Steam Treatment of Waste Polylactid Acid (PLA) Based Products for Lactic Acid Recovery Steam Treatment of Waste Polylactid Acid (PLA) Based Products for Lactic Acid Recovery

Abstract-Thermal treatment of 2.5 grams (dry weight) and 7.5 grams (dry weight) batches of Polylactic acid (PLA)-product waste was carried out at 121 oC and 160 oC and exposed to different treatment time periods. Molecular weight reduction was not affected by the amount of PLA material loaded. Rate of molecular weight reduction was about six times faster at 160 oC than at 121 oC. Complete depolymerization of the PLA-product waste was not possible at the temperatures used here. A maximum recovery (yield) of lactic acid of 35% was obtained at a loading of 7.5 g, temperature at 121 °C and exposure time of 720 min. At 160°C , recovery was 25% but obtained within 120 minutes. Results suggest that PLA-product waste behaviour will differ from pure PLA pellet. With PLA-product waste complete lactic acid recovery was not possible and other by-products like acetic and propionic acids were produced from thermal treatment. Keywords Abstract-Thermal treatment of 2.5 grams (dry weight) and 7.5 grams (dry weight) batches of Polylactic acid (PLA)-product waste was carried out at 121 o C and 160 o C and exposed to different treatment time periods. Molecular weight reduction was not affected by the amount of PLA material loaded. Rate of molecular weight reduction was about six times faster at 160 o C than at 121 o C. Complete depolymerization of the PLA-product waste was not possible at the temperatures used here. A maximum recovery (yield) of lactic acid of 35% was obtained at a loading of 7.5 g, temperature at 121 °C and exposure time of 720 min. At 160°C , recovery was 25% but obtained within 120 minutes. Results suggest that PLA-product waste behaviour will differ from pure PLA pellet. With PLA-product waste complete lactic acid recovery was not possible and other by-products like acetic and propionic acids were produced from thermal treatment

Anaerobic digestion of sugar beet pulp after acid thermal and alkali thermal pretreatments

In this study, biogas production was investigated in mesophilic conditions from sugar beet pulp (SBP). In untreated conditions, water dissolution rate was 15.5% and biogas production rate was 168.7 mL/g TS (total solid). Alkaline thermal pretreatments were applied at 100 °C with 3 N NaOH and KOH solutions. Amounts of alkaline and acid were added in an amount equal to 5%, 10%, 15%, 20%, and 30% of the solids in the reactor. Acid thermal pretreatments were applied at 100 °C with 5% (v/v) H2SO4 and HNO3 solutions. The anaerobic digestion (AD) time was shortened by approximately 10 days after pretreatment. The highest biogas yield was 458.4 mL/g TS as a result of KOH thermal pretreatment. In this reactor, soluble chemical oxygen demand (sCOD) removal was 87.1%, and cellulose, hemicellulose, and lignin removals were 32.4%, 28.6%, and 33.5% w/w, respectively. It was observed that the cumulative biogas production (CBP) successfully fitted the modified Richards (MR) model and modified Gompertz (MG) model. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.Sivas Cumhuriyet Üniversitesi: CUBAP-M-665The financial support of this study was provided by the scientific research projects unit of the Cumhuriyet University (CUBAP-M-665). We would like to thank you for your contribution to the related institution