CN113929198A

CN113929198A - Treatment method of pickle pickling wastewater

Info

Publication number: CN113929198A
Application number: CN202111151136.9A
Authority: CN
Inventors: 曾旭
Original assignee: Taizhou Congyuan Environmental Technology Co ltd
Current assignee: Taizhou Congyuan Environmental Technology Co ltd
Priority date: 2021-09-29
Filing date: 2021-09-29
Publication date: 2022-01-14

Abstract

The invention relates to a method for treating pickle curing wastewater, which comprises the following steps: 1) crushing rice hulls into particles with the diameter less than 2mm, adding the particles into the pickle pickling wastewater according to a certain proportion, raising the temperature to a certain temperature, and carbonizing the rice hulls to form a catalyst in situ; 2) introducing oxygen, raising the temperature to a certain value, and then carrying out catalytic oxidation reaction on the wastewater under the action of a catalyst formed by carbonizing the rice hulls, so that the wastewater is subjected to oxidative degradation. Compared with the prior art, the method provided by the invention fully utilizes the agricultural waste rice hulls as the raw material of the catalyst to carry out catalytic oxidation degradation on the pickle pickling wastewater, solves the problem of high cost for purchasing active carbon or other catalysts, realizes resource utilization of the organic waste rice hulls, and has higher economic benefits and environmental benefits.

Description

Treatment method of pickle pickling wastewater

Technical Field

The invention belongs to the technical field of wastewater treatment, and relates to a method for treating pickle pickling wastewater.

Background

The waste water for pickling pickles generally comprises salting water (which is discharged intermittently, although the discharge amount is not large, the salt content is up to 15-20%, and COD and ammonia nitrogen are high), and processing workshop waste water (desalted water, cleaning water, flushing water and the like in the deep processing process, the indexes of pollutants in the waste water are not high, but the discharge amount is large).

The wet oxidation technology is a treatment method for oxidizing dissolved or suspended organic matters in water by using oxygen or air as an oxidant (ozone, hydrogen peroxide and the like are also used at present) in a liquid phase of water under high-temperature and high-pressure reaction conditions, and the final products are carbon dioxide and water. The wet oxidation reaction process is complex, and the main mechanism of the reaction is believed to be a free radical reaction from strong oxidation sending of free radicals, which mainly comprises two processes of mass transfer and chemical reaction, wherein the reaction is divided into three stages of chain initiation, chain development or transfer and chain termination. The wastewater to be treated is pressurized by a high-pressure pump, heated in a heat exchanger to the temperature required by the reaction and then enters a reactor; meanwhile, air or pure oxygen is pressed into the reactor through an air compressor. Within the reactor, oxidizable contaminants in the wastewater are oxidized by oxygen. After the reaction product is discharged from the reactor, the reaction product firstly enters a heat exchanger to be cooled and simultaneously heat the raw water; then, the reaction product enters a gas-liquid separator, and a gas phase, a small amount of unreacted low molecular organic matters and a liquid phase are separated and then are respectively discharged. At present, no relevant report is found when the technology is applied to the treatment of the pickle curing wastewater.

The Chinese patent with application publication number CN105709745A discloses a method for preparing a catalytic wet oxidation catalyst, which comprises the following core-shell structural components, wherein the core-shell structural components take transition metal loaded activated carbon as a core and rare earth metal loaded alumina or amorphous silica-alumina as a shell, the preparation method comprises the steps of pulping the transition metal loaded activated carbon after being treated by amino acid, introducing activated carbon slurry in the gelling process of alumina or amorphous silica-alumina and rare earth metal compound, and aging the like to obtain the catalyst after gelling. In the technical scheme disclosed in the patent, although the catalyst has high reaction activity and use stability, the preparation process of the catalyst is complex, the production cost is high, and further the treatment steps and the treatment cost of the industrial sludge are increased.

The wet oxidation method is applied to the treatment of the pickle curing wastewater, so that the influence of organic pollutants can be effectively removed, the generated acetate is favorable for curing, and the salt can be recycled, so that the method has a good application prospect.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide an economic and environment-friendly method for treating the pickle curing wastewater by a catalytic wet oxidation method.

The purpose of the invention can be realized by the following technical scheme:

a treatment method of pickle preserving wastewater comprises the following steps:

1) crushing rice hulls into particles with the diameter less than 2mm, adding the particles into the pickle pickling wastewater according to a certain proportion, raising the temperature to a certain temperature, and carbonizing the rice hulls to form a catalyst in situ;

2) introducing oxygen, raising the temperature to a certain temperature, and then carrying out catalytic oxidation reaction on the pickle preserving wastewater under the action of a catalyst formed by carbonizing the rice hulls, so that the pickle preserving wastewater is subjected to oxidative degradation.

In the step 1), the mass ratio of the rice hull addition amount to the pickle pickling wastewater is 15-20%.

In the step 1), the reaction temperature of the in-situ reaction is 150-160 ℃, and the reaction time is 3-4 h.

In the step 1), the in-situ reaction is carried out under an anoxic condition.

In the step 1), the catalyst comprises one or two of rice hull carbide or rice hull carbon.

In the step 2), in the catalytic wet oxidation process, the reaction temperature is 200-220 ℃, the reaction pressure is 2-2.5 MPa, and the reaction time is 1-2 h.

In the step 2), a certain amount of oxygen is introduced in the catalytic wet oxidation process (the oxygen amount is calculated according to COD (chemical oxygen demand) of the pickle curing wastewater, and is preferably 120-140% of the oxygen demand).

According to the method, high-temperature conditions required by catalytic wet oxidation reaction are utilized, before oxygen is introduced for catalytic wet oxidation treatment, the organic waste rice hulls are added to synthesize the catalyst in situ, namely, the temperature is increased to 150-160 ℃, the reaction time is 3-4 hours, and the rice hulls are carbonized and converted into hydrothermal carbon or hydrothermal carbide to serve as the catalyst for catalytic wet oxidation reaction; and then introducing a certain amount of oxygen (the oxygen amount is calculated according to the COD of the pickled vegetable pickling wastewater, and is preferably 120-140% of the oxygen demand), reacting at the temperature of 200-220 ℃, under the reaction pressure of 2-2.5 MPa for 1-2h, and carrying out catalytic oxidation reaction on the pickled vegetable pickling wastewater to obtain oxidative degradation.

When the catalyst is prepared in situ, the rice hulls are mixed into the pickle pickling wastewater by adopting a hydrothermal carbon synthesis method, so that most of carbon in the rice hulls is converted into hydrothermal carbon, and a small part of carbon is transferred into a liquid phase and a gas phase, and the hydrothermal carbon can be used as the catalyst for the next step. The in-situ synthesized hydrothermal carbon has the advantages of large specific surface area, developed pore structure, mesh plane composition of hexagonal arrangement of carbon and the like, not only is a good adsorbent, but also can be used as a catalyst in a catalytic oxidation system to degrade various organic matters. Can remove the target substance by adsorption; in a catalytic oxidation system, the catalyst can react with water under the action of high temperature and high pressure to generate high-activity hydroxyl radicals, so that a series of radical chain reactions are initiated to effectively remove target pollutants.

Compared with the prior art, the invention has the following characteristics:

1) the high-temperature condition required by catalytic wet oxidation reaction is fully utilized, a step is added before oxygen is introduced for catalytic wet oxidation reaction, namely, the rice hulls are utilized to generate a high-efficiency hydrothermal carbon or hydrothermal carbide catalyst in situ, and the catalyst is utilized to catalyze organic matters to carry out wet oxidation reaction, so that the problem of high cost for purchasing active carbon or other catalysts is solved, the resource utilization of organic waste rice hulls is realized, and the high-temperature-resistant organic waste rice hulls catalytic wet oxidation catalyst has high economic benefit and environmental benefit;

2) the solid substance after the treatment process is mainly a hydrothermal carbon catalyst or a hydrothermal carbide catalyst and can be used as a catalyst for recycling; if the catalyst loses catalytic activity after being used for many times, the catalyst can also be used as a soil remediation agent to further exert the utilization value of the soil remediation agent.

Detailed Description

The present invention will be described in detail with reference to specific examples. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.

Example 1:

the COD of certain pickles pickling wastewater is 20000-30000 mg/L, rice hulls are crushed into particles with the diameter of less than 2mm and added into the pickles pickling wastewater, the mass ratio of the addition amount to the pickles pickling wastewater is 20%, the mixed solution is added into a hydrothermal reaction kettle, the reaction temperature of in-situ reaction under the anoxic condition is 150-160 ℃, the reaction time is 3-4 hours, rice hull carbide is generated, the reaction temperature is continuously increased to 200-220 ℃, the reaction pressure is 2-2.5 MPa, the reaction time is 1-2 hours, a certain amount of oxygen is introduced (the oxygen amount is calculated according to the pickling wastewater of the pickles, the preferable oxygen amount is 140% of the oxygen demand, the COD removal rate of the pickles pickling wastewater can reach more than 80%, the process utilizes the catalyst to catalyze organic matters to carry out wet oxidation reaction, the problem of high cost of purchasing active carbon or other catalysts is solved, and the resource utilization of the organic waste rice hulls is realized, has higher economic benefit and environmental benefit; the solid substance after the treatment process is mainly a hydrothermal carbon catalyst or a hydrothermal carbide catalyst and can be used as a catalyst for recycling; if the catalyst loses catalytic activity after being used for many times, the catalyst can also be used as a soil remediation agent to further exert the utilization value of the soil remediation agent.

Claims

1. A treatment method of pickle curing wastewater is characterized by comprising the following steps:

2. The method for treating the waste water from pickling of vegetables as claimed in claim 1, wherein in the step 1), the mass ratio of the rice hull addition amount to the waste water from pickling of vegetables is 15-20%.

3. The method for treating the pickle curing wastewater as claimed in claim 1, wherein in the step 1), the reaction temperature of the in-situ reaction is 150-160 ℃, and the reaction time is 3-4 h.

4. The method for treating wastewater from pickling of vegetables as claimed in claim 1, wherein the in-situ reaction in step 1) is carried out under anoxic conditions.

5. The method for treating the waste water from pickling of vegetables as claimed in claim 1, wherein in the step 1), the catalyst comprises one or both of rice hull carbide and rice hull carbon.

6. The method for treating the pickle curing wastewater as claimed in claim 1, wherein in the step 2), the reaction temperature is 200-220 ℃, the reaction pressure is 2-2.5 MPa, and the reaction time is 1-2h in the catalytic wet oxidation process.

7. The method for treating wastewater from pickling of vegetables as claimed in claim 1, wherein in step 2), a certain amount of oxygen is introduced during the catalytic wet oxidation process (the oxygen amount is calculated according to the COD of the wastewater from pickling of vegetables, and is preferably 120-140% of the oxygen demand).