Keywords: sewage treatment
I. Purpose of internship:
Production internship is a very important practical part of students' university study. Internship is a must for every college graduate, it not only allows us to learn a lot of knowledge in the classroom simply can not learn, but also makes us broaden the horizons, growth of insight, for us to better apply the knowledge we have learned to the actual work to lay a solid foundation. Through the production internship to make me more in-depth contact with professional knowledge, further understanding of the actual environmental protection work, to understand the environmental governance process of the problems and the theory and practice of the conflict of the difficult problems, and through the writing of the internship report, so that I can learn to comprehensively apply the knowledge I have learned to improve the ability to analyze and solve professional problems.
II. Internship specific content:
(a) West District Sewage Treatment Plant
Internship time: October 19, 2004 - November 29, 2004
1. Sewage plant overview:
Guangzhou Economic and Technological Development Zone Sewage Treatment Plant is the Development Zone Management Committee investment Key environmental protection projects, the main plant is located in Guangzhou Economic and Technological Development Zone, Zhicheng Avenue West 22 (West Base Industrial Zone), covers an area of 78,600 square meters. Daily treatment of industrial wastewater and domestic sewage 30,000 tons, the vision of 90,000 tons.
Guangzhou Economic and Technological Development Zone sewage treatment plant plant in September 1992 groundbreaking, August 1994 was put into operation. Since its construction, the plant insists on the implementation of comprehensive quality management, human management as the key to quality management, production and operation management as the core of quality management, equipment management as the basis for quality management, pay attention to every link, to ensure that the effluent quality of sewage treatment all meet the design requirements and better than the design of the national secondary discharge standards. Emphasizing and strengthening the technological transformation, the plant has achieved better economic and social benefits in terms of energy saving and consumption reduction, and was awarded the National Advanced Unit of Operation and Management of Urban Sewage Treatment Plant and the Advanced Unit of Guangdong Province in 1999 and 2001 respectively. The plant is the designated internship base of South China University of Technology, South China Normal University and other institutions of higher learning.
In June 2001, the plant successfully passed the ISO14000:1996 environmental management system certification, and became the first urban sewage treatment plant in China to pass the ISO14000 environmental management system certification.
The plant has 8 lifting pumping stations in the periphery of the main sewage treatment plant, the sewage treatment plant in the East District of Guangzhou Economic and Technological Development Zone (Export Processing Zone), and the sewage treatment plant in the Yonghe Economic Zone of Guangzhou Economic and Technological Development Zone (Taiwan Business Investment Zone). The main plant adopts the form of lifting and transmission of water from peripheral pumping stations to collect and treat industrial wastewater and domestic sewage in the western area of Guangzhou Economic and Technological Development Zone. The main function of the plant is to be responsible for the safe and normal operation of the sewage pumping station, sewage treatment and sludge treatment, and to ensure that all sewage coming into the plant meets the standard of discharge after treatment. The functional departments of the main plant include the director's office, deputy director's office, production section, technical section, comprehensive section, office and so on.
The main positions in the production section are pumping station operation, sewage treatment operation, sludge treatment operation, laboratory and warehouse management.
2. Treatment process:
Western District General Plant adopts the traditional activated sludge process with impeller surface aeration as the main body, and all domestic equipment is used. Sewage treatment uses various methods to purify sewage by separating the pollutants in the sewage or transforming them into harmless substances. Classification of sewage treatment methods:
(1). Physical treatment method. Such as filtration method, precipitation method.
(2). Physicochemical method. Such as coagulation precipitation method.
(3). Biological treatment method. The use of microorganisms to adsorb, decompose, oxidize organic matter in sewage, degrade unstable organic matter into stable and harmless substances, so that sewage can be purified. Activated sludge method is a kind of biological treatment method.
Activated sludge process is the most widely used wastewater aerobic biochemical treatment technology, which is mainly composed of aeration tank, two precipitation settling tank, aeration system and sludge return system.
The wastewater enters into the aeration tank at the same time with the activated sludge flowing back from the bottom of the secondary sedimentation tank after the primary sedimentation tank, and the activated sludge is in a suspended state through the aeration and comes into full contact with the wastewater. Suspended solids and colloidal substances in wastewater are adsorbed by the activated sludge, and soluble organic matter in wastewater is used as nutrition for their own reproduction by microorganisms in the activated sludge, metabolically transformed into material cells, and oxidized to become the final product (mainly CO2). Non-soluble organic matter needs to be converted into soluble organic matter before it can be metabolized and utilized. Wastewater is thus purified. After purification, the wastewater and activated sludge are separated in the secondary sedimentation tank, and the upper effluent is discharged, and a part of the separated and concentrated sludge is returned to the aeration tank to ensure that a certain concentration of activated sludge is maintained in the aeration tank, and the rest of it is residual sludge, which is discharged from the system.
The influencing factors of activated sludge reaction are as follows:
(1). BOD loading rate (F/M), also known as organic loading rate(2). Water temperature(3). PH (4). Dissolved oxygen (5). Nutrient balance(6). Toxic substances
Aeration device:
1. Blower aeration device
(1) micro-bubble aerator (2) bubble aerator (3) hydraulic shear air aerator (4) hydraulic impact air aerator
2. Mechanical aerator
(1) vertical shaft mechanical aerator (2) horizontal axis mechanical aerator
3. p>3. The main operation mode of activated sludge method
(1) Push-flow activated sludge method
(2) Complete mixed activated sludge method
(3) Segmented aeration activated sludge method
(4) Adsorption-regeneration activated sludge method
(5) Delayed aeration activated sludge method
(6) High-load activated sludge method
(7) High-load activated sludge method /p>
(7) shallow aeration, deep water aeration, deep well aeration activated sludge method
(8) pure oxygen aeration activated sludge method
(9) oxidation ditch process
(10) sequential batch activated sludge method
Treatment of industrial wastewater with traditional aerobic activated sludge method is a method that is economic, purification effect is good, the disadvantage of the pollutant concentration of wastewater will change, especially the pollutant concentration of wastewater will change. The disadvantage is that the concentration of pollutants in wastewater will change, especially some inhibitory pollutants have obvious inhibitory effect on bacterial activity. On the basis of the traditional method, the aerobic activated sludge is domesticated, and the domesticated activated sludge can resist the inhibitory effect of the pollutants in high concentration, for example, the toxic organic chloride can be continuously degraded by the domesticated mixed bacteria, and the purification effect is effectively improved. In addition, the sludge generation of the traditional activated sludge method is relatively large, which is also a relatively large disadvantage of the traditional activated sludge method.
The process flow diagram of the West District General Plant is as follows:
The following figure is the aerial view of the West District General Plant:
3. Design parameters of the West District General Plant:
Treatment scale: the total design treatment scale is 90,000 tons/day, and the first phase is designed to be treated with 30,000 tons/day at present.
◎The main process used: the traditional activated sludge method based on impeller surface aeration.
◎Designed influent water quality: COD ≤ 500mg / LSS ≤ 250mg / LBOD5 ≤ 200mg / L
◎Designed effluent water quality: COD ≤ 120mg / LSS ≤ 30mg / LBOD5 ≤ 30mg / L
The plant implements the "Guangdong Province, local standards for water pollutants discharge limits" (DB44/26) -2001), the effluent water quality standards for
COD ≤ 60mg / LSS ≤ 30mg / LBOD5 ≤ 30mg / L
The current actual treatment situation (average daily treatment of 24,000 tons of water, of which more than 70% of the industrial wastewater.)
Project
Inlet water (mg/L)
Outlet water (mg/L)
Treatment efficiency (%)
COD
544
48.1
91.2
BOD5
270
9.8
96.4
SS
278
28.7
89.7
Main Structures:
Serial No.
Name of Structure
Type of Structure
Specification (L×B×H, m)
Effective Volume (m3)
Number
1
Aeration Sedimentation Tank
Aeration Sedimentation Tank
13.5×2.5×3.78
109
1
2
First Sedimentation Tank
Radial Flow Sedimentation Tank
D=20, H=5.65
< p>11042
3
Aeration Tanks
Surface Aerated Biochemical Tanks
12×12×4.5
648
10
4
Secondary Sedimentation Tanks
Radial Flow Settling Tanks
D=34, H=5.65
D=34, H=4.15 4.15
3282
2
5
Thickening Tank
Gravity Thickening Tank
D=9, H=8.6
365
2
Main Equipment
Equipment name
Model
Type and Specification
Manufacturer
Model and Specification
Model and Specification
Model and Specification
Model and Specification
Type and Specification Manufacturer
Quantity
Remarks
Grid Cleaning Machine
XGS1350-1200
Tangshan Qingyuan Environmental Protection Company
1
Grid Pitch 10mm, Pitch 100mm
Sand Water Separator
LS SF-260B
Major Equipment
Nanjing Lanshen Pumping Group
Nanjing Lanshen Pump Group1
One Sinking Tank Mud Scraper
D20
Jiangdu Water Supply and Drainage Equipment Manufacturing Factory
2
Single-arm peripheral-driven amplitude-flow scraper
One Sinking Tank Mud Pump
AS55-4CB
Nanjing Lanshen Pump Group
Nanjing Lanshen Pump Group
2Nanjing Lanshen Pump Group
Nanjing Lanshen Pump Group
Nanjing Lanshen Pump Group
2
Aerator
PE150
Anhui No.1 Textile Machinery Factory
10
SIEMENS Frequency Converter Stepless Speed Control
Sludge Return Pump
WQ-300-15
Nanjing Lanshen Pump Group
4
Dual Settling Tank Scraping and Suction Pump
2
Separate Suction Pump
AS55-4CB
Nanjing Lanshen Pump Group
Separate Suction Pump
Dual sedimentation tank scraper and suction machineD34
Jiangdu Water Supply and Drainage Equipment Manufacturing Factory
2
Double-arm peripheral-driven amplitude-flow scraper and suction machine
Belt filter press
DYL-2000
Henan Mall environmental protection factory
2
POWTRAN- RICH Inverter stepless adjustment of filter belt speed
Roots blower
SSR-100
Shandong Zhanghuang Machinery Industry Co. Group
2
Filter Belt Flushing Pump
IS65-40-250
Hubei Shishou Pump Factory
2
Sludge Transfer Pump
80WJ4012
Shanghai Ligong Pump Industry Co. SIEMENS Frequency Converter Stepless Speed Regulation
Dosing Metering Pump
JD
Tianjin General Machinery Factory
2
Air Compressor
V-0.3/10
Guangzhou Tianhe Overseas Chinese Enterprise Company Huatong Compressor Factory
1
Mobile Air Compressor
Chlorine Dioxide Sterilizer
HT908-500
Shenzhen OuTaiHua Co.
1
Main test items:
Chemical Oxygen Demand (COD)
Biochemical Oxygen Demand (BOD) BOD5
Aeration Tank Mixed Liquid (MLSS)
Return Flow Sludge MLSS
Suspended SS
PH value
Total Nitrogen TN
30-minute Settling Ratio SV
Sludge Index SVI
Ammoniacal Nitrogen NH3-N
Total Phosphorus TP
Phosphate PO43-P
Water Content
Organic matter
Chloride
(2)Overview of the East District Sewage Treatment Plant:
Visit Time:November 28, 2004 morning
1.Overview of the plant :
The East District Sewage Treatment Plant is located in the East District of Guangzhou Economic and Technological Development Zone (Export Processing Zone) Hongguang Road, Guangzhou Economic and Technological Development Zone Management Committee, the use of Austrian The plant was built by the Guangzhou Economic and Technological Development Zone Management Committee with the use of international payments from Austria. The first phase of the design scale of 26,000 tons / day, to deal with industrial and domestic sewage in the East District, using the SBR process, basically using imported equipment, sewage into the plant in a self-flowing manner.
2. Treatment process:
Sequential batch activated sludge method or interstitial activated sludge method, referred to as the SBR process, is the last decade or so in the activated sludge treatment system in the more striking kind of wastewater treatment process, according to the literal interpretation is the procedure, a batch by batch biochemical treatment of sewage.
SBR is a variant of the current activated sludge method, and its reaction mechanism and pollutant removal mechanism is basically the same as that of the traditional activated sludge method, only the operation is different.
The SBR operation mode consists of five basic processes: influent, reaction, sedimentation, effluent and standby. From the beginning of the sewage inflow to the end of the standby time is counted as a cycle. In a cycle, all processes are carried out sequentially in a reaction tank equipped with aeration or mixing devices, and this operation cycle is repeated week after week to achieve the purpose of continuous sewage treatment.
Inlet process: the inlet process is the reaction pool to accept the sewage process.
Reaction process: when the wastewater injection reaches a predetermined volume, aeration or mixing to achieve the purpose of the reaction (removal of BOD, nitrification, denitrification and dephosphorization).
Sedimentation process: aeration and mixing are stopped, and the activated sludge fluff is subjected to gravity sedimentation and supernatant separation.
Drainage process: the supernatant after activated sludge precipitation is discharged as treated effluent until the lowest water level. Most of the activated sludge settled at the bottom of the reactor is used as return sludge for the next treatment cycle, and the excess residual sludge is led out for discharge.
Standby process: the period after settling to the beginning of the next cycle.
Equipment and devices for SBR process
(1). Decanter: electro-mechanical rocker type, sleeve type, siphon type, rotary type, float type and so on.
(2). Aeration device: mechanical aeration, blast aeration.
(3). Valve, mud draining system.
(4). Automatic control system.
The SBR method is characterized by the following:
(1). SBR method will be biochemical treatment process of water intake, aeration, sedimentation, drainage, and idle regeneration and other steps are concentrated in a device or pool, so the basic process of treatment is conditioning tank → SBR, the process becomes very short, and less equipment, easy to operate and maintain.
(2). In the SBR, in addition to aerobic biochemistry carried out by aeration, there is a longer period of aerobic microorganisms do not bear the organic load of the regeneration period, as well as anaerobic microorganisms of the hydrolysis process. Therefore, the SBR method has good settling performance and clear effluent. And thus it is possible to maintain the high sludge concentration of SBR, thus obtaining a high load and an extraordinary treatment efficiency and ability to deal with difficult biochemical sewage.
(3). During the operation cycle of SBR, the time of programs such as water intake, aeration, settling, drainage, and idling can be completely adjusted according to the actual situation of water quality and water quantity, so it is adaptable and convenient for debugging and normal operation.
(4). As the sludge has a regeneration process and can maintain a high concentration, the sludge is not only of good character and easy to dewater and dry, but also has a low sludge production rate.
(5). SBR is not only a large biomass, but also quite rich in organisms, so it has a better ability to remove nitrogen.
(6). Due to the short process, less equipment, the elimination of the second sedimentation tank, scraper and connecting pipelines, etc., so the capital investment is saved
3. Treatment process flow diagram:
(C) Yonghe sewage treatment plant overview:
1. Plant overview:
Yonghe sewage treatment plant is located in Guangzhou Economic and Technological Development Zone Yonghe Economic Zone (Taiwan Investment Zone) Yongshun Avenue next to the first phase of Project sewage treatment capacity of 2000 tons / day, mainly using biological contact oxidation process (biofilm method) as the core of the integrated sewage treatment plant, supplemented by coarse and fine grating machine, sand sedimentation tank and other pre-treatment facilities, to deal with Yonghe Economic Zone to industrial wastewater-based sewage. The second phase of the project is currently under construction, which adopts a flexible biochemical sewage treatment system with a daily sewage treatment capacity of 6,000 tons.
2. Treatment process
Biofilm method and activated sludge method, the same belongs to aerobic biological treatment methods. But the activated sludge method is to rely on the aeration tank suspended in the flow of activated sludge to remove organic matter, while the biofilm method is to rely on solid in the solid media surface of the microorganisms to remove organic matter, so this method is also known as biological filtration method.
Biofilm method has the following characteristics: solid on the solid surface of the microorganisms on the quality of wastewater, water changes have a strong adaptability; and activated sludge method, compared with the management is more convenient; due to the microorganisms solid on the surface of the solid medium, even if the slow proliferation rate of microorganisms can also habitat, thus constituting a stable ecosystem; the more the higher trophic level of microorganisms, the sludge volume is naturally the less. It is generally believed that the biological filtration method than the activated sludge method of the remaining sludge is less.
Of course, due to the solid on the surface of the solid media microbial amount is more difficult to control, and thus in the operation of the operation of the poor scalability; and due to the small surface area of the filter media, BOD volume load is limited, and thus the space effect is poor; coupled with the use of natural ventilation for feeding the biofilm in the inner layer of the anaerobic layer is often formed, which reduces the effective volume with purification function. However, due to the successful development of new processes and new filter media, biofilm method as a good aerobic biological treatment technology is still widely used.
The biofilm method is divided into the following three categories:
(1). Wetted wall type biofilm method. Wastewater and air flow along the biofilm on the surface of the fixed or rotating contact media, such as biofilter and bio-turntable.
(2). Submerged biofilm method. Contact filter media fixed in the aeration tank, completely submerged in water, using blast aeration, such as contact oxidation method.
(3). Fluidized bed type biofilm method. Make attached biofilm activated carbon, sand and other small particle size contact media suspended flow in the aeration pool.
3. Treatment process:
The following figure is a schematic diagram of the process flow of the first phase of the Yonghe Wastewater Treatment Plant:
Yonghe Wastewater Treatment Plant design of the influent and effluent water quality against the actual situation.
Project
Designed influent (mg/L)
Designed effluent (mg/L)
Actual influent range
BOD5
180
30
15~40
COD
300
80
60~140
SS
250
70
50~150
Grease
30
10
Unmeasured
III. Internship Summary:
This internship in Huangpu Development Zone Wastewater Treatment Plant enables me to study the activated sludge process to the greatest extent possible at the student stage. Activated sludge is the aerobic biochemical treatment technology commonly used in the treatment of municipal and industrial wastewater. Its process is relatively simple, low cost, good treatment effect, high BOD/COD removal rate, and thus can be widely favored. With the improvement of process technology, sequencing batch activated sludge (SBR) has been more and more attention and application. SBR method electrification and automation requirements of a high degree, and has an extraordinary processing efficiency and the ability to deal with difficult to biochemical sewage, a great saving of labor and land area, is more advanced and better prospects for the treatment process.