Method for treating nitrobenzene exhaust gas by coupling bacterium biological filter bed

A biological filter bed, nitrobenzene technology, applied in gas treatment, separation methods, chemical instruments and methods, etc., can solve the problems of long start-up period of fungal filter bed, easy to contaminate bacteria, low metabolism rate, etc.

Active Publication Date: 2017-07-04

NANJING POLYTECHNIC INSITUTE

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AI-Extracted Technical Summary

Problems solved by technology

However, the fungal reactor itself also has disadvantages. Compared with the aerobic bacterial biological filter bed, the metabolic rate is low, which makes the fungal filter bed start-up period longer.

The fungal filter bed also has the disadvantages of poor biodiversity and easy contamination

In addition, due to its filamentous structure, the reaction is prone to cloggi...

Method used

Although embodiment 1 and comparative example 1 are except that the pH of nutrient solution is different, other operating conditions are all the same, but the removal rate and removal capacity of embodiment 1 are respectively high 54% and 43.7g m-3h than comparative example 1 -1. This is mainly because nitrobenzene is a typical hydrophobic VOCs, and its mass transfer efficiency in traditional biofilters is low, which affects the degradation efficiency of biofilters. In Example 1, the pH value of the nutrient solution was adjusted to 5.0, the original microbial community structure in the biofilm was change...

Abstract

The invention relates to a method for treating nitrobenzene exhaust gas by a coupling bacterium biological filter bed. Polyurethane foam is used as a filler, the aerobic activated sludge of a nitrobenzene wastewater treatment plant is used as an inoculated strain, and the pH of the nutrient solution is adjusted to 5.0 so that a fungal-bacterial coupled biological filter bed is constructed. Fungi can directly contact with nitrobenzene exhaust gas through hyphae so that the problem that hydrophobic VOCs in the traditional bacterial filter bed have low mass transfer efficiency is solved. Based on the high biological diversity and mineralization capacity of bacteria, fungal metabolites can be further mineralized into carbon dioxide and water. When the nitrobenzene concentration is 300 to 500 mg*m<-3>, the removal rate can reach 95% to 97%, and the removal load can reach 52.4 to 85.5 g*m<-3>*h<-1>.

Application Domain

Gas treatmentDispersed particle separation +1

Technology Topic

Bacterial FilterChemistry +13

Image

Examples

Experimental program(3)
Comparison scheme(1)

Example Embodiment

[0028] Example 1

[0029] Choose polyurethane foam blocks with a side length of 4-6mm as the filler to construct the packed tower, which not only has a large surface area, but also does not cause the packing to be compacted after filming; the polyurethane foam blocks are filled into the packed tower in a random pile , The porosity of the polyurethane foam block filler is 95%, the pore size is 0.8mm, and the bulk density is 0.015g cm -3 , The surface area is 1.7cm 2 cm -3 , Water holding capacity is 55g-H 2 O g -1; The temperature of the filler layer is controlled at 20-25℃.

[0030] Formulated nutrient solution: 0.5g K per liter 2 HPO 4 , 0.1g MgSO 4 ·7H 2 O, 4.5g KH 2 PO 4 , 2g NH 4 Adjust the pH value of the nutrient solution to 5.0 with Cl and 2mL vitamin and trace mineral solution.

[0031] Take the sludge from the secondary sedimentation tank of the sewage treatment plant of a nitrobenzene production enterprise as the inoculation bacteria, and adopt the gas-liquid circulation filming method for dynamic domestication and filming; the concentration of the inoculated sludge is controlled at 2000 mg L -1 , The mixed solution composed of sludge and nutrient solution is sprayed alternately with the pure nutrient solution, the spray period is 0.5h and 0.25h respectively, and the spray volume is controlled at 1.0L h -1;

[0032] After inoculation, the nutrient solution with pH value of 5.0 is sprayed from the top of the tower through the metering pump from top to bottom to the packing layer, spraying for 2 hours every day to construct a coupled bacteria biological filter bed, and the nutrient solution dosage is 174Lm -3 Polyurethane foam block filler d -1;

[0033] Under the accelerating voltage of 15kV, the biofilm was observed with a scanning electron microscope model Quanta 250FEG (FEI, USA). figure 2 This is the biofilm characterization diagram of the fungus-bacteria coupled biological filter bed in Example 1. From the SEM image, it can be clearly seen that a large number of filamentous bacteria and some cocci are intertwined. The measurement data of biofilm qPCR shows that the fungal copy number is 3.2×10 6 copies/μL, bacterial copy number is 1.8×10 5 copies/μL. The results of qualitative analysis and quantitative determination are consistent.

[0034] Nitrobenzene waste gas enters from the bottom of the biological filter bed, and contacts the nutrient solution sprayed from the top of the tower countercurrently on the surface of the packing. The bottom of the tower is equipped with an air distribution device, which is made of inert and elastic materials. The air distribution pipe opening is flushed by the air flow when the air is in, and the air distribution pipe opening is automatically closed when the air is stopped to avoid clogging; the air inlet pipe is equipped with a check valve to avoid Backflow of nutrient filtrate, exhaust gas, etc.

[0035] When the nitrobenzene intake concentration is 450mg m -3 , The intake rate is 107.6m h -1 , The residence time is 20s, the removal rate is 95.3%, and the removal capacity can reach 77.2g m -3 h -1.

Example Embodiment

[0039] Example 2

[0040] The remaining operations are the same as in Example 1. After the biological filter bed is successfully mounted, adjust the pH value of the nutrient solution to 5.0, when the nitrobenzene inlet concentration is 400 mg m -3 , The intake rate is 107.6m h -1 , The residence time is 20s, the removal rate is 96%, and the removal capacity can reach 69.1g m -3 h -1.

Example Embodiment

[0041] Example 3

[0042] The remaining operations are the same as in Example 1. After the biological filter bed is successfully mounted, adjust the pH value of the nutrient solution to 5.0, when the nitrobenzene inlet concentration is 350 mg m -3 , The intake rate is 107.6m h -1 , The residence time is 20s, the removal rate is 96.6%, and the removal capacity can reach 60.9g m -3 h -1.

PUM

Property	Measurement	Unit
Side length	4.0 ~ 6.0	mm
Aperture	0.8	mm

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