Method for recycling meal box cleaning wastewater

Abstract

The invention discloses a meal box cleaning wastewater recycling method which comprises the following steps: discharge adjustment: adjusting the water quality and discharge speed of cleaning wastewater, and improving the water quality and water quantity stability of the cleaning wastewater; pretreatment: removing suspended matters and floating matters in the cleaning wastewater; biochemically removing organic matters, namely removing the organic matters from the cleaning wastewater for improving the biodegradability by an anoxic and aerobic serial activated sludge method; and the cleaning wastewater subjected to biochemical treatment is returned to the meal box cleaning process, and the dosage of the cleaning agent for meal box cleaning is reduced according to the effective components of the cleaning agent in the returned cleaning wastewater. According to the method, the biodegradability of the cleaning wastewater is adjusted, and a subsequent biochemical method is matched to remove organic matters, so that the content of the organic matters in the cleaning wastewater is greatly reduced, the recycling of the cleaning wastewater is achieved, in addition, the water quality and the water quantity are adjusted before the cleaning wastewater is treated, the subsequent treatment control on the cleaning wastewater is facilitated, and the environmental pollution is reduced. The treatment efficiency and the treatment quality of the cleaning wastewater are improved in an auxiliary manner.

Description

Technical Field

[0001] The present invention relates to the field of wastewater treatment, and particularly to a method for recycling the washing wastewater of lunch boxes. Background Art

[0002] The technical project of recycling disposable takeaway lunch boxes aims to solve the problems of large consumption of takeaway lunch boxes and environmental pollution. With the rapid development of the takeaway industry, the usage of disposable takeaway lunch boxes has increased rapidly, bringing a serious burden to the environment. In order to achieve sustainable development, waste takeaway lunch boxes are recycled, regenerated and reused, thereby reducing the negative impact on the environment. It mainly adopts the method of physical recycling, and the consumed takeaway lunch boxes are washed, crushed, melted, granulated, etc., and finally made into recycled plastic pellet raw materials with quality close to that of new materials.

[0003] During the cleaning process of takeaway lunch boxes, a certain amount of wastewater will be generated. The wastewater contains degreasing agents, oil stains and residual meals. The direct discharge of the washing wastewater of takeaway lunch boxes not only causes environmental pollution, but also causes waste of water resources, and there are certain defects. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for recycling the washing wastewater of lunch boxes to achieve efficient treatment of the washing wastewater and achieve the purpose of recycling.

[0005] To solve the above technical problems, the present invention provides a method for recycling the washing wastewater of lunch boxes, including:

[0006] Discharge adjustment, adjusting the water quality and discharge rate of the washing wastewater to improve the stability of the water quality and water volume of the washing wastewater;

[0007] Pretreatment, removing suspended solids and floating substances in the washing wastewater;

[0008] Biochemical removal of organic matter, removing organic matter from the washing wastewater with improved biodegradability through the activated sludge method in series of anoxic and aerobic processes;

[0009] Recycling use, returning the washing wastewater after biochemical treatment to the lunch box washing process, and reducing the dosage of the cleaning agent for lunch box washing according to the effective components of the cleaning agent in the returned washing wastewater.

[0010] Further, the discharge adjustment uses an adjustment tank to reduce the discharge impact of the washing wastewater and slow down the water quality change, and improve the stability of the water quality and water volume change of the washing wastewater.

[0011] Further, the pretreatment specifically includes the following steps:

[0012] Using a rotary grille machine to conduct preliminary treatment on the suspended solids and floating substances in the washing wastewater;

[0013] The suspended solids in the pretreated cleaning wastewater are finely treated by the coagulation sedimentation process to reduce the content of suspended solids in the cleaning wastewater.

[0014] Furthermore, in the fine treatment process, a flocculant is added into a vertical flow sedimentation tank, and the suspended solids aggregated by the flocculant are removed by sedimentation.

[0015] Furthermore, the flocculant is one or more of polyacrylamide, polyaluminum chloride, and polyferric sulfate.

[0016] Furthermore, the specific steps for adjusting the biodegradability include:

[0017] Adjust the pH of the pretreated cleaning wastewater, and at the same time add a hydrogen peroxide solution to change the treatment environmental parameters of the pretreated cleaning wastewater;

[0018] Add a catalyst to the cleaning wastewater with changed treatment environmental parameters, use the catalyst to construct a photo-Fenton system and treat the pretreated cleaning wastewater to improve the biodegradability of the treated cleaning wastewater.

[0019] Furthermore, the pH of the pretreated cleaning wastewater is adjusted to 2.6 - 3.8.

[0020] Furthermore, the mass fraction of the hydrogen peroxide solution is 30%, and the concentration of the hydrogen peroxide solution put into the solvent wastewater is 0.08 mol / L - 0.12 mol / L.

[0021] Furthermore, the catalyst is a graphene oxide supported nano-magnetite composite material.

[0022] Furthermore, the specific steps for biologically removing organic matter include:

[0023] Through the action of microorganisms, the COD of the cleaning wastewater after adjusting the biodegradability is removed and reduced, and under anoxic conditions, heterotrophic bacteria carry out denitrification through the action of denitrifying bacteria;

[0024] Under aerobic conditions, the cleaning wastewater treated under anoxic conditions is treated through the nitrification of autotrophic bacteria, and the cleaning wastewater is returned to the anoxic conditions for denitrification.

[0025] Compared with the prior art, the present invention has at least the following beneficial effects:

[0026] In the process of treating the cleaning wastewater, the present invention adjusts the biodegradability of the cleaning wastewater and combines with the subsequent biochemical method to remove organic matters, greatly reducing the content of organic matters in the cleaning wastewater, so as to achieve the recycling of the cleaning wastewater. In addition, before treating the cleaning wastewater, the water quality and water volume are adjusted to facilitate the subsequent treatment control of the cleaning wastewater, and the treatment efficiency and quality of the cleaning wastewater are assisted to be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a flow chart of the method for recycling the cleaning wastewater of the lunch box of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The method for recycling the cleaning wastewater of the lunch box of the present invention will be described in more detail below with reference to the schematic diagrams, in which the preferred embodiments of the present invention are shown. It should be understood that those skilled in the art can modify the present invention described herein and still achieve the beneficial effects of the present invention. Therefore, the following description should be understood as a broad guidance for those skilled in the art and not as a limitation to the present invention.

[0029] The present invention will be described more specifically by way of example in the following paragraphs with reference to the drawings. The advantages and features of the present invention will be clearer according to the following description and the claims. It should be noted that the drawings are all in a very simplified form and use non-precise scales, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0030] As Figure 1 shown, an embodiment of the present invention provides a method for recycling the cleaning wastewater of a lunch box, including the following steps:

[0031] S100. Discharge adjustment, adjusting the water quality and discharge speed of the cleaning wastewater to improve the stability of the water quality and water volume of the cleaning wastewater.

[0032] Specifically, the cleaning wastewater generated in the lunch box cleaning process is intermittently drained, and the water quality and water volume change greatly. If the discharge speed control and water quality adjustment of the cleaning wastewater are not carried out, the subsequent treatment process of the cleaning wastewater will be difficult to withstand the impact of the water volume and water quality, and the dosing of drugs will also be difficult to control, and it is not easy to form flocculent precipitates. At the same time, a submersible agitator is arranged in the adjustment tank to play a role in mixing the incoming water evenly. Therefore, in order to improve the treatment effect of the cleaning wastewater, it is necessary to set up an adjustment tank to make the water quality and water volume of the incoming water relatively stable, so as to reduce the load of the subsequent cleaning wastewater treatment and facilitate the subsequent treatment.

[0033] S200. Pretreatment, removing the suspended solids and floating matters in the cleaning wastewater.

[0034] Specifically, first, a rotary grille is used to conduct preliminary treatment on the suspended solids and floating matters in the cleaning wastewater.

[0035] Rotary grille machine, also known as rotary grille sewage removal machine. It can continuously and automatically intercept and remove various large solid impurities in sewage. It is applied to the pre-sewage removal before pumps in urban sewage stations and sewage treatment plants. The rotary grille rotates continuously. The rake teeth intercept the solid suspended matters in the sewage. When the intercepted matters are conveyed to the upper part of the equipment, the rake teeth change the movement direction, and the solid sundries fall by themselves. The sundries stuck on the rake teeth are cleaned by the reverse rotation of the rubber brush of the sewage cleaning mechanism. When overloaded, the spring is pressed down, the proximity plate approaches the proximity switch, and the motor stops running.

[0036] There are many suspended and floating particles in the cleaning wastewater. Using a rotary grille can have a good effect on removing suspended and floating particles, and can also continuously clean the water passing section. The grid residues generated are collected and transported out regularly.

[0037] Then, the coagulation and sedimentation process is used to finely treat the suspended matters in the pretreated cleaning wastewater to reduce the content of suspended matters in the cleaning wastewater. According to the properties of the water such as turbidity, an appropriate amount of flocculant is added to the cleaning wastewater. Through chemical reactions and flocculation, flocs are formed and settle down, making the water clear.

[0038] Among them, in the fine treatment process, the flocculant is added into a vertical flow sedimentation tank, and the suspended matters aggregated by the flocculant are removed by sedimentation. The flocculant is one or more of polyacrylamide, polyaluminum chloride, and polyferric sulfate.

[0039] The water quality in the cleaning wastewater is relatively complex, and the suspended matter index in the cleaning wastewater is relatively high. The suspended matters must be removed in advance by coagulation and sedimentation to ensure the smooth progress of the subsequent treatment process of the cleaning wastewater. If there are too many particulate matters in the cleaning wastewater, the particulate matters will accumulate in the subsequent reactor, reducing the space left for microorganisms in the reactor and affecting the working efficiency of the reactor.

[0040] S300. Adjust the biodegradability, use a catalyst to construct a photo-Fenton system and treat the pretreated cleaning wastewater to improve the biodegradability of the cleaning wastewater.

[0041] Specifically, according to the treatment difficulty of the wastewater from lunch box cleaning, it is selected whether biochemical property adjustment is needed. During the biochemical property adjustment process, first adjust the pH of the pretreated cleaning wastewater, and at the same time add hydrogen peroxide solution to change the treatment environmental parameters of the pretreated cleaning wastewater.

[0042] Among them, the pH of the pretreated cleaning wastewater is adjusted to 2.6 - 3.8, the mass fraction of the hydrogen peroxide solution is 30%, and the concentration of the hydrogen peroxide solution added to the solvent wastewater is 0.08 mol / L - 0.12 mol / L. After the pretreated cleaning wastewater is adjusted by the treatment environmental parameters, the biodegradability performance improvement treatment can be effectively carried out.

[0043] Subsequently, a catalyst is added to the cleaning wastewater with changed treatment environmental parameters, and the catalyst is used to construct a photo-Fenton system to treat the pretreated cleaning wastewater, so as to improve the biodegradability of the treated cleaning wastewater.

[0044] Among them, the catalyst is a graphene oxide supported nano-magnetite composite material.

[0045] A biodegradability adjustment experiment is carried out on the pretreated cleaning wastewater. When the pH of the cleaning wastewater is 3.1, the concentration of the hydrogen peroxide solution is 0.12 mol / L, and 3.2 g / L of the graphene oxide supported nano-magnetite composite material is added and reacted for 2 h, the COD (chemical oxygen demand) removal rate is 88.1%, the BOD (biochemical oxygen demand) removal rate is 84.1%, the biodegradability of the wastewater is increased from 0.22 to 0.46, and the biodegradability is increased by 109.1%, providing a good basis for the subsequent biochemical method to remove organic matters.

[0046] S400. Biochemical removal of organic matters. The organic matters in the cleaning wastewater with improved biodegradability are removed by the activated sludge method with anoxic and aerobic in series.

[0047] Specifically, for the biochemical method to remove organic matters, the A / O treatment process is adopted. The A / O treatment process is an activated sludge method that combines anoxia and aeration in series. The A / O process method is also called the anaerobic-aerobic process method. A is the anoxic section, which is used for denitrification and phosphorus removal; O is the aerobic section, which is used for removing organic matters in water. Its superiority is that in addition to degrading organic pollutants, it also has a certain denitrification and phosphorus removal function. The anaerobic hydrolysis technology is used as the pretreatment of the activated sludge. Therefore, the A / O method is an improved activated sludge method.

[0048] During the cleaning wastewater treatment process, in the A anoxic section, it is mainly used for denitrification; in the O aerobic section, it is mainly used for removing organic matters in water. In addition to removing organic pollutants in the wastewater, it can also remove nitrogen and phosphorus at the same time. For high-concentration organic wastewater and refractory wastewater, a hydrolysis acidification section is set before the aerobic section, which can significantly improve the biodegradability of the wastewater. Stirring in the A section only serves to suspend the sludge and avoid the increase of DO (dissolved oxygen). Strong aeration is adopted in the front section of the O section, and the air volume is reduced in the rear section to reduce the DO content of the internal circulation liquid to ensure the anoxic state of the A section.

[0049] On the one hand, the action of microorganisms is continued to further remove and reduce COD. At the same time, under the anoxic condition in section A, heterotrophic bacteria, through the action of denitrifying bacteria, reduce nitrate in the oxygen-consuming section to molecular nitrogen, thereby achieving the purpose of nitrogen removal. Under the aerobic condition in section O, ammonium ions are oxidized to nitrate through the nitrification of autotrophic bacteria, and the generated nitrate finally returns to section A under anoxic conditions for nitrogen removal.

[0050] In the A / O treatment process, the process flow is simple, the operation is convenient, the operation cost is low, and the organic matter in the cleaning wastewater can be used as the carbon source of microorganisms, so there is no need to add external carbon source.

[0051] S500 is recycled, and the cleaning wastewater after biochemical treatment is returned to the lunch box cleaning process. According to the effective components of the cleaning agent in the returned cleaning wastewater, the dosage of the cleaning agent for lunch box cleaning is reduced.

[0052] Specifically, the treated cleaning wastewater can be reused for cleaning takeout lunch boxes, realizing the recycling of cleaning wastewater and reducing the waste of water resources. At the same time, the cleaning agent for subsequent lunch box cleaning can be reduced.

[0053] Compared with the prior art, the present invention has at least the following beneficial effects:

[0054] In the process of treating cleaning wastewater, the present invention adjusts the biodegradability of the cleaning wastewater and cooperates with the subsequent biochemical method to remove organic matter, greatly reducing the content of organic matter in the cleaning wastewater, thereby achieving the recycling of cleaning wastewater. In addition, before treating the cleaning wastewater, the water quality and water volume are adjusted, which is convenient for subsequent treatment control of the cleaning wastewater and helps to improve the treatment efficiency and treatment quality of the cleaning wastewater.

[0055] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these changes and modifications.

Claims

1. A method for recycling the washing wastewater of lunch boxes, characterized in that, Including: Discharge regulation, regulating the water quality and discharge rate of the cleaning wastewater, and improving the stability of the water quality and quantity of the cleaning wastewater; Pretreatment, removing suspended solids and floating matters in the cleaning wastewater; Biochemical removal of organic matters, removing organic matters from the cleaning wastewater with improved biodegradability through the activated sludge method with anoxic-aerobic series connection; Recycling use, returning the cleaning wastewater after biochemical treatment to the lunch box cleaning process, and reducing the dosage of the cleaning agent for lunch box cleaning according to the effective components of the cleaning agent in the returned cleaning wastewater.

2. The method for recycling the washing wastewater of the lunch box according to claim 1, characterized in that The discharge regulation uses a regulating tank to reduce the discharge impact of the cleaning wastewater and slow down the water quality change, and improve the stability of the water quality and quantity change of the cleaning wastewater.

3. The method for recycling the washing wastewater of the lunch box according to claim 1, wherein, The specific steps of the pretreatment are as follows: Using a rotary grille machine to conduct primary treatment on the suspended solids and floating matters in the cleaning wastewater; Using a coagulation sedimentation process to conduct fine treatment on the suspended solids in the preliminarily treated cleaning wastewater, and reducing the content of suspended solids in the cleaning wastewater.

4. The method for recycling the washing wastewater of the lunch box according to claim 3, wherein, In the fine treatment process, a flocculant is added into a vertical flow sedimentation tank, and the suspended solids aggregated by the flocculant are removed by sedimentation.

5. The method for recycling the washing wastewater of the lunch box according to claim 4, characterized in that, The flocculant is one or more of polyacrylamide, polyaluminum chloride and polyferric sulfate.

6. The method for recycling the washing wastewater of the lunch box according to claim 1, characterized in that, Before the biochemical removal of organic matters process, the biodegradability is regulated. The specific steps of regulating the biodegradability include: Adjusting the pH of the cleaning wastewater after pretreatment, and simultaneously adding a hydrogen peroxide solution to change the treatment environmental parameters of the cleaning wastewater after pretreatment; Adding a catalyst to the cleaning wastewater with changed treatment environmental parameters, using the catalyst to construct a photo-Fenton system and treating the cleaning wastewater after pretreatment, and improving the biodegradability of the treated cleaning wastewater.

7. The method for recycling the washing wastewater of the lunch box according to claim 6, wherein The pH of the cleaning wastewater after pretreatment is adjusted to 2.6 - 3.

8.

8. The method for recycling the washing wastewater of the lunch box according to claim 6, wherein, The mass fraction of the hydrogen peroxide solution is 30%, and the concentration of the hydrogen peroxide solution input into the solvent wastewater is 0.08 mol / L - 0.12 mol / L.

9. The method for recycling the washing wastewater of the lunch box according to claim 6, wherein, The catalyst is a graphene oxide supported nano-ferroferric oxide magnetic composite material.

10. The method for recycling the washing wastewater of the lunch box according to claim 1, characterized in that, The specific steps of the biochemical removal of organic matters include: Through the action of microorganisms, removing and reducing the COD of the cleaning wastewater after regulating the biodegradability, and under anoxic conditions, heterotrophic bacteria carry out denitrification through the action of denitrifying bacteria; Under aerobic conditions, treating the cleaning wastewater treated under anoxic conditions through the nitrification of autotrophic bacteria, and returning the cleaning wastewater to anoxic conditions for denitrification.

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