A method for treating dye wastewater by using biomass combined with fungi and microalgae

Abstract

The application discloses a method for treating dye wastewater by using biomass combined with fungi and microalgae, which comprises the following steps: (1) taking biomass, adding the biomass into dye wastewater after pretreatment for adsorption; (2) separating the biomass after adsorbing dyes, inoculating white rot fungi and chlorella in the biomass, and carrying out fermentation under room temperature and illumination conditions. The application uses biomass combined with fungi solid-state fermentation, and designs a new method for treating dye wastewater through the symbiotic and mutual promotion technology of fungi and algae. The secretion of laccase in the mixed ecological system of fungi and algae promotes the solid-state fermentation process of biomass, and the heterotrophic process of algae also consumes organic carbon. The fungi and algae promote and symbiotize each other, form a stable O2-CO2 exchange system, cooperatively treat the dye wastewater, and greatly improve the pollutant removal efficiency.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of dye wastewater treatment, and particularly relates to a method for treating dye wastewater by using biomass combined with fungi and microalgae. BACKGROUND

[0002] With the increasing production of dyes in China, a large amount of dye wastewater which is harmful to the environment and human body is produced. The dye wastewater has high organic matter content, complex composition and biological toxicity. Since the dye wastewater has great harm, it is extremely important to discharge the dye wastewater up to the standard. At present, the dye wastewater is treated by common adsorption method, microbial decomposition method, photocatalysis method, ozone method and the like. However, due to the problems of cost and secondary pollution, the methods have limitations in practical application.

[0003] The existing methods for treating dye wastewater mainly include physical method, chemical method and biological method, but all have disadvantages. For example, the adsorption method only enriches dye molecules and does not effectively degrade the dye molecules, so further disposal is needed; the flocculation method has certain harm to human body and environment, and the use of flocculants produces a large amount of sludge, which has high disposal cost; the ozone oxidation method has high cost due to the expensive continuous supply of ozone; the electrolysis method is not suitable for treating dye wastewater with large water volume; and the single biological method has great difficulty in treating dye wastewater with complex composition and unstable water quality, and has general decolorization effect.

[0004] In order to overcome the disadvantages of the prior art, a method for decolorizing printing and dyeing wastewater by using immobilized fungal thalli is disclosed in Chinese patent application No. CN200810228636.6. A spore or mycelium segment of one or more fungi is cultured to prepare a 10 10 ml inoculation suspension, the inoculation suspension is inoculated into a liquid culture medium containing immobilized substrate material at a volume ratio of 5%-20%, and then the inoculation suspension is vibrated at 60-200 r / min at 20-35 DEG C for 3-7 days. After the mycelium covers the substrate material, the mycelium is inactivated at high temperature, and then is put into the printing and dyeing wastewater for decolorization treatment.

[0005] Chinese patent application No. 201410081449.5 discloses a method for treating printing and dyeing wastewater by using waste straw. First, the waste straw is chemically modified by using polysaccharide compounds. Then, the modified waste straw is used to adsorb the printing and dyeing wastewater, so that the treatment cost of the wastewater is reduced, and the method is an economic and environmental treatment method.

[0006] However, the above-mentioned methods still have the problems of complex treatment process, high cost and unsatisfactory treatment effect, and the treated waste still needs further treatment. SUMMARY

[0007] The application aims to provide a method for treating dye wastewater by using agricultural waste combined with fungi and microalgae through solid-state fermentation technology, so as to reduce the treatment cost of dye wastewater and improve the treatment efficiency.

[0008] The technical scheme adopted by the application is as follows:

[0009] The method for treating dye wastewater by using biomass combined with fungi and microalgae comprises the following steps:

[0010] (1) biomass is taken, pretreated and then added into dye wastewater for adsorption;

[0011] (2) the biomass after adsorbing dyes is separated, white rot fungi and chlorella are inoculated in the biomass, and fermentation is carried out under room temperature and light conditions.

[0012] As a preferred scheme, in step (1), the biomass is preferably one or a combination of wheat straw, corn straw and peanut shell; and the adding amount of the biomass is 2-18 g per liter of dye wastewater.

[0013] As a preferred scheme, in step (1), the pretreatment comprises: being cut into 1-3 cm small pieces and being dried for standby.

[0014] As a preferred scheme, in step (1), the dye wastewater is dye wastewater containing crystal violet, and the concentration of crystal violet is 10-400 mg / L.

[0015] As a preferred scheme, in step (1), the adsorption is carried out under natural pH, stirring and room temperature conditions for 8-16 hours, and the stirring speed is 100-200 r / min.

[0016] As a preferred scheme, in step (2), the biomass after adsorbing dyes is separated by filtering the biomass through a filter screen, and then dried and crushed, deionized water is added, sterilized, and then white rot fungi and chlorella are inoculated.

[0017] As a preferred scheme, in step (2), the white rot fungi are selected from one or a combination of laetiporus, pleurotus and lentinus.

[0018] As a preferred scheme, in step (2), the inoculation amount of white rot fungi is 1 fungus piece / 2.5-3.5 g of straw; and the inoculation ratio of white rot fungi and chlorella is 1: (8-12).

[0019] As a preferred solution, in step (2), after the fermentation, the newly separated biomass can also be dried and crushed, added with deionized water, sterilized, and then mixed uniformly with the original fermented biomass for continuous fermentation.

[0020] As a preferred solution, in step (2), the fermentation conditions are: maintaining moisture culture at a constant temperature of 25-30 ℃, light intensity of 150-200 μmol / m 2 ·s, 12 h light and 12 h dark photoperiod for 5-7 days.

[0021] Beneficial effects: Compared with the prior art, the present application has the following advantages:

[0022] (1) A new method for treating dye wastewater is designed by using biomass combined with fungal solid-state fermentation and through the technical design of symbiotic and mutual promotion of fungi and algae. The secretion of laccase in the mixed ecological system of fungi and algae promotes the solid-state fermentation process of biomass, and the heterotrophic process of algae also consumes organic carbon. Fungi and algae promote symbiosis, forming a stable O2-CO2 exchange system, and cooperating to treat dye wastewater, greatly improving the pollutant removal efficiency.

[0023] (2) By using agricultural waste straw, the dye molecules are quickly attached to the surface of the straw through adsorption, significantly reducing the content of dye components in the wastewater, and the adsorption effect is good.

[0024] (3) Compared with other adsorbents such as activated carbon, the price of waste straw is more affordable and the source is more extensive. The overall process is simple, the use of chemical agents is reduced through biological treatment of dye wastewater, and secondary pollution to the environment caused by residual agents is avoided. It is an economical, efficient and environmentally friendly method for treating dye wastewater. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is the adsorption rate of wheat straw (WS), peanut shell (PS), and corn straw (CS) on different concentrations of crystal violet solution;

[0026] Figure 2 is the degradation rate of Laetiporus, Pleurotus, and Lentinus edodes on wheat straw (WS), peanut shell (PS), and corn straw (CS) crystal violet;

[0027] Figure 3 is the laccase activity value secreted by Laetiporus, Pleurotus, and Lentinus edodes on wheat straw (WS), peanut shell (PS), and corn straw (CS);

[0028] Figure 4 is the loss of wheat straw (WS), peanut shell (PS), and corn straw (CS) after solid-state fermentation treatment. DETAILED DESCRIPTION

[0029] The present application relates to a method for promoting fungal solid-state fermentation to treat dye wastewater adsorbed on waste straw by using algae. Specifically, the straw is pretreated into small pieces of 1-3 cm, and added to dye wastewater with a concentration of 10-400 mg / L to adsorb dye molecules. Then, fungi and chlorella are inoculated on the straw adsorbed with dye molecules, and solid-state fermentation is carried out for 5-7 days under the conditions of a temperature of 25-30 ℃, a light intensity of 200 μmol / m 2 ·s, a light cycle of 12 h light and 12 h darkness. The present technology is based on solid-state fermentation technology, and comprehensively utilizes the adsorption of straw on dye wastewater, the solid-state fermentation technology of fungi, the symbiotic and mutual promotion of fungi and algae, and the collaborative treatment of dye wastewater technology, so as to reduce the colority and pollutant concentration of the effluent, and thus solve the problems of large production, deep colority, and difficult degradation of dye wastewater.

[0030] In the present application, three typical white rot fungi are selected, which are Pycnoporus sanguineus SYBC-L3, Pleurotus ostreatus, and Lentinula edodes. Pycnoporus sanguineus SYBC-L3 (Genbank database accession number: JX861099) is isolated from rotten dry wood, and is collected from subtropical Guangdong Province, China. Pleurotus ostreatus and Lentinula edodes are obtained by isolating and purifying the respective fruiting bodies (purchased from the market).

[0031] The white rot fungi in the present application have the ability to grow by using straw and pollutants. Chlorella can autotrophically grow by using light energy, and can exchange O2-CO2 with fungi, which is beneficial to the stability of the system and the accumulation of biomass. In addition, chlorella can also grow and reproduce under heterotrophic conditions by using organic carbon sources, and also has the ability to treat organic pollutants. The straw-fungi-chlorella system can be used for biodegradation of dye wastewater. The dye wastewater in the present application is selected from crystal violet.

[0032] In one representative embodiment, the method of the present invention for treating dye wastewater using waste biomass in combination with fungi and microalgae includes the following steps: ① straw pretreatment: wheat straw, peanut hulls, corn straw are cut into small pieces with a size of 1-3 cm using a chopper, and are naturally dried outdoors for later use; ② adsorption of dye wastewater: the straw is added to 50 ml of a crystal violet solution with a concentration of 10, 50, 100, 200, 400 mg / L in an amount of 2, 6, 10, 14, 18 g / L, and is adsorbed for 12 hours under natural pH and room temperature conditions, with the dye being adsorbed in the straw; ③ selection and purification of P. rhodocarpa, P. ostreatus, Lentinula edodes: the fungi obtained from the natural environment are continuously selected using PDA medium under light-avoiding and constant temperature conditions of 30°C to obtain the final purified strains; ④ cultivation of Chlorella vulgaris, which is added to a mixed medium containing BG11 medium, 2% maltose and 0.5% yeast extract. Then the changes in the morphology of the mycelium are monitored and observed; ⑤ solid state fermentation: the straw adsorbed with dye wastewater in ② is filtered out, and the fungi and Chlorella vulgaris in ③ and ④ are inoculated into the straw at a concentration ratio of 1:10, and are cultured for 5-7 days under room temperature and light conditions, with the crystal violet being removed by the degradation of P. rhodocarpa, P. ostreatus, Lentinula edodes and the heterotrophic growth of Chlorella vulgaris.

[0033] The preferred concentration range of all dye wastewater crystal violet solutions is 10-400 mg / L.

[0034] The preferred conditions for adsorption are a temperature of 25°C, a stirring speed of 160 r / min, and an adsorption time of 12 h.

[0035] The preferred inoculation amount of P. rhodocarpa, P. ostreatus, Lentinula edodes is 1 piece of fungus per 3 g of straw; the solid state fermentation temperature is 25-30°C, the ratio of straw to sterilized water is 1:3-1:5, the light intensity is 200 μmol / m 2 ·s, the light cycle is 12 h light and 12 h darkness, and the fermentation time is 5-18 days.

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described below in a clear and complete manner in combination with the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present invention.

[0037] In one representative embodiment, the basic steps of the method of the present invention include the following:

[0038] ① straw pretreatment: the recovered wheat straw, peanut hulls, corn straw are cut into small pieces, and are naturally dried for later use;

[0039] ②Adsorption: the pretreated straw in step ① is added to the dye wastewater for adsorption;

[0040] ③Fungal screening, purification, rejuvenation and cultivation of chlorella;

[0041] ④Filtration: the straw adsorbing dyes is separated for next step treatment;

[0042] ⑤Solid state fermentation: the fungi and chlorella cultivated in step ③ are inoculated on the straw in step ④, and are cultivated and fermented under room temperature and light conditions.

[0043] Example 1: Pretreatment of waste straw

[0044] In order to increase the contact area of straw with dye wastewater and improve the adsorption efficiency, and facilitate the separation of straw and dye wastewater, the straw needs to be screened and pretreated, and the specific process is as follows: the wheat straw, peanut shell and corn straw are cut into small pieces with a size of 1-3 cm with a cutter, and are naturally dried outdoors for standby.

[0045] Example 2: Screening, purification, rejuvenation of laetiporus coccinus, pleurotus ostreatus and lentinula edodes strains, and cultivation of chlorella

[0046] The tissue blotting method is used for isolation and screening, and the isolation and screening method is as follows: rotten wood, pleurotus ostreatus fruiting body and lentinula edodes fruiting body are taken and soaked in sterile water for 2 hours. Then the liquid sample is diluted into different gradients and coated on PDA (20% potato extract, 2% glucose, 2% agar) medium containing 4% 2,6-dimethoxybenzene. The growth of colonies on the medium and whether there is a red discoloration ring around the colonies are observed every day, and the strains with red discoloration ring around the colonies are selected and transferred to new PDA medium, and finally the purified strains are obtained. The purified strains are inoculated on PDA slant and stored in a refrigerator at 4 ℃ for subsequent use.

[0047] In order to restore the activity of fungi in low temperature storage state, the fungi need to be rejuvenated, and the specific process is as follows: under sterile operation, the low temperature preserved strains are placed in PDA medium and incubated at 30 ℃ for 8-12 h, and the pure and strong culture is obtained by stepwise expansion, that is, the fungi with high activity and sufficient inoculation quantity are obtained.

[0048] Chlorella sp. was cultivated and propagated in BG11 medium containing K2HPO4·3H2O (0.04 g / L), MgSO4·7H2O (0.075 g / L), CaCl2·2H2O (0.036 g / L), citric acid (0.006 g / L), ferric ammonium citrate (0.006 g / L), EDTA (0.001 g / L), NaNO3 (1.5 g / L), Na2CO3 (0.02 g / L) and trace metal mixture A5 (1.0 mL). The trace metal mixture A5 solution was composed of H3BO3 (2.86 g / L), MnCl2·4H2O (1.81 g / L), ZnSO4·7H2O (0.222 g / L), NaMoO4·2H2O (0.39 g / L), CuSO4·5H2O (0.079 g / L) and CoCl2·6H2O (0.05 g / L), and the pH was adjusted to 7.1. The culture conditions were as follows: temperature 25±0.5 ℃, light intensity 200 μmol / m 2 ·s, light cycle 12 h light and 12 h dark.

[0049] Example 3: Adsorption of dye wastewater by wheat straw, peanut shell and corn straw

[0050] Compared with the traditional physical method, chemical method and biochemical method for treating dye wastewater, the biological method adopted in the present technology selects straw waste as an adsorbent, and the adsorption efficiency reaches about 90%, realizing the concept of "waste treatment with waste". On this basis, the growth and metabolism of fungi are used to degrade pollutants in dye wastewater, truly realizing effective removal without secondary pollution. The enterprise treatment cost is reduced while the income of farmers is increased.

[0051] Effect of dye wastewater concentration on adsorption effect: the concentration of dye wastewater was adjusted to 10, 50, 100, 200 and 400 mg / L respectively, and 2 g / L of wheat straw, peanut shell and corn straw were added to the centrifuge tube containing 50 mL of dye wastewater. After oscillation for 12 h under natural pH and room temperature, the reacted solution was centrifuged at 4000 r / min for 5 min, and the supernatant was taken out and measured for light transmittance at 590 nm wavelength by ultraviolet-visible spectrophotometer. The concentration of dye wastewater after adsorption was calculated by the pre-fitted standard curve, and the adsorption rate was calculated by the following formula:

[0052]

[0053] Effect of straw addition amount on adsorption effect: The concentration of dye wastewater was adjusted to 50 mg / L, and the addition amount of wheat straw, peanut shell, and corn straw was adjusted to 2, 6, 10, 14, and 18 g / L. The dye wastewater was added to a centrifuge tube containing 50 mL of dye wastewater. After oscillation for 12 h at room temperature under natural pH, the solution was centrifuged at 4000 r / min for 5 min. The supernatant was taken out and the transmittance was measured at 590 nm using a UV-visible spectrophotometer. The concentration of the adsorbed dye wastewater was calculated by a standard curve, and the adsorption rate was calculated by the following formula:

[0054]

[0055] As shown in Figure 1 , wheat straw, peanut shell, and corn straw all have good adsorption effect on dye wastewater. When the concentration of dye wastewater is 10 mg / L, the adsorption rate is nearly 90%. With the increase of the concentration of dye wastewater, the adsorption rate decreases, but even when the concentration of dye wastewater is as high as 400 mg / L, nearly 40% of the dye wastewater can be adsorbed. This shows that wheat straw, peanut shell, and corn straw have feasibility in adsorbing dye wastewater.

[0056] Example 4: Application of white rot fungi and chlorella in dye pollutant treatment

[0057] The dye-adsorbed straw was separated from the dye wastewater, and the specific process was as follows: The dye-adsorbed straw was filtered out using a filter screen with appropriate mesh size.

[0058] The dye-adsorbed wheat straw, peanut shell, and corn straw were dried at 80°C and then crushed. Deionized water was added in a solid-liquid ratio of 1:4, and the mixture was sterilized at 121°C and 0.12 MPa for 20 min. The sterilized straw was used as the culture medium for fungi and chlorella. The activated blood-red antrodia, pleurotus, lentinus, and chlorella in BG11 culture medium were inoculated on the dye-adsorbed wheat straw, peanut shell, and corn straw, respectively. The culture was carried out at a temperature of 25-30°C, a light intensity of 200 μmol / m 2 ·s, a light period of 12 h light and 12 h dark, and a culture time of 5-7 days. It was found that the dye degradation effect of the straw inoculated with blood-red antrodia and pleurotus was better, and the degradation rate on the three straws could reach about 95%. See Figure 2 .

[0059] The analysis shows that the most effective component for fungi to degrade dye wastewater is laccase. Laccase is a new type of green biological catalyst, which has a wide range of applications in dye wastewater treatment, soil remediation, food processing, biopharmaceuticals, chemical synthesis, cloth dyeing and decolorization, biofuels, etc. Algae can secrete specific small molecule chemicals QSMs, which mainly include alcohols, oxygenated lipids, small molecule peptides, aldehydes and volatile organic compounds (VOCs). These small molecule chemicals can promote the production of laccase by fungi, and further enhance the fermentation effect of fungi. The mycelium of fungi can also significantly promote the growth of chlorella. Under light, chlorella can perform photosynthesis to produce oxygen, and exchange O2-CO2 with fungi. Under non-light conditions, chlorella can utilize organic pollutants to further improve the removal effect of pollutants.

[0060] The enzyme activity secreted by the blood red pore fungus-chlorella, the shiitake mushroom-chlorella and the lentinus edodes-chlorella was measured. It was found that the enzyme activity secreted by the blood red pore fungus-chlorella on the wheat straw, peanut shell and corn straw was always the highest. Especially on the corn straw, the highest reached 3.2 U / g. See Figure 3 .

[0061] As Figure 4 shown, the remaining straw residues after degradation were weighed to measure the biomass loss rate of the straw. It was found that the straw had different degrees of loss, the lowest was 16%, and the highest was 43%. It shows that the straw can provide nutrients for the production of fungi.

[0062] The above describes the embodiments of the present application in detail in combination with the drawings and specific examples, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the purpose of the present application.

Claims

1. A method for treating dye wastewater using biomass in combination with fungi and microalgae, characterized by, The method comprises the following steps: (1) taking biomass, after pretreatment, adding to dye wastewater for adsorption; (2) the biomass after adsorbing the dyes is inoculated with white rot fungi and chlorella, and fermentation is carried out at room temperature and under illumination; the white rot fungi are selected from Lentinula edodes; the fermentation is carried out under the conditions of constant temperature 25-30 ℃, illumination intensity 150-200 μmol / m 2 ·s, 12 h illumination and 12 h darkness of the illumination cycle, and moisture culture is carried out for 5-7 days.

2. The method for treating dye wastewater using biomass in combination with fungi and microalgae according to claim 1, wherein, In step (1), the biomass is preferably one or a combination of several of wheat straw, corn straw, and peanut shell; the adding amount of the biomass is 2-18 g per liter of dye wastewater.

3. The method for treating dye wastewater using biomass in combination with fungi and microalgae according to claim 1, characterized in that, In step (1), the pretreatment comprises: processing into small pieces of 1-3 cm, drying and reserving.

4. The method for treating dye wastewater using biomass in combination with fungi and microalgae according to claim 1, wherein, In step (1), the dye wastewater is dye wastewater containing crystal violet, wherein the concentration of crystal violet is 10-400 mg / L.

5. The method for treating dye wastewater using biomass in combination with fungi and microalgae according to claim 1, wherein, In step (1), the adsorption is carried out for 8-16 hours under the conditions of natural pH, stirring, and room temperature, and the stirring speed is 100-200 r / min.

6. The method for treating dye wastewater using biomass in combination with fungi and microalgae according to claim 1, wherein, In step (2), the biomass after adsorbing dyes is filtered out by a filter screen, then dried and crushed, deionized water is added, sterilized, and then inoculated with white rot fungus and chlorella.

7. The method for treating dye wastewater using biomass in combination with fungi and microalgae according to claim 1, wherein, In step (2), the inoculation amount of white rot fungus is 1 fungus piece / 2.5-3.5 g of straw; the inoculation ratio of white rot fungus and chlorella is 1: (8-12).

8. The method for treating dye wastewater using biomass in combination with fungi and microalgae according to claim 1, wherein, In step (2), after fermentation, the newly separated biomass can also be dried and crushed, deionized water is added, sterilized, and then mixed uniformly with the original fermented biomass for further fermentation.

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