Shimp R J, Larson R J
Professional and Regulatory Services, Winton Hill Technical Center, Cincinnati, Ohio 45217.
Ecotoxicol Environ Saf. 1996 Jun;34(1):85-93. doi: 10.1006/eesa.1996.0048.
A two-step procedure is described to characterize the removal and biodegradation potential of nonvolatile 14C-labeled organic compounds in activated sludge. In the first step, trace concentrations of radiolabeled test materials are dosed in influent wastewater to continuous-flow activated sludge (CAS) systems which have been previously exposed or acclimated to unlabeled test material. Radiolabel is quantified in influent, effluent, and activated sludge mixed liquor to determine total 14C removal and partitioning of radiolabel in solid and liquid compartments. The 14C data are used to calculate the amount of removal due to sorption and biodegradation and to estimate the apparent sorption coefficients for 14C activity to activated sludge solids. The 14C-labeled CAS studies are followed by biodegradation studies in batch-activated sludge (BAS) systems using sludge derived from the CAS system. The kinetics of biodegradation (defined as mineralization to 14CO2) are measured in the BAS system to confirm the CAS biodegradation results and generate mineralization rate constants for kinetic modeling. The two-step procedure was applied to radiolabeled anionic (linear alkylbenzene sulfonate) and cationic (dodecyltrimethylammonium chloride, distearyldimethylammonium chloride) surfactants which differed greatly in their biodegradation and sorption profiles. Laboratory removal figures for these materials were comparable to values measured in full-scale wastewater treatment systems, although the amount of removal due to sorption and biodegradation varied significantly for the different surfactants. In general, the 14C method has several advantages over standard methods used in the United States and Europe which employ unlabeled materials. These advantages include the use of realistic concentrations and test conditions for acclimating and dosing activated sludge microorganisms and the ability to generate partitioning and kinetic constants that can be used more broadly in environmental fate and exposure models.
本文描述了一种两步法，用于表征活性污泥中不挥发的14C标记有机化合物的去除和生物降解潜力。第一步，将痕量浓度的放射性标记测试材料投加到连续流活性污泥（CAS）系统的进水废水中，该系统先前已接触或适应未标记的测试材料。对进水、出水和活性污泥混合液中的放射性标记进行定量，以确定总14C去除量以及放射性标记在固体和液体部分的分配情况。14C数据用于计算吸附和生物降解导致的去除量，并估算14C活性对活性污泥固体的表观吸附系数。在14C标记的CAS研究之后，使用来自CAS系统的污泥在间歇活性污泥（BAS）系统中进行生物降解研究。在BAS系统中测量生物降解动力学（定义为矿化生成14CO2），以确认CAS生物降解结果并生成用于动力学建模的矿化速率常数。该两步法应用于放射性标记的阴离子（直链烷基苯磺酸盐）和阳离子（十二烷基三甲基氯化铵、二硬脂基二甲基氯化铵）表面活性剂，它们的生物降解和吸附特性差异很大。这些材料的实验室去除数据与在全尺寸废水处理系统中测得的值相当，尽管不同表面活性剂因吸附和生物降解导致的去除量差异显著。总体而言，14C方法相对于美国和欧洲使用未标记材料的标准方法具有几个优点。这些优点包括使用实际浓度和测试条件来驯化和投加活性污泥微生物，以及能够生成可更广泛应用于环境归宿和暴露模型的分配和动力学常数。
