Patent Application
20100270218
The invention is an apparatus and process for treatment of water and wastewater for removal of suspended solids and dissolved impurities.
Filtration systems are used for treatment of water and wastewater for removal of suspended solids and dissolved impurities.
The filtration systems are usually one-stage, gravity or pressure flow systems.
The gravity flow filtration systems depend on a static water pressure (head) above the filter media for the water to flow through the media. The available static water pressure above the filter media is directly proportional to the filtration operating cycle before the filter media has to be backwashed. Therefore, the higher the filter vessel above the filter media the longer the operating cycle is expected for the same water quality and flow rate treated.
The filtration systems are usually provided for removal of suspended solids or dissolved impurities and each usually requires an independent filtration apparatus.
If two stage suspended solids filtration system is required, two independent filtration apparatus', operating in series are used
Similarly, if suspended solids filtration and dissolved impurities filtration processes are required two independent filtration apparatus, operating in series are used.
Filter media need to be backwashed and rinsed after they are plugged with the impurities which they remove. Each filtration apparatus is backwashed and rinsed independently. The backwash and rinse water is predominantly wasted.
The invention offers several advantages over the conventional filtration systems as follows:
The filtration system of the present invention is a process and apparatus for treatment of water and wastewater for removal of suspended solids and dissolved impurities.
The filtration system as shown on
The two-stage filtration system in one apparatus, as shown on
The two-stage filtration system uses the one-stage syphon piping and control system design.
The two-stage filtration system backwashing of the filtration media can be done separately for each stage or jointly for both stages which results in a reduction of the backwash water volume requirements.
The filtration system comprises:
Both, the one-stage and two-stage filtration systems operation can be fully automated with a PLC control system.
Having thus generally described the invention, it will be referred to more specifically by reference to accompanying drawings illustrating preferred embodiments, and in which:
According of the embodiment of the invention, as shown on
The filter unit 1 comprises; a filter vessel 2, filter media 3, a filter underdrain system 4, an outlet water internal pipe 5, a water level sensor and controller 6, an inlet water external pipe 12, an inlet water external valve 13, an inlet water internal distribution pipe 14, and a backwash water collector trough 15.
The filter piping and control valves 28 comprise; an outlet water pipe 16, an outlet water control valve 17, an outlet water syphon pipe 18, an outlet water discharge pipe 19, a syphon control valve 20, a syphon vent pipe 21, a rinse water discharge pipe 22, a rinse water control valve 23, a backwash water supply pipe 25, a backwash water control valve 26, a backwash water rate of flow control valve 27, a backwash water discharge pipe 29, and an air vacuum pump 30.
The filter controller 41 comprises indicating lights, switches, relays, and a PLC, and it is connected to the water level sensor and controller 6 and the control valves 17, 20, 23, and 26, with control wires 42.
The water level sensor and controller 6 provides inputs to the filter controller 41 on water levels 8 and 9 in the filter vessel 2.
The filter controller 41 controls open and closed status of the control valves 17, 20, 23 & 26 according to the water levels 8 & 9 in the filter vessel and a time logic program contained in the PLC.
The filter media 3 can be a single or multi-media composed of sand, anthracite, activated carbon or other proprietary media designed to remove specific suspended solids or dissolved impurities.
The filter underdrain system 4 can be made of sand and gravel, single or multilayer or constructed with a false bottom with slotted or perforated nozzles provided with metering tubes for air scour before the water backwashing.
The inlet water external pipe 12 is provided with an inlet water valve 13 which is a non-return valve in a gravity inlet water supply system.
The backwash water collector trough 15 is a slotted or perforated pipe to collect the backwash water from the entire cross-section of the filter vessel 2.
The outlet water syphon pipe 18 is located above the filter media 3, preferably 150 to 200 mm, to ensure a minimum water level 7 of 150 to 200 mm in the filter above the filter media 3.
The inlet water enters the filter through the inlet water external pipe 12, the non-return valve 13 and the internal distribution pipe 14, and it flows downward as indicated by an arrow 10. The inlet water passes through the filter media 3, the underdrain system 4, the outlet internal pipe 5, the external outlet pipe 16, the control valve 17, the syphon pipe 18 and the discharge pipe 19.
The backwash water is provided through the backwash water supply pipe 25, the control valve 26 and the rate of flow control valve 27 into the pipe 5, and the underdrain system 4, the filter media 3, and it flows upward, as indicated by an arrow 11, into the backwash water collector trough 15 and the discharge pipe 29.
During the rinse cycle, the inlet water flows through the filter media 3 into the underdrain system 4 and the outlet pipes 5 and 16 and the rinse water discharge pipe 22 to the backwash water discharge pipe 29.
The filter operating cycles comprise a filtration cycle without syphon action, a filtration cycle with syphon action, a backwashing cycle and a rinsing cycle.
During the filter operating cycles the control valve status is as follows:
The filtration with the syphon action is provided by the filter discharge pipes 16, 18 & 19 arrangement in an inverted ‘U’ shape and closure of the control valve 20. By opening of the control valve 20 the syphon action is lost and the filter operates without the syphon action.
The syphon action is activated by closing the control valve 20 when the water in the filter vessel 2 reaches the level 8. This operation is controlled by the water level sensor and controller 6 and the filter controller 41.
The syphon action causes the water level in the filter vessel 2 to drop initially, but the water level will rise again, after a certain time, as the filter media 3 are further plugged with the water impurities retained by the filter media.
When the water level in the filter vessel 2 reaches the level 9 the backwashing cycle is activated and it continues for a predetermined period of time, controlled by the filter controller 41.
The filter rinsing cycle follows immediately the backwashing cycle for a predetermined period of time, controlled by the filter controller 41.
After the rinsing cycle, the filter operation returns to the filtration cycle without the syphon action.
During the filtration cycle with the syphon action air or other gas may be released from the water and it may accumulate in the filter syphon pipe 18. If this condition is detected the air vacuum pump 30 is activated to remove the air or other gas from the syphon pipe 18. This ensures an efficient action of the syphon piping system.
The rinse water discharge pipe 22 is connected to the backwash water discharge pipe 29 at the same level as the syphon pipe 18 elevation, to ensure that the water level in the filter vessel 2 does not drop below the low water level 7 during the filter rinsing cycle. This prevents the filter media 3 from being exposed and disturbed on the surface by the inlet water.
A second embodiment of the invention is shown on
For the various embodiments disclosed here, the same reference numeral numbers are used for the same or substantially similar features.
The filter vessel 2 comprises two independent filter media 3 and 31, two independent underdrain systems 4 and 32, two independent water outlet pipes 5 and 33, two independent backwash water collecting troughs 15 and 34, and two independent backwash water supply pipes 25 & 38 and control valves 26 & 39 and rate of flow control valves 27 & 40.
The other additional features comprised in this embodiment are control valves 35, 36 & 37, and a differential pressure switch 43.
The filter operating cycles are the same in this embodiment as those outlined in the first embodiment and they comprise:
The filter backwashing can be performed jointly or independently for both filter media 3 and 31 followed by a joint or independent rinsing cycles of each filter media respectively.
If a joint filter backwashing and rinsing cycles are performed for both filter media 3 and 31, the filter media 3 backwashing and rinsing cycles can be extended beyond those performed for the filter media 31 as required.
The various combinations of the backwashing and rinsing cycles are outlined as follows:
