System and method for the treatment of wastewater

Abstract

A system and method for the treatment of wastewater. In one aspect, the invention can be a method of treating wastewater comprising: a) introducing wastewater having a first turbidity level into a wastewater treatment system; b) injecting an aqueous polymer mixture into the wastewater to flocculate suspended solids within the wastewater; and c) removing the flocculated suspended solids from the wastewater to form a treated water having a second turbidity, the second turbidity being lower than the first turbidity.

What is claimed is: 
     
         1 . A method of treating wastewater comprising:
 a) flowing the wastewater along an axis of a treatment line;   b) measuring a turbidity level of the wastewater;   c) forming an aqueous polymer mixture comprising water and a polymer, the aqueous polymer mixture being formed to have a concentration of the polymer that is based on the measured turbidity level and a flow rate of the wastewater through the treatment line;   d) injecting the aqueous polymer mixture into the wastewater in the treatment line at a flow rate that is based on the flow rate of the wastewater and the measured turbidity level, the aqueous polymer mixture being injected into the treatment line at multiple injection points to flocculate suspended solids within the wastewater, the multiple injection points arranged in a circumferentially spaced apart manner about the axis, wherein the aqueous polymer mixture is injected into the wastewater in a direction transverse to the axis by each of the multiple injection points, wherein the multiple injection points comprise a first injection point, a second injection point, a third injection point, and a fourth injection point, the first and third injection points located within a first plane that is transverse to the axis and being oriented at an obtuse angle relative to one another, the second and fourth injection points located within a second plane that is transverse to the axis and being oriented at an obtuse angle relative to one another, the first and fourth injection points being circumferentially spaced apart by 180°, and the first and second planes being spaced apart from one another along the axis; and   e) removing the flocculated suspended solids from the wastewater to form a treated water.   
     
     
         2 . The method of  claim 1  wherein the first, second, third, and fourth injection points are all positioned along a first 180° are about the axis and wherein a second 180° are about the axis is free of an injection point. 
     
     
         3 . The method of  claim 1  wherein the first injection point comprises a first polymer injection nozzle, the second injection point comprises a second polymer injection nozzle, the third injection point comprises a third polymer injection nozzle, and the fourth injection point comprises a fourth polymer injection nozzle; and wherein flow of the aqueous polymer mixture through each of the first, second, third and fourth polymer injection nozzles is adjustable independent of the others of the first, second, third and fourth polymer injection nozzles. 
     
     
         4 . The method of  claim 1  wherein step c) comprises mixing the polymer with a re-circulated portion of the treated water. 
     
     
         5 . The method of  claim 1  further comprising:
 wherein step b) comprises repetitively measuring the turbidity level of the wastewater using a turbidity sensor; and 
 wherein the concentration of the polymer in the aqueous polymer mixture formed in step c) is adjusted using a controller based on changes of the measured turbidity level. 
 
     
     
         6 . A method of treating wastewater comprising:
 a) flowing the wastewater along an axis through a polymer injector operably coupled to a treatment line, the polymer injector comprising a plurality of injector nozzles arranged in a circumferentially spaced apart manner about the axis, each of the plurality of injector nozzles located within a first plane that is transverse to the axis;   b) measuring a turbidity level of the wastewater upstream of the polymer injector;   c) forming an aqueous polymer mixture comprising water and a polymer, the aqueous polymer mixture being formed to have a concentration of the polymer that is based on the measured turbidity level and a flow rate of the wastewater through the treatment line;   d) injecting the aqueous polymer mixture into the wastewater at a flow rate based on the flow rate of the wastewater and the measured turbidity level, the aqueous polymer mixture being injected into the wastewater via the plurality of injector nozzles to flocculate suspended solids in the wastewater, wherein flow of the aqueous polymer mixture through each of the plurality of injector nozzles is adjustable independent of the other ones of the plurality of injector nozzles;   e) removing the flocculated suspended solids from the wastewater to form a treated water;   f) re-circulating a portion of the treated water; and   g) mixing the re-circulated portion of the treated water with a raw polymer prior to any mixing of the re-circulated portion of the treated water with the untreated wastewater to form the aqueous polymer mixture that is injected in step d).   
     
     
         7 . The method of  claim 6  wherein step d) further comprises injecting the aqueous polymer mixture into the wastewater in a direction towards the axis, and wherein the plurality of injector nozzles are arranged in a circumferentially equi-spaced apart manner about the axis. 
     
     
         8 . The method of  claim 6  wherein the plurality of injector nozzles are oriented so that the aqueous polymer mixture is injected into the wastewater in a direction transverse to the axis. 
     
     
         9 . The method of  claim 6  wherein a first set of the plurality of injector nozzles is located within a first plane that is transverse to the axis and a second set of the plurality of injector nozzles is located within a second plane that is transverse to the axis, the first and second planes being spaced apart from one another along the axis. 
     
     
         10 . The method of  claim 6  wherein step c) comprises mixing the polymer with the re-circulated portion of the treated water. 
     
     
         11 . A system for treating wastewater comprising:
 a treatment line having an inlet for introducing wastewater into the system at a flow rate and an outlet for discharging treated water from the system;   a turbidity sensor operably coupled to the treatment line to measure a turbidity level of the wastewater;   a first polymer injector operably coupled to the treatment line downstream of the turbidity sensor to introduce a first aqueous polymer mixture into the treatment line at a flow rate; and   the system configured to automatically adjust the flow rate of the first aqueous polymer mixture injected into the treatment line based on the measured turbidity level and the flow rate of the wastewater.   
     
     
         12 . The system of  claim 11  further comprising:
 a pH sensor operably coupled to the treatment line upstream of the first polymer injector to measure a pH level of the wastewater; 
 a pH adjustment chemical injector operably coupled to the treatment line to introduce a pH adjustment chemical into the treatment line; and 
 wherein the system is configured to adjust a flow rate at which the pH adjustment chemical is introduced into the treatment line based on the measured pH level and a flow rate of the wastewater. 
 
     
     
         13 . The system of  claim 12  wherein the pH adjustment chemical is introduced into the treatment line upstream of the first polymer injector. 
     
     
         14 . The system of  claim 13  further comprising a separator operably coupled to the treatment line downstream of the first polymer injector to remove the flocculated suspended solids from the wastewater to form the treated water. 
     
     
         15 . The system of  claim 14  further comprising a recirculation line operably coupled to the treatment line downstream of the separator and to the first polymer injector, the recirculation line recirculating at least a portion of the treated water. 
     
     
         16 . The system of  claim 15  further comprising a first raw polymer tank containing a first raw polymer operably coupled to the recirculation line, and wherein the system is configured to introduce the first raw polymer into the recirculation line to form the first aqueous polymer mixture. 
     
     
         17 . The system of  claim 16  further comprising a second polymer injector operably coupled to the treatment line downstream of the first polymer injector to introduce a second aqueous polymer mixture into the treatment line at a flow rate. 
     
     
         18 . The system of  claim 17  wherein the system is configured to automatically adjust the flow rate of the second aqueous polymer mixture being injected into the treatment line based on the measured turbidity level and the flow rate of the wastewater. 
     
     
         19 . The system of  claim 18  further comprising a second raw polymer tank containing a second raw polymer operably coupled to the recirculation line, and wherein the system is configured to introduce the second raw polymer into the recirculation line to form the second aqueous polymer mixture. 
     
     
         20 . The system of  claim 19  wherein the system is further configured to selectively inject the second aqueous polymer mixture into the treatment line through one of the second polymer injector or a third polymer injector, the second polymer injector being upstream of the third polymer injector.