With the rapid development of social economy and continuous improvement of industrialization and urbanization, water pollution problem becomes more and more serious so water environment pollution and water quality eutrophication become prominent. In order to meet the new requirements of water environment protection project, key projects of urban sewage plant’s pollutants discharge standard （GB18918-2002） use A standard of the 1st class as required by the nation. Currently, the regular deep treatment technique process includes the following plans:
◆ Coagulation,sedimentation, filtration treatment and disinfection
◆ micro flocculation reaction+filtration+disinfection (or pipe blending+filtration+disinfection)
◆ Film treatment which means micro flocculation +reverse osmosis double membrane processing+disinfection
◆ micro flocculation reaction+ rotary disk micro filter processing+disinfection
The above four plans can meet the requirements for deep treatment. The 1st and 2nd plans will produce good quality water with stable operation. However, the two plans cover a large area with high investment and 1st class water pumps are needed so the operation cost is high and management is complicated. The 3rd plan will produce good quality water with small area but much investment and operation cost especially when the membrane is replaced. The 4th plan is a new process used in deep treatment abroad in recent years. This process saves investment with no need to improve sewage, low operation cost, small space, easy management and is adaptive to deep treatment and upgrading and rebuilding plan for urban municipal sewage. It filters sewage finely and removes suspended solids like SS, CODcr, BOD5 and total phosphorous. The outlet water can reach A level of 1st class discharge standard. It is widely recognized as good outlet water quality, stable effect, low operation cost and easy management after real operation.
◆ Upgrading and reconstructing of the current sewage treatment factory: Emission standard is raised from 1st class B level to 1st class A level.
◆ Recycle water from industrial production: recycling cooling water in steel plant and power plant.
◆ Recycling of urban non-drinking water
◆ Water for paper-making and printing and dyeing industry
◆ Water treatment in aquaculture, etc.
Raw water enters center drum through center water inlet pipe and then enters the filter disk fixed around the drum through the holes at the center drum. The two sides of filter disk are installed with filter cloth woven by stainless steel wire or polyester filament. Raw water becomes clean water and flows out of filter disk after filtration by cloth and discharges from effluent weir. With the process of filtration, impurities in the inner side of filter cloth increase and the clean water which flows from the filter disk decreases gradually. Water level in the disk increases. When the liquid level reaches the set value inside the filter disk, the drum starts to rotate and when the high-pressure water provided by reverse flushing device washes the filter disk surface, impurities will fall into the sewage collection trough fixed in the filter and then enter dredge pipe for discharge. With the progress of washing, water level inside the disk reduces continuously. When it reaches at the set liquid level, reverse flushing will stop automatically and drum will stop rotating. The system then reenters static filtration process.
Reverse-flushing stage will not influence operation of equipment. Filter will operate by continuous water inflow, step-by-step reverse flushing and continuous water outflow.
Description of types
Quantity of discs
Diameter of discs
Internal type
External type
Fiber rotary disc filter
Figure 1 : Structure and operation principle of filter disk
Filter disc
Filter water outlet
Back washing water outlet
Sewage inlet
Filter water
Fiber rotary disc filter
The whole set disk filter system includes raw water collection device, central water inflow and distribution equipment, filter disk, drive device, reverse-flushing device (including reverse-flushing pump and spray system), sludge discharge system, liquid level tank and matched liquid level instrument and controlling system.
◆ Raw water collection device
It is equipped with a “to-be-filtered” device which collects flocculation pool water. The material is 304 stainless steel and it is connected to center water distribution drum.
◆ Central water inflow and distribution equipment
It is equipped with a central inflow pipe, water drum, gearing, drive chain, rolling bearing and sealing element and other accessories. The upper end of central water distribution drum is equipped with a collection sewage tank. All main parts are made of 304 stainless steel.
◆ Filter cloth and filter disk
Each filter disk is made up of 14 independent fan shards and is installed around the center drum. Both sides of fan shard are installed with filter cloth woven by stainless steel wire or polyester filament. Special assembled structure of fan frame enables each fan shade to be moved up easily for replacement instead of using any special tools. The connection part between filter cloth and fan frame is impermeable to guarantee good filtration result.
◆ Reverse flushing system
Reverse flushing system uses high pressure pump to flush the filter cloth from outside to inside so that the impurities stored inside the filter cloth can be removed. In order to ensure good cleaning effect, we use umbrella-shape high-speed injection system with resistance to high pressure.
Reverse flushing system can be manually operated and its reverse-flushing times and period can be adjusted and controlled automatically by liquid level. It will not influence the filtration procedures in normal cleaning process.
Reverse-flushing system consists of reverse-flushing device, security filter, sewage collection trough, sludge discharge pipe and reverse-flushing pump.
◆ Drive device
Drive device includes motor, gear case, drive gear and drive chains. Gear case is high torque oblique gear type with service factor of no less than 1.5 and drive motor power of 380V/50HZ/3 phase, protection grade of IP65 and operation noise of less than 75dB.
◆ Matched instrument
Each disk filter is equipped with a set of liquid level detector for detecting water level and automate controlling of operation of reverse flushing system.
◆ Automate controlling system
Automate controlling system can be manually or automatically switched or have far-distance monitoring function. It can also control pump by feedback control through liquid level detector.
◆ Fixed supports and parts
All fixed supports and parts are made of 304 stainless steel.
Disk filter
Disk diameter
Filter precision
Maximum damage by water
Filter disk rotating speed
Filter area of each disk
External temperature
Medium temperature
Maximum emergency head
Maximum immersion depth
Unit
Parameter
75% of filtration area
Inlet SS
Mg/L
SS-interception g/m2*h
Filtration speed m/h
◆ The design is solid and compact with long service life. It is normally made of 304 stainless steel or 316L stainless steel.
◆ It covers small space (is beneficial to upgrading project). The space is 75% smaller compared to that of sand filter.
◆ It has simple design with low head loss which greatly reduces energy consumption.
◆ It features easy operation and maintenance and is operated automatically with no need for special personnel to look after it.
◆ Early-stage investment and operation cost are much lower than those of other techniques.
◆ Outlet water quality is stable.
Model Case size No case size
Service field of disc filter
Firstly. The sewage flows into filter cloth filter chamber, and flows through filter cloth by gravity action, the filtered water enters the filter disc and is discharged or reused through central tube. With the process of filtration, the sediments are increased on the filter cloth, the filtration speed is reduced gradually, the water level of the filter chamber rises gradually. When the water level rises to the set level, negative pressure anti-pumping will start, at the same time, the filter disc rotates slowly, then the filter cloth is cleaned.
Description of types
Quantity of discs
Diameter of discs
Internal type
External type
Fiber rotary disc filter
Drum driving motor
Inlet
Filter disc
Suction device
The whole set disk filter system includes central drum, filter disc, anti-suction system, mud discharge system, control system, driving gear.
1.Anti-suction system
Anti-suction system is mainly composed of anti-suction pump, anti-suction pipeline, sucking disk. Sucking disk is fixed on two sides of filter disk by supports. When the water level rises to the set level, the negative pressure produced by anti-suction pump will suck the filtered water out from disc, at the same time, the solid matters precipitated on filter disc will be sucked out, then the purpose of filter disc cleaning is achieved. The sucked slag water is finally discharged by anti-suction pipeline and anti-suction pump.
2.Mud discharge system
Mud discharge system is mainly made up of sludge pipe, dredge pipe, sludge pump. Sludge pump discharges the sludge at the bottom of filter chamber regularly.
3.Automatic control system
IP65 system control center controls the operation of filter. Touch screen can help know variation in water level and running conditions of filter disc by automatic or manual control, liquid level control or time control running mode can be applied as needed, the operation of parameter setting is very easy. Remote monitoring and failure alarm are set to ensure more reliable operation.
1.Apply the fiber filter cloth with villus on surface in micro porous filter technology, uniform pore and high precision filter can intercept suspended matters efficiently.
2.Modern design, impact load resistance.
3.Stainless steel structure of frame, long service life.
4.Constant rotation, low vacancy rate.
5.Diameters of 2.2mm, 3.0mm can be selected, single unit of discs can reach 20 pieces, and combination is more flexible.
6.Higher filtration requirements and treating capacity can be met by changing and increasing discs.
7.Fully-flooded design increases filtration area, reduces using quantity of discs efficiently.
Disk filter
Disk diameter
Filter precision
Maximum damage by water
Filter disk rotating speed （measurable）
Filter area of each disk
External temperature
Medium temperature
Maximum emergency head
Maximum immersion depth
Unit
Parameter
100% of filtration area
Surface dimensions of equipment
Model Case size No case size
