Identification of Biodegradable, Compostable or Toxic Plastic Bags with Two Beetles of the Tenebrionidae Family

Abstract

Various studies have demonstrated the environmental problems caused by plastic bags (PB) made with hydrocarbons, and therefore international policies have been established to replace the use of conventional PB by biobags or compostable bags, which are designed to be biodegradable and/or composted in the environment. However, the methods used to characterize such bags are still far from being effectively assessed. This study evaluated a technique to identify biodegradable, compostable and/or toxic PB by feeding compostable bags certified by recognized institutions to larvae of the Tenebrionidae family, particularly Tenebrio molitor and Zophobas morio species. Three brands of single-use bags were studied, and the following parameters were evaluated: rate of consumption (of bags by larvae), percentage of biomass (weight increase in larvae), percentage of survival (percentage of larvae eating bags), percentage of biodegradability by evaluating the total organic carbon (TOC) in stool, and stool analysis by spectroscopy and spectrometry. The results showed differences between the rate of consumption, the EHappy bag being the most consumed; there were differences in the percentage of biomass, the EHappy bag showing less potential for biomass increase; both species showed lower survival with the Ealternative bag. TOC evaluation indicated that the WCare bag presents the highest biodegradability; the total reflectance attenuated infrared analysis showed a decrease in the representative peaks of the spectrum of PB, evidencing biodegradation; and the amount of metals in feces was found within the Maximum Permissible Limits. The two species showed a good performance, demonstrating that they can be used as a suitable and viable tool to evaluate toxicity, biodegradability and compostability.