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Abstract

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.

Cleavage of the main carbon chain backbone of high molecular weight polyacrylamide by aerobic and anaerobic biological treatment

“…Previous study has shown that molecular weights above 3 Â 10 3 Da was recalcitrant to microbial mineralization (El-Mamouni et al, 2002). Previous study has shown that molecular weights above 3 Â 10 3 Da are recalcitrant to microbial mineralization (El-Mamouni et al, 2002). In addition, although Bacillus (Bao et al, 2010), Acinetobacter (Matsuoka et al, 2002), Pseudomonas (Yu et al, 2015), and Clostridium (Ma et al, 2010) grew in the four reactors, their abundances were low.…”

“…PAM has been reportedly broken down by physical-chemical factors, including sunlight, chemical, mechanical, and thermal degradation (Caulfield et al, 2002;El-Mamouni et al, 2002). Since the Anaerobic 55 C system was most efficient in the degradation of PAM (Fig.…”

“…On the other hand, inlet PAM with high molecular weight is unable to pass the microbial membranes (Guezennec et al, 2015). Previous study has shown that molecular weights above 3 Â 10 3 Da was recalcitrant to microbial mineralization (El-Mamouni et al, 2002). Previous study has shown that molecular weights above 3 Â 10 3 Da are recalcitrant to microbial mineralization (El-Mamouni et al, 2002).…”

Current status on the biodegradability of acrylic polymers: microorganisms, enzymes and metabolic pathways involved

“…Assisted bioremediation techniques that involve synergy between physical, chemical, and biological methods have been tested for AP waste treatment. Some of them include photodegradation by UV radiation (El-Mamouni et al 2002), oxidation with the Fenton reagent (Zhang et al 2019), or with zerovalent iron/EDTA/air (Lu and Wei 2011), as a pretreatment for aerobic or anaerobic biological process. In most cases, pretreatment improves AP solubilization by reducing Mw; thus, hybrid technologies increase AP removal rates and enhance mineralization.…”

Waste-Activated Sludge Fermentation for Polyacrylamide Biodegradation Improved by Anaerobic Hydrolysis and Key Microorganisms Involved in Biological Polyacrylamide Removal

“…For example, PAM from soil or oilfield wastewater can be hydrolyzed as a nitrogen (i.e., amide hydrolysis) or carbon (i.e., carbon chain hydrolysis) source during an aerobic or anaerobic process. Similarly, Haveroen et al 16 , El-Mamouni et al 17 and Nakamiya et al 18 reported that PAM from sewage sludge could be hydrolyzed as a carbon or nitrogen source during an anaerobic or aerobic process ( Table S1 , Supplementary Information). However, several studies revealed that PAM from sewage sludge or riverbed mud might be difficult to hydrolyze during an anaerobic or aerobic process 15 19 .…”