Combining photolysis and bioprocesses for mineralization of high molecular weight polyacrylamides.
The influence of ultraviolet photolysis as a pretreatment to the aerobic and anaerobic biological mineralization of a 14C-polyacrylamide was assessed using a series of radiorespirometry bioassays. The polyacrylamide studied was non-ionic with molecular weights ranging between 100,000 and 1 million. Aerobic and anaerobic biomineralization of the unphotolysed (raw) polyacrylamide was found to be only 0.60% and 0.70%, respectively, after 6 weeks of incubation, and hence indicative of the natural recalcitrance of polyacrylamide to microbial degradation. The effectiveness of UV irradiation in the physical breakdown of the polyacrylamide chain into oligomers was demonstrated by the shift in the molecular weight distribution and the positive correlation between the time of irradiation and the degree of its biological mineralization. The molecular weight fraction below 3 kD, which represents only 2% of the raw polyacrylamide, was increased to 41, 60 and 80% after 12, 24 and 48 hours of photolysis, respectively. This in turn, yielded, after 6 weeks of incubation, an aerobic mineralization of 5, 17 and 29% of 150 mg/L polyacrylamide, respectively, and an anaerobic mineralization of 3, 5 and 17%, respectively. Biomass acclimation substantially improved the specific initial rate of biomineralization of the photolysed polyacrylamides, but not the overall percentage of polyacrylamides mineralized.
El-Mamouni
Rachid
R
Biotechnology Research Institute, National Research Council Canada, 6100 Royalmount Avenue, Montreal H4P 2R2, Canada.
Frigon
Jean-Claude
JC
Hawari
Jalal
J
Marroni
Dennis
D
Guiot
Serge R
SR
D000180:Acrylic Resins / Q000737:chemistry* / Q000528:radiation effects; D000332:Aerobiosis; D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D001681:Biological Assay; D018533:Biomass; D008903:Minerals / Q000737:chemistry* / Q000528:radiation effects; D008970:Molecular Weight; D010782:Photolysis; D013997:Time Factors; D014466:Ultraviolet Rays; D014871:Water Microbiology; D000099166:Polyacrylamides
D000180:Acrylic Resins; D008903:Minerals; D000099166:Polyacrylamides