overview
With the rapid development of the social economy and the continuous improvement of industrialization and urbanization levels, water pollution has become increasingly serious, leading to more prominent water environment pollution and eutrophication problems in China. In order to meet the new requirements of water environment protection engineering, the country has implemented the A standard of the first level standard for key projects of urban sewage treatment plant pollutant discharge standards (GB18918-2002). Currently, the conventional deep treatment process mainly includes the following treatment schemes:
1. Coagulation, sedimentation, filtration treatment+disinfection
2. Perform micro flocculation reaction+filtration treatment+disinfection (or pipeline mixing+filtration treatment+disinfection)
3. Perform membrane treatment including microfiltration, reverse osmosis dual membrane treatment, and disinfection
4. Perform micro flocculation reaction+rotary disc micro filter treatment+disinfection
The above four treatment schemes can all meet the requirements for deep treatment. The first and second treatment schemes have good effluent quality and stable operation, but they require a large footprint and high investment, requiring the addition of a first stage water pump for upgrading, high operating costs, and complex management. The third option has good effluent quality and a small footprint, but requires high investment and high operating costs, especially when replacing membrane materials, which often incurs high expenses. The fourth scheme is a new process adopted by foreign countries in recent years for deep treatment. This process has the advantages of low investment, no need to upgrade sewage, low operating costs, small footprint, and simple management. It is particularly suitable for the deep treatment and upgrading of urban municipal sewage. The sewage is finely filtered to remove suspended solids SS, CODcr, BOD5, and total phosphorus, and the effluent can meet the A standard of the first level discharge standard. Through actual production and operation, it is unanimously recognized that the effluent quality is good, the effect is stable, the operating cost is low, and the management is simple.
2、 Application Fields
1. Upgrading and renovation of existing sewage treatment plants: upgrading from Level B to Level A standard discharge
2. Industrial production recycled water: circulating cooling water for steel mills and power plants
3. Urban miscellaneous water reuse
4. Water for papermaking, printing and dyeing industry
5. Aquaculture and other water treatment
3、 Characteristics
1. The design is sturdy and compact, with a long service life, usually made of 304 stainless steel or 316L stainless steel.
2. Small footprint (conducive to upgrading and renovation projects), with a 75% smaller footprint compared to sand filters.
3. The design is simple, with minimal head loss, greatly reducing energy consumption.
4. Simple operation and maintenance, fully automatic operation, no need for dedicated personnel supervision.
5. The initial investment and operating costs are significantly lower than other processes.
6. The effluent quality is stable.
4、 Working principle
The fiber turntable filter consists of a central drum, turntable, backwashing system, and supporting control electrical system. The turntable is fixed around the central drum and has a communication hole with the central drum. Raw water (sewage) flows into the central drum through one end opening and enters each turntable through a connecting hole. The turntable is equipped with filter cloth on both sides, which is woven from stainless steel wire or polyester wire, with a minimum filter aperture of 10 μ m. After the raw water is filtered through the filter cloth, the clean water flows out of the filter cloth and is discharged from the filtered water outlet outside the system. As the filtration progresses, the trapped impurities inside the filter cloth continue to increase, the filtration pressure difference increases, and the amount of water passing through the filter cloth decreases. When impurities accumulate to a certain extent and the liquid level of the central drum reaches the set value, backwashing is required to remove the impurities accumulated on the inside of the filter cloth. The backwash water pump extracts clean water that has passed through the filter cloth and sprays it onto the outside of the filter cloth,
Rinse off the trapped impurities on the inside of the filter cloth, and after rinsing, the sewage falls into the receiving tray and is then discharged outside the device. During backwashing, the turntable rotates and backwash water sprays filter cloth at different angles until the turntable rotates once and all filter cloth is cleaned. Backwashing stops and the static filtration process resumes until backwashing is performed again.
The fiber disc filter adopts imported high-efficiency filter cloth as the filtering medium. The filter cloth is woven from metal wires with special warp and weft lines, and has the characteristics of high precision, high flux, high strength, and strong slag aggregation ability. The filtration accuracy can reach up to 10um, and the unit area flux can reach up to 76L/s · m2 (@ 300mm hydrostatic head), which can withstand a backwash water pressure of 7.5bar and effectively improve the backwash effect. As the filtration progresses, the trapped impurities inside the filter cloth continue to increase, the filtration pressure difference increases, and the amount of water passing through the filter cloth decreases. When impurities accumulate to a certain extent and the liquid level of the central drum reaches the set value, backwashing is required to remove the impurities accumulated on the inside of the filter cloth. The backwash water pump extracts clean water that has passed through the filter cloth, sprays it onto the outside of the filter cloth, and flushes out the trapped impurities on the inside of the filter cloth. After flushing, the sewage falls into the receiving tray and is then discharged outside the device. During backwashing, the turntable rotates and backwash water sprays filter cloth at different angles until the turntable rotates once and all filter cloth is cleaned. Backwashing stops and the static filtration process resumes until backwashing is performed again.
The raw water enters the central drum through the central inlet pipeline and enters the filter disc fixed around the drum through the water distribution holes of the central drum. The filter disc is equipped with filter cloth woven with stainless steel wire or polyester wire on both sides. After the raw water is filtered through the filter cloth, the clean water flows out of the filter disc and is discharged from the outlet weir into the system. As the filtration continues, the impurities trapped inside the filter cloth continue to increase, and the amount of clean water flowing out of the filter disc gradually decreases. The water level inside the disc continues to rise. When the liquid level in the filter disc reaches the set value, the drum starts to rotate, and the high-pressure water provided by the backwash device automatically flushes the filter disc surface. The impurities then fall into the dirt collection tank fixed inside the filter and enter the sludge discharge pipeline for external discharge. As the flushing continues, the water level in the tray decreases continuously. When it reaches the set liquid level value, the backwash automatically stops, the drum also stops rotating, and the system enters the static filtration process again.
The backwashing stage does not affect the operation of the device, and the filter operates in a continuous water inlet, staged backwashing, and continuous water outlet manner.
5、 Construction
1. Composition of equipment
A complete set of rotary filtration system, including raw water receiving device, central inlet water distribution device, filter disc, driving device, backwashing device (including backwashing water pump and spray system), sludge discharge system, liquid level tank, and supporting liquid level instruments and control system.
2. Raw water receiving device
Equipped with a device for receiving filtered water from the flocculation tank, made of 304 stainless steel, and connected to the central water distribution drum
Connect.
3. Central water inlet and distribution device
It consists of a central water inlet pipeline, a water distribution drum, a linkage gear, a transmission chain, a rotating bearing, seals and other accessories. The upper end of the central water distribution drum is equipped with a collection and drainage tank. All main components are made of 304 stainless steel.
4. Filter cloth filter disc
Each filter disc consists of 14 independent fan-shaped segments, installed around the central drum. The fan-shaped segments are equipped with filter cloth woven from stainless steel or polyester wire on both sides. The special assembly structure of the fan-shaped frame makes it relatively easy to remove and replace each fan-shaped segment from the central drum without the need for special tools. The tight fit between the filter cloth and the fan-shaped frame is sealed by a special process, ensuring no water leakage and ensuring the filtering effect.
5. Backwash system
The backwash system uses a high-pressure pump to flush the filter cloth from the outside to the inside, thereby removing the debris accumulated on the inside of the filter cloth. To ensure the cleaning effect, we adopt a high-pressure umbrella shaped high-speed spraying system.
Backwash can be manually controlled, with adjustable backwash frequency and time, and can also be automatically controlled through liquid level. During normal cleaning processes, it will not affect the filtration process.
The backwash system consists of a backwash device, a security filter, a waste collection tank, a sludge discharge pipeline, and a backwash pump.
6. Drive device
The driving device consists of a motor, a gearbox, driving teeth, and a driving chain. The gearbox is a high torque helical gear type with a service factor of not less than 1.5. The power supply of the driving motor is 380V/50HZ/3-phase, with a protection level of IP65. The operating noise of the equipment is less than 75dB.
7. Supporting instruments
Each set of rotary filter is equipped with one set of liquid level detector, which is used to sense the water level and automatically control the operation of the backwash system.
8. Automatic control system
The self-control system can achieve manual/automatic conversion, remote monitoring and other functions, and can feedback control the operation of the water pump through a liquid level detector.
9. Fixed bracket and components
All fixed brackets and components are made of stainless steel 304 material.