Process for treating waste water containing cellulose nitrate particles

• US 3,939,068 A
• Filed: 02/04/1975
• Issued: 02/17/1976
• Est. Priority Date: 12/06/1973
• Status: Expired due to Term

• Current Assignee: The United States Of America As Represented By The Secretary Of The Army
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Kaplan, Arthur M., Wendt, Theodore M.
• Primary Examiner(s): Hart, Charles N.
• Assistant Examiner(s): Hruskoci, Peter A.
• Application Number:
  US05/546,953
• Time in Patent Office: 378 Days
• Field of Search: 210/2-7, 210/11, 210/12, 210/15, 210/16, 210/18, 210/59, 210/60, 210/DIG. 27
• US Class Current: 210/605
• CPC Class Codes: C02F 3/302 Nitrification and denitrification treatment C02F3/308 takes precedence
• CPC Class Codes: Y10S 210/903 Nitrogenous
• CPC Class Codes: Y10S 210/919 using combined systems by merging parallel diverse waste systems

Abstract

Total removal of cellulose nitrate particles from a waste water stream is accomplished by a combination of chemical and biological treatments which result in an effluent having a greatly reduced concentration of nitrogen compounds and having an acceptable BOD. The first step in the process requires that the insoluble, non-biodegradable cellulose nitrate particles be chemically digested with alkali to produce soluble products. Following digestion, the waste stream is supplemented with domestic raw sewage and a microbially utilizable carbon source and the supplemented waste stream is subjected first to an anaerobic microbial denitrification treatment to eliminate the oxidized forms of nitrogen and then to an aerobic microbial treatment to reduce BOD and to oxidize reduced nitrogen compounds. The effluent therefrom is again supplemented with a microbially utilizable carbon source and subjected to a final anaerobic microbial denitrification to remove nitrates present in the waste water resulting from nitrification processes occurring during the aerobic treatment step.

Claims

1. A process for treatment of a waste stream from nitrocellulose manufacture containing at least 50 ppm of insoluble, non-biodegradable nitrocellulose material which comprises the following steps taken in sequence:

a. chemically digesting by reacting with alkali at a pH of at least 11.5 said insoluble nitrocellulose material in said waste stream to convert said insoluble material to soluble and biodegradable organic and nitrate products,

b. neutralizing said waste stream upon completion of said chemical digestion to a pH within the range of about 6.0 to 9.0,

c. combining said neutralized waste stream with domestic raw sewage and with a microbially utilizable carbon material to form a mixed liquor, said raw sewage added in sufficient quantity to reduce the nitrate content of the mixed liquor to less than 200 ppm and said carbon material added in sufficient quantity to sustain microbial denitrification of substantially all nitrates in the mixed liquor,

d. microbially denitrifying said liquor to convert the nitrate content of said mixed liquor to nitrogen gas, and thereafter separating solids from said liquor,

e. subjecting the solids-free liquor from step (d) to an aerobic microbial treatment to break down the organic products and to convert reduced nitrogen compounds present in said liquor to nitrates, and

f. microbially denitrifying the effluent from step (e) to reduce the nitrate compounds to nitrogen gas and to provide a substantially nitrate-free effluent having an ecologically acceptable BOD level.

2. A process according to claim 1 wherein said insoluble nitrocellulose material is digested with alkali at a temperature of at least 60°

C.

3. A process according to claim 2 wherein sufficient microbially, utilizable carbon material is added to the denitrifying step (f) to sustain denitrification of substantially all nitrates in said final denitrification step.

4. A process according to claim 3 wherein after microbial denitrification in step (f) any remaining solid products are allowed to settle and this solid material is then combined with the material undergoing the aerobic microbial treatment of step (e).

5. A process according to claim 4 wherein after microbial denitrification step (d) solids are separated and returned for further denitrification in step (d).

6. A process according to claim 5 wherein the microbial utilizable carbon material is selected from the group consisting of methanol, ethanol, acetone, sugar, glucose, acetic acid and mixtures thereof.

7. A process according to claim 6 wherein microbial denitrification occurs in an anaerobic activated sludge system and the aerobic microbial treatment occurs in an aerated activated sludge system.

8. A process for the treatment of waste water from nitrocellulose manufacture containing at least 50 ppm of nitrocellulose fines which comprise the following steps in sequence:

a. treating said waste water containing insoluble, nonbiodegradable nitrocellulose fines with alkaline material at a pH of at least 11.5 to digest said nitrocellulose to soluble organic and nitrate products and then neutralizing the alkaline waste water to a pH within the range of about 6.0 to 9.0,

b. combining the neutralized nitrocellulose digested waste water with domestic raw sewage and with a microbially utilizable carbon material to form a mixed liquor, said raw sewage added in an amount sufficient to reduce the nitrate content of the mixed liquor to less than 200 ppm and said carbon material added in an amount sufficient to sustain microbial denitrification of substantially all nitrates in the mixed liquor,

c. microbially denitrifying said mixed liquor under conditions in which there is insufficient oxygen to satisfy the microorganisms in the mixed liquor to convert the nitrate content of said mixed liquor to nitrogen gas, and thereafter separating solids from said liquor,

d. aerating said denitrified mixed liquid at a rate and for a time sufficient to cause aerobic microbial reduction of the organic products and to convert reduced nitrogen compounds present in said liquor to nitrates, and

e. combining said mixed liquor from step (d) with a microbial utilizable carbon source and microbially denitrifying this mixture under conditions in which there is insufficient oxygen to satisfy microorganisms in the mixture to convert the nitrate compounds to nitrogen gas and providing a substantially nitrate-free effluent having an ecologically acceptable BOD.

9. A process for the treatment of waste water containing nitrocellulose fines according to claim 8 wherein a microbially utilizable carbon source is added to the mixed liquor from the aeration step in sufficient quantity to sustain microbial denitrification of substantially all nitrates in the final denitrification step.

10. A process for the treatment of waste water containing nitrocellulose fines according to claim 9 wherein after denitrification step (c), the solids in the liquor are allowed to separate and are returned for further denitrification in step (c) and after denitrification step (e) the solids are allowed to settle and are then combined with the material undergoing the aerobic microbial treatment.

11. A process for the treatment of waste water containing nitrocellulose fines according to claim 10 wherein the microbially utilizable carbon material is selected from the group consisting of methanol, ethanol, acetone, sugar, glucose, acetic acid and mixtures thereof.

12. A process for the treatment of waste water containing nitrocellulose fines according to claim 11 wherein the alkaline material is sodium hydroxide.