With population expansion and industrialization, water pollutions have become one of the biggest threat to human society today. The combination of biotechnology and nanotechnology offers a new and green way to the problems. Cellulose nanofibers cellulose nanocrystals and chitin nanocrystals have nanoscaled diameters and have high specific surface areas, an advantage in membrane technology and the efficiency can be further enhanced using specific functionalization, enabling highly specific interactions with targeted contaminant entities in water. Moreover, the nano-dimensions of the used active species allow the fabrication of compact and ultra-thin multifunctional membranes by introducing an orientation and/or concentration gradient. This novel water purification approach combines the physical filtration process and the adsorption process exploring the capability of the nanocellulose and/or nanochitin (with or without functionalization) to selectively adsorb, store and desorb contaminants from industrial water and drinking water while passing through a highly permeable membranes/ filters. The aim is to tailor membarnes and filters with high flux which reduces pressure and thereby energy consumption while keeping the high selectivity efficiency due to surface adsorption. The results showed highly efficient removal of metal ions (Ag+, Cu2+ and Fe3)+ from mirror making industry using nanocellulose based membranes. High removal efficiency of dyes, nitrates and organic foulants using bio- based membranes/ filters was also confirmed. The nanocellulose and nanochitin based membranes also showed significant resistance to bio-fouling. The scaled up membranes is expected to be used in the form of spiral wound modules, cartridge modules and MBR modules for water treatment in mirror industries, printing industries, mining industries as well as municipal water and storm water in Europe.