Department of Civil and Environmental Engineering, University of Houston, Houston, TX, 77004, USA.
Department of Materials Science and Engineering, University of Houston, Houston, TX, 77004, USA.
Water Res. 2020 Jul 15;179:115863. doi: 10.1016/j.watres.2020.115863. Epub 2020 May 3.
Reverse osmosis (RO) technology is promising in the sustainable production of fresh water. However, expansion of RO use has been hindered by membrane fouling, mainly inorganic fouling known as scaling. Although membrane mineral scaling by chemical means have been investigated extensively, mineral scaling triggered by microbial activity has been largely neglected. In this study, the simultaneous biomineralization of CaCO and CaSO in the presence of three different microbial communities from fresh water, wastewater, and seawater was investigated. In the presence of either 13 or 79 mM of Ca and SO in the media, the fresh water microbial community produced calcite/vaterite and vaterite/gypsum, respectively; the wastewater community produced vaterite and vaterite/gypsum, respectively; and the seawater community produced aragonite in both conditions. The results showed that the concentration of salts and the microbial composition influence the types of precipitates produced. The mechanisms of crystal formation of CaCO and gypsum by these communities were also investigated by determining the need for metabolic active cells, the effect of a calcium channel blocker, and the presence of extracellular polymeric substances (EPS). The results showed that metabolically active cells can lead to production of EPS and formation of Ca gradient along the cells through calcium channels, which will trigger formation of biominerals. The prevention of biomineralization by these consortia was also investigated with two common polymeric RO antiscalants, i.e. polyacrylic acid (PAA) and polymaleic acid (PMA). Results showed that these antiscalants do not prevent the formation of the bio-precipitates suggesting that novel approaches to prevent biomineralization in RO systems still needs to be investigated.
反渗透（RO）技术在可持续生产淡水方面具有广阔的前景。然而，由于膜污染，特别是无机污染（即结垢），RO 的应用受到了限制。尽管已经广泛研究了通过化学方法防止膜结垢，但微生物活性引起的膜结垢问题在很大程度上被忽视了。在本研究中，考察了来自淡水、废水和海水的三种不同微生物群落同时在存在 CaCO 和 CaSO 的情况下的生物矿化作用。在介质中存在 13 或 79 mM Ca 和 SO 的情况下，淡水微生物群落分别产生了方解石/文石和文石/石膏；废水微生物群落分别产生了文石和文石/石膏；而海水微生物群落则在两种条件下均产生了霰石。结果表明，盐浓度和微生物组成会影响沉淀的类型。还通过确定代谢活跃细胞的需求、钙通道阻滞剂的作用以及细胞外聚合物物质（EPS）的存在，研究了这些群落形成 CaCO 和石膏晶体的机制。结果表明，代谢活跃的细胞可以通过钙通道产生 EPS 和形成 Ca 梯度，从而触发生物矿化的形成。还研究了两种常见的聚合物反渗透阻垢剂，即聚丙烯酸（PAA）和聚马来酸（PMA）对这些群落生物矿化的抑制作用。结果表明，这些阻垢剂并不能阻止生物沉淀物的形成，这表明仍然需要研究防止 RO 系统中生物矿化的新方法。
