Heterogeneous photocatalysis (HPC) has been widely investigated in recent decades for the removal of a number of contaminants from aqueous matrices, but its application in real wastewater treatment at full scale is still scarce. Indeed, process and technological limitations have made HPC uncompetitive with respect to consolidated processes/technologies so far. In this manuscript, these issues are critically discussed and reviewed with the aim of providing the reader with a realistic picture of the prospective application of HPC in wastewater treatment. Accordingly, consolidated and new photocatalysts (among which the visible active ones are attracting increasing interest among the scientific community), along with preparation methods, are reviewed to understand whether, with increased process efficiency, these methods can be realistically and competitively developed at industrial scale. Precipitation is considered as an attractive method for photocatalyst preparation at the industrial scale; sol-gel and ultrasound may be feasible only if no expensive metal precursor is used, while hydrothermal and solution combustion synthesis are expected to be difficult (expensive) to scale up. The application of HPC in urban and industrial wastewater treatment and possible energy recovery by hydrogen production are discussed in terms of current limitations and future prospects. Despite the fact that HPC has been studied for the removal of pollutants in aqueous matrices for two decades, its use in wastewater treatment is still at a "technological research" stage. In order to accelerate the adoption of HPC at full scale, it is advisable to focus on investigations under real conditions and on developing/improving pilot-scale reactors to better investigate scale-up conditions and the potential to successfully address specific challenges in wastewater treatment through HPC. In realistic terms, the prospective use of HPC is more likely as a tertiary treatment of wastewater, particularly if more stringent regulations come into force, than as pretreatment for industrial wastewater to improve biodegradability.

中文翻译：

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通过紫外线和可见光-活性非均相光催化处理废水的局限性和前景：关键评论。

近几十年来，已经广泛研究了非均相光催化（HPC）来去除水性基质中的许多污染物，但是在实际的大规模废水处理中仍然缺乏这种应用。实际上，到目前为止，过程和技术的局限性使得HPC在合并的过程/技术方面没有竞争力。在本手稿中，对这些问题进行了严格的讨论和审查，目的是为读者提供有关HPC在废水处理中的潜在应用的真实图片。因此，对固结和新的光催化剂（可见光活性催化剂正在引起科学界越来越大的兴趣）以及制备方法进行了审查，以了解是否随着工艺效率的提高，这些方法可以在工业规模上现实地和有竞争力地开发。沉淀被认为是工业规模制备光催化剂的一种有吸引力的方法。仅在不使用昂贵的金属前驱体的情况下，溶胶-凝胶法和超声法才可行，而水热法和溶液燃烧法合成则难以（昂贵）地扩大规模。从目前的局限性和未来前景出发，讨论了高性能计算在城市和工业废水处理中的应用以及可能通过制氢回收能源的问题。尽管已经对HPC去除水性基质中的污染物进行了二十年的研究，但HPC在废水处理中的使用仍处于“技术研究”阶段。为了加速全面采用HPC，建议着重于实际条件下的研究以及开发/改进中试规模的反应器，以更好地研究放大条件，以及通过HPC成功解决废水处理中特定挑战的潜力。实际上，与对工业废水进行预处理以提高生物降解性相比，对HPC的预期用途更可能用作废水的第三级处理，尤其是在更严格的法规生效的情况下。