Biodesign Swette Center for Environmental Biotechnology, Arizona State University, Tempe, AZ 85287-5701, USA.
Water Res. 2018 Apr 1;132:135-145. doi: 10.1016/j.watres.2017.12.043. Epub 2017 Dec 28.
Having worked with biofilms since the 1970s, I know that they are ubiquitous in nature, of great value in water technology, and scientifically fascinating. Biofilms are naturally able to remove BOD, transform N, generate methane, and biodegrade micropollutants. What I also discovered is that biofilms can do a lot more for us in terms of providing environmental services if we give them a bit of help. Here, I explore how we can use active substrata to enable our biofilm partners to provide particularly challenging environmental services. In particular, I delve into three examples in which an active substratum makes it possible for a biofilm to accomplish a task that otherwise seems impossible. The first example is the delivery of hydrogen gas (H) as an electron donor to drive the reduction and detoxification of the rising number of oxidized contaminant: e.g., perchlorate, selenate, chromate, chlorinated solvents, and more. The active substratum is a gas-transfer membrane that delivers H directly to the biofilm in a membrane biofilm reactor (MBfR), which makes it possible to deliver a low-solubility gaseous substrate with 100% efficiency. The second example is the biofilm anode of a microbial electrochemical cell (MxC). Here, the anode is the electron acceptor for anode-respiring bacteria, which "liberate" electrons from organic compounds and send them ultimately to a cathode, where we can harvest valuable products or services. The anode's potential is a sensitive tool for managing the microbial ecology and reaction kinetics of the biofilm anode. The third example is intimately coupled photobiocatalysis (ICPB), in which we use photocatalysis to enable the biodegradation of intrinsically recalcitrant organic pollutants. Photocatalysis transforms the recalcitrant organics just enough so that the products are rapidly biodegradable substrates for bacteria in a nearby biofilm. The macroporous substratum, which houses the photocatalyst on its exterior, actively provides donor substrate and protects the biofilm from UV light and free radicals in its interior. These three well-developed topics illustrate how and why an active substratum expands the scope of what biofilms can do to enhance water sustainability.
自 20 世纪 70 年代以来，我一直从事生物膜的研究，我知道它们在自然界中无处不在，在水技术中有很大的价值，并且具有科学魅力。生物膜自然能够去除 BOD、转化 N、产生甲烷，并生物降解微量污染物。我还发现，如果我们给生物膜一些帮助，它们可以为我们提供更多的环境服务。在这里，我探讨了如何利用活性基质使我们的生物膜伙伴能够提供特别具有挑战性的环境服务。特别是，我深入研究了三个例子，在这些例子中，活性基质使生物膜能够完成一项看似不可能的任务。第一个例子是输送氢气 (H) 作为电子供体，以驱动越来越多的氧化污染物的还原和解毒：例如，高氯酸盐、硒酸盐、铬酸盐、氯化溶剂等。活性基质是一种气体传输膜，它在膜生物膜反应器 (MBfR) 中将 H 直接输送到生物膜中，从而可以以 100%的效率输送低溶解度的气态底物。第二个例子是微生物电化学电池 (MxC) 的生物膜阳极。在这里，阳极是阳极呼吸细菌的电子受体，它们从有机化合物中“释放”电子，并最终将其发送到阴极，我们可以在阴极收获有价值的产品或服务。阳极的电位是管理生物膜阳极微生物生态学和反应动力学的敏感工具。第三个例子是紧密耦合的光生物催化 (ICPB)，我们利用光催化使难生物降解的有机污染物可生物降解。光催化使难生物降解的有机物转化得足以使产物成为附近生物膜中细菌的快速可生物降解底物。多孔基质在其外部容纳光催化剂，主动提供供体底物，并保护生物膜免受内部的紫外线和自由基的伤害。这三个成熟的主题说明了活性基质如何扩展生物膜的功能范围，以增强水的可持续性。
