Alternative ways of foamed polystyrene recycling using insects as an element of sustainable development

Abstract

Pursuant to the principles of sustainable development, so as not to diminish the chances of living on our planet for future generations, special attention should be paid to certain aspects of our economy, including waste management. This paper presents an alternative way of recycling Styrofoam, by employing larvae of one of the common warehouse pests, the mealworm beetle (Tenebrio molitor L.). The aims of the research were to assess the biometric and enzymatic parameters of T. molitor larvae fed on Styrofoam, and to evaluate their possible use to decompose polystyrene waste. The experiment consisted of maintaining larvae for 10 weeks on nutrient substrates composed of foamed polystyrene (the control substrate was composed of oatmeal flakes). During the experiment, the mass of insects and the mass of ingested substrate were controlled. On the termination of the culture, digestive tracts of larvae from each replication was dissected to determine the enzymatic activity of the digestive system cells. To the biochemical analyses were made using the API® type assays. It has been demonstrated that owing to the enzymatic activity of the larval digestive tract and that of the gut microflora, mealworm larvae were able to digest waste slow to biodegrade, including polystyrene. A solution has been proposed, where providing suiTable conditions it will be possible to use mealworm larvae to utilise polystyrene waste.

The Ability of Insects to Degrade Complex Synthetic Polymers

“…It has also been opined that besides Exiguobacterium sp., a variety of microorganisms play an essential role in the digestion process of mealworms [71,72]. The information indicates that PS biodegradation and mineralisation occur within the gut of yellow mealworms [73]. During consumption, the larva generally produce hollows in Styrofoam samples, resulting in a decrease in Styrofoam mass [17] and the resultant small fragments of Styrofoam samples have an increased surface area.…”

Biodegradation of typical plastics and its mechanisms

“…此外, 塑料会影响肠道菌群的丰度, 引起肠道 微生物组成和消化酶活性产生差异 [53] . 例如, 以PS为食 的黄粉虫幼虫肠道内的β-半乳糖苷酶、精氨酸双水解 酶等酶活性比以麦麸为食的黄粉虫幼虫更高, 这是由 于黄粉虫幼虫具有高度适应性, 摄食PS会导致其肠道 微生物的快速繁殖, 从而增强对PS的消化能力 [54] [26] . 这可能与塑料的密度、塑料自身的 结构或者肠道微生物的组成有关 [27,51] .…”