Method of removing recalcitrant organic pollutants

Patent metadata

Field	Value
Publication number	US-9994470-B2
Application number	US-201114003667-A
Country	US
Kind code	B2
Filing date	Mar 7, 2011
Priority date	Mar 7, 2011
Publication date	Jun 12, 2018
Grant date	Jun 12, 2018

Abstract

Recalcitrant chemical oxygen demand (COD) of a liquid is reduced in a water treatment system. The method includes pretreating the liquid in a pretreatment unit to remove indigenous bacteria or microbes to a population level below which the indigenous organisms can interfere with the screened and externally introduced microorganisms. The liquid is then provided to a reactor that has a filter bed formed with a carrier material. Special microbes are screened and used to colonize the carrier material to remove recalcitrant COD. A biofilm is cultured on the surface of the carrier material to immobilize the screened microbes in the reactor. The method further includes percolating the liquid from the pretreatment unit through the filter bed colonized with the screened microbes to degrade at least part of the recalcitrant COD under aerobic conditions. In one embodiment, the filter is formed with biological granular activated carbon (GAC) as the carrier material and the screened microbes comprise at least one microbial species selected from the group consisting of Bacillus, Comamonas, Arthrobacter, Micrococcus, Pseudomonas, Pediococcus, Achromobacter, Flavobacterium, Mycobacterium, Rhodanobacter, Stenotrophomonas and Yeast.

First claim

What is claim is:

1. A method for reducing the recalcitrant chemical oxygen demand (COD) of a liquid in a water system, the method comprising the steps of:
providing a reactor having a filter bed with carrier material disposed therein;
screening microbes that can remove recalcitrant COD and colonizing said carrier material with said screened microbes, wherein the screened microbes comprise externally introduced microbes;
culturing a dense biofilm on the carrier material surface to immobilize said screened microbes in said filter bed;
pretreating said liquid in a pretreatment unit to reduce the amount of indigenous bacteria or microbes in said liquid to a population level below which said indigenous bacteria or microbes will interfere with said screened microbes that have been colonized on said carrier material;
percolating the liquid from said pretreatment unit through said filter bed colonized with said screened microbes for a retention time sufficient to degrade at least a portion of said recalcitrant COD under aerobic conditions; and
dosing a growth substrate comprising phenolic compounds and derivatives thereof on the surface of the carrier material to activate and produce enzymes to maintain biofilm formation and induce cometabolism with the screened microbes thereby enhancing the removal of the recalcitrant COD by at least about 35%, wherein a concentration of the growth substrate in the percolated liquid is less than about 50 mg/L such that the growth substrate is fully consumed in the reactor during removal of said recalcitrant COD.

2. The method of claim 1 wherein the liquid to be treated has been sufficiently treated in prior steps so that a ratio of a 5-day biochemical oxygen demand (BOD 5 ) to the COD of the liquid is less than 0.2.

3. The method of claim 1 wherein the liquid to be treated has been sufficiently treated in prior steps so that a 5-day biochemical oxygen demand (BOD 5 ) of the liquid is less than 30 mg/L.

4. The method of claim 1 wherein the carrier material filled in the reactor is of any type of carriers that can be used for microbial immobilization to form a biofilm and effectively adsorb at least part of the recalcitrant COD of the liquid.

5. The method of claim 4 wherein the carrier material filled in the reactor is a member chosen from the group consisting of activated carbon containing materials, lignite, zeolites, and synthetic adsorbent materials.

6. The method of claim 4 wherein the carrier material filled in the reactor is a granular activated carbon (GAC).

7. The method of claim 1 wherein the screened microbes comprise at least one microbial species selected from the group consisting of Bacillus, Comamonas, Arthrobacter, Micrococcus, Pseudomonas, Pediococcus, Achromobacter, Flavobacterium, Mycobacterium, Rhodanobacter, Stenotrophomonas and yeast.

8. The method of claim 1 wherein the liquid to be treated is treated in prior steps comprising treating the liquid using processes selected from activated sludge, clarification, membrane bioreactor and filtration.

9. The method of claim 1 wherein air sparging or other means of oxygenation is used to provide oxygen during the culturing step to provide for biofilm formation and for biodegradation of the recalcitrant COD.

10. The method of claim 1 wherein the liquid is percolated through the filter bed for a retention time of less than 10 hours.

11. The method of claim 1 wherein the liquid is percolated through the filter bed for a retention time of less than 5 hours.

Assignees

• Wang Sijing
• Cheng Zhonghong
• Xu Weiqing
• Gen Electric

Inventors

• Wang Sijing
• Cheng Zhonghong
• Xu Weiqing

Classifications

• C02F3/106

  Carbonaceous materials · CPC title

• C02F1/283

  using coal, charred products, or inorganic mixtures containing them · CPC title

• C02F3/348 Primary

  characterised by the way or the form in which the microorganisms are added or dosed · CPC title

• C02F3/06 Primary

  using submerged filters · CPC title

• C02F3/34

  characterised by the microorganisms used · CPC title