近日，大湾区城市环境安全与绿色发展教育部重点实验室学术骨干何頔、王樟新教授团队在环境领域顶级期刊《Environmental Science & Technology》上发表了题为“Aqueous Iron(IV)-oxo Complex: An Emerging Powerful Reactive Oxidant Formed by Iron(II)-based Advanced Oxidation Processes for Oxidative Water Treatment”的学术论文。

 论文DOI：https://doi.org/10.1021/acs.est.1c01638

淡水危机是一个全球性的问题。人类每天的工业活动会将大量的淡水转化成为含盐废水，而这些废水的排放可能会造成严重的环境污染，使得淡水危机加剧。为了防止这种现象的发生，废水的排放标准变得越来越严格。近些年来，废水零排放(ZLD)这一标准被提了出来。具体来说，ZLD是将废水中的所有的水资源进行回收，只留下固体进行处理处置。ZLD可完全消除废水排放造成水污染的风险，同时实现水资源的高效利用。由于实现ZLD的成本很高，废水近零排放（MLD）这一标准被提了出来。相比于ZLD，MLD可对经济成本与环境影响之间进行平衡。

早期的ZLD系统完全是由蒸发器构成的，故其成本极高。近些年来，为了降低ZLD的成本，反渗透（RO）被应用于ZLD系统。具体来说，盐水先通过RO进行浓缩减量，再进入蒸发器，降低了后者的处理负荷，进而降低了整个ZLD系统的成本。与此同时，RO在MLD系统中也有着广泛的应用。然而，虽然使用了RO，ZLD的成本依然很高，这是因为RO对盐水浓缩减量的能力受限于其操作压力（图1）。目前，RO组件能承受的最大压力不超过85 bar，所能将盐水浓缩的最大浓度不超过100,000 mg/L TDS，而蒸发器较优的进水浓度一般都大于200,000 mg/L TDS。类似地，MLD中淡水的回收率也受到了RO操作压力的限制。

英文摘要：

Minimum and zero liquid discharge (MLD/ZLD) are emerging brine management strategies that attract heightened attention. Although conventional reverse osmosis (RO) can improve the energy efficiency of MLD/ZLD processes, its application is limited by the maximum hydraulic pressure (ΔPmax) that can be applied in current membrane modules. To overcome such limitation, novel RO-based technologies, including osmotically assisted RO (OARO) and low-salt-rejection RO (LSRRO), have been proposed. Herein, we utilize process modeling to systematically compare the energy consumption of OARO and LSRRO for MLD/ZLD applications. Our modeling results show that the specific energy consumption (SEC) of LSRRO is lower (by up to ∼30%) than that of OARO for concentrating moderately saline feed waters (<∼35,000 mg/L TDS) to meet MLD/ZLD goals, whereas the SEC of OARO is lower (by up to ∼40%) than that of LSSRO for concentrating higher salinity feed waters (>∼70,000 mg/L TDS). However, by implementing more stages and/or an elevated ΔPmax, LSRRO has the potential to outperform OARO energetically for treating high-salinity feed waters. Notably, the SEC of both OARO and LSRRO could be 50% lower than that of mechanical vapor compressor, the commonly used brine concentrator in MLD/ZLD applications. We conclude with a discussion on the practicability of OARO and LSRRO based on membrane module availability and capital cost, suggesting that LSRRO could potentially be more feasible than OARO.