CN102515448A - Process for promoting biological denitrification by performing ultrasonic disintegration on residual sludge to reflow and replenish denitrification carbon source - Google Patents

Abstract

The invention discloses a process for ultrasonic cracking excess sludge to reflow and replenish denitrification carbon source to promote biological denitrification, which comprises the following steps: (1) after part of the excess sludge is concentrated, it is transported to an ultrasonic processor through pipelines for continuous cracking; 2) After cracking, the sludge mixture enters the hydrolysis acidification tank for hydrolysis and acidification treatment; (3) After hydrolysis and acidification, the sludge mixture flows back to the front end of the biological anoxic tank, and the denitrifying bacteria use it as a carbon source to convert the nitrate nitrogen in the sewage converted to nitrogen. The process of the invention makes full use of the carbon source in the excess sludge without adding any additional carbon source, thereby improving the efficiency of biological denitrification. The present invention can be applied to the upgrading of the biological treatment process of the AO denitrification sewage treatment plant, the new biological denitrification process, etc. After promotion, the efficiency of biological denitrification can be improved, the sludge output can be reduced, the carbon source in the remaining sludge can be fully utilized, and the sewage can be realized. Mud resources, reduce operating costs, produce significant environmental and economic benefits.

Description

A process of ultrasonically cracking excess sludge backflow to supplement denitrification carbon source to promote biological denitrification

technical field

The invention belongs to the field of wastewater biological treatment, and mainly relates to a process for supplementing carbon sources to promote biological denitrification. the

Background technique

Eutrophication is one of the major water pollution problems facing the world today, and nitrogen and phosphorus are the main factors causing eutrophication in water bodies. With the improvement of public environmental awareness and the increasingly stringent standards for nitrogen and phosphorus discharge restrictions at home and abroad. Biological denitrification technology is currently the most widely used sewage denitrification technology, that is, nitrogen removal is achieved through the action of nitrifying bacteria and denitrifying bacteria. Sufficient carbon sources are the key to achieving efficient denitrification. It is generally believed that when the influent C/N of the biological pool is lower than 3.4, an additional carbon source is required to ensure a good biological denitrification effect, and the C/N ratio of sewage entering the biological pool from most urban sewage treatment plants in my country is lower than this Insufficient organic carbon source in sewage leads to low efficiency of biological nitrogen removal. In order to improve the efficiency of biological denitrification and achieve the discharge of effluent total nitrogen (TN) up to the standard, it is necessary to add methanol and ethanol to supplement the organic carbon source, which increases the operating cost of the sewage treatment plant. It can be seen that whether the carbon source problem is solved or not is related to the level of biological denitrification efficiency and the level of operating costs of urban sewage treatment plants. the

There are a lot of organic carbon sources in the remaining sludge. How to use this part of organic matter to improve the efficiency of biological denitrification, reduce sludge discharge, and carry out secondary utilization is of great significance to the development of low carbon nitrogen ratio sewage biological denitrification technology in my country. the

Contents of the invention

In order to solve the problems in the prior art, the present invention provides a process for ultrasonically cracking excess sludge backflow to supplement denitrification carbon source to promote biological denitrification, which solves the current problems of large sludge discharge and high cost of denitrification carbon source . the

The process of ultrasonic cracking excess sludge reflux supplementing denitrification carbon source of the present invention to promote biological denitrification comprises the following steps:

1) Ultrasonic cracking of excess sludge

After 20%-50% of the remaining sludge is concentrated to a solid content of 2-4%, it is transported through a pipeline to a multi-probe ultrasonic processor for continuous cracking. After ultrasonic cracking, a large amount of organic matter in the sludge, such as protein, polysaccharide, Lipid substances, etc. dissolve into the water phase. the

The optimal conditions for ultrasonic cracking of excess sludge are: sludge concentration: 1-4%; cracking time: 5-60 minutes; 40mm, the ultrasonic sound energy density is 0.2-3kW/m ³ .

2) Hydrolytic acidification of cracked sludge mixture

After cracking, the sludge mixture enters the hydrolysis acidification tank for hydrolysis and acidification treatment. After full hydrolysis and acidification, the slow biodegradable substances in the sludge mixture, such as proteins, polysaccharides, lipids, etc., are decomposed into volatile fatty acids, such as acetic acid , propionic acid, butyric acid, etc. These substances can be used as carbon sources for denitrifying bacteria to achieve biological denitrification and denitrification. the

The optimal hydraulic retention time of the hydrolytic acidification tank is 1-4h. the

3) A new biological denitrification process of cracking liquid reflux

After hydrolysis and acidification, the sludge mixture flows back to the front end of the biological anoxic tank, and the denitrifying bacteria use it as a carbon source to convert nitrate nitrogen in the sewage into nitrogen gas to achieve biological denitrification. the

The optimal hydraulic retention time for the anoxic pool is 2-4h. the

Through a large number of experimental studies, the present invention compares the organic carbon source dissolution effect of ultrasonic cracking excess sludge under different conditions (such as sound intensity, sound energy density, ultrasonic action time, ultrasonic reactor form, etc.), and comprehensively considers ultrasonic energy consumption, Ultrasonic cracking of organic matter concentration, hydrolyzate and other factors in the sludge, choose the appropriate ultrasonic reaction conditions to crack the remaining sludge, and return the cracking solution to the anoxic tank to supplement the organic matter in the influent, and obtain a new process and the best process operating parameters (such as sludge cracking degree, hydraulic retention time, etc.). the

Compared with the traditional AO (anoxic-aerobic) biological denitrification process, the present invention has the advantages of making full use of the carbon source in the excess sludge without adding additional carbon source, and improving the efficiency of biological denitrification. The present invention can be applied to the upgrading of the biological treatment process of the AO denitrification sewage treatment plant, the new biological denitrification process, etc. After promotion, the efficiency of biological denitrification can be improved, the sludge output can be reduced, the carbon source in the remaining sludge can be fully utilized, and the sewage can be realized. Mud resources, reduce operating costs, produce significant environmental and economic benefits. the

Description of drawings

Fig. 1 is a flow chart of the present invention applied to the anoxic-aerobic biological denitrification process. the

Detailed ways

The present invention will be further described below in conjunction with specific examples. the

Example 1

10%-20% of the remaining sludge enters the multi-probe ultrasonic reactor for ultrasonic cracking pretreatment. The frequency of the ultrasonic reactor is 20kHz, the diameter of the probe is 20mm, the sound energy density is 2.1kW/m ³ It is 2.6%, and the cracking time is 5 minutes. After cracking, the sludge mixture enters the hydrolytic acidification tank for hydrolytic acidification reaction for 2.5 hours, and then the mixed solution flows back to the front end of the anoxic tank to supplement the carbon source required for denitrification. The whole process runs continuously for 3 months in summer, and the denitrification effect is stable. The monitoring data found that the influent chemical oxygen demand (COD) is 100-200mg/L, the total nitrogen (TN) is 40-50mg/L, the secondary sedimentation tank effluent COD50-60mg/L, TN 8-12mg/L, and the effluent reaches a Class A standard (GB18918-2002), and reduce the amount of residual sludge discharge, to achieve sludge reduction.

Example 2

20%-25% of the remaining sludge enters ^the multi-probe ultrasonic reactor for ultrasonic cracking pretreatment. The solid content of the sludge is 2.8%. After cracking, the sludge mixture enters the hydrolytic acidification tank for hydrolysis and acidification reaction for 1.5 hours, and then the mixed solution flows back to the front end of the anoxic tank to supplement the carbon source required for denitrification. The whole process runs continuously for 3 months in autumn, and the denitrification effect is stable. The monitoring data found that the influent chemical oxygen demand (COD) is 100-200mg/L, the total nitrogen (TN) is 30-45mg/L, the secondary sedimentation tank effluent COD50-60mg/L, TN 10-12mg/L, and the effluent reaches a Class A standard (GB18918-2002).

Example 3

30%-40% of the remaining sludge enters ^the multi-probe ultrasonic reactor for ultrasonic cracking pretreatment. The solid content of the sludge is 3%. After cracking, the sludge mixture enters the hydrolytic acidification tank for hydrolysis and acidification reaction for 4 hours, and then the mixed solution flows back to the front end of the anoxic tank to supplement the carbon source required for denitrification. The whole process runs continuously for 3 months in winter, and the denitrification effect is stable. The monitoring data found that the influent chemical oxygen demand (COD) is 100-200mg/L, the total nitrogen (TN) is 30-45mg/L, the secondary sedimentation tank effluent COD50-60mg/L, TN 10-15mg/L, and the effluent reaches a Class A standard (GB18918-2002).

Claims (3)

1. the technology of a ultrasonic disintegration residual sludge reflux supplementing denitrifying carbon source promotion biological denitrificaion is characterized in that, comprises the steps:

(1) after the part excess sludge concentrates, cracks continuously through pipe-line transportation to ultrasonic processor;

(2) crack the back mud mixed liquid and get into the hydrolysis acidification pool acidification that is hydrolyzed;

(3) mud mixed liquid is back to biological anoxic pond front end behind the acidication, and it is carbon source that denitrifying bacterium utilizes it, and nitrate nitrogen in the sewage is converted into nitrogen.

2. promote the technology of biological denitrificaion according to the said ultrasonic disintegration residual sludge reflux of claim 1 supplementing denitrifying carbon source; It is characterized in that; The condition of said step (1) ultrasonic disintegration mud is: it is after the 2-4% that the excess sludge of 20%-50% is concentrated into solid content; Through pipe-line transportation at the most the probe type ultrasonic treater crack breaking sludge concentration: 1-4% continuously; Crack the time: 5-60min, cracking used ultrasonic processor form is many sonde-types, and ultrasonic frequency is 18-30kHz, and probe diameter is 20-40mm, and ultrasonic acoustic density is 0.2-3kW/m ³

3. promote the technology of biological denitrificaion according to the said ultrasonic disintegration residual sludge reflux of claim 1 supplementing denitrifying carbon source, it is characterized in that said step (2) hydrolysis acidification pool hydraulic detention time is 1-4h.

Images