A Novel Method for Biological Perchlorate Reduction Using Elemental Sulfur as an Electron Donor

CBET-0755670智力价值。本项目描述了一种全新的过程，可以将受污染的地表水中的高氯酸盐完全分解为无害产品。我们已经丰富了一个微生物联合体能够耦合单质硫（S0）氧化与高氯酸盐还原。这种稳定的复合物不仅能以S0作为唯一电子供体成功降解高氯酸盐，而且还能在离子交换（IX）盐水中典型的NaCl浓度下成功降解高氯酸盐，这是目前常用的去除技术。此外，我们最近在该系统中分离出一种能够还原高氯酸盐的细菌菌株。初步的上流式填充床生物反应器实验表明，在空床接触时间为8小时时，高氯酸盐的降解从100到4 ppb；然而，高氯酸盐浓度随反应器深度的变化曲线表明，更高的负载率是可行的。使用S0作为电子供体是一种优雅且经济高效的生物高氯酸盐去除方法。单质硫是石油炼制工业的副产品，相对便宜且容易获得。使用硫酸钠可以减少由于有机基质携带到配水系统或地下水补给系统而导致的生物不稳定性风险。硫氧化细菌是生长缓慢的自养生物，虽然代谢非常活跃，但产生的多余污泥很少，减少了反冲洗的需要。硫颗粒可以用作简单填充床生物反应器的介质，也可以集成到IX盐水处理和再利用系统或原位渗透反应屏障（PRB）系统中。拟议的跨学科研究项目的具体目标是：(1)调查硫氧化、高氯酸还原的条件（包括浓度、盐度、pH、温度和共污染物NO3 -、RDX和HMX）；(2)确定参与高氯酸还原的主要和活跃的社区成员；(3)研究填料床硫氧化生物反应器直接处理生物反应器中高氯酸盐污染水或高氯酸盐污染IX盐水的操作条件和性能。实验将在烧瓶、柱和中试规模上进行。在环境工程和微生物研究小组之间紧密联系和建立良好的互动中，我们将使用传统和培养独立技术确定微生物联盟的其他成员（例如硫酸盐还原剂和硫氧化剂），并将生物反应器降解率与高氯酸代谢培养的遗传潜力进行比较。这些知识将使我们能够在不同条件下的反应堆运行期间跟踪社区鲁棒性，并开发可用于新系统的种子社区和协议。实验规模的生物反应器实验将用于研究处理废IX再生盐水的条件，并检查共污染物对高氯酸盐降解的影响。在马萨诸塞州一个受污染的地点进行中试规模的生物反应器实验，将用于检查高氯酸盐的装载率、运行稳定性、规模和典型的水公用事业应用的成本以及共污染物效应。这项研究将扩大对受污染含水层系统中自养细菌支持的高氯酸盐还原的理解，并导致新的和具有成本效益的生物修复解决方案。这项研究的广泛影响是多样和深远的。该项目将提供关于从供水中去除高氯酸盐同时尽量减少处理工艺废物的可行性的资料。本研究还将定义一个与人类活动相关的不寻常的微生物群落。预期的好处包括为设计可靠且具有成本效益的生物处理系统、原位PRBs和IX系统提供数据，这些系统可以去除高氯酸盐并回收受污染的盐水流。随着高氯酸盐的新标准即将出台，该项目将成为饮用水公用事业和军事场所的典范。此外，pi还加入了马萨诸塞大学的一个核心研究小组，该小组正在研究高氯酸盐的发生、毒理学和治疗方法。该小组将共享设备和专业知识，开发跨学科的教育项目，如研讨会和期刊俱乐部，并在新英格兰组织有关这一主题的会议。pi在吸引本科生、初高中科学教师和高中生参与研究方面有着出色的记录。我们将与马萨诸塞大学工程学院REU项目以及我们与教职员工建立的联系合作，从波多黎各马亚圭斯大学招募本科生参与这个项目。我们将开发高氯酸盐模块。

CBET-0755670 ErgasIntellectual Merit. This project describes a novel process to entirely break down perchlorate in contaminated ground and surface waters to innocuous products. We have enriched a microbial consortium capable of coupling elemental sulfur (S0) oxidation with perchlorate reduction. This stable consortium not only successfully degrades perchlorate using S0 as the sole electron donor, but also does this at NaCl concentrations typical of ion exchange (IX) brines, currently a common removal technique.In addition, we have recently isolated a bacterial strain capable of perchlorate reduction in this system. Preliminary upflow packed bed bioreactor experiments show degradation of perchlorate from 100 to 4 ppb at empty bed contact times of eight hours; however, profiles of perchlorate concentration vs. depth in the reactors indicate higher loading rates are feasible. The use of S0 as an electron donor is an elegant and cost-effective method of biological perchlorate removal. Elemental sulfur, a by-product of the petroleum refining industry, is relatively inexpensive and available. Use of S0 reduces the risk of bioinstability due to carry over of organic substrates to water distribution or groundwater recharge systems. Sulfur-oxidizing bacteria are slow growing autotrophs that, although metabolically very active, produce very little excess sludge, reducing the need for backwashing. Sulfur granules can be used as media in simple packed bed bioreactors, or can be integrated into IX brine treatment and reuse systems or in situ permeable reactive barrier (PRB) systems. Specific objectives of the proposed interdisciplinary research project are (1) to investigate conditions for sulfur-oxidizing, perchlorate-reduction (including concentration, salinity, pH, temperature, and cocontaminants NO3 -, RDX, and HMX), (2) to determine dominant and active community members involved in perchlorate reduction, (3) to investigate operating conditions and performance of packed bed sulfur-oxidizing bioreactors for direct treatment of perchlorate contaminated water in bioreactors or perchlorate contaminated IX brines.Experiments will be carried out at flask, column and pilot scale. In a closely knit and well established interaction between environmental engineering and microbiology research groups, we will identify additional members of the microbial consortium (e.g. sulfate-reducers and sulfur-oxidizers) using both traditional and culture independent techniques, and compare bioreactor degradation rates to the genetic potential of the perchlorate-metabolizing culture. This knowledge will allow us to follow community robustness during reactor operation under varying conditions, and to develop a seed community andprotocols that can be used in new systems. Bench-scale bioreactor experiments will be used to investigate conditions for treatment of spent IX regenerant brines and to examine the effect of co-contaminants on perchlorate degradation. Pilot-scale bioreactor experiments, at a contaminated site in Massachusetts, will be used to examine perchlorate loading rates, operational stability, scale-up, and costs for typical water utility applications along with co-contaminant effects. This research will expand the understanding of perchlorate reduction supported by autotrophic bacteria in contaminated aquifer systems and lead to novel and cost-effective bioremediation solutions.The broader impacts of this research are varied and far-reaching. The project will provide information on the feasibility of removing perchlorate from water supplies while minimizing disposal of process wastes.This study will also define an unusual microbial community relevant to human activities. Anticipated benefits include data for design of reliable and cost-effective biological treatment systems, in situ PRBs, and IX systems that can remove perchlorate and recycle contaminated brine streams. With upcoming new standards for perchlorate this project will serve as a model for drinking water utilities and military sites.In addition, the PIs join a core group of researchers at the University of Massachusetts who are studying the occurrence, toxicology, and treatment of perchlorate. This group will share equipment and expertise, develop interdisciplinary educational programs, such as seminars and journal clubs, and organize conferences on this topic in New England.The PIs have an excellent track record in engaging undergraduates, middle and high school science teachers, and high school students in research. We will work with the UMass College of Engineering REU program and our established connections with faculty to recruit undergraduates from the University of Puerto Rico Mayaguez to work on this project. We will develop modules on perchlorate.