Disc filter pre-screen dual media disc filter

Abstract

According to various aspects and embodiments, a system and method for two-stage filtration is provided. The system includes an inlet fluidly connectable with wastewater, a first stage filter assembly that is fluidly connectable with the inlet and has a rotary drum with a filter surface configured for radially inward fluid flow, a second stage filter assembly that is fluidly connectable with the first stage filter and has a plurality of filter discs configured for radially outward fluid flow, and an outlet fluidly connectable with filtrate generated by the second stage disc filter assembly.

What is claimed is: 
     
         1 . A filter device for filtering wastewater, the filter device comprising:
 a drum filter including a rotary drum with a filter surface having a first side facing an interior of the drum and a second side facing an exterior of the rotary drum and being fluidly connectable with a source of wastewater; and   a disc filter having an inlet fluidly connectable with the first side of the filter surface of the rotary drum.   
     
     
         2 . The filter device of  claim 1 , wherein the disc filter includes a plurality of disc-shaped filter members attached to a central drum that are configured to receive filtered wastewater passed through the filter surface of the drum filter and to filter the filtered wastewater. 
     
     
         3 . The filter device of  claim 2 , wherein the inlet of the disc filter is fluidly connectable with an interior of the central drum of the disc filter. 
     
     
         4 . The filter device of  claim 2 , wherein the rotary drum of the drum filter and the central drum of the disc filter are positioned along a common longitudinal axis. 
     
     
         5 . The filter device of  claim 4 , wherein the rotary drum of the drum filter is coupled to the central drum of the disc filter. 
     
     
         6 . The filter device of  claim 5 , further comprising a housing that at least partially surrounds the drum filter and the disc filter, the housing having an inlet trough fluidly connectable with the wastewater and the second side of the filter surface of the rotary drum filter, an outlet trough fluidly connectable with filtrate, and a sealing plate configured to separate the inlet trough from the outlet trough. 
     
     
         7 . The filter device of  claim 6 , further comprising a drum filter collection trough fluidly connectable with the exterior of the rotary drum. 
     
     
         8 . The filter device of  claim 7 , further comprising a backwashing system comprising:
 a first plurality of spray nozzles configured to spray filtrate onto the plurality of disc-shaped filter members;   a disc filter backwash trough configured to collect backwashed filtrate from the plurality of disc-shaped filter members; and   a second plurality of spray nozzles configured to spray filtrate onto the first side of the filter surface of the rotary drum, wherein the drum filter collection trough is configured to collect backwash from the filter surface of the rotary drum.   
     
     
         9 . The filter device of  claim 1 , wherein the filter surface of the rotary drum is configured to retain solids on the second side while permitting the wastewater to filter through the filter material to the first side of the filter material and the interior of the rotary drum as filtered wastewater. 
     
     
         10 . The filter device of  claim 1 , wherein the filter surface of the drum filter has openings with a diameter in a range of about 20 microns to about 800 microns. 
     
     
         11 . The filter device of  claim 10 , wherein the filter surface of the drum filter comprises one of wedge wire screen material or woven filter media material. 
     
     
         12 . The filter device of  claim 10 , wherein the plurality of disc-shaped filter members include a filter media with openings having a diameter in a range of about 6 microns to about 300 microns. 
     
     
         13 . The filter device of  claim 1 , wherein the wastewater is from one of a secondary or primary treatment process. 
     
     
         14 . A two-stage filtration system for filtering wastewater, the system comprising:
 an inlet fluidly connectable with the wastewater;   a first stage filter assembly fluidly connectable with the inlet and having a rotary drum with a filter surface configured for radially inward fluid flow;   a second stage filter assembly fluidly connectable with the first stage filter assembly and having a plurality of filter discs configured for radially outward fluid flow; and   an outlet fluidly connectable with filtrate generated by the second stage filter assembly.   
     
     
         15 . The two-stage filtration system of  claim 14 , wherein the plurality of filter discs are attached to a central drum that is fluidly connectable with an interior of the rotary drum of the first stage filter assembly. 
     
     
         16 . The two-stage filtration system of  claim 14 , wherein the first stage filter assembly and the second stage filter assembly are rotatable around a common longitudinal axis, and the system further comprises a drive assembly coupled to the first stage filter assembly and the second stage filter assembly. 
     
     
         17 . The two-stage filtration system of  claim 16 , further comprising a backwashing system having a first plurality of spray nozzles configured to spray the filtrate onto the plurality of filter discs and a second plurality of spray nozzles configured to spray the filtrate onto an inwardly facing side of the filter surface of the rotary drum. 
     
     
         18 . The two-stage filtration system of  claim 17 , further comprising a level sensor configured to provide measurements of a level of wastewater provided by the inlet to the first stage filter assembly. 
     
     
         19 . The two-stage filtration system of  claim 18 , further comprising a controller operatively coupled to the level sensor, the drive assembly, and the backwashing system, the controller configured to control at least one of the drive assembly and the backwashing system based on measurements from the level sensor. 
     
     
         20 . The two-stage filtration system of  claim 14 , wherein the filter surface of the drum filter has openings with a diameter in a range of about 20 microns to about 800 microns. 
     
     
         21 . The two-stage filtration system of  claim 20 , wherein the filter discs include a filter media with openings having a diameter in a range of about 6 microns to about 300 microns. 
     
     
         22 . The two-stage filtration system of  claim 14 , wherein the inlet is fluidly connectable with a secondary clarifier of a secondary treatment process. 
     
     
         23 . The two-stage filtration system of  claim 14 , wherein the inlet is fluidly connectable with influent to a primary treatment process. 
     
     
         24 . The two-stage filtration system of  claim 14 , wherein the second stage disc filter assembly comprises:
 a central drum configured to receive filtered wastewater from the first stage filter assembly, the central drum including a plurality of drum apertures;   a frame comprising a plurality of frame supports each having an attachment portion coupled to the central drum and a radial strut portion extending from the attachment portion, each of the plurality of frame supports defining a single frame aperture that extends through the attachment portion and along an entire length of the radial strut portion to correspond with the shape of the frame support; and   a plurality of adjacent filter segments positioned around the central drum, each of the plurality of adjacent filter segments defining a cavity in fluid communication with at least one of the plurality of drum apertures and supported at a first side by a first frame support and at a second side by a second frame support,   the plurality of frame apertures and cavities arranged to form a circumferential open fluid channel extending continuously around the central drum to enable the filtered wastewater to pass substantially unimpeded through the plurality of drum apertures and through the plurality of adjacent filter segments.   
     
     
         25 . The two-stage filtration system of  claim 24 , wherein the single frame aperture forms an inverted substantially T-shaped configuration. 
     
     
         26 . A method of treating wastewater, comprising:
 introducing the wastewater to a first-stage filtration operation comprising a barrier filter to produce filtered wastewater; and   introducing the filtered wastewater to a second-stage filtration operation comprising a disc filter to produce treated water.   
     
     
         27 . The method of  claim 26 , further comprising measuring a level of the wastewater introduced to the barrier filter of the first stage filtration operation. 
     
     
         28 . The method of  claim 27 , further comprising backwashing a filter surface of the barrier filter based on the measured level of wastewater. 
     
     
         29 . The method of  claim 26 , wherein the barrier filter comprises a rotary drum configured for radially inward fluid flow. 
     
     
         30 . The method of  claim 29 , wherein the disc filter is configured for radially outward fluid flow.