In the quest to manage the growing mountain of bioplastic waste, a team of researchers has made a significant stride. Their work, published in the *Journal of Hazardous Materials Letters*, explores a dual approach to degrade polylactic acid (PLA), a popular bioplastic, using ultraviolet-C (UVC) irradiation and subcritical water extraction (SWE), followed by composting with food waste. This research, led by Christian Adi Pratama from Chulalongkorn University in Bangkok, Thailand, offers promising insights for the agriculture sector and beyond.
PLA is widely used in food packaging, disposable tableware, and agricultural films due to its biodegradable nature. However, its degradation in natural environments is slow, posing waste management challenges. The study found that UVC irradiation reduced the mechanical strength and molecular weight of PLA, with more pronounced effects on thin films than thicker materials like beverage cups. “The UVC treatment made the PLA more susceptible to further degradation processes,” explains Pratama.
The researchers then subjected the PLA cups to SWE, which drastically reduced their molecular weight, making them more amenable to biological degradation. The pulverized SWE-treated PLA was used to induce protease and esterase enzymes in a PLA-degrading bacterial consortium, EAc. This active inoculum was then introduced into a food composter to degrade UVC-treated PLA cups mixed with food waste.
The results were striking. The bioaugmented composter achieved a 42% weight loss of PLA after 56 days, compared to just 1% in a naturally attenuated composter. The residual PLA in the bioaugmented compost showed significant surface erosion and a lower molecular weight. Moreover, the bioaugmentation process enhanced bacterial diversity and community interactions, as revealed by 16S rRNA gene amplicon sequencing.
This research could have substantial commercial impacts, particularly in the agriculture sector where PLA is commonly used for mulching films and other applications. “By optimizing the degradation process, we can reduce the environmental footprint of agricultural practices that rely on bioplastics,” says Pratama. The dual approach of UVC irradiation followed by composting with an active bacterial inoculum could be scaled up to manage PLA waste more efficiently in agricultural settings.
The study also opens avenues for further research. Understanding the specific bacterial strains and enzymes involved in PLA degradation could lead to the development of more targeted and efficient bioaugmentation strategies. Additionally, exploring the economic viability of this approach at an industrial scale will be crucial for its widespread adoption.
As the world grapples with the challenges of plastic waste, innovative solutions like this dual approach offer hope. By harnessing the power of UV irradiation, subcritical water extraction, and microbial activity, we can pave the way for more sustainable waste management practices in agriculture and other sectors. The research led by Christian Adi Pratama, affiliated with the International Program in Hazardous Substance and Environmental Management (IP-HSM) and the Center of Excellence in Microbial Technology for Marine Pollution Treatment (MiTMaPT) at Chulalongkorn University, marks a significant step forward in this endeavor.