BFMS water treatment technology
Technical scheme of 20,000 tons/day urban sewage treatment
1, project overview
The daily treatment capacity of the sewage treatment plant is 20,000 tons/day, and the designed effluent quality reaches the first-class B standard (tentative).
2. Project scale
Normal production capacity: 20,000 tons/day
Peak throughput: 24,000 tons/day
3. Design inlet and outlet water quality
1) Inlet water quality (actual data shall be provided by the owner)
PH = 6 ~ 9； CODcr≤500mg/L； bo D5≤280mg/L；
Suspended solids ≤ 300mg/L; Total phosphorus ≤ 5.0 mg/L; Ammonia nitrogen ≤ 40.0 mg/L.
2) Effluent quality (effluent standard required by the owner, tentatively Grade B)
PH = 6 ~ 9； CODcr≤60mg/L； bo D5≤20mg/L；
Suspended solids ≤ 20mg/L; Total phosphorus ≤ 1.0 mg/l; Ammonia nitrogen ≤15.0 mg/l;
Total nitrogen ≤ 20.0 mg/L; Fecal Escherichia coli ≤ 10000/L
4. Process principle and advantages of loaded flocculation magnetic separation (BFMS)
BFMS technology is to add magnetic powder to the traditional flocculation process to enhance the flocculation effect, form high-density flocs and increase the proportion of flocs, so as to achieve the purpose of efficient decontamination and rapid sedimentation. The ionic polarity and metal characteristics of magnetic powder, as the core of floc, greatly enhance the flocculation binding ability of suspended pollutants in water, reduce the dosage of flocculant, and have better effect in removing suspended substances, especially phosphorus, bacteria, viruses, oil and heavy metals than traditional processes. Because the specific gravity of magnetic powder is as high as 5.0× 10? kg/m？ , about twice as much as sand. The specific gravity of floc mixed with magnetic powder increased, and the floc quickly settled, with the speed exceeding 20 meters per hour. The whole water treatment can be completed in about 10 minutes from the water inlet to the water outlet. Magnetic powder in sludge is separated by magnetic drum according to its own characteristics, and then recovered and recycled in the system. The high gradient magnetic filter captures the residual fine particles in the water flow, and the magnetic filter automatically cleans according to the set requirements to achieve the purpose of highly purifying the effluent. It is reported that BFMS is used for advanced water treatment in the United States, and magnetic filters can remove 26 nm bacteria. The following figure illustrates the processing of BFMS process.
Magnetic separation process of supported flocculation by BFMS method
Flocculation/+loading flocculation+precipitation separation+magnetic filtration
Coagulation+biological flocculation+solid separation+magnetic separation
This technology was rarely used in engineering before, because the magnetic seed recovery technology has not been well solved, but now this technical difficulty has been successfully broken through, and the magnetic seed recovery rate has reached over 99%. This technology has also been demonstrated and operated in American commercial projects. Our company applied for a number of patents in China, which formed our own intellectual property rights. In the past three years, our company has successfully conducted a number of experiments with different operating parameters in urban sewage treatment, reclaimed water reuse, surface water and groundwater treatment, tap water treatment, river water treatment, lake water treatment, high phosphorus wastewater treatment, paper-making wastewater treatment, mine wastewater treatment, oil refining and oilfield wastewater treatment, and achieved good results; 10000 tons/day trial operation was put into operation in Qingdao Licun estuary municipal sewage for one month in May 2007, and the operation was good. The effluent from the sewage treatment plant in Beijing Jinyuan Economic Development Zone has been deeply dephosphorized for more than one month, and the treatment effect is good. As an Olympic emergency urban sewage treatment project, Beijing Qinghe Sewage Treatment Plant has installed six sets of 4× 1 10,000 tons/day and 2× 5,000 tons/day BFMS systems, and the comprehensive treatment effect is good. This technology has been used in the first phase project of Dongying Shengli Oilfield (5000 tons/day) to treat the oil production sewage of Shengli Oilfield, and the 500 tons/day groundwater BFMS project and the 30000 tons/day oil production water BFMS project are also being implemented.
Compared with other processes, magnetic separation technology has the following advantages:
1) BFMS process can be applied to primary, secondary and tertiary municipal sewage, reclaimed water, various industrial sewage and drinking water.
2) The treatment effect is good, and the effluent quality is equivalent to that of ultrafiltration membrane. BFMS process can effectively remove particulate pollutants, microbial pollutants and some pollutants that have been dissolved in water, such as COD, BOD, suspended solids, total phosphorus, chromaticity and turbidity, especially for phosphorus. It can also be combined with biological method to remove nitrogen very effectively and economically.
3) Strong impact load resistance and unique impact resistance to water quality. When there is a problem in the previous process or other harmful metal ions enter the sewage treatment system, the sewage can directly enter the magnetic separation system, and the system can still maintain a high removal effect and greatly remove pollutants in the water.
4) The floor space is very small. The building area of 20000t/d BFMS system is about 400㎡, and the total building area of walkway, dosing and operation facilities is about 700㎡.
5) Less investment and obvious advantages over membrane treatment.
6) Low operating cost and long service life of equipment. In addition to normal maintenance, there is no need to replace parts, and the secondary investment is high.
7) Convenient operation and management, quick start and simple operation and management.
5. Suggestions on process design of sewage treatment plant
According to the experience of engineering operation, in order to ensure the continuous operation of the sewage plant, it is necessary to remove floating objects and mud and sand from the sewage and pretreat the sewage entering the BFMS system. According to the working principle of BFMS system, conventional pretreatment is enough, that is, coarse and fine grids and sedimentation tanks. Sewage crushing pump can also be considered for pretreatment.
BFMS technology has a strong ability to remove phosphorus and suspended solids, and also has a strong ability to remove nitrogen. For the treatment of municipal sewage, it is suggested that the following biochemical processes (such as BAF, SBR, A/O, etc.) should be adopted. ) It should be designed only according to ammonia nitrogen load, and the remaining CODcr and BOD5 can meet the emission requirements by adjusting the dosage of BFMS system. Because biochemical denitrification needs necessary carbon source, if the removal rate of BFMS system is too high, it will lead to insufficient carbon source in biochemical system, slow growth of microorganisms and poor denitrification ability. Therefore, it is suggested to lay the standby pipeline system of sludge storage tank and use the returned sludge as the standby carbon source.
6, process flow
Considering the water quality characteristics of urban sewage, combined with the technical advantages of BFMS process, and considering the investment and operation effect, it is suggested that the process flow of sewage treatment plant is as follows:
urban sewage
Regular outbound transportation
Discharge up to standard
BFMS process is an important part of sewage treatment process, and the excess sludge discharged from BFMS system must be treated.
The following figure is only the BFMS process flow chart:
Sewage discharged from sewage plant
Sludge dewatering system
The layout of BFMS system is as follows:
7. Design of 7.BFMS system
1)BFMS system ***2 sets, with a single processing capacity of 10000 tons/day.
2) Others
(1)BFMS system is recommended to be placed indoors. The equipment space is required to be L30× W20× h10m, and light steel structure is adopted.
(2) It is suggested that the sludge storage tank and sludge thickener should be directly used to treat the surplus sludge discharged from BFMS system, instead of the thickener. During normal operation, the water content of sludge discharged from BFMS system is 98-99%.
(3) The supporting voltage is 380V, the installed capacity of each BFMS system is 6 1KW (excluding the water inlet pump), and the operating load is 40KW. Total installed capacity 122KW and total operating load of 80KW.
(4) Each BFMS system is operated for 3 times in 4 shifts per shift 1 operator, and all operators are trained on the job.
(5) Sludge output: 0.4kgGS/m? Wastewater.
8. Water treatment cost of 8.BFMS system
1) Direct operating cost: 0.2446 yuan/ton of sewage.
Agent:
Flocculant dry powder (29% purity): 2500 yuan/ton; The added concentration is 20ppm(AL2O3), and the cost is 0. 17 yuan/ton of sewage;
PAM crystal: 25,000 yuan/ton; The added concentration is 1ppm, and the cost is 0.025 yuan/ton of sewage.
B power consumption
0.04 1 kwh/ton of sewage, if the electricity fee is 0.57 yuan/kwh, the cost is 0.0234 yuan/ton of sewage.
C Labor: 0.0 14 yuan/ton of sewage.
D Maintenance of 0.0 12 yuan/ton sewage.
2) Total cost: 0.3244 yuan/ton of sewage.
A direct operating cost: 0.252 yuan/ton of sewage.
B depreciation of fixed assets (average life method) 15: 0.052 yuan/ton of sewage.
C management and other expenses: 0.03 1 yuan/ton of sewage.
9, 20000 tons/day BFMS system investment
This project * * * needs two sets of10000t/d BFMS systems, and the investment of 20000t/d BFMS system is * * * * * (including design, installation, debugging and system equipment).
10, description:
* Because we don't know the actual sewage discharge situation and haven't tested the water, the operating cost of BFMS system is only an estimate, and the specific data can only be determined after testing.
* The content of this article is for internal use only.