水解污泥上清液的蛋白质含量通常用凯氏定氮法测定,但是这种方法操作复杂,处理时间长,和大量的化学品消耗。在本文中,Lowry,二辛可宁酸(BCA),和Bradford方法用于测试通过碱性热水解(ATH)水解的污泥上清液中蛋白质的精度和加标回收率,酶促水解(EH),和超声辅助酶水解(UEH),并将结果与凯氏定氮法的结果进行了比较。对于所有的水解过程,三种测试方法测定的污泥蛋白值在0.05以内,满足实验对精度的要求。Lowry和BCA方法的回收率均为95-105%,而布拉德福德方法显示出较大的偏差,可靠性不高。3种蛋白质测定方法与凯氏定氮法比较,差异有统计学意义(P<0.05)。然而,Kjeldahl和BCA方法之间的相对偏差最小(3-5%),其次是Kjeldahl和Lowry(11-21%)和布拉德福德(21-90%)之间的方法,并根据蛋白质水解物的组成和不同检测方法的机理分析了产生偏差的原因。根据这些结果,选择BCA方法作为最适合用于污泥蛋白提取的定量方法,并用于分析从两个污水处理厂获得的剩余污泥样品中提取的蛋白质含量。验证了该方法的可靠性,这为污泥蛋白的提取和回收奠定了基础。
The protein contents of hydrolyzed sludge supernatant are commonly determined with the Kjeldahl method, but this method suffers from complicated operations, long process times, and large quantities of chemicals consumed. In this paper, the Lowry, bicinchoninic acid (BCA), and Bradford methods were used to test the precision and spiked recovery of proteins from sludge supernatants hydrolyzed by alkaline-thermal hydrolysis (ATH), enzymatic hydrolysis (EH), and ultrasound-assisted enzymatic hydrolysis (UEH), and the results were compared with those obtained with the Kjeldahl method. For all the hydrolytic processes, the sludge protein values determined with the three tested methods were within 0.05 of each other, which met the experimental requirement for accuracy. Both the Lowry and BCA methods had recovery rates of 95-105%, while the Bradford method showed large deviations and was not highly reliable. The three protein determination methods showed significant differences with the Kjeldahl method (P<0.05). However, the relative deviation between the Kjeldahl and BCA methods was the smallest (3-5%), followed by those between the Kjeldahl and the Lowry (11-21%) and Bradford methods (21-90%), and the causes of the deviations were analyzed based on the protein hydrolysate components and the mechanisms for the different detection methods. On the basis of these results, the BCA method was chosen as the most appropriate quantification method for use with sludge protein extraction, and it was used to analyze the protein contents extracted from residual sludge samples obtained from two sewage treatment plants. The reliability of the method was verified, and this lays a foundation for the extraction and reclamation of sludge proteins.