Helmholtz-Zentrum Dresden-Rossendorf, Helmholtz Institute Freiberg for Resource Technology, Halsbrücker Straße 34, 09599 Freiberg, Germany.
Helmholtz Zentrum Dresden-Rossendorf, Institute of Resource Ecology, Bautzner Landstraße 400, 01328 Dresden, Germany.
Waste Manag. 2017 Apr;62:211-221. doi: 10.1016/j.wasman.2017.02.005. Epub 2017 Feb 20.
In most modern technologies such as flat screens, highly effective magnets and lasers, as well as luminescence phosphors, Rare Earth Elements (REE) are used. Unfortunately no environmentally friendly recycling process exists so far. In comparison to other elements the interaction of microorganisms with REE has been studied to a less extent. However, as REE are ubiquitously present in nature it can be assumed that microorganisms play an important role in the biogeochemistry of REE. This study investigates the potential of organic acid-producing microbes for extracting REE from industrial waste. In Germany, 175 tons of fluorescent phosphor (FP) are collected per year as a distinct fraction from the recycling of compact fluorescent lamps. Because the FP contains about 10% of REE-oxides bound in the so-called triband dyes it is a readily accessible secondary resource of REE. Using the symbiotic mixed culture Kombucha, consisting of yeasts and acetic acid bacteria, REE were leached at a significant rate. The highest leaching-rates were observed in shake cultures using the entire Kombucha-consortium or its supernatant as leaching agent compared to experiments using the isolates Zygosaccharomyces lentus and Komagataeibacter hansenii as leaching organisms. During the cultivation, the pH decreased as a result of organic acid production (mainly acetic and gluconic acid). Thus, the underlying mechanism of the triband dye solubilisation is probably linked to the carboxyl-functionality or a proton excess. In accordance with the higher solubility of REE-oxides compared to REE-phosphates and -aluminates, the red dye YO:Eu containing relatively expensive REE was shown to be preferentially solubilized. These results show that it is possible to dissolve the REE-compounds of FP with the help of microbial processes. Moreover, they provide the basis for the development of an eco-friendly alternative to the currently applied methods that use strong inorganic acids or toxic chemicals.
在大多数现代技术中，如平板显示器、高效磁铁和激光器以及发光荧光粉，都使用了稀土元素（REE）。不幸的是，到目前为止还没有环保的回收工艺。与其他元素相比，微生物与 REE 的相互作用研究还不够深入。然而，由于 REE 在自然界中普遍存在，可以假设微生物在 REE 的生物地球化学中起着重要作用。本研究调查了产酸微生物从工业废物中提取 REE 的潜力。在德国，每年从紧凑型荧光灯的回收中收集 175 吨荧光磷（FP）作为一个独特的部分。由于 FP 中含有约 10%的 REE 氧化物，结合所谓的三带染料，它是一种易于获得的 REE 二次资源。使用共生混合培养物 Kombucha，由酵母和醋酸菌组成，以相当高的速率浸出 REE。与使用分离株 Zygosaccharomyces lentus 和 Komagataeibacter hansenii 作为浸出生物的实验相比，在使用整个 Kombucha 联合体或其上清液作为浸出剂的摇瓶培养中观察到最高的浸出率。在培养过程中，由于有机酸的产生（主要是乙酸和葡萄糖酸），pH 值下降。因此，三带染料溶解的潜在机制可能与羧基功能或质子过剩有关。根据 REE 氧化物的溶解度高于 REE 磷酸盐和铝酸盐的原理，含有相对昂贵 REE 的红色染料 YO:Eu 被证明是优先溶解的。这些结果表明，有可能借助微生物过程溶解 FP 的 REE 化合物。此外，它们为开发一种环保的替代方法提供了基础，这种方法目前使用的是强无机酸或有毒化学品。
