CN109020070A - Method for treating wastewater generated in antioxidant production - Google Patents

Abstract

The invention belongs to the field of wastewater treatment, and particularly discloses a method for treating antioxidant production wastewater, which comprises acidification treatment, flocculation precipitation treatment, electrocatalytic oxidation treatment, anaerobic reaction treatment and hydrolytic acidification/aerobic treatment; the method adopts the 5 steps to treat the antioxidant production wastewater, the 5 steps are carried out in sequence, and the steps are mutually influenced and matched, so that the method is more suitable for treating the antioxidant production wastewater.

Description

Treatment method of antioxidant production wastewater

technical field

The invention relates to the technical field of wastewater treatment, in particular to a treatment method for antioxidant production wastewater.

Background technique

Antioxidants are substances that can delay or inhibit the oxidation and aging of polymers and prolong their service life. The residual liquid and equipment cleaning water in the production process will be discharged in the form of waste water, which contains a large amount of aromatics. and heterocyclic substances, and the COD is as high as 20000-50000 mg/L, which is a kind of wastewater with high concentration of pollutants and difficult biodegradation. At present, there is no systematic solution to the treatment method of antioxidant production wastewater. Chinese Patent Publication No. CN 107572692A discloses a method and device for removing antioxidants in sewage. It is a combined process of Fenton-like catalytic oxidation technology and flocculation precipitation. The treated raw water is low in COD, and it is not specifically for antioxidant production wastewater, but for wastewater containing antioxidants in other industries.

Once the antioxidant production wastewater is discharged, the dissolved oxygen content in the water body will drop significantly, causing the death of aquatic organisms, and the water body will be black and smelly. In addition, aromatic and heterocyclic substances are carcinogenic, teratogenic, and mutagenic, and are difficult to degrade, which will cause long-term harm to the ecological environment and human beings. Therefore, there is an urgent need for a simple, efficient, and cost-effective method for treating wastewater from antioxidant production.

Contents of the invention

In order to solve the defects in the prior art, the present invention provides a treatment method for antioxidant production wastewater, including acid precipitation treatment, flocculation precipitation treatment, electrocatalytic oxidation treatment, anaerobic reaction treatment, hydrolytic acidification/aerobic treatment; The method adopts the above five steps to treat the wastewater from antioxidant production. The five steps are carried out in sequence, and each step interacts with each other, which is more suitable for the treatment of wastewater from antioxidant production.

Concretely, the present invention provides a kind of treatment method of antioxidant production wastewater, it is characterized in that, comprises the following steps:

(1) Acid precipitation treatment: use acid solution to adjust the pH of antioxidant production wastewater to 3.0-3.5;

(2) Flocculation and precipitation treatment: use iron salt inorganic flocculant and polyacrylamide to carry out flocculation and precipitation treatment on the wastewater treated in step (1);

(3) Electrocatalytic oxidation treatment: use catalytically active electrode plates to perform electrocatalytic oxidation treatment on the wastewater treated in step (2); the treatment time is 2 to 4 hours;

(4) Anaerobic reaction treatment: adjust the pH value of the treated wastewater in step (3) to 6.5~7.5, and then use an anaerobic reactor for anaerobic reaction treatment;

(5) Hydrolytic acidification/aerobic treatment: perform hydrolytic acidification/aerobic treatment on the wastewater treated in step (4).

The method of the present invention uses 5 steps to process the wastewater from antioxidant production. The 5 steps are carried out in sequence, and each step interacts with each other, which is more suitable for the treatment of wastewater from antioxidant production. In the first step, before the flocculation and sedimentation treatment, the raw wastewater produced by the antioxidant is raised to the acid analysis tank, and the acid solution is used to adjust the pH value of the raw wastewater to 3.0-5.0, and the macromolecular organic acids in the wastewater can be separated out first. , this step can be completed through the pH automatic control system; in the second step, the wastewater after acid analysis treatment continues to be flocculated and precipitated: first, the wastewater after acid analysis enters the first reaction tank of flocculation and sedimentation, and is put into the iron salt inorganic flocculant for further treatment. reaction, and then, the wastewater enters the second reaction tank for flocculation and sedimentation, and polyacrylamide is added for reaction. Finally, the wastewater enters the sedimentation tank for precipitation; Suspended solids and colloidal substances in the water; in the third step, the wastewater after flocculation and sedimentation treatment is treated with electrocatalytic oxidation; For organic matter in wastewater, the reaction time is 2 to 4 hours. This step is set after flocculation and precipitation, which greatly shortens the reaction time, degrades aromatic and heterocyclic organic matter in wastewater, and converts them into small molecules and easily degradable substances. , this step does not require additional chemicals, and is fully automated; it not only reduces the toxicity and COD of wastewater, improves biodegradability, but also provides water quality conditions for subsequent biochemical treatment; the fourth step further uses anaerobic Reaction treatment, anaerobic reactor with high volume load, impact resistance, no need for sedimentation tank, less residual sludge, and biogas energy can be recovered; the fifth step, using hydrolytic acidification/aerobic treatment, A/O biochemical system can further reduce wastewater COD , and remove the total nitrogen through nitrification/denitrification to ensure that the COD and total nitrogen of the wastewater are stable and up to standard. This method adopts five steps in combination, carried out in a certain order, and cooperates with each other to produce unexpected technical effects. After the final wastewater treatment, its COD value is within 100 mg/L, and the total nitrogen is within 20 mg/L. within; in the preferred scheme, its COD value reached 87.4 mg/L, and its total nitrogen reached 5.6 mg/L.

The present invention is the most suitable combination selected for the characteristics of antioxidant production wastewater. Acid flocculation creates water quality conditions for electrocatalysis, electrocatalysis reduces wastewater toxicity and creates water quality conditions for biochemistry, and finally ensures the stable compliance of COD and total nitrogen in wastewater through biochemistry. .

In some embodiments, the acid solution is sulfuric acid, hydrochloric acid, acetic acid or any combination thereof; the acid precipitation treatment takes 20-30 minutes.

One or more combinations of sulfuric acid, hydrochloric acid, and acetic acid are used as acid solution to treat wastewater by acid analysis, which itself has less environmental pollution, and the treatment time is 20-30 minutes. The choice of acid and the combination of time are more effective It is beneficial to a series of subsequent wastewater treatment steps.

In some embodiments, the iron salt inorganic flocculant is ferric chloride, ferric sulfate or polyferric sulfate; wherein, the inorganic flocculation treatment in step (2) is 10-20 min; the polyacrylamide flocculation treatment in step (2) is 10-20 min.

The iron salt inorganic flocculant is ferric chloride, ferric sulfate or polyferric sulfate, and the treatment time is 10-20 minutes, and then polyacrylamide is used for flocculation treatment, and the treatment time is 10-20 minutes, so as to achieve the optimal flocculation and sedimentation effect.

In some embodiments, the usage amount of the iron salt inorganic flocculant is 100-200 mg/L; the usage amount of the polyacrylamide is 2-5 mg/L.

According to the characteristics of antioxidant production wastewater and the acid precipitation treatment in the previous step, 100-200mg/L iron salt inorganic flocculant was selected, and polyacrylamide was selected as the organic polymer flocculant to achieve a better technical effect.

In some embodiments, the anode of the electrode plate is a graphite electrode or a titanium-based dimensionally stable electrode coated with one or more metal oxides in ruthenium, iridium, lead, tin, antimony; It is titanium electrode, stainless steel electrode or graphite electrode.

Different electrode plate materials have different electrocatalytic oxidation efficiency and effects, and the requirements of different wastewater components are also different. The inventor of the present application has studied the situation of the wastewater after the first two steps of treatment, and investigated the properties and applications of various electrode plate materials. Specifically, the anode has been selected as a graphite electrode or coated with ruthenium, iridium, lead, tin, and antimony. Titanium-based dimensionally stable electrodes of one or several metal oxides, and the cathode is an electrode plate of a titanium electrode, a stainless steel electrode or a graphite electrode for electrocatalytic oxidation treatment, achieving unexpected technical effects.

In some embodiments, in step (3), the current density of the electrode plate is 20-60 mA/cm ² ; wherein, when the influent COD is lower than 10000 mg/L, the processing time of step (3) 2 h; when the influent COD is between 10,000 and 20,000 mg/L, the processing time of step (3) is 3 h; when the influent concentration is higher than 20,000 mg/L, the processing time of step (3) is 4h.

In terms of the current density of the electrode plate, the inventors of the present application have also done related research. In order to achieve the electrocatalytic oxidation reaction with the lowest energy consumption and the highest efficiency, they creatively proposed to select different treatment times according to the different COD in the antioxidant production wastewater. And through further research to find the treatment time corresponding to the appropriate concentration, and carry out grading treatment.

In some embodiments, the anaerobic reactor is an upflow anaerobic sludge bed UASB, anaerobic baffle reactor ABR, anaerobic granular sludge expanded bed reactor EGSB or an internal circulation anaerobic reactor IC.

In some embodiments, the sludge concentration of the anaerobic reactor is controlled above 30 g VSS/L, and the volume load is 2-4 kg COD/(m ³ ▪d).

Due to the particularity of antioxidant production wastewater, it is necessary to carry out further anaerobic reaction treatment. The sludge concentration must be controlled above 30 g VSS/L, and the volume load should be 2-4 kg COD/(m ³ ▪ d) is the preferred option.

In some embodiments, the residence time of the hydrolytic acidification section in the hydrolytic acidification/aerobic treatment is 6-8 h, the residence time of the aerobic section is 18-24 h, and the reflux ratio of the mixed solution is 100-200%.

Hydrolytic acidification/aerobic process (A/O) is a commonly used method for treating wastewater. This application selected the residence time of the hydrolytic acidification section to be 6~ 8 h, the residence time in the aerobic section is 18-24 h, and the reflux ratio of the mixed solution is 100-200%, achieving better wastewater treatment effect.

In some embodiments, the treatment method of antioxidant production wastewater of the present invention comprises the following steps:

(1) Acid precipitation treatment: use acid solution to adjust the pH of antioxidant production wastewater to 3.0-3.5; the acid solution is sulfuric acid, hydrochloric acid, acetic acid or any combination thereof; acid precipitation treatment time is 20-30 minutes;

(2) Flocculation and sedimentation treatment: use iron salt inorganic flocculant and polyacrylamide to carry out flocculation and sedimentation treatment on the wastewater treated in step (1); the iron salt inorganic flocculant is ferric chloride, ferric sulfate or polyferric sulfate; The inorganic flocculation treatment in the flocculation precipitation treatment is 10-20 minutes; the polyacrylamide flocculation treatment in the flocculation precipitation treatment is 10-20 minutes; the usage amount of the iron salt inorganic flocculant is 100-200 mg/L; The usage amount of described polyacrylamide is 2～5 mg/L;

(3) Electrocatalytic oxidation treatment: Electrocatalytic oxidation treatment is carried out on the wastewater treated in step (2) by using a catalytically active electrode plate; the anode material of the electrode plate is graphite electrode or coated with ruthenium, iridium, lead, tin 1. Titanium-based dimensionally stable electrode of one or several metal oxides in antimony; the cathode of the electrode plate is a titanium electrode, a stainless steel electrode or a graphite electrode; the current density of the electrode plate is 20-60 mA/cm ² ; When the influent COD is lower than 10,000 mg/L, the electrocatalytic oxidation treatment time is 2 h; when the influent COD is between 10,000 and 20,000 mg/L, the electrocatalytic oxidation treatment time is 3 h; When the influent concentration is higher than 20000 mg/L, the electrocatalytic oxidation treatment time is 4 h;

(4) Anaerobic reaction treatment: adjust the pH value of the wastewater treated in step (3) to 6.5~7.5, and then use an anaerobic reactor for anaerobic reaction treatment; the anaerobic reactor is an upflow anaerobic sewage Mud bed UASB, anaerobic baffle reactor ABR, anaerobic granular sludge expanded bed reactor EGSB or internal circulation anaerobic reactor IC; the sludge concentration of the anaerobic reactor is controlled above 30 g VSS/L , volume load 2～4 kg COD/(m ³ ▪d);

(5) Hydrolytic acidification/aerobic treatment: perform hydrolytic acidification/aerobic treatment on the wastewater treated in step (4); the residence time of the hydrolytic acidification section in the hydrolytic acidification/aerobic treatment is 6-8 h The residence time of the stage is 18-24 h, and the reflux ratio of the mixed liquid is 100-200%.

Terminology Explanation

As used in the present invention, the term "iron salt inorganic flocculant" refers to a flocculant composed of iron salt inorganic components. The flocculant mainly increases the collision of coagulated solids, making its hydrolyzate agglomerate and bridging flocculation to form Setttable or filterable flocs.

As used in accordance with the present invention, the term "catalytically active electrode plate" means that the electrode plate is capable of catalyzing an oxidation reaction.

As used in the present invention, the term "anaerobic reaction" refers to the reaction treatment of wastewater in an anaerobic reactor.

According to the present invention, the term "electrocatalytic oxidation" electrocatalytic oxidation technology refers to the generation of intermediates with high oxidation activity near the electrode plate with catalytic function under the action of an external electric field, which can oxidize and degrade organic matter.

As used in accordance with the present invention, the term "hydrolytic acidification/aerobic" is abbreviated as A/O, A designating the hydrolytic acidification phase and O designating the aerobic phase.

As used in accordance with the present invention, the term "COD" stands for chemical oxygen demand, which is a chemical measure of the amount of reducing substances in a water sample that need to be oxidized. The oxygen equivalent of substances (generally organic matter) that can be oxidized by strong oxidants in wastewater, wastewater treatment plant effluent and polluted water. It is an important parameter of organic pollution that can be determined relatively quickly.

As used in the present invention, the term "mixed liquid reflux ratio" means that the mixed liquid in the aeration tank returns to the water inlet and enters the hydrolysis acidification tank for reaction together with the influent. The mixed liquid reflux ratio is the ratio of the mixed liquid flow rate to the influent water flow rate.

The "polyacrylamide" described in the present invention is not limited to a specific ionic type, in some embodiments it is anionic; in some embodiments it is cationic; in some embodiments it is nonionic. Suitable ionic mixtures can be used if desired.

Description of drawings

Fig. 1 is the schematic flow sheet of antioxidant production wastewater treatment method in the present invention

The drawings described here are used to provide a further understanding of the present invention and constitute a part of the application. The schematic embodiments and descriptions of the application are used to explain the application and do not constitute an improper limitation to the application.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention. In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as there is no conflict with each other.

Example 1

The present embodiment provides a kind of treatment method of antioxidant production wastewater, comprising the following steps:

(1) The wastewater in the raw water collection tank enters the acid analysis reaction tank through the lift pump, and sulfuric acid is added through the pH automatic control system to control the pH value to 5.0 and react for 30 minutes;

(2) The wastewater treated in step (1) first enters the first pool of flocculation reaction, add 100 mg/L polyferric sulfate, react for 20 minutes, the effluent from the first reaction pool enters the second pool of flocculation reaction, and add polypropylene Amide 2 mg/L, react for 20 minutes, the effluent from the second reaction tank enters the sedimentation tank, and after precipitation, the effluent enters the electrocatalytic oxidation equipment;

(3) The electrocatalytic oxidation reaction uses a titanium-based dimensionally stable electrode coated with antimony-doped tin dioxide as the anode and a titanium electrode as the cathode, and reacts for 2 h at a current density of 40 mA/cm ² ;

(4) Step (3) Adjust the pH value of the effluent to 7.2 before entering the UASB reactor. The sludge concentration is controlled above 30 gVSS/L, and the volume load is 2 kg COD/(m ³ ▪d). After the reaction, the effluent enters the A/O biochemical system;

(5) The wastewater treated in step (4) is subjected to advanced treatment in the hydrolysis acidification/aerobic (A/O) process section, the residence time of the hydrolysis acidification section is 6 h, the residence time of the aerobic section is 18 h, and the reflux ratio of the mixed solution is 100 %.

After the wastewater is treated by hydrolytic acidification/aerobic (A/O), it finally enters the secondary settling tank, and the effluent from the secondary settling tank can be directly discharged up to the standard.

The test results of wastewater quality after treatment by various treatment methods are as follows: (raw water is untreated wastewater)

project Chemical oxygen demand COD (mg/L) Total nitrogen (mg/L) Raw wastewater 26892.3 125.8 Acid analysis 15954.9 117.2 Flocculation 12167.8 105.3 electrocatalytic oxidation 2791.5 32.1 anaerobic 549.4 18.4 A/O 87.4 5.6

Conclusion: The COD of the antioxidant production wastewater treated through the above steps has reached 87.4 mg/L, and the total nitrogen is 5.6 mg/L, which are far lower than the results obtained by other methods in the prior art.

Example 2

The present embodiment provides a kind of treatment method of antioxidant production wastewater, comprising the following steps:

(1) The wastewater in the raw water collection tank enters the acid analysis reaction tank through the lift pump, and sulfuric acid is added through the pH automatic control system to control the pH value to 5.0 and react for 30 minutes;

(2) The wastewater treated in step (1) first enters the first pool of flocculation reaction, add 150 mg/L polyferric sulfate, react for 20 minutes, the effluent from the first reaction pool enters the second pool of flocculation reaction, and add polypropylene Amide 4 mg/L, react for 20 minutes, the effluent from the second reaction tank enters the sedimentation tank, and after precipitation, the effluent enters the electrocatalytic oxidation equipment;

(3) A titanium-based dimensionally stable electrode coated with ruthenium dioxide and iridium dioxide mixed metal oxide was used as the anode, and the titanium electrode was used as the cathode, and the reaction was carried out at a current density of 60 mA/cm ² for 4 h;

(4) Step (3) Adjust the pH value of the effluent to 6.8 before entering the UASB reactor. The sludge concentration is controlled above 30 gVSS/L, and the volume load is 2.5 kg COD/(m ³ ▪d). After the reaction, the effluent enters the A/O biochemical system;

(5) The wastewater treated in step (4) is subjected to advanced treatment in the hydrolysis acidification/aerobic (A/O) process section, the residence time of the hydrolysis acidification section is 8 h, the residence time of the aerobic section is 24 h, and the reflux ratio of the mixed solution is 100 %.

The wastewater enters the secondary settling tank after being treated by hydrolytic acidification/aerobic (A/O), and the effluent from the secondary settling tank can be discharged directly up to the standard.

The test results of wastewater quality after treatment by various treatment methods are as follows: (raw water is untreated wastewater)

project Chemical oxygen demand COD (mg/L) Total nitrogen (mg/L) Raw wastewater 43892.3 265.8 Acid analysis 28514.2 247.1 Flocculation 21614.8 232.9 electrocatalytic oxidation 2928.5 53.7 anaerobic 632.3 31.5 A/O 92.6 17.4

Conclusion: The COD of the antioxidant production wastewater treated through the above steps reached 92.6 mg/L, and the total nitrogen was 17.4 mg/L, far lower than the results obtained by other methods in the prior art.

Apparently, the above-mentioned embodiments are only examples for clear description, rather than limiting the implementation. Other modifications or equivalent replacements made by those skilled in the art to the technical solution of the present invention shall fall within the scope of the claims of the present invention as long as they do not deviate from the spirit and scope of the technical solution of the present invention.

Claims (10)

1. a kind of processing method of anti-oxidant agent production waste water, which comprises the following steps:

(1) acid out is handled: the use of the pH that acid solution adjusts anti-oxidant agent production waste water being 3.0~3.5；

(2) flocculation sedimentation is handled: using molysite inorganic flocculating agent and polyacrylamide, to step (1), treated, and waste water is wadded a quilt with cotton Solidifying precipitation process；

(3) electrocatalytic oxidation is handled: using having the electrode plate of catalytic activity to carry out electro-catalysis to step (2) treated waste water Oxidation processes；The processing time is 2~4 h；

(4) anaerobic reaction is handled: between the pH value of set-up procedure (3) processed waste water to 6.5 ~ 7.5, then using anaerobic reactor Carry out anaerobic reaction processing；

(5) hydrolysis acidification/Aerobic Process for Treatment: to step (4), treated that acidification/Aerobic Process for Treatment is hydrolyzed in waste water.

2. the processing method of anti-oxidant agent production waste water according to claim 1, which is characterized in that the acid solution is sulphur Acid, hydrochloric acid, acetic acid or their arbitrary combinations；The time of the acid out processing is 20~30min.

3. the processing method of anti-oxidant agent production waste water according to claim 1, which is characterized in that the inorganic wadding of molysite Solidifying agent is iron chloride, ferric sulfate or bodied ferric sulfate；Wherein, inorganic 10~20 min of flocculation treatment in step (2)；Step (2) Middle 10~20 min of polyacrylamide flocculation treatment.

4. the processing method of anti-oxidant agent production waste water according to claim 1, which is characterized in that the inorganic wadding of molysite The usage amount of solidifying agent is 100~200 mg/L；The usage amount of the polyacrylamide is 2 ~ 5 mg/L.

5. the processing method of anti-oxidant agent production waste water according to claim 1, which is characterized in that the sun of the electrode plate The extremely titanium-based dimensionally stable electrode of one or more of graphite electrode or coating ruthenium, iridium, lead, tin, antimony metal oxide；Institute The cathode for stating electrode plate is Ti electrode, stainless steel electrode or graphite electrode.

6. the processing method of anti-oxidant agent production waste water according to claim 1, which is characterized in that in step (3), institute The current density for stating electrode plate is 20~60 mA/cm²；Wherein, when influent COD is lower than 10000 mg/L, the place of step (3) The reason time is 2 h；When influent COD is between 10000~20000 mg/L, the processing time of step (3) is 3 h；Work as water inlet When concentration is higher than 20000 mg/L, the processing time of step (3) is 4 h.

7. the processing method of anti-oxidant agent production waste water according to claim 1, which is characterized in that the anaerobic reaction Device is upflow anaerobic sludge blanket process UASB, anaerobic baffled reactor ABR, expanded granular sludge bed reactor reactor EGSB or interior Circulation anaerobic reactor IC.

8. the processing method of anti-oxidant agent production waste water according to claim 1, which is characterized in that the anaerobic reactor Sludge concentration control more than 30 g VSS/L, 2~4 kg COD/(m of volumetric loading³D).

9. the processing method of anti-oxidant agent production waste water according to claim 1, which is characterized in that the hydrolysis acidification/ The hydrolysis acidification section residence time in Aerobic Process for Treatment is 6~8 h, and the aerobic section residence time is 18~24 h, return current ratio of the mixed liquid It is 100~200%.

10. the processing method of -9 described in any item anti-oxidant agent production waste waters according to claim 1, which is characterized in that including Following steps:

(1) acid out is handled: being adjusted antioxidant using acid solution and is produced wastewater pH 3.0~3.5；The acid solution be sulfuric acid, hydrochloric acid, Acetic acid or their arbitrary combinations；Acid out handles the time as 20~30 min；

(2) flocculation sedimentation is handled: using molysite inorganic flocculating agent and polyacrylamide, to step (1), treated, and waste water is wadded a quilt with cotton Solidifying precipitation process；The molysite inorganic flocculating agent is iron chloride, ferric sulfate or bodied ferric sulfate；In the flocculation sedimentation processing Inorganic 10~20 min of flocculation treatment；10~20 min of polyacrylamide flocculation treatment in the flocculation sedimentation processing；It is described The usage amount of inorganic flocculating agent is 100~200 mg/L；The usage amount of the polyacrylamide is 2 ~ 5 mg/L；

(3) electrocatalytic oxidation is handled: using having the electrode plate of catalytic activity to carry out electro-catalysis to step (2) treated waste water Oxidation processes；The anode material of the electrode plate is one or more of graphite electrode or coating ruthenium, iridium, lead, tin, antimony metal The titanium-based dimensionally stable electrode of oxide；The cathode of the electrode plate is Ti electrode, stainless steel electrode or graphite electrode；The electricity The current density of pole plate is 20~60 mA/cm²；When influent COD is lower than 10000 mg/L, when the electrocatalytic oxidation is handled Between be 2 h；When influent COD is between 10000~20000 mg/L, the electrocatalytic oxidation processing time is 3 h；Work as water inlet When concentration is higher than 20000 mg/L, the electrocatalytic oxidation processing time is 4 h；

(4) anaerobic reaction is handled: between set-up procedure (3) treated pH value of waste water to 6.5 ~ 7.5, then using anaerobic reactor Carry out anaerobic reaction processing；The anaerobic reactor be upflow anaerobic sludge blanket process UASB, anaerobic baffled reactor ABR, Expanded granular sludge bed reactor reactor EGSB or internal-circulation anaerobic reactor IC；The sludge concentration of the anaerobic reactor controls More than 30 g VSS/L, 2~4 kg COD/(m of volumetric loading³D)；

(5) hydrolysis acidification/Aerobic Process for Treatment: to step (4), treated that acidification/Aerobic Process for Treatment is hydrolyzed in waste water；The hydrolysis The hydrolysis acidification section residence time in acidification/Aerobic Process for Treatment is 6~8 h, and the aerobic section residence time is 18~24 h, and mixed liquor returns Stream is than being 100~200%.