually contain calcium hardness ions, so the method for realizing the resource recycling of the organic phosphorus by utilizing the calcium hardness ions has better development prospect. However, the sedimentation performance of the calcium hydroxy phosphate precipitate generated by the method is insufficient, an additional solid-liquid separation process is needed, and the high pH value of the treated wastewater cannot meet the discharge requirement, so that the method still has certain limitations in practical application.

Disclosure of Invention

According to the defects of the prior art, the invention provides an electrochemical method for synchronously realizing the treatment and resource utilization of organic phosphorus wastewater, an electrochemical reaction system of 'anodic oxidation-cathodic enrichment' is established, a large amount of hydroxyl free radicals with strong oxidizing property are generated on the surface of an anode to rapidly degrade organic phosphorus pollutants into inorganic phosphate ions, and meanwhile, the inorganic phosphate ions and calcium hardness ions are induced to be enriched on the surface of a cathode under the local strong alkaline atmosphere on the surface of the cathode, so that the problem of resource recycling of the organic phosphorus pollutants is solved.

The technical scheme of the invention is as follows: the enrichment of inorganic phosphate ions and calcium hardness ions generated by the rapid oxidation of the organic phosphorus pollutants by the anode on the surface of the cathode is induced and strengthened by utilizing the local strong alkaline atmosphere generated by the reaction of the electrolyzed water on the surface of the cathode, so that phosphate minerals capable of being recycled are formed, and the removal and the recycling of the organic phosphorus pollutants in the wastewater are realized. .

Wherein, the preferred scheme is as follows:

the cathode is a titanium mesh/plate, a steel mesh/plate and the like.

The anode is BDD electrode, DSA electrode, Sn-Sb electrode, Ru-Ir electrode, Ir-Ta electrode and PbO₂Electrodes, and the like.

The distance between the anode and the cathode in the electrochemical reaction system is 0-500mm, and the current density is 0.1-50mA/cm²。

The molar concentration ratio of hardness ions to total phosphorus in the organophosphorus wastewater is 0.5:1-20: 1.

The principle of the invention is as follows:

the anodization mechanism is exemplified by a BDD electrode. BDD electrodes are typical materials of non-active anodes with their high oxygen evolution overpotentialCan electrolyze water on the surface to generate more^·And (5) OH. The mechanism is as the formula (1, 2):

BDD+H₂O→BDD(^·OH)+H⁺+e^-(1)

BDD(^·OH) + organics → BDD + CO₂+H₂O + inorganic ion (2)

Cathode electrolysis water reaction generates a large amount of OH^-，OH^-On one hand, the surface of the cathode generates local strong alkaline atmosphere to induce the enrichment of phosphate minerals, and on the other hand, the phosphate minerals and inorganic phosphate ions and calcium hardness ions generate calcium hydroxy phosphate precipitation together. The mechanism is as the formula (3, 4):

H₂O+e^-→OH^-+H₂↑ (3)

PO₄ ^3-+Ca²⁺+OH^-→Ca₁₀(PO₄)₆(OH)₂↓ (4)

the invention has the advantages that:

(1) the enrichment of calcium hydroxy phosphate is induced by utilizing the local strong alkaline atmosphere on the surface of the cathode, acid and alkali are not required to be added additionally, and the dosage of chemicals is greatly reduced.

(2) The cathode is used as an enrichment carrier to fix the calcium hydroxy phosphate, so that the problem of insufficient settling property of precipitates is solved, and an additional solid-liquid separation process is not needed.

(3) Different mechanisms of the cathode and the anode are reasonably utilized, and the treatment and resource utilization of the organophosphorus wastewater are synchronously realized through the synergistic effect of the cathode and the anode.

Description of the drawings:

FIG. 1 shows the time-dependent changes of (a) the total phosphorus concentration and (b) the inorganic phosphorus concentration in the treatment of an organic phosphorus wastewater having an organic phosphorus concentration of 10mg/L by the method of the present invention for 180 minutes. As can be seen from FIG. 1, after 180min, the electrochemical anode can oxidize and degrade almost 100% of the organic phosphorus pollutants into inorganic phosphorus, and the electrochemical cathode can enrich 86% of the inorganic phosphorus ions on the cathode plate.

FIG. 2 is a graph showing the change of the total phosphorus concentration with time during the treatment of an organophosphorus wastewater having an organophosphorus concentration of 10mg/L for 180 minutes using different current densities in the process of the present invention. As can be seen from FIG. 2, the resource recovery of total phosphorus is in a positive correlation with the current density.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described, and it is obvious that the described embodiments are a part of the embodiments of the present invention, but 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.

Example 1:

adding 50mg/L Ca into the wastewater solution with the concentration of organic phosphorus of 10mg/L²⁺And 0.1M anhydrous sodium sulfate, adding sulfuric acid to adjust pH to 6.0, and regulating current density at normal temperature and pressure to 20mA/cm²And (4) processing. The total phosphorus concentration in the wastewater treated for 180min was 1.41mg/L, and the inorganic phosphorus concentration was 1.30mg/L, as shown in FIG. 1.

Example 2:

adding 50mg/L Ca into the wastewater solution with the concentration of organic phosphorus of 10mg/L²⁺And 0.1M anhydrous sodium sulfate, adding sulfuric acid to adjust pH to 6, and respectively controlling current density at 0mA/cm under normal temperature and normal pressure²、5mA/cm²、10mA/cm²、20mA/cm²、30mA/cm²And (4) processing. The total phosphorus concentration in the wastewater treated for 180min is respectively reduced to 10.48mg/L, 5.97mg/L, 3.80mg/L, 1.42mg/L and 1.01mg/L, as shown in FIG. 2.

Comparative example 1:

adding 0.1M anhydrous sodium sulfate into wastewater solution with organic phosphorus concentration of 10mg/L, adding sulfuric acid to adjust pH to 6.0, and regulating current density to 20mA/cm at normal temperature and normal pressure²And (4) processing. The total phosphorus concentration in the wastewater treated for 180min was 10.52mg/L, and the inorganic phosphorus concentration was 10.25mg/L, as shown in FIG. 1.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art without departing from the principle and spirit of the present invention.

Claims

1. an electrochemical method for synchronously realizing organic phosphorus wastewater treatment and resource utilization, is characterized in that: electrochemical anode is used for the rapid oxidation of organic phosphorus pollutants to inorganic phosphorus, and the cathode surface can produce localized due to electrolytic water reaction. The strong alkaline atmosphere induces and strengthens the enrichment of inorganic phosphate ions and calcium hardness ions on the cathode surface to form phosphate minerals that can be recycled and reused, and realize the removal of organic phosphorus pollutants in wastewater and the resource utilization of phosphorus.

2 . The electrochemical method for synchronously realizing organophosphorus wastewater treatment and resource utilization according to claim 1 , wherein the cathode is a titanium mesh/plate, a steel mesh/plate, and the like. 3 .

3. a kind of electrochemical method of synchronously realizing organophosphorus wastewater treatment and resource utilization according to claim 1, is characterized in that: described anode is BDD electrode, DSA electrode, tin antimony electrode, ruthenium iridium electrode, iridium Tantalum electrodes, PbO ₂ electrodes, etc.

4. a kind of electrochemical method for synchronously realizing organophosphorus wastewater treatment and resource utilization according to claim 1, is characterized in that: the anode-cathode electrode spacing in the described electrochemical reaction system is 0-500mm, and the current density is 0.1-50mA/cm ² .

5. a kind of electrochemical method for simultaneously realizing organophosphorus wastewater treatment and resource utilization according to claim 1, is characterized in that: the molar concentration ratio of hardness ion and total phosphorus in the described organophosphorus wastewater is 0.5:1 -20:1.