Idachaba M A, Nyavor K, Egiebor N O, Rogers R D
Environmental Engineering Program, Department of Chemical Engineering, Tuskegee University, Tuskegee, AL 36088, USA.
J Hazard Mater. 2000 Oct 2;77(1-3):133-47. doi: 10.1016/s0304-3894(00)00236-3.
The development of an accurate assessment protocol is critical for the prediction of long-term performance of waste disposal systems under field conditions. In this study, the development of a biofilm formation method for the evaluation of waste forms stability to microbially induced degradation (MID) is reported. The development process involved significant modifications to the existing Nuclear Regulatory Commission (NRC) approach. In the biofilm formation method, the control media and fermenter broths are designed to be of similar pH to avoid overestimation of the microbe's capability to degrade the waste forms. In the NRC approach, the pH values are different. The existing one-stage process of the NRC approach is also replaced with a two-stage process in the biofilm formation method. This is to ensure full evaluation of the microbe's involvement in waste forms degradation. The first stage of the two-stage process is for biofilm formation and the second is for biofilm evaluation. The use of a two-stage process eliminates the possibility of substrate limitation, resulting in values of degradation indices that are about two times higher than those obtained using the single-stage NRC approach. Two waste forms (100% Tuskegee cement and 21% cobalt chloride/79% cement) were used in the development of the biofilm formation method. Both waste forms showed evidence of biofilm formation. The formation of biofilm on the cobalt-containing waste form indicates a lack of anti-microbial capability of cobalt.
开发一种准确的评估方案对于预测野外条件下废物处理系统的长期性能至关重要。在本研究中，报告了一种用于评估废物形式对微生物诱导降解（MID）稳定性的生物膜形成方法的开发。开发过程涉及对现有核管理委员会（NRC）方法的重大修改。在生物膜形成方法中，对照培养基和发酵罐肉汤的设计pH值相似，以避免高估微生物降解废物形式的能力。在NRC方法中，pH值不同。生物膜形成方法还将NRC方法现有的单阶段过程替换为两阶段过程。这是为了确保全面评估微生物在废物形式降解中的作用。两阶段过程的第一阶段用于生物膜形成，第二阶段用于生物膜评估。使用两阶段过程消除了底物限制的可能性，导致降解指数值比使用单阶段NRC方法获得的值高约两倍。在生物膜形成方法的开发中使用了两种废物形式（100%塔斯基吉水泥和21%氯化钴/79%水泥）。两种废物形式均显示出生物膜形成的迹象。含钴废物形式上生物膜的形成表明钴缺乏抗菌能力。
