# Bio-Sourced and Biodegradable Membranes
## 4 Green Membrane Technology Applications
### Wastewater Treatment  
Membrane technology has been extensively used for water purification, wastewater treatment, and seawater desalination due to its superior separation performance, ease of operation, and reasonable energy consumption [2]. One of the most common applications of biodegradable membranes is wastewater treatment, including but not limited to oil separation and removing heavy metals, dye, pathogens, and proteins from aqueous solutions. Biodegradable membranes are strong candidates for wastewater treatment owing to their excellent stability, high durability, energy efficiency, high permeability, and selectivity [2]. Depending on the industry that releases wastewater and the pollution type, various membranes can be used in filtration processes. For instance, in oil absorption (oil/water separation), membranes with underwater superoleophilic/superhydrophobic characteristics are more desirable. On the other hand, composite membranes, containing hydrophilic materials such as PVA, CS, CA, etc., have been widely used to remove dyes from industrial wastewater [8; 78; 186; 187; 188].  
PLA is among the biodegradable materials that can be used to prepare a porous superhydrophobic membrane and replace the non-biodegradable commercial membranes such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polypropylene (PP), etc. [113; 116; 179; 189; 190; 191; 192; 193]. [PERSON] et al. [179] prepared the superhydrophobic PLA membrane with excellent oil adsorption capacity using non-solvent induced phase separation. The preparation method may affect the surface roughness, porosity, and free energy of the membrane and its hydrophobicity. In their study, the prepared membranes displayed a high water contact angle of about 152\({}^{\circ}\), and they were capable of absorbing oils by 4-5 times their weight.  
Colorant effluent is one source of severe water pollution that can cause serious concerns for human and marine lives. The colorant effluent, mainly from the textile industry, may have low molecular concentrations and inert properties, which makes it difficult to remove from wastewater streams [143]. Adsorption techniques using bridgeable materials are innovative methods for removing dyes from industrial effluents. Incorporating nature-based nanoparticles or polymers with high adsorption capacities would also improve the separation efficiency of the filtration membranes and at the same time maintain their biodegradability [194]. In this regard, [PERSON] et al. [176] employed porous carbon nanoparticles to improve the adsorption capacity of biodegradable CA membrane for Methylene Blue (MB) removal. The prepared membrane showed excellent reusability with 98.2% of MB removal and 76.03 LMH of water flux. Aside from dye removal, biodegradable composite membranes have been employed in several applications for heavy metal, pathogen organic, and inorganic matter removal [138; 195; 196; 197; 198; 199]. Table 1 represents various studies that utilized biodegradable membranes in wastewater treatment applications.  
Figure 11: Applications of biodegradable polymers-based membranes.