APESA, Pôle Valorisation, Cap Ecologia, 64230, Lescar, France; Université de Pau et des Pays de L'Adour / E2S UPPA / CNRS, IPREM UMR5254, Institut des Sciences Analytiques et de Physicochimie pour L'Environnement et Les Matériaux, Chimie et Microbiologie de L'Environnement, 64000, Pau, France.
Université de Pau et des Pays de L'Adour / E2S UPPA / CNRS, IPREM UMR5254, Institut des Sciences Analytiques et de Physicochimie pour L'Environnement et Les Matériaux, Chimie et Microbiologie de L'Environnement, 64000, Pau, France.
Chemosphere. 2022 Jun;297:133986. doi: 10.1016/j.chemosphere.2022.133986. Epub 2022 Feb 14.
To date, the introduction of biodegradable plastics such as PLA in anaerobic digestion systems has been limited by a very low rate of biodegradation. To overcome these limitations, pretreatment technologies can be applied. In this study, the impact of pretreatments (mechanical, thermal, thermo-acid, and thermo-alkaline) was investigated. Mechanical pretreatment of PLA improved its biodegradation rate but did not affect the ultimate methane potential (430-461 NL CH kg VS). In parallel, thermal and thermo-acid pretreatments exhibited a similar trend for PLA solubilization. Both of these pretreatments only achieved substantial solubilization (>60%) at higher temperatures (120 and 150 °C). At lower temperatures (70 and 90 °C), negligible solubilization (between 1 and 6%) occurred after 48 h. By contrast, coupling of thermal and alkaline pretreatment significantly increased solubilization at the lower temperatures (70 and 90 °C). In terms of biodegradation, thermo-alkaline pretreatment (with 5% w/v Ca(OH)) of PLA resulted in a similar methane potential (from 325 to 390 NL CH kg VS) for 1 h at 150 °C, 6 h at 120 °C, 24 h at 90 °C, and 48 h at 70 °C. Reduction of the Ca(OH) concentration (from 5% to 0.5% w/v) highlighted that a concentration of 2.5% w/v was sufficient to achieve a substantial level of biodegradation. Pretreatment at 70 and 90 °C using 2.5% w/v Ca(OH) for 48 h resulted in biodegradation yields of 73% and 68%, respectively. Finally, a good correlation (R = 0.90) was found between the PLA solubilization and its biodegradation.
迄今为止，可生物降解塑料如 PLA 在厌氧消化系统中的应用受到极低生物降解率的限制。为了克服这些限制，可以应用预处理技术。在这项研究中，研究了预处理（机械、热、热-酸和热-碱）的影响。PLA 的机械预处理提高了其生物降解率，但不影响最终的甲烷潜力（430-461NLCHkgVS）。同时，热和热-酸预处理对 PLA 的溶解表现出相似的趋势。这两种预处理仅在较高温度（120 和 150°C）下才能实现实质性的溶解（>60%）。在较低温度（70 和 90°C）下，48 小时后几乎没有发生溶解（1-6%）。相比之下，热和碱性预处理的耦合显著提高了较低温度（70 和 90°C）下的溶解率。就生物降解而言，PLA 的热-碱性预处理（5%w/vCa(OH))在 150°C 下 1 小时、120°C 下 6 小时、90°C 下 24 小时和 70°C 下 48 小时的甲烷潜力（325-390NLCHkgVS）相似。将 Ca(OH)浓度降低（从 5%降至 0.5%w/v）表明，2.5%w/v 的浓度足以实现实质性的生物降解水平。在 70 和 90°C 下用 2.5%w/vCa(OH)预处理 48 小时，分别得到 73%和 68%的生物降解率。最后，PLA 的溶解与其生物降解之间存在良好的相关性（R=0.90）。
