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Simulation of biowastes and biodegradable plastics co-digestion in semi-continuous reactors: Performances and agronomic evaluation
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This study looked at whether "biodegradable" plastics (like those in compostable food containers) actually break down when mixed with food waste in biogas facilities. The good news: one type (PHB) fully broke down, while the other (PLA) only partially degraded unless pretreated with a chemical bath first, meaning some biodegradable plastics may not fully disappear during typical waste processing, which matters because leftover plastic fragments could end up in the fertilizer made from this waste and spread on farmland. The upside is that adding either plastic didn't harm the quality of that fertilizer, but the findings suggest not all "biodegradable"
The development of selective biowaste collection in most European countries provides new opportunities for the anaerobic digestion sector. In parallel, extensive development of biodegradable plastics like polylactic-acid (PLA) and polyhydroxybutyrate (PHB), which facilitates the replacement of conventional plastics, has taken place in the past decade. This study investigated anaerobic co-digestion in semi-continuous reactors of biowastes (75 % Volatil Solids) and biodegradable plastics (25 % Volatil Solids, PLA and PHB). PHB was estimated to be fully biodegraded in the reactors. By contrast, PLA accumulated in the reactor, and an average biodegradation of 47.6 ± 17.9 % was estimated during the third hydraulic retention time. Pretreatment of PLA, by thermo-alkaline hydrolysis at 70 °C, with 2.5 w/v of Ca(OH)2 for 48 h, improved the biodegradation yield of PLA to 77.5 ± 9.3 %. Finally, it was highlighted that PLA or PHB addition to the feed did not further affect the agronomic properties of the digestate.
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Impact of the thermo-alkaline pretreatment on the anaerobic digestion of poly(butylene adipate-co-terephthalate) (PBAT) and poly(lactic acid) (PLA) blended plastics
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Researchers tested whether a heat-and-alkali pretreatment could improve the breakdown of biodegradable plastics PBAT and PLA through anaerobic digestion. They found that pretreatment significantly improved methane production from PLA-containing blends but had limited effect on PBAT alone, which remained resistant to digestion. The results suggest that even plastics labeled as biodegradable may not break down easily in real-world composting and waste treatment systems.
Data of studies reviewed for: "Plastic contamination in bio waste anaerobic digestion systems: understanding the role of biodegradable plastics"
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This paper compiles data from existing research on how "compostable" and biodegradable plastics behave in real-world waste treatment plants, where food scraps and yard waste are broken down into fertilizer. The findings suggest that some of these plastics don't fully break down as expected, meaning tiny plastic fragments can end up contaminating the "compost" (called digestate) that later gets spread on farmland. This matters because it means plastic labeled as "compostable" may still contribute to microplastic pollution in soil, potentially entering our food and water supply.
Plastic contamination in bio-waste anaerobic digestion systems: Understanding the role of biodegradable plastics
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This review pulls together existing research on "biodegradable" plastics used in food waste recycling systems, finding they often don't fully break down as expected, potentially leaving plastic fragments in the fertilizer made from that waste. Since this fertilizer gets spread on farmland, unresolved plastic contamination could mean more microplastics entering soil, crops, and eventually our food supply.
Chemical composition and mesophilic anaerobic digestion of commercial compostable food packaging: Implications for bio-waste management
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Not all "compostable" food packaging actually breaks down the way you'd expect: researchers tested 34 products (bags, coffee capsules, cups, forks) in conditions mimicking anaerobic digesters, and found only certain cellulose-based and PHBV-based items truly biodegraded well, while many popular "compostable" plastics like PLA barely broke down at all. This matters because packaging labeled compostable may actually persist in waste systems, potentially contributing to plastic pollution and microplastic buildup instead of safely disappearing as promised.
Numerical framework for anaerobic digestion and/or composting of bioplastics and organic waste performance evaluation under real-like large scale operating conditions
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Researchers used computer modeling to simulate how well certified biodegradable plastics — including PLA cups and starch-based bags — actually break down in real anaerobic digestion and composting facilities, finding that industrial composting alone only degrades 42–44% of PLA in 28 days. The study warns that current waste infrastructure may not be sufficient to handle the growing volumes of bioplastics, potentially leading to microplastic-like contamination of compost and soil.
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When a large batch of papers lands in the Atlas, we read through it and send a short write-up of what stood out.