淀粉废水生产微生物絮凝剂及发酵动力学特征

Production and fermentation kinetics characteristics of a bioflocculant by using potato starch wastewater

以淀粉生产废水为原料制备微生物絮凝剂,考察了外加磷酸盐、氮源对微生物絮凝剂产量和絮凝活性的影响,分析了絮凝菌的生长与代谢特征,检测了发酵过程中pH值、COD、氨氮、及总磷的变化规律,分别利用Logistic和Luedeking-Piret模型对絮凝菌生长和代谢产物生成的动力学过程进行了拟合,并探索了微生物絮凝剂对淀粉废水的絮凝沉降性能.结果表明,外加6g/L的磷酸盐(K2HPO4:KH2PO4=2:1,w/w)和2g/L的尿素,所制备微生物絮凝剂的产量和絮凝活性分别显著提高至0.96g/L和92.8%.在对数生长期,菌体干重、细胞浓度OD600和菌落数分别迅速增加至1.58g/L、0.86和5.3×107cfu/mL,淀粉废水培养基的COD、氨氮、总磷分别由7836、975、712mg/L迅速降低至1736、188、146mg/L.絮凝菌发酵结束后,发酵培养基的pH值由6.8略降至6.5.絮凝菌代谢获得的微生物絮凝剂中多糖含量为96.2%,基本不含蛋白质.Logistic和Luedeking-Piret模型的拟合结果能够较好地描述絮凝菌生长和代谢产物生成的动力学过程.此外,本实验制备的微生物絮凝剂在投加量为30mg/L时,能够去除淀粉废水中48.6%的COD和71.9%的浊度.

Potato starch wastewater was used for bioflocculant-producing bacteria Rhodococcus erythropolis to producebioflocculant. Effects of extra phosphate and nitrogen in potato starch wastewater medium on bioflocculant yield and itsflocculating activity were discussed. In addition, solution pH values and concentrations of COD, ammonium, and totalphosphorus (TP) in the fermentation process were examined, and growth and producing kinetics of the bacteria weredescribed by using Logistic and Luedeking-Piret models. Furthermore, settlement of the potato starch wastewater by thisbioflocculant was investigated. The bioflocculant yield and its flocculating activity increased to 0.96g/L and 92.8% whenthe extra phosphate (K2HPO4: KH2PO4 = 2:1, w/w) and nitrogen were adjusted to 6g/L and 2g/L, respectively. During thelogarithm phase, cell dry weight, cell density OD600, and the number of colonies were increased to 1.58g/L, 0.86 and5.3×107cfu/mL, respectively. Concentrations of COD, ammonium, and TP of the potato starch medium were consumedrapidly from 7836, 975, and 712mg/L to 1736, 188, and 146mg/L, respectively. After the fermentation, pH value of thepotato starch medium was slightly decreased to 6.5. The bioflocculant obtained during the strain’s metabolism mainlycontained 96.2% of polysaccharide, and there was almost no protein. Cell growth and bioflocculant production could besimulated with both the Logistic and Luedeking-Piret equations pretty well. Furthermore, when the bioflocculant dose wasadjusted to 30mg/L, it can remove 48.6% of COD and 71.9% of turbidity from the potato starch wastewater in this study.