Periphytic biofilm, also known as periphyton, which is a microflora aggregate composed of heterotrophic and autotrophic microorganisms, such as microalgae, bacteria, fungi, and protozoa, ubiquitously grows at the interface of water and soil/ sediment of almost every aquatic ecosystem ranging from small ponds to large oceans, also including paddy fields (Wu 2016; Sun et al. 2021). It well reflects a critical vision of the Sustainable Development Goals that employing the ubiquitous periphytic biofilm in water discharge systems due to its characteristics of environment friendly and functional diversity. Periphytic biofilm has shown potential in entrapping nutrients, removing heavy metals, degrading organics, controlling harmful algal blooms, and so on. Taking advantages of periphytic biofilm, it may play a huge role in treating pollutants in water discharge systems.