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Tham khảo tài liệu 'advances in applied biotechnology part 3', khoa học tự nhiên, công nghệ sinh học phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Total Recycle System of Food Waste for Poly-L-Lactic Acid Output 29 The proposed PLLA process has an energy advantage over even the general poly-lactide process because the feedstock is totally food waste. In the process with corn starch nearly 30 of gross fossil energy use goes into producing and processing corn to provide dextrose to feed the lactic acid fermentation. Since the feedstock to the proposed PLLA process is food waste that must otherwise be disposed of the only upstream fossil energy allocated to the production of PLLA would be that required for collection of the separated waste Sakai 2004b 2007 . Water 16kg Residue from esterification w --.v Butyl-esterificalion ----- ------- 25kg -------- Discharge 79kg I Ammonia I I 2. lkg meso-Lactide I Ukg --- A Food waste . 100kg rPropionic acid fermentation I I Saccharification I Lactic acid fermentation t I Filter press I f Fermentation residue Concentrated broth 163kg I Distillation I ------- I I n-Butanol I Hydrolysis I-------- I Watcr i L-Lactic acid 1 ----- ị I Pre-polymer ---------------J- 1 .sip I Distillation-CrystalBzation p I LL-Lactide I Ĩ w I Ring-Opening jjolymenzation Poly-L-lactic acid -------------------------J 7.0kg Fig. 5. Process outline of PLLA production from food waste A Food waste B concentrated broth after lactic acid fermentation C Purified L-lactic acid D Fermentation residue E Pellets of PLLA. Optical purity 97.5 Average molecular weight 200kDa Melting point 175 C Glass transition temperature 58 C Table 4. Characteristics of PLLA produced from collected food waste. The material balance and energy requirements of the total process are summarized in Table 5. The overall experimental process yielded 68.8 g PLLA from 1 kg food waste 1.0 kg PLLA 14.6 kg food waste . This means that 34 of total carbon in the food waste was recovered as PLLA. In comparison the first commercial PLLA plant operated by Cargill Dow Polymers reportedly requires gross fossil process energy of 39.5 MJ kg Vink et .
