Department of Chemical Engineering, University of Patras, 1 Karatheodori Str., University Campus, 26500 Patras, Greece.
Waste Manag. 2014 Jan;34(1):167-73. doi: 10.1016/j.wasman.2013.09.027. Epub 2013 Oct 28.
The use of abundant waste materials with high carbohydrate content may contribute substantially to reduction of biofuels production cost. The present study aimed at optimizing the combined effect of thermo-chemical pretreatment and enzymatic hydrolysis of kitchen wastes (KW) for maximizing the production of fermentable soluble sugars. To this end, acid pretreatment of KW samples was performed with hydrochloric acid (0-3% HCl) at 30-100 °C for 0-120 min treatment time. Alternatively, alkaline pretreatment of KW samples was performed with potassium hydroxide solution (0-11%) at constant temperature and time (0 °C and 20 min, respectively). KOH pretreatment at such conditions targets to degrade the resistant starch of KW samples. Both acid and alkaline pretreatments were followed by addition of variable levels of enzyme dosage (0-3.6% v/v α-amylase and 0-3.2% v/v amyloglucosidase-AMG) at constant pH, temperature and time (pH = 5, T = 50 °C and t = 30 min, respectively). Based on our results, glucose concentration increased by ~300% after pretreatment with either acid or KOH in combination with enzymatic hydrolysis (2% HCl, 85 °C, 80 min, 0.1% α-amylase, AMG, and 1% KOH, 0 °C, 20 min, 1.1% α-amylase, 0.4% AMG) compared to raw (untreated) KW. Estimating the different YG yields at KW loading of 5%, an increase of 192% and 121% for total soluble monosugars and total soluble sugars, respectively, was succeeded compared to untreated KW. The effect of solids loading on the obtained sugar yields using the optimum conditions for thermo-chemical pretreatment followed by enzymatic hydrolysis was also tested resulting to 27.5% increase of the soluble glucose yield when half of the solids loading (2.5%) was used. A decrease of total soluble sugars yield by 32.2% was observed when solely acid hydrolysis at optimum conditions from our previous study was applied at 30% solids loading.
利用富含碳水化合物的大量废弃材料可能会大大降低生物燃料的生产成本。本研究旨在优化热化学预处理和厨房垃圾（KW）酶水解的联合作用，以最大限度地生产可发酵的可溶性糖。为此，采用盐酸（0-3%HCl）在 30-100°C 下对 KW 样品进行酸预处理，处理时间为 0-120min。或者，采用氢氧化钾溶液（0-11%）在恒温和时间（分别为 0°C 和 20min）下对 KW 样品进行碱预处理。在这种条件下，KOH 预处理的目的是降解 KW 样品中的抗性淀粉。酸和碱预处理后，分别添加不同水平的酶剂量（0-3.6%v/vα-淀粉酶和 0-3.2%v/v 淀粉葡萄糖苷酶-AMG），在恒定的 pH、温度和时间（pH=5、T=50°C 和 t=30min）下。根据我们的结果，无论是用酸预处理还是用 KOH 预处理，然后再用酶水解，葡萄糖浓度都比原 KW 增加了约 300%（2%HCl，85°C，80min，0.1%α-淀粉酶，AMG，和 1%KOH，0°C，20min，1.1%α-淀粉酶，0.4%AMG）。估计在 KW 负荷为 5%时，与未经处理的 KW 相比，总可溶性单糖和总可溶性糖的 YG 产量分别增加了 192%和 121%。用优化的热化学预处理和酶水解条件测试了固体负荷对获得的糖产量的影响，当使用一半的固体负荷（2.5%）时，可发酵葡萄糖的产量增加了 27.5%。当仅在 30%的固体负荷下应用我们之前研究中的最佳条件下进行酸水解时，总可溶性糖的产量下降了 32.2%。
