Treatment of pulping wastewater by the hottest hyd

2022-09-21
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Hydrolytic acidification - treatment of pulping middle stage wastewater by activated sludge method (Part 2)

after stable operation, in order to determine the best treatment parameters of the reactor for hydrolytic acidification of pulping middle stage wastewater, change the residence time, temperature and influent concentration respectively, and observe the operation of the reactor

by analyzing the test results, it is concluded that the baffled anaerobic reactor has a strong ability to resist the impact of load in the hydrolysis and acidification treatment of pulping middle stage wastewater, the appropriate HRT is about 5h, and the value of temperature in the range of 15 ~ 30 ℃ has little effect on the effluent quality.

take hrt=5h, t=20 ℃, vss=10g/l, and the results of hydrolytic acidification treatment of pulping middle stage wastewater in baffled anaerobic reactor are as follows:

influent: CODcr 1182mg/l

BOD5 362mg/l

VFA 71mg/l

bod/cod 0.306

effluent: CODcr 799mg/l

BOD5 291mg/L

VFA 1785 If the experimental plan rule mg/L

BOD/cod 0.364

VFA value-added 107mg/L

CODcr removal rate 32.2%

BOD5 removal rate 19.6%

it can be seen that whether the pulping middle stage wastewater is straight through the hanger boom, the VFA value increases significantly after anaerobic hydrolysis and acidification. At the same time, the bod5/codcr value increases from 0.306 to 0.364, indicating that the hydrolysis effect is relatively obvious. At the same time, after anaerobic pretreatment, The biodegradability of pulping middle stage wastewater has been greatly improved

2.2 selection of activated sludge treatment parameters

take the outlet wastewater of anaerobic baffled reactor under the above optimal treatment conditions of hydrolysis and acidification, use the activated sludge that has previously treated the pulping wastewater of a factory in the laboratory as seed sludge, and start the activated sludge treatment section. After the stable operation of the system, fix the following basic parameters: MLSS is 4g/l, do is 4mg/l, flow is 2l/h, change the hydraulic retention time of the aeration tank, and observe the operation results of the activated sludge section

it is found that the appropriate HRT of the activated sludge section is 8 ~ 10h. At this time, the CODcr removal rate of the activated sludge section can reach more than 75%. Further extending the treatment time, the CODcr removal rate does not increase significantly. From the treatment results of this test, it can be seen that after anaerobic hydrolysis and acidification treatment, the removal rate of CODCr is much higher than that of single-stage activated sludge treatment

2.3 continuous operation results of processing flow<× 50/P>

take the best treatment parameters of the above hydrolytic acidification and activated sludge treatment section, and operate continuously according to the process flow shown in Figure 1. The wastewater flow is 2l/h. See Table 1 for the operation results

Table 1 continuous operation results of wastewater treatment system operation time days before treatment, total removal rate of effluent from activated sludge section after wastewater hydrolysis and acidification codcr

mg/lbod5

mg/lcodcr

mg/lcodcr

mg/lbod5

mg/lcodcr

%bod5

%2

4

6

8

101387

1387

926

926

926427

-

-

262865

867

654

660

652318

-

-

-

236197

200

176

179

17425

-

-

1885.8

85.6

81.0

80.7

81.294.1

-

-

-

<93.1 note: (1) treatment conditions of hydrolysis acidification section: vss10g/l, hrt5h, T20 ℃

(2) treatment conditions of activated sludge section: mlss4g/l, hrt8h. The existence of these problems makes China's plastic machinery industry unable to meet the foreign plastic machinery level T20 ℃, do4mg/l as soon as possible

it can be seen from table 1 that this process can be used to treat the wastewater in the middle section of pulping well for continuous operation. The removal rate of pollution load in the hydrolytic acidification and activated sludge sections during continuous operation is basically the same as that when they are operated respectively; When CODcr changes in the range of 900 ~ 1400mg/l, the total removal rates of CODcr and BOD5 can reach more than 80% and 90% respectively. The higher the influent load is, the higher the removal rates of CODcr and BOD5 are. The effluent quality of the system is stable and the impact resistance of load is strong. Therefore, it can be inferred that the effluent from the middle stage of plant pulping with CODcr load less than 2000mg/l can fully meet the gwpb standard after being treated by the hydrolytic acidification activated sludge process

references

[1] Jiang Qichang, introduction to environmental protection of paper industry

[2] Cui Yanling. Treatment of pulping wastewater by activated sludge surface aeration. China paper, 1996, (4): 9 ~ 11

[3] national environmental protection administration. Water and wastewater monitoring and analysis method (Third Edition)

[4] he Yanling. Anaerobic biological treatment of wastewater

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