Reactive electrochemical membrane filtration

Patent metadata

Field	Value
Publication number	US-2017334751-A1
Application number	US-201715589219-A
Country	US
Kind code	A1
Filing date	May 8, 2017
Priority date	May 18, 2016
Publication date	Nov 23, 2017
Grant date	—

Abstract

A system and method for algal harvesting and destabilization are provided. The system includes a multifunctional reactive electrochemical membrane (REM). The application of an electrical current generates reactive species at the REM surface and oxidizes algae and soluble organic compounds. This novel type of membrane filtration avoids the use of harmful chemical additives. In addition, it provides the benefits of avoiding polymer aging, membrane fouling, and high costs caused by high transmembrane pressures and frequent membrane cleaning. Traditional membrane separation that significantly suffers from membrane fouling due to either the formation of a cake layer of algal cells, or more commonly due to organic matter adsorption onto the membrane surface is significantly avoided.

First claim

What is claimed is:

1 . An electrochemical membrane filtration system for water purification and biomass separation, comprising:
a multifunctional reactive electrochemical membrane (REM) having a porous substance and a filtration REM surface, the membrane acting as an electrode and disposed in a filtration tank; an electrically conductive mesh having a mesh surface and surrounding the membrane and performing as a counter electrode to the membrane; and a power source connected to the membrane and the mesh wherein an electrical current generates reactive species at the REM surface and oxidizes algae and soluble organic compounds.

2 . The electrochemical membrane filtration system in claim 1 , wherein the membrane is made of ceramic material.

3 . The electrochemical membrane filtration system in claim 2 , wherein the ceramic is sub-stoichiometric titanium oxide (Ti 4 O 7 ).

4 . The electrochemical membrane filtration system in claim 1 , wherein the membrane is made of a conductive material in the form of tube or flat membrane.

5 . The electrochemical membrane filtration system in claim 1 , wherein the mesh is a stainless steel mesh.

6 . The electrochemical membrane filtration system in claim 1 , wherein the mesh completely surrounds the membrane.

7 . The electrochemical membrane filtration system in claim 1 , wherein the power source is an AC power, or a DC power, or a combination of AC/DC power, and is used to polarize the membrane or a mesh surface to generate radicals for organic compound degradation and removal and repulsion of surface foulants.

8 . The electrochemical membrane filtration system in claim 7 , wherein surface radicals are generated by applying an AC current intermittently at a radio frequency of 100 to 500 MHz to polarize the membrane surface or the mesh surface or both the membrane and mesh surfaces for inducing oxidant or radical production and electrostatic repulsion against potential foulants.

9 . The electrochemical membrane filtration system in claim 7 , wherein the AC or DC power is applied continuously.

10 . The electrochemical membrane filtration system in claim 7 , wherein surface radicals are generated by applying an DC polarization from 50 A·m −2 to 250 A·m −2 or approximately 10 to 22 V of cell voltage, wherein 0.0045 mM to 0.022 mM chlorine is generated on a cathode surface within 2 hours in the presence of chlorine (Cl − ) and 8 μM to 55 μM H 2 O 2 is generated on an anode surface.

11 . The electrochemical membrane filtration system in claim 1 , further including a baffle settling tank in communication with the filtration tank, wherein the baffle settling tank is used for a pre-settling process to concentrate biomass.

12 . An electrochemical membrane filtration system for water purification and biomass separation, comprising:
a multifunctional reactive electrochemical membrane (REM) having a porous sub-stoichiometric titanium oxide (Ti 4 O 7 ) substance and a filtration REM surface, the membrane acting as an electrode and disposed in a filtration tank; a stainless steel mesh having a mesh surface and surrounding the membrane inside the filtration tank, wherein the mesh is a counter electrode to the membrane; a baffle settling tank for receiving a biomass feed and concentrating algal biomass, the baffle settling tank in communication with the filtration tank; a receiving tank in communication with the membrane and containing filtered water from the filtration tank; and a power source connected to the membrane and the mesh wherein an electrical current generates reactive species at the REM surface and oxidizes algae and soluble organic compounds.

13 . The electrochemical membrane filtration system in claim 12 , further including a three-way valve disposed between the membrane and reeving tank, wherein the three-way valve switches between a permeate discharge position and a backwash water position to withdraw water from the receiving tank.

14 . The electrochemical membrane filtration system in claim 12 , wherein the receiving tank further includes a water level sensor or an absorption sensor.

15 . The electrochemical membrane filtration system in claim 14 , further including a controller in communication with the water level sensor or absorption sensor, wherein the controller receives at least one process parameter, and adjusts operation of the system based upon processing of the at least one process parameter.

16 . The electrochemical membrane filtration system in claim 15 , further including a flow meter disposed between the membrane and the receiving tank.

17 . The electrochemical membrane filtration system in claim 16 , wherein surface fouling or pore clogging on the membrane is indicated by the changes of a permeate flux measured by the flow meter or the water level sensor, and backwash is performed together with DC or AC polarization when the permeate flux declines.

18 . A method of using an electrochemical membrane filtration system for water purification and biomass separation, comprising:
receiving a biomass feed in a baffle settling tank, and separating the biomass feed into a biomass suspension and a concentrated biomass; transporting concentrated biomass from the bottom of the baffle settling tank to a waste facility; transporting the biomass suspension to a filtration tank, wherein the filtration tank includes a multifunctional reactive electrochemical membrane (REM) having a porous sub-stoichiometric titanium oxide (Ti 4 O 7 ) substance and a filtration REM surface, the membrane acting as an electrode and disposed in the filtration tank; and a stainless steel mesh having a mesh surface and surrounding the membrane inside the filtration tank, wherein the mesh is a counter electrode to the membrane, and wherein the membrane and the mesh are connected to a power source; filtering the biomass suspension through the membrane, and applying an electrical current from the power source to generate reactive species at the membrane surface or mesh surface or both the membrane and mesh surfaces to oxidize algae and soluble organic compounds in the biomass suspension.

19 . The method in claim 18 , further comprises transporting clean water from the filtration tank to a receiving tank.

20 . The method in claim 19 , further comprises
detecting surface fouling or pore clogging on the membrane is by changes of permeate flux measured by a flow meter or a water level sensor in the receiving tank; and performing a backwash by withdrawing water from the receiving tank into the membrane to physically cleanse membrane pores together with applying DC or AC polarization to maximize foulant removal and permeate recovery by promoting surface radicals generation and oxidation of surface foulants.

Assignees

• New Jersey Inst Technology

Inventors

• Zhang Wen
• Hau Likun

Classifications

• C02F3/1273

  Submerged membrane bioreactors · CPC title

• C02F1/4672

  by electrooxydation · CPC title

• C02F2001/46171

  Cylindrical or tubular shaped · CPC title

• C02F2001/46157

  Perforated or foraminous electrodes · CPC title

• C02F3/322

  use of algae · CPC title