Greening systems are among the most environmentally friendly technologies for cleaning water and air in urban settlements. The application of green walls has recently broadened from solely offering aesthetic values to focusing on solving urban environmental challenges including wastewater treatment, thereby increasing the efficiency of green buildings. Indeed, green wall is an alternative form of constructed wetlands, which has been well recognized and widely applied worldwide for various wastewater treatments, particularly in greywater treatment. This review aims in shedding light on the current state of the new application of green walls, and highlighting the potential for further system and operational developments of this technology. Initially, the types of green wall systems, their various classifications, system designs, their benefits and performance in the treatment of wastewater for reuse purposes were reviewed. It shows that though the green wall has been largely limited for greywater treatment, the system has the potential to treat high strength organic wastewater. Furthermore, the integration of the green wall with disinfecting techniques has a high likelihood of producing treated effluent that meets water regulation standards for a wider range of reuse applications. Analysis of organic pollutant and nutrient removal efficiencies from experiments and case studies reviewed show that green wall design, choice of substrate and vegetation under the right operational conditions can significantly improve the overall performance of the green wall system. Finally, the future research directions are suggested for wide and wiser application of this kind of technology.

绿化系统是清洁城市住区水和空气的最环保技术之一。绿墙的应用最近已从单纯提供美学价值扩展到专注于解决包括污水处理在内的城市环境挑战，从而提高绿色建筑的效率。事实上，绿墙是人工湿地的另一种形式，它已被广泛认可并在世界范围内广泛应用于各种废水处理，特别是灰水处理。本综述旨在阐明绿墙新应用的现状，并强调该技术进一步系统和操作发展的潜力。最初，绿墙系统的类型，它们的各种分类，系统设计，审查了它们在处理废水以供再利用方面的好处和性能。这表明，尽管绿墙在处理灰水方面受到很大限制，但该系统具有处理高浓度有机废水的潜力。此外，绿墙与消毒技术的结合极有可能产生符合水法规标准的处理过的污水，以实现更广泛的再利用应用。从实验和案例研究中对有机污染物和养分去除效率的分析表明，在正确的操作条件下，绿墙设计、基质和植被的选择可以显着提高绿墙系统的整体性能。最后，为该技术的更广泛和更明智的应用提出了未来的研究方向。