Accelerated degradation of low-density polyethylene by cold plasma activation and hydrocarbon biostimulation in...

The inherent resistance of low-density polyethylene (LDPE) to degradation leads to its continued accumulation in the natural environment. The present study evaluates an integrated approach coupling cold atmospheric plasma (CAP) pretreatment with hydrocarbon-driven biostimulation to accelerate microbial degradation of LDPE. The degradation of untreated and pretreated LDPE was analyzed in Winogradsky columns with diesel as a co-substrate. After 45 days, the system containing both pretreated LDPE and diesel (W4) showed the highest LDPE weight loss (4.22 ± 0.73%), outperforming systems with only CAP-pretreated LDPE (3.06 ± 0.99%) and untreated LDPE with diesel (1.14 ± 0.39%). The LDPE sheet in the W4 system also exhibited an increase in hydrophilicity, indicated by a reduction in the water contact angle (52.43 ± 7.15^°) as compared to the unaided system (70.03 ± 3.80^°). The appearance of carbonyl functional groups, together with ester formation detected by GC-MS, further confirmed advanced LDPE oxidation in the W4 system. The synergistic LDPE treatment resulted in a decrease in crystallinity from 0.50 ± 0.06 (untreated LDPE) to 0.39 ± 0.01. Moreover, the enzymes involved in LDPE depolymerization, including laccase, manganese peroxidase, alkane monooxygenase, and cutinase, showed elevated activity under biostimulated conditions. The LDPE-degrading microbes were dominated by Gammaproteobacteria, Bacilli, Alphaproteobacteria, and Actinobacteria. Further, the amplification of cAMP signaling, secondary metabolite biosynthesis, and the ether lipid metabolism pathway in the W4 system supported enhanced microbial adaptation to LDPE. The synergy of plasma pretreatment with biostimulation for LDPE degradation offers a low-energy, environmentally sustainable approach that surpasses the performance of each method used independently.