Keywords: sewage treatment
First, the purpose of the internship:
Production practice is a very important practical link in students' college study. Internship is a compulsory course for every college graduate. Not only let us learn a lot of knowledge that we can't learn in class, but also broaden our horizons and increase our knowledge, laying a solid foundation for us to better apply what we have learned to practical work in the future. Through production practice, I can get in touch with professional knowledge more deeply, further understand the reality of environmental protection work, understand the problems existing in the process of environmental governance and the difficult problems that conflict between theory and practice, and write an internship report, so that I can learn to comprehensively use what I have learned and improve my ability to analyze and solve professional problems.
Two. The specific content of the internship:
(1) West Sewage Treatment Plant
Internship time: June 65438+1October 09, 2004-June 65438+1October 29, 2004.
1. Overview of sewage plants:
Guangzhou Economic and Technological Development Zone Sewage Treatment Plant is a key environmental protection project invested by the Development Zone Management Committee. The main workshop is located at No.22, Zhicheng Avenue West (Xiji Industrial Zone), Guangzhou Economic and Technological Development Zone, covering an area of 78,600 square meters. Daily treatment of industrial wastewater and domestic sewage is 30,000 tons, and long-term planning is 90,000 tons.
Guangzhou Economic and Technological Development Zone Sewage Treatment Plant General Factory broke ground in September 1992 and was completed and put into operation in August 1994. Since the establishment of our factory, we have insisted on implementing total quality management, taking human management as the key of quality management, production operation management as the core of quality management, equipment management as the basis of quality management, and paying attention to every link to ensure that the effluent quality of sewage treatment all meets the design requirements and is superior to the national second-class discharge standard stipulated in the design. Attaching importance to and strengthening technological transformation has achieved good economic and social benefits in energy saving and consumption reduction. 1999 and 200 1 were rated as advanced units in operation and management of urban sewage treatment plants in China and advanced units in Guangdong province. Our factory is the designated practice base of South China University of Technology, South China Normal University and other institutions of higher learning.
In June of 20001year, our factory successfully passed the ISO 14000: 1996 environmental management system certification, becoming the first municipal sewage treatment plant in China to pass the ISO 14000 environmental management system certification.
The plant has jurisdiction over 8 lifting pumping stations around the sewage treatment plant, the sewage treatment plant in the East Zone of Guangzhou Economic and Technological Development Zone (Export Processing Zone) and the sewage treatment plant in Yonghe Economic Zone of Guangzhou Economic and Technological Development Zone (Taiwanese Investment Zone). The general plant adopts the form of pumping water from surrounding pumping stations to collect and treat industrial wastewater and domestic sewage from the west 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 sewage pumping station, sewage treatment and sludge treatment, and to ensure that all sewage entering the plant is discharged after treatment. The functional departments of the general factory include the director's office, the deputy director's office, the production department, the technical department, the comprehensive department and the office.
The main positions of the production department are pumping station operation, sewage treatment operation, sludge treatment operation, laboratory test and warehouse management.
2. Processing technology:
The western general plant adopts the traditional activated sludge process with impeller surface aeration as the main body, all of which adopt domestic equipment. Sewage treatment adopts various methods to separate pollutants in sewage or convert them into harmless substances, thus purifying sewage. Classification of sewage treatment methods:
(1). Physical therapy. Such as filtration and precipitation.
(2) Physical and chemical methods. Such as coagulation and precipitation.
(3) Biological treatment. Organic matter in sewage is adsorbed, decomposed and oxidized by microorganisms, and unstable organic matter is degraded into stable and harmless substances, thus purifying sewage. Activated sludge process is a biological treatment process.
Activated sludge process is the most widely used aerobic biochemical treatment technology for wastewater, which is mainly composed of aeration tank, secondary sedimentation tank, aeration system and sludge reflux system.
After the wastewater passes through the primary sedimentation tank, it enters the aeration tank together with the activated sludge flowing back from the bottom of the secondary sedimentation tank. Through aeration, activated sludge is suspended and fully contacted with wastewater. Suspended substances and colloidal substances in wastewater are adsorbed by activated sludge, while soluble organic substances in wastewater are self-propagated by microorganisms in activated sludge as nutrients, metabolized into substance cells, and oxidized into final products (mainly CO2). Insoluble organic matter needs to be converted into soluble organic matter before it can be metabolized and utilized. The waste water is thus purified. The purified wastewater and activated sludge are separated in the secondary sedimentation tank, and the upper effluent is discharged. 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 is surplus sludge, which is discharged by 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 value (4). Dissolved oxygen (5). Nutritional balance (6). Toxic substances.
Inflator:
1. Blowing aeration device
(1) bubble aerator (3) hydraulic shear air aerator (4) micro-bubble aerator (2) in hydraulic impact air aerator
2. Mechanical aerator
(1) vertical shaft mechanical aerator (2) horizontal shaft mechanical aerator
3. Main operation modes of activated sludge process
(1) plug-flow activated sludge process
(2) Completely mixed activated sludge process
(3) sectional aeration activated sludge process
(4) Adsorption-regeneration activated sludge process
(5) Extended aeration activated sludge process.
(6) high-load activated sludge process
(7) shallow aeration, deep aeration and deep well aeration activated sludge process.
(8) Pure oxygen aeration activated sludge process
(9) oxidation ditch process
(10) sequencing batch activated sludge process
The traditional aerobic activated sludge process is an economical and effective method to treat industrial wastewater, but the disadvantage is that the concentration of pollutants in wastewater will change, especially some pollutants with inhibitory effect have obvious inhibitory effect on bacterial activity. On the basis of traditional methods, aerobic activated sludge is domesticated, and the domesticated activated sludge can resist the inhibition of high concentration pollutants. For example, the domesticated mixed bacteria can continuously degrade toxic organic chlorides and effectively improve the purification effect. In addition, the sludge produced by the traditional activated sludge process is relatively large, which is also a major disadvantage of the traditional activated sludge process.
The process flow chart of West General Factory is as follows:
The picture below is a bird's eye view of the West General Factory:
3. Design parameters of West General Factory:
◎ Treatment scale: The total design treatment scale is 90,000 tons/day, and the current design treatment scale of Phase I is 30,000 tons/day.
◎ The main process adopted: the traditional activated sludge method with impeller surface aeration as the main method.
◎ Design inlet water quality: COD ≤ 500mg/LSS ≤ 250mg/LBOD5 ≤ 200mg/L.
◎ Design effluent quality: COD ≤120mg/LSS ≤ 30mg/LBOD5 ≤ 30mg/L.
Our factory implements the local standard of Guangdong Province, Discharge Limits of Water Pollutants (DB44/26-200 1), and the effluent quality standards are as follows.
Chemical oxygen demand ≤ 60mg/LSS ≤ 30mg/L.
At present, the actual treatment situation (the daily average treatment water volume is 24,000 tons, of which more than 70% is industrial wastewater. )
project
Water inflow (mg/L)
Effluent (mg/L)
Processing efficiency (%)
cash on delivery
544
48. 1
9 1.2
BOD5
270
9.8
96.4
sage
278
28.7
89.7
Main structure:
serial number
Structure name
structure type
Specification (length× width× height, m)
Effective volume (m3)
amount
1
aerated grit chamber
aerated grit chamber
13.5×2.5×3.78
109
1
2
Primary sedimentation tank
sedimentation basin
D=20，H=5.65
1 104
2
three
Inflatable tank
Surface aeration biochemical pool
12× 12×4.5
648
10
four
secondary sedimentation tank
sedimentation basin
D=34，H=4. 15
3282
2
five
Concentration tank
Gravity concentration tank
D=9，H=8.6
365
2
Main equipment
device name
Model setting
manufacturer
amount
comment
Grille cleaner
XGS 1350- 1200
Tangshan Qingyuan environmental protection company
1
Grid spacing is10mm and spacing is100mm.
Sand settling water separator
LSSF-260B
Nanjing Shen Lan Zhibeng Group
1
Primary sedimentation tank mud scraper
D20
Jiangdu water supply and drainage equipment manufactory
2
Single-arm circumferential drive amplitude flow mud scraper
Sludge pump of primary sedimentation tank
AS55-4CB
Nanjing Shen Lan Zhibeng Group
2
aeration machine
PE 150
Anhui first textile machinery factory
10
Stepless speed regulation of Siemens inverter
Sludge reflux pump
WQ-300- 15
Nanjing Shen Lan Zhibeng Group
four
Scraping and suction machine for secondary sedimentation tank
D34
Jiangdu water supply and drainage equipment manufactory
2
Double-arm circumferential drive amplitude flow mud scraper
Belt filter press
DYL-2000
He' nan shopping mall environmental protection factory
2
Fuchuan frequency converter stepless adjustment of filter belt speed
roots blower
SSR- 100
Shandong Huang Zhang Machinery Industry Co., Ltd.
2
Stepless speed regulation of Siemens inverter
Surplus sludge pump
AS75-4CB
Nanjing Shen Lan Zhibeng Group
2
Filter belt flushing pump
IS65-40-250
Hubei Shishou water pump factory
2
Sludge transfer pump
80WJ40 12
Shanghai Gong Li Pumps Co., Ltd.
2
Chemical corrosion-resistant pump, Siemens frequency converter stepless speed regulation
Quantitative metering pump
Jurum Doctor
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., ltd
1
Main test items:
Chemical oxygen demand
Biochemical oxygen demand BOD5
Mixed liquid MLSS in aeration tank
Return sludge MLSS
Suspended substance SS
pH value
Total nitrogen TN
30-minute sedimentation rate SV
SVI sludge index
Ammonia nitrogen NH3-N
Total phosphorus TP
phosphate
Moisture/water content
organic matter
Treat with chloride
(2) Overview of sewage treatment plants in East District:
Visit time: 165438+20041the morning of October 28th.
1. factory profile:
East District Sewage Treatment Plant is located in Hongguang Road, East District (Export Processing Zone) of Guangzhou Economic and Technological Development Zone, which was built by Guangzhou Economic and Technological Development Zone Management Committee with Austrian international loan. The design treatment scale of the first phase is 26,000 tons/day, and the industrial and domestic sewage in the east area is treated by SBR process, basically using imported equipment, and the sewage enters the factory by gravity.
2. Processing technology:
Sequencing batch activated sludge process or intermittent activated sludge process, referred to as SBR process, is a remarkable wastewater treatment process in activated sludge treatment system in recent ten years. Literally means batch biochemical treatment of sewage according to procedures.
SBR is a variant of activated sludge process at present, and its reaction mechanism and pollutant removal mechanism are basically the same as those of traditional activated sludge process, but its operation mode is different.
SBR operation mode consists of five basic processes: water inflow, reaction, precipitation, water outflow and standby. From the beginning of sewage inflow to the end of standby time, it is counted as a cycle. In a cycle, all processes are carried out in turn in a reaction tank with aeration or stirring device, and the cycle is repeatedly operated to achieve the purpose of continuous sewage treatment.
Water inflow process: the water inflow process is the process of receiving sewage in the reaction tank.
Reaction process: When the wastewater is injected into a predetermined volume, it is aerated or stirred to achieve the reaction purpose (BOD removal, nitrification, nitrogen and phosphorus removal).
Precipitation process: stop aeration and stirring, and carry out gravity precipitation and supernatant separation on activated sludge flocs.
Drainage process: the supernatant after activated sludge precipitation is discharged as treated water until it reaches the lowest water level. Most of the activated sludge deposited at the bottom of the reaction tank is used as reflux sludge for the next treatment cycle, and the remaining sludge is discharged.
Standby process: the period from precipitation to the beginning of the next cycle.
Equipment and device of SBR process
(1). decanters: electromechanical rocker arm type, sleeve type, siphon type, rotary type, buoy type, etc.
(2) Aeration device: mechanical aeration and blast aeration.
(3) Valve and sludge discharge system.
(4) Automatic control system.
The characteristics of SBR method are as follows:
(1).SBR method concentrates several steps of biochemical treatment, such as water inflow, aeration, sedimentation, drainage and idle regeneration, in one device or pool, so the basic process of treatment is to adjust the pool →SBR, which becomes very short and has few devices, which is convenient for operation and maintenance.
(2) In SBR, besides aerobic biochemistry by aeration, there is still a long regeneration period when aerobic microorganisms can't bear the organic load and the hydrolysis process of anaerobic microorganisms. Therefore, SBR method has good sedimentation performance and clear effluent. Therefore, the high sludge concentration of SBR can be maintained, so that high load can be obtained, and it has extraordinary treatment efficiency and the ability to treat refractory sewage.
(3) In the operation cycle of SBR, the time of water intake, aeration, sedimentation, drainage, idle and other procedures can be completely adjusted according to the actual situation of water quality and quantity, which has strong adaptability and is convenient for debugging and normal operation.
(4) Because sludge has a regeneration process and can maintain a high concentration, it is not only good in properties, easy to dehydrate and dry, but also low in sludge yield.
(5) SBR not only has a large biomass, but also is rich in biomass and has good denitrification ability.
(6) Due to short process and less equipment, the secondary sedimentation tank, mud scraper and connecting pipeline are cancelled, which saves capital investment.
3. Process flow chart:
(3) Overview of Yonghe Sewage Treatment Plant:
1. factory profile:
Yonghe Sewage Treatment Plant is located next to Yongshun Avenue in Yonghe Economic Zone, Guangzhou Economic and Technological Development Zone (Taiwanese investment zone). The sewage treatment capacity of the first phase project is 2000 tons/day. Yonghe Economic Zone is an integrated sewage treatment device with biological contact oxidation (biofilm process) as the core, supplemented by coarse and fine grid machines, grit chambers and other pretreatment facilities, which is mainly used to treat industrial wastewater. At present, the second phase project is under construction. The second phase adopts a flexible biochemical sewage treatment system with a daily sewage treatment capacity of 6000 tons.
2. Processing technology
Biofilm process, like activated sludge process, belongs to aerobic biological treatment process. The activated sludge method relies on suspended activated sludge flowing in the aeration tank to remove organic matter, while the biofilm method relies on microorganisms fixed on the surface of solid media to remove organic matter, so this method is also called biological filtration method.
Biofilm method has the following characteristics: microorganisms fixed on solid surface have strong adaptability to the change of wastewater quality and quantity; Compared with the activated sludge process, the management is more convenient; Because microorganisms are fixed on the surface of solid culture medium, even microorganisms with slow proliferation can survive, thus forming a stable ecosystem; The more microorganisms with high trophic level, the less sludge. It is generally believed that the excess sludge of biological filtration method is less than that of activated sludge method.
Of course, because it is difficult to control the number of microorganisms fixed on the surface of solid media, the scalability in operation is poor; Due to the small surface area of filter material, the BOD volume load is limited and the space effect is poor; In addition, natural ventilation often forms an anaerobic layer in the inner layer of biofilm, thus reducing the effective volume with purification function. However, due to the successful development of new technologies and new filter materials, biofilm process is still widely used as a good aerobic biological treatment technology.
Biofilm method is divided into the following three categories:
(1). Wet biofilm method. Wastewater and air flow along the biofilm on the surface of fixed or rotating contact media (such as biofilter and biological turntable).
(2) Submerged biofilm method. The contact filter material is fixed in the aeration tank, completely immersed in water, and aerated by blast, such as contact oxidation.
(3) Fluidized bed biofilm method. The contact medium with smaller particles, such as activated carbon and sand attached with biofilm, flows in suspension in the aeration tank.
3. Treatment process:
The following figure shows the process flow diagram of Yonghe Sewage Treatment Plant Phase I Project:
Comparison between the designed inlet and outlet water quality of Yonghe Sewage Treatment Plant and the actual situation.
project
Design water inflow (mg/L)
Design wastewater (mg/L)
Actual water inflow range
BOD5
180
30
15~40
cash on delivery
300
80
60~ 140
sage
250
70
50~ 150
oil
30
10
Unforeseen
Three. Internship summary:
This internship in the sewage treatment plant of Huangpu Development Zone allowed me to learn the treatment process of activated sludge method to the greatest extent during my student stage. Activated sludge process is an aerobic biochemical treatment technology commonly used to treat municipal and industrial sewage at present. Its technological process is relatively simple, the treatment cost is low, the treatment effect is good, and the BOD/COD removal rate is high, so it can be widely favored. With the development of technology, sequencing batch reactor (SBR) has been paid more and more attention and applied. SBR process requires high electrification and automation, has extraordinary treatment efficiency and the ability to treat refractory sewage, and greatly saves labor and land area. This is an advanced and promising treatment.