可同化有机碳(AOC)产率系数测定优化及接种方法对比研究

Optimization of yield coefficient and comparison of inoculation methods for assimilable organic carbon

在对测定可同化有机碳(AOC)所需接种液中荧光假单胞杆菌P17及螺旋菌NOX的浓度随培养时间变化规律进行研究的基础上,进一步研究了两种细菌培养后其浓度与标准乙酸碳(Ac-C)浓度之间的相关性.结果表明,当Ac-C浓度<75μg·L^(-1)时,标准乙酸碳溶液的浓度与细菌浓度具有较好的线性关系;当Ac-C浓度>75μg·L^(-1)时,两者的线性关系减弱;传统AOC检测方法选取[Ac-C]=100μg·L^(-1)作为产率对照在低浓度条件下是不准确的.本文在此基础上提出了产率系数的优化计算方法并确定其适用范围(AOC-P17:0～75μg·L^(-1);AOC-NOX:0～75μg·L^(-1)),该方法进一步提高了该范围内AOC测定结果的准确性.通过对AOC测定过程中3种接种方式的对比研究,发现分别接种法误差较大;同时接种法在平板计数阶段两种细菌菌落之间存在掩盖现象,结果不稳定;先后接种法测定结果较为准确,可较好地反映水中AOC的浓度.将优化后的产率系数测定方法应用于先后接种法并与传统测定方法进行对比,结果证明,优化后的测定方法准确度更高.

Based on the changing rule of the concentrations of Pseudomonas fluorescens P17 and spirochetes NOX in the inoculum required for the determination of assimilable organic carbon（AOC） with culture duration, the correlation between the concentrations of the two types of bacteria and the standard acetic acid carbon concentration was further studied. When Ac-C was <75 μg·L-1, the concentration of standard acetic acid carbon solution had a significant linear relationship with the concentration of bacteria. When Ac-C was >75 μg·L-1, the linear relationship between the two was less obvious, and the correlation became insignificant. The traditional AOC detection method, with Ac-C=100 μg·L-1 as the yield control, was inaccurate under low concentration conditions. Hence, this paper proposed the optimized calculation method of the yield coefficient and its scope of application. This method further improved the accuracy of the AOC measurement in the range of AOC-P17: 0～75 μg·L-1 and AOC-NOX:0～75 μg·L-1. Comparative study of the three inoculation methods in the determination process showed that the error was relatively large after separate inoculation; NOX was covered by P17 when counted on the plate after simultaneous inoculation, and the result was unstable. Determination results were more accurate after successive inoculation, and could better reflect the concentration of AOC in water. The adjusted AOC determination method combined with optimized yield coefficient were more accurate as com pared to the traditional method.