壳聚糖对活性污泥动力学参数的影响

壳聚糖具有良好的吸附性以及生物降解性,作为一种天然高分子絮凝剂,具有絮凝效果好、无毒无害,不会造成二次污染等优点,在水质净化工艺中具有广阔的应用前景。以活性污泥为研究对象,在壳聚糖(分子量为50kDa、脱乙酰度85 %)添加质量浓度分别为0,15,25,35 mg·L^-1时,采用耗氧速率表征方法,测定计算了活性污泥的动力学参数:COD_Cr 最大比去除速率(v_mS)、COD_Cr去除半饱和常数(K_S)、氨氮最大比去除速率(v_mN)、氨氮去除半饱和常数(K_N)。结果表明,一定质量浓度的壳聚糖能导致活性污泥的v_mS及v_mN降低,K_S及K_N增大,对活性污泥降解COD_Cr和氨氮有抑制作用。壳聚糖的抑制作用受壳聚糖浓度的影响,但并不随之增大而增强,即存在最大抑制作用。当壳聚糖质量浓度为25 mg·L^-1时,抑制作用最强,而壳聚糖的絮凝作用则不受此影响。

The Effects of Chitosan on Activated Sludge Kinetic Parameters

Chitosan has good adsorption and biodegradation. It is a natural polymer flocculant which has good flocculation effect, non-toxic/harmless and non-secondary pollution, etc., so it is widely used in water purification process. The paper studied activated sludge with addition of chitosan (molecular weight 50 kDa, deacelation degree 85 %) at concentration of 0, 15, 25 and 35 mg/L. The following kinetic parameters of activated sludge were measured and calculated using oxygen utilization rate methods: specific maximum COD_Cr removal rate (v_mS), half saturation constant for COD_Cr removal (K_S), specific maximum ammonia nitrogen removal rate (v_mN), and half saturation constant for ammonia nitrogen removal (K_N). The research results show that a certain concentration of chitosan can result in reduction of v_mS and v_mN, and increase of K_S and K_N of activated sludge, so there is restriction effect of COD_Cr and ammonia nitrogen degradation by activated sludge. The restriction effect depends on chitosan concentration. Because it is not increased with the increase of chitosan concentration, there is a concentration with maximum restriction effect. The concentration with maximum restriction effect is 25 mg/L, while flocculation effect of chitosan is not affected.