Application of pyrolytic charcoal in relieving activity inhibition of sulfur-driven autotrophic denitrification granular sludge by zinc ions

Abstract

The invention belongs to the technical field of biological sewage treatment, and discloses an application of pyrolytic biochar in relieving activity inhibition of zinc ions on sulfur-driven autotrophic denitrification granular sludge, which is characterized in that biochar is added into wastewater containing zinc ions, and then the wastewater is added into a sulfur autotrophic denitrification sludge system; the inhibition of zinc ions on the activity of the sulfur autotrophic denitrification sludge is relieved. According to the method, the activity of the sulfur autotrophic denitrification sludge can be greatly improved in a short time, in addition, by adding the charcoal, the activity of the sulfur autotrophic denitrification sludge can be improved, meanwhile, the biological exclusion can be avoided, and the cost is reduced. The invention provides a new method and thought for promoting wide application of a sulfur autotrophic denitrification process.

Description

Technical Field

[0001] The invention belongs to the technical field of biological sewage treatment, and relates to the application of pyrolytic biochar in alleviating the inhibition of zinc ions on the activity of sulfur-driven autotrophic denitrification granular sludge. Background Art

[0002] Heavy metals are a class of non-degradable harmful pollutants that can pose a serious threat to human health through bioconcentration and biomagnification. Heavy metals mainly come from the metallurgical, etching and electroplating industries. In 2012, the total amount of heavy metal discharge in wastewater in China reached 388.4 tons. In addition, with the rapid development of livestock and poultry farming, a large amount of zinc ions are added to feed and released into wastewater through animal urine and feces. High concentrations of zinc ions may have a negative impact on the pollutant removal efficiency of the biological treatment unit of the sewage treatment plant.

[0003] Sulfur autotrophic denitrification refers to the process in which sulfur autotrophic denitrifying bacteria use NO3 - -N and NO2 - -N is an electron acceptor and inorganic reduced sulfur is an electron donor. Compared with the traditional heterotrophic denitrification process, the sulfur autotrophic denitrification process has huge technical advantages. The sulfur autotrophic denitrification sludge production is reduced by 80%, organic carbon resources are saved by 100%, and greenhouse gas emissions are reduced by 95-100%. In addition, compared with heterotrophic denitrification, the application of sulfur autotrophic denitrification can reduce operating costs by 43.4%. At the same time, the sludge output of the sulfur autotrophic denitrification process is also much lower than that of the traditional biological denitrification process, which significantly reduces the treatment and disposal costs of the excess sludge.

[0004] Therefore, in the biological denitrification treatment of conventional sewage treatment plants, sulfur autotrophic denitrification technology is undoubtedly an efficient, energy-saving and environmentally friendly biological denitrification technology. However, sulfur autotrophic denitrifying bacteria grow slowly, and zinc ions in wastewater will affect the growth and metabolism of sulfur autotrophic denitrifying bacteria and inhibit the activity of sulfur autotrophic denitrifying sludge, which greatly limits the large-scale application of sulfur autotrophic denitrification technology in the actual wastewater treatment field.

[0005] Therefore, developing a method to alleviate the inhibition of zinc ions on the activity of sulfur autotrophic denitrification granular sludge has important practical significance for the promotion and application of sulfur autotrophic denitrification technology. Summary of the invention

[0006] In view of the shortcomings in the art, the present invention provides the application of biochar in alleviating the inhibition of zinc ions on the activity of sulfur autotrophic denitrification granular sludge. The biochar is mixed with sulfur autotrophic denitrification sludge, and then zinc ion-containing wastewater is added, and finally the toxicity of zinc ions on sulfur autotrophic denitrification granular sludge is successfully reduced.

[0007] One of the purposes of the present invention is to prepare an environmentally friendly biochar to alleviate the inhibition of zinc ions on the activity of sulfur autotrophic denitrification granular sludge.

[0008] The present invention successfully reduces the toxicity of zinc ions to sulfur-autotrophic denitrifying granular sludge by utilizing the adsorption of zinc ions by biochar and the method in which the biochar itself acts as an electron shuttle to strengthen the extracellular electron transfer process.

[0009] The technical solution of the present invention:

[0010] The invention discloses an application of pyrolytic biochar in alleviating the inhibition of zinc ions on the activity of sulfur-driven autotrophic denitrification granular sludge. The pyrolytic biochar and zinc ions are simultaneously added into the sulfur autotrophic denitrification system to alleviate the inhibition of zinc ions on the activity of sulfur autotrophic denitrification.

[0011] The optimal dosage of the biochar is 10 g / L, and the effect is significantly reduced below 10 g / L.

[0012] The conditions for preparing the pyrolysis biochar are as follows: corn stalks are used as a precursor, which is washed and dried at 60°C for 48 hours, and then ground through a 100-mesh sieve; the temperature is raised to 300°C at 5° / min in a tubular furnace and then maintained for 150 minutes, during which high-purity nitrogen is always introduced to maintain an anaerobic atmosphere; and the temperature is naturally lowered to room temperature to obtain low-temperature pyrolysis biochar.

[0013] The dominant functional bacteria of the sulfur autotrophic denitrification granular sludge is Thiobacillus.

[0014] The concentration of the sulfur autotrophic denitrification sludge in the mixed wastewater is 3-5 g VSS L -1 .

[0015] The concentration of the zinc ions is 10 mg / L.

[0016] The wastewater may also contain NO3 - -N. Preferably, NO3 - The concentration of -N is 500 mg / L.

[0017] The test method for alleviating the inhibition of zinc ions on the activity of sulfur autotrophic denitrification granular sludge of the present invention can adopt an acute toxicity experimental method, comprising the steps of:

[0018] (a) The sulfur autotrophic denitrification sludge was washed several times with distilled water, and 5 g of the sulfur autotrophic denitrification sludge was transferred to a 300 mL serum bottle.

[0019] (b) Adding simulated wastewater including NaNO3, sulfur powder, zinc ions, NaHCO3, biochar and an inorganic salt solution into a serum bottle, wherein the inorganic salt solution includes components including NaH2PO4, MgCl2 and NH4Cl.

[0020] (c) The simulated wastewater in the conical flask was mixed with the sulfur autotrophic denitrifying granular sludge, and the pH value of the mixed solution in the serum bottle was adjusted to 7.4-7.6 with HCl solution. Argon gas was introduced into the serum bottle for aeration for 10 minutes to remove the dissolved oxygen in the mixed solution in the serum bottle to avoid inhibition of sulfur autotrophic denitrifying bacteria due to excessive dissolved oxygen.

[0021] (d) The aerated serum bottle was sealed and placed in a constant temperature shaking incubator at 30°C in the dark. A certain amount of supernatant was taken from the serum bottle at regular intervals as a sample and the NO3 content in the sample was determined. - -N and NO2 - -N concentration.

[0022] Under the method of the present invention, the addition of biochar significantly alleviates the stress of zinc ions on sulfur autotrophic denitrifying granular sludge.

[0023] Beneficial effects of the present invention: Compared with the prior art, the present invention can significantly improve the activity of sulfur autotrophic denitrification sludge in a short period of time. In addition, the addition of biochar can avoid biological rejection while improving the activity of sulfur autotrophic denitrification sludge and reduce costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Graph showing the change in specific sulfur autotrophic denitrification activity in the example. DETAILED DESCRIPTION

[0025] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0026] A method for alleviating the inhibition of zinc ions on the activity of sulfur-driven autotrophic denitrification granular sludge by pyrolyzing biochar, comprising:

[0027] (1) The sulfur autotrophic denitrification sludge whose dominant functional bacteria genus was Thiobacillus was washed several times with distilled water, and 5 g of the sulfur autotrophic denitrification sludge was transferred to a 300 mL serum bottle.

[0028] (2) Add simulated wastewater to the conical flask, including: 500 mg L -1 NaNO3 - -N, 5g L -1 NaHCO3, 2.5 g sulfur powder, inorganic salts, biochar, and 10 mg L -1 The zinc ion, the inorganic salt component and its concentration are: 10mg L -1 NaH2PO4, 5.6 mg L -1 MgCl2, 5mg L -1 NH4Cl.

[0029] (3) A control group was set up, in which 5 g of sulfur autotrophic denitrification granular sludge was placed in a 300 mL serum bottle, zinc ions were added to the simulated wastewater, and no biochar was added. A batch experiment was conducted to determine the specific sulfur autotrophic denitrification activity of the sludge.

[0030] (4) In steps (3) to (4), the experiment for determining the specific sulfur autotrophic denitrification activity of the sludge is specifically as follows:

[0031] Add 2 g L -1 75 mL of NaNO3 stock solution, 2.5 g of sulfur powder and 6 mL of inorganic salt solution were added, and the volume was adjusted to 300 mL with pure water. The pH value of the mixed solution in the serum bottle was adjusted to 7.4-7.6 with HCl solution, and argon was introduced into the serum bottle for 10 minutes to ensure an anaerobic environment. The aerated serum bottle was sealed and placed in a constant temperature shaking incubator at 30°C in the dark for 9 days. Every 12 hours, 2 mL of the supernatant in the serum bottle was taken to determine NO3 - -N and NO2 - -N concentration.

[0032] The final experimental results are as follows Figure 1 As shown: Under zinc ion inhibition, the final nitrate concentration was 180.59 ± 19.17 mg L -1 After adding biochar, the final nitrate concentration decreased to 19.33 ± 12.41 mg L -1 .

[0033] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. An application of pyrolytic biochar in alleviating the inhibition of zinc ions on the activity of sulfur-driven autotrophic denitrification granular sludge, characterized in that: Pyrolyzed biochar and zinc ions are added simultaneously to the sulfur autotrophic denitrification system to alleviate the inhibition of zinc ions on the sulfur autotrophic denitrification activity.

2. The use according to claim 1, characterized in that: The optimal dosage of the pyrolysis biochar is 10 g / L.

3. The use according to claim 1, characterized in that: The precursor of the pyrolysis biochar is corn stalks.

4. The use according to claim 1, characterized in that: The dominant functional bacteria of the granular sludge in the sulfur autotrophic denitrification system is Thiobacillus.

5. The use according to claim 1, characterized in that: The concentration of sulfur autotrophic denitrification sludge in the mixed wastewater in the sulfur autotrophic denitrification system is 3-5 g VSS L -1 .

6. The use according to claim 1, characterized in that: The concentration of the zinc ions in the wastewater is 10 mg / L.

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