Method for synergistic biological evaporation treatment of coffee wastewater and solid waste

Abstract

The present application relates to the field of high-concentration organic wastewater and solid waste resource utilization, and discloses a method for synergistic biological evaporation treatment of coffee wastewater and solid waste. The method of the present application performs synergistic biological evaporation treatment on biofilm coffee husks, bio-dried coffee husks and bio-dried sludge which respectively serve as an expanding agent and a microbial carrier, kitchen waste as a supplementary carbon source, and coffee wastewater. The present application can achieve a good effect of synergistic treatment of agricultural and forestry waste or bio-dried sludge and coffee wastewater, and achieve the purpose of comprehensive utilization of resources by treating waste with waste.

Description

A method for treating coffee wastewater by using solid waste and bio-evaporation

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on September 1, 2023, with application number CN202311119076.1 and invention name “A method for treating coffee wastewater by synergistic biological evaporation of solid waste”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to a method for treating coffee wastewater by using solid waste in synergistic biological evaporation, and belongs to the field of high-concentration organic wastewater and solid waste resource utilization. Background Art

[0003] Coffee is one of the three most consumed beverages globally. Since the beginning of the 21st century, statistics show that the average annual production of fresh coffee beans has reached 9 million tons. Yunnan is China's largest coffee producer, accounting for 98.51% of the country's total coffee output. Every liter of coffee beans processed generates 1-15 liters of coffee wastewater. This acidic wastewater contains high concentrations of organic matter and nutrients, which can easily cause eutrophication and lead to serious health problems, including skin irritation, dizziness, nausea, and respiratory distress. Furthermore, agricultural and forestry waste, such as coffee husks, generated during the coffee processing process, although rich in nutrients, is rarely used to feed livestock due to its active ingredients, such as polyphenols, tannins, and caffeine. Consequently, the majority of coffee husks are discarded or incinerated, resulting in the current lack of comprehensive utilization of coffee husk resources.

[0004] Summary of the Invention

[0005] In response to the treatment problems of coffee wastewater and the need for optimal expansion agents and microbial carriers in the coffee wastewater treatment process, the present application provides a method for treating coffee wastewater by co-evaporating solid waste, so as to achieve an efficient resource treatment method for coffee wastewater and reduce the resource waste of solid waste.

[0006] The technical contents of this application include the following:

[0007] The present invention provides a method for treating coffee wastewater by using solid waste in synergistic biological evaporation, wherein biofilm coffee shells, bio-dried coffee shells or bio-dried sludge are used as swelling agents and microbial carriers to carry out biological evaporation treatment of coffee wastewater.

[0008] Preferably, the preparation method of the biological dried sludge is as follows:

[0009] (1) drying the fresh dewatered sludge in sunlight until the moisture content reaches 60-65% to obtain sun-dried sludge;

[0010] (2) adding the sun-dried sludge obtained in step (1) into a reactor for biological drying to obtain biologically dried sludge, wherein the biologically dried sludge is used as a bulking agent and microbial carrier for biological evaporation treatment of coffee wastewater.

[0011] Preferably, the preparation method of the biofilm coffee husk is as follows:

[0012] (1) Fresh coffee husks were uniformly mixed with activated sludge for inoculation and immersed in a cylindrical reactor filled with synthetic wastewater for biofilm cultivation;

[0013] (2) Add 2-2.5 L min -1 Aeration speed is 28~30L·min with peristaltic pump. -1 COD of 600-850 mg·L was continuously added into the cylindrical reactor at a flow rate of -1 The synthetic wastewater is discharged at the same flow rate until the biofilm is successfully formed;

[0014] (3) The coffee shells that have successfully formed biofilms are centrifuged and dehydrated to obtain biofilm coffee shells, which are used as expansion agents and microbial carriers for bioevaporation treatment of coffee wastewater.

[0015] Preferably, in step (1), the mass ratio of fresh coffee husks to activated sludge is 8:25; the synthetic wastewater consists of a major element solution, a calcium and magnesium solution, and a trace element solution, and 100 mL of synthetic wastewater is added to every 800 g of fresh coffee husks.

[0016] Preferably, the preparation method of the bio-dried coffee husk is as follows:

[0017] (1) drying fresh coffee husks in sunlight until the moisture content reaches 60-65%, thereby obtaining sun-dried coffee husks;

[0018] (2) placing the bio-dried sludge and the dewatered sludge under sunlight for drying respectively to obtain loose bio-dried sludge and sun-dried sludge with different moisture contents;

[0019] (3) The sun-dried coffee husks obtained in step (1) are uniformly mixed with the bio-dried sludge and sun-dried sludge obtained in step (2), and the resulting mixture is added to a reactor for bio-drying to obtain bio-dried coffee husks, which are used as a swelling agent and microbial carrier for the biological evaporation treatment of coffee wastewater.

[0020] Preferably, the moisture content of the biologically dried sludge and the sun-dried sludge in step (2) is independently 40-60%.

[0021] Preferably, in step (3), the mass ratio of sun-dried coffee shells to biologically dried sludge or sun-dried sludge is 20:3

[0022] Preferably, the method for biological evaporation treatment of coffee wastewater is as follows:

[0023] (1) Coffee wastewater and restaurant kitchen waste were placed in a reactor for the first round of experiments; the reactor was respectively filled with biofilm coffee shells, bio-dried coffee shells or bio-dried sludge as a bulking agent and a microbial carrier;

[0024] (2) In the subsequent rounds of experiments, only 90% of the amount of coffee wastewater from the previous round was added to the reactor and mixed with the product from the previous round;

[0025] (3) Wrap the reactor with insulation material to prevent temperature loss until the temperature drops to 20°C to 25°C, which means the reaction is complete.

[0026] Preferably, the activated sludge is obtained from the sewage treatment station of Kunming University of Science and Technology.

[0027] Preferably, the number of rounds of the experiment is one, two or six.

[0028] Preferably, when the biofilm coffee shells are used as a swelling agent and a microbial carrier, after two rounds of experiments, the average water removal rate of the pile formed by coffee wastewater and kitchen waste is 60.45%, and the average VS removal rate is 20.06%.

[0029] Preferably, when the bio-dried coffee husks are used as a swelling agent and a microbial carrier, after one round of experiments, the average water removal rate of the pile formed by coffee wastewater and kitchen waste is the best at 87.58%, and the average VS removal rate is the best at 56.09%.

[0030] Preferably, when the bio-dried sludge is used as a bulking agent and microbial carrier, the average water removal rate of the pile formed by coffee wastewater and kitchen waste is 57.26% and the average VS removal rate is 16.63% after six rounds of experiments.

[0031] Beneficial effects of this application:

[0032] The method described in the present application uses biofilm coffee shells, bio-dried coffee shells and bio-dried sludge as expanders and microbial carriers respectively to coordinate the bioevaporation treatment of coffee wastewater, thereby achieving the simultaneous treatment of solid waste and coffee wastewater. It is an economical and environmentally friendly new invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG1 is a comparison chart of water removal rates from biological evaporation of coffee wastewater in Example 1 of the present application;

[0034] FIG2 is a comparison chart of bioevaporation VS removal rate of coffee wastewater in Example 1 of the present application;

[0035] FIG3 is a comparison chart of water removal rates from biological evaporation of coffee wastewater in Example 2 of the present application;

[0036] FIG4 is a comparison chart of bioevaporation VS removal rate of coffee wastewater in Example 2 of the present application;

[0037] FIG5 is a comparison diagram of water removal by biological evaporation and VS of coffee wastewater in Example 3 of the present application. DETAILED DESCRIPTION

[0038] To better illustrate the purpose, technical solutions and advantages of this application, the application will be further described below in conjunction with specific embodiments. However, the scope of protection of this application is not limited to the contents described above.

[0039] Example 1

[0040] This embodiment uses biofilm coffee husks as a bulking agent and microbial carrier to carry out a bioevaporation experiment on coffee wastewater, specifically including the following steps:

[0041] (1) 160 g of fresh coffee husks and 500 g of activated sludge were uniformly mixed in a mass ratio for inoculation and immersed in a cylindrical reactor filled with synthetic wastewater for biofilm cultivation;

[0042] (2) Add 2.2 L min -1 Aeration was performed at a rate of 29 L min using a peristaltic pump. -1 COD of 700 mg·L was continuously added into the cylindrical reactor at a flow rate of -1 The synthetic wastewater is discharged at the same flow rate until the biofilm is successfully formed;

[0043] (3) centrifuging and dehydrating the coffee shells that have successfully formed biofilms to obtain biofilm coffee shells, and using the biofilm coffee shells as a swelling agent and microbial carrier for bioevaporation of coffee wastewater;

[0044] (4) Using cultured biofilm coffee shells as a bulking agent and microbial carrier, 150 g of coffee wastewater and 67 g of restaurant kitchen waste were added to the experimental group reactor, while 204 g of coffee wastewater was added to the control group reactor for the first round of bioevaporation experiments;

[0045] (5) In the subsequent rounds of experiments, only 90% of the amount of coffee wastewater from the previous round was added to the reactor and mixed with the products from the previous round;

[0046] (6) Wrap the reactor with insulation material to prevent temperature loss until the temperature drops to 25°C, which means the reaction is complete;

[0047] (7) After bioevaporation treatment using biofilm coffee shells as a bulking agent and microbial carrier, the pile formed by coffee wastewater and kitchen waste had an average water removal rate of 60.45% (as shown in Figure 1) and an average volatile solid (VS) removal rate of 20.06% (as shown in Figure 2) after two rounds of experiments.

[0048] Example 2

[0049] This example uses bio-dried coffee husks as a bulking agent and microbial carrier to conduct a bioevaporation experiment on coffee wastewater, specifically including the following steps:

[0050] (1) 600 g of coffee husks with a moisture content of 60% were uniformly mixed with 90 g of bio-dried sludge and sun-dried sludge with different moisture contents. The mixtures were added to the reactor for a bio-drying experiment (specific parameters are shown in Table 1). The obtained bio-dried coffee husks were used as a bulking agent and microbial carrier in the bioevaporation experiment of coffee wastewater.

[0051] Table 1 Preparation experiment of bio-dried coffee husk

[0052] (2) 150 g of coffee wastewater was uniformly mixed with seven bio-drying products to control the amount of water added to be the same so that the moisture content (MC) in the reactor was between 65% and 67% (the surface of the coffee shell is smooth and too much water is added, which makes it difficult for the pile to absorb). The mixed materials were added to the reactor for the first round of bioevaporation experiments;

[0053] (3) In the subsequent rounds of experiments, only 90% of the amount of coffee wastewater from the previous round was added to the reactor and mixed with the products from the previous round;

[0054] (4) Wrap the reactor with insulation material to prevent temperature loss until the temperature drops to 20°C, which means the reaction is complete.

[0055] After bioevaporation treatment using bio-dried coffee husks as a bulking agent and microbial carrier, the pile formed by coffee wastewater and kitchen waste showed an optimal average moisture removal rate of 87.58% (as shown in Figure 3) and an optimal average volatile solid (VS) removal rate of 56.09% (as shown in Figure 4) after one round of experiments.

[0056] Example 3

[0057] This embodiment uses bio-dried sludge as a bulking agent and microbial carrier to carry out a bioevaporation experiment on coffee wastewater, specifically including the following steps:

[0058] (1) drying the fresh dewatered sludge in sunlight until the moisture content reaches 65% to obtain sun-dried sludge;

[0059] (2) adding the sun-dried sludge obtained in step (1) into a reactor for bio-drying, and the obtained bio-dried sludge is used as a bulking agent and microbial carrier in the coffee wastewater bioevaporation experiment;

[0060] (3) Using bio-dried sludge as bulking agent and microbial carrier, 150 g of coffee wastewater and 67 g of restaurant kitchen waste were added to the experimental group reactor, while 204 g of coffee wastewater was added to the control group reactor for the first round of bioevaporation experiment;

[0061] (4) In the subsequent rounds of experiments, only 90% of the amount of coffee wastewater from the previous round was added to the reactor and mixed with the products from the previous round;

[0062] (5) Wrap the reactor with insulation material to prevent temperature loss until the temperature drops to 20°C, which means the reaction is complete;

[0063] After bioevaporation treatment using bio-dried sludge as a bulking agent and microbial carrier, the results are shown in Figure 5. After six rounds of experiments, the pile formed by coffee wastewater and restaurant kitchen waste had an average water removal rate of 57.26%, with a total removal amount of 479.98 g; the average volatile solid (VS) removal rate was 16.63%, with a total removal amount of 138.52 g.

[0064] Although the above embodiment provides a detailed description of the present application, it is only a part of the embodiments of the present application rather than all the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present application.

Claims

1. A method for treating coffee wastewater by using solid waste in combination with biological evaporation, characterized in that: Coffee wastewater is treated by biological evaporation using biofilm coffee husks, biodried coffee husks or biodried sludge as bulking agents and microbial carriers.

2. The method according to claim 1, characterized in that: The preparation method of the biological dried sludge is as follows: (1) placing the fresh dehydrated sludge under sunlight and drying it until the moisture content is 60-65%, thereby obtaining sun-dried sludge; (2) adding the sun-dried sludge obtained in step (1) into a reactor for biological drying to obtain biologically dried sludge, wherein the biologically dried sludge is used as a bulking agent and microbial carrier for biological evaporation treatment of coffee wastewater.

3. The method according to claim 1, characterized in that The preparation method of the biofilm coffee shell is as follows: (1) fresh coffee husks are uniformly mixed with activated sludge for inoculation, and immersed in a cylindrical reactor filled with synthetic wastewater for biofilm cultivation; (2) Add 2 to 2.5 L / min into the cylindrical reactor. -1 Aeration speed: 28-30 L / min with peristaltic pump -1 COD of 600 to 850 mg·L is continuously added into the cylindrical reactor at a flow rate of -1 The synthetic wastewater is discharged at the same flow rate until the biofilm is successfully formed; (3) The coffee shells that have successfully formed biofilms are centrifuged and dehydrated to obtain biofilm coffee shells, and the biofilm coffee shells are used as a swelling agent and microbial carrier for biological evaporation treatment of coffee wastewater.

4. The method according to claim 3, characterized in that In step (1), the mass ratio of fresh coffee husk to activated sludge is 8:25; the synthetic wastewater consists of a macroelement solution, a calcium and magnesium solution, and a trace element solution, and 100 mL of synthetic wastewater is added to every 800 g of fresh coffee husk.

5. The method according to claim 1, characterized in that The preparation method of the bio-dried coffee husk is as follows: (1) placing fresh coffee husks under sunlight and drying them until the moisture content is 60-65%, thereby obtaining sun-dried coffee husks; (2) placing the bio-dried sludge and the dewatered sludge under sunlight for drying respectively, thereby obtaining loose bio-dried sludge and sun-dried sludge having different moisture contents; (3) uniformly mixing the sun-dried coffee husks obtained in step (1) with the bio-dried sludge and sun-dried sludge obtained in step (2), respectively, and adding the obtained mixture to a reactor for bio-drying to obtain bio-dried coffee husks; The bio-dried coffee husks are used as a bulking agent and a microbial carrier for bioevaporation treatment of coffee wastewater.

6. The method according to claim 5, characterized in that In step (2), the moisture content of the biologically dried sludge and the sun-dried sludge is independently 40-65%.

7. The method according to claim 5, characterized in that In step (3), the mass ratio of sun-dried coffee husk to biologically dried sludge or sun-dried sludge is 20:

3.

8. The method according to claim 1, characterized in that The method for biological evaporation treatment of coffee wastewater is as follows: (1) coffee wastewater and restaurant kitchen waste are placed in a reactor for a first round of experiments; the reactor is respectively filled with biofilm coffee shells, bio-dried coffee shells or bio-dried sludge as a bulking agent and a microbial carrier; (2) In the subsequent rounds of experiments, only 90% of the amount of coffee wastewater from the previous round was added to the reactor and mixed with the product from the previous round; (3) Wrap the reactor with insulation material to prevent temperature loss until the temperature drops to 20-25° C., indicating that the reaction is complete.

9. The method according to claim 8, characterized in that The number of rounds of the experiment is one round, two rounds or six rounds.

10. The method according to claim 8 or 9, characterized in that: When the biofilm coffee shell is used as a swelling agent and a microbial carrier, the average water removal rate of the pile formed by coffee wastewater and kitchen waste is 60.45% and the average VS removal rate is 20.06% after two rounds of experiments.

11. The method according to claim 8 or 9, characterized in that: When the bio-dried coffee shells are used as a swelling agent and a microbial carrier, after one round of experiments, the average water removal rate of the pile formed by coffee wastewater and kitchen waste is the best at 87.58%, and the average VS removal rate is the best at 56.09%.

12. The method according to claim 8 or 9, characterized in that: When the biological dried sludge is used as a bulking agent and a microbial carrier, after six rounds of experiments, the average water removal rate of the pile formed by coffee wastewater and restaurant kitchen waste is 57.26%, and the average VS removal rate is 16.63%.

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