Dairy wastewater treatment system and method

Abstract

Systems for treating dairy wastewater. The systems typically include an equalization tank configured to receive a dairy wastewater stream; a flash pump in fluidic communication with the equalization tank to receive the dairy wastewater stream, wherein the dairy wastewater stream includes dairy wastewater and an acid; and a pipe reactor in fluidic communication with the flash pump and configured to receive the pump outlet stream. The pipe reactor is fluidically coupled to a cationic coagulant feed stream conduit to receive a cationic coagulant feed stream and fluidically coupled to a flocculation feed stream conduit to receive the flocculation feed stream. The system also includes a dissolved air flotation unit configured to produce a liquid stream by separating coagulated and/or flocculated materials from a pipe reactor outlet stream.

What is claimed is: 
     
         1 . A system for treating dairy wastewater comprising:
 an equalization tank configured to receive a dairy wastewater stream at a first pH;   a flash pump in fluidic communication with the equalization tank to receive the dairy wastewater stream and an acid, wherein a pump outlet stream comprises a mixture of the dairy wastewater stream and the acid at a second pH that is lower than the first pH;   a pipe reactor in fluidic communication with the flash pump and configured to receive the pump outlet stream, the pipe reactor fluidically coupled to a cationic coagulant feed stream conduit to receive a cationic coagulant feed stream and fluidically coupled to a first flocculation feed stream conduit to receive a first portion of a flocculation feed stream, wherein a pipe reactor outlet stream comprises the pump outlet stream, the cationic coagulant feed stream, and the first flocculation feed stream; and   a dissolved air flotation unit configured to produce a liquid stream by separating coagulated and/or flocculated materials from the pipe reactor outlet stream.   
     
     
         2 . The system of  claim 1 , wherein the second pH is sufficiently low to cause the mixture of the dairy wastewater stream and the acid to curdle. 
     
     
         3 . The system of  claim 1 , wherein the acid is an acidic byproducts of a dairy processing facility. 
     
     
         4 . The system of  claim 1 , wherein the acid is added to the dairy wastewater stream via a first acid stream and a second acid stream between the equalization tank and the flash pump, wherein the first acid stream and the second acid stream are configured to deliver the acid into the dairy wastewater stream in succession without any substances delivered into the dairy wastewater stream therebetween. 
     
     
         5 . The system of  claim 1 , further comprising a first pH meter positioned in the equalization tank, a second pH meter positioned between the equalization tank and the flash pump, a third pH meter positioned after the pipe reactor, and a fourth pH meter after the dissolved air flotation unit. 
     
     
         6 . The system of  claim 4 , wherein the second pH meter is positioned downstream of an acid inflow. 
     
     
         7 . The system of  claim 1 , wherein the pipe reactor is fluidically coupled to a first caustic feed stream conduit to receive a first portion of a caustic feed stream, wherein the pipe reactor outlet stream further comprises the first portion of the caustic feed stream. 
     
     
         8 . The system of  claim 7 , wherein the dissolved air flotation unit is configured to receive a second flocculation feed stream conduit to receive a second portion of the flocculation feed stream. 
     
     
         9 . The system of  claim 8 , wherein the liquid stream is configured to exit the dissolved air flotation unit via an exit conduit, the exit conduit fluidically coupled to a first acid feed stream conduit and a second caustic feed stream conduit to receive a first portion of the acid and a second portion of the caustic feed stream, respectively. 
     
     
         10 . The system of  claim 9 , wherein the exit conduit is further fluidically coupled to a second acid feed stream conduit and a third caustic feed stream conduit to receive a second portion of the acid and a third portion of the caustic feed stream, respectively, and wherein a first pH meter is positioned downstream the first acid stream conduit and the second caustic feed stream conduit, the first pH meter positioned upstream of the second acid feed stream conduit and the third caustic feed stream conduit. 
     
     
         11 . The system of  claim 10 , further comprising a second pH meter positioned downstream of the second acid feed stream conduit and the third caustic feed stream conduit to measure the pH of the liquid stream in the exit conduit. 
     
     
         12 . The system of  claim 1 , wherein the flocculation feed stream comprises an anionic flocculant. 
     
     
         13 . A system for treating dairy wastewater comprising:
 a first equalization tank configured to receive a dairy wastewater stream at a first pH;   a first acid feed stream conduit fluidically coupled to the first equalization tank and configured to deliver a first portion of an acid feed stream into the first equalization tank;   a first caustic feed stream conduit fluidically coupled to the first equalization tank and configured to deliver a first portion of a caustic feed stream into the first equalization tank;   a second equalization tank fluidically coupled to the first equalization tank and configured to receive a first equalization tank outlet stream comprising the dairy wastewater stream, the first portion of the acid feed stream, and the first portion of the caustic feed stream;   a second acid feed stream conduit fluidically coupled to the second equalization tank and configured to deliver a second portion of the acid feed stream into the second equalization tank;   a second caustic feed stream conduit fluidically coupled to the second equalization tank and configured to deliver a second portion of the caustic feed stream into the second equalization tank;   a flash pump in fluidic communication with the second equalization tank to receive a second equalization tank outlet stream comprising the first equalization tank outlet stream, the second portion of the acid feed stream, and the second portion of the caustic feed stream, wherein the flash pump is fluidically coupled to a pump outlet conduit to receive a pump outlet stream comprising the second equalization tank outlet stream;   a third acid feed stream conduit fluidically coupled to the pump outlet conduit and configured to deliver a third portion of the acid feed stream therein to form a mixture with a second pH that is less than the first pH;   a pipe reactor in fluidic communication with the pump outlet conduit and configured to receive the pump outlet stream and the third acid stream, the pipe reactor fluidically coupled to: a cationic coagulant feed stream conduit to receive a cationic coagulant feed stream; a first flocculation feed stream conduit to receive a first portion of a flocculation feed stream; and a second flocculation feed stream conduit to receive a second portion of the flocculation feed stream, wherein a pipe reactor outlet stream comprises the pump outlet stream, the third portion of the acid feed stream; the cationic coagulant feed stream, the first portion of the flocculation feed stream, and the second portion of the flocculation feed stream; and   a dissolved air flotation unit configured to produce a liquid stream by separating coagulated and/or flocculated materials from the pipe reactor outlet stream.   
     
     
         14 . The system of  claim 13 , wherein the first portion of the flocculation feed stream is an anionic flocculant, and the second portion of the flocculation feed stream is a cationic flocculant. 
     
     
         15 . The system of  claim 13 , further comprising a first pH meter configured to measure the pH within the first equalization tank, a second pH meter configured to measure the pH of within the second equalization tank, and a third pH meter configured to measure the pH of the pipe reactor outlet stream. 
     
     
         16 . The system of  claim 13 , wherein the dissolved air flotation unit is fluidically coupled to a liquid conduit in which the liquid stream is configured to flow therethrough, the system further including a fourth acid feed stream conduit fluidically coupled to the liquid conduit and configured to deliver a fourth portion of the acid feed stream therein, the system further including a third caustic feed stream conduit fluidically coupled to the liquid conduit and configured to deliver a third portion of a caustic feed stream therein. 
     
     
         17 . The system of  claim 16 , wherein the dissolved air flotation unit is fluidically coupled to a solid stream conduit in which sludge is configured to flow therethrough, the system further including a fifth acid feed stream conduit fluidically coupled to the solid stream conduit and configured to deliver a fifth portion of the acid feed stream therein, the system further including a fourth caustic feed stream conduit fluidically coupled to the solid stream conduit and configured to deliver a fourth portion of a caustic feed stream therein. 
     
     
         18 . The system of  claim 13 , wherein the second pH is sufficiently low to cause the mixture to curdle. 
     
     
         19 . The system of  claim 13 , wherein the acid feed stream is an acidic byproducts of a dairy processing facility. 
     
     
         20 . The system of  claim 1 , wherein the pH of the contents of the second equalization tank is maintained between 3.9 and 4.3 for an isoelectric state.