Method for the preparation of biopolymers

Abstract

The present invention relates to a method of preparing and separating biopolymers and biopolymer fractions useful for wastewater treatment applications from sewage sludge comprising the steps of disrupting the bacterial cell walls of bacteria present in the sewage sludge by at least 75% to release the intracellular contents of the bacterial cells and separating the biopolymers from any contaminants present.

1 . A method of preparing and separating biopolymers and biopolymer fractions from sewage sludge, the method comprising the following steps:
 i) disrupting the bacterial cell walls of bacteria present in the sewage sludge by at least 75% to release the intracellular contents of the bacterial cells; and   ii) separating the biopolymers from any contaminants present.   
     
     
         2 . A method according to  claim 1  further comprising the step of:
 removing extracellular polymeric substances (EPS) from the bacterial cells in the sewage sludge prior to disrupting the bacterial cell walls. 
 
     
     
         3 . A method according to  claim 1  or  2  further comprising the step of:
 precipitating the soluble biopolymers from the cell lysate prior to separating the biopolymers from any contaminants present. 
 
     
     
         4 . A method according to  claim 3  wherein the soluble biopolymers precipitated comprise nucleic acids. 
     
     
         5 . A method according to  claim 1  or  2  wherein the cell lysate is anaerobically digested and peptidoglycan present in the cell lysate is separated and isolated. 
     
     
         6 . A method according to any of  claims 1  to  5  wherein the sewage sludge is a biological sludge. 
     
     
         7 . A method according to any of  claims 1  to  6  wherein the ruptured bacterial cell walls are ground to disperse or dissolve peptidoglycan present therein. 
     
     
         8 . A method according to any of  claims 1  to  7  wherein the extracellular polymeric substances (EPS) are removed using a mechanical means. 
     
     
         9 . A method according to any of  claims 1  to  7  wherein the extracellular polymeric substances (EPS) are removed using a chemical means. 
     
     
         10 . A method according to any of  claims 1  to  7  wherein the extracellular polymeric substances (EPS) are removed using enzyme treatments. 
     
     
         11 . A method according to any of the preceding claims wherein the bacterial cell walls are disrupted by means of one or more of: ultra-sonication, and/or bead mills, and/or caustic treatments. 
     
     
         12 . A method according to any of the preceding claims wherein peptidoglycan present in the cell lysate is separated and isolated from the cell DNA. 
     
     
         13 . A method according to  claim 12  wherein the cell lysate is anaerobically digested. 
     
     
         14 . A method according to  claim 12  wherein the cell lysate is filtered. 
     
     
         15 . A method according to any of  claims 1  to  14  wherein the biopolymers are treated before, during or post the precipitation step with one or more chemicals. 
     
     
         16 . A method for the preparation and separation of biopolymers and biopolymer fractions from sewage sludge, the method comprising the following steps:
 i) removing extracellular polymeric substances (EPS) from bacteria cells in the sewage sludge;   ii) disrupting the bacterial cell walls by at least 75% to release the intracellular contents of the bacterial cells;   iii) precipitating soluble biopolymers to form a cell lysate and separating the biopolymers from any contaminants present.   
     
     
         17 . Use of DNA isolated using the method of any of  claims 1  to  16  as flocculants and coagulants. 
     
     
         18 . Use of peptidoglycan isolated using the method of any of  claims 1  to  16  as flocculants and coagulants.