**3. Contribution of membrane technology for water treatment**

Reverse osmosis (RO), forward osmosis (FO), nanofiltration (NF), ultrafiltration (UF), microfiltration (MF), and particle filtration are working in water treatment process to treat the raw or wastewater depends on their pore sizes. **Figure 2** summarizes the various membrane filtration processes related to common materials that would be filtered out through each process during water treatment.

**Figure 3** illustrates the application of FO and reverse osmosis process for water purification of sea water and wastewater.

**Figure 2.**

*Illustration of different membrane filtration spectrum.*

#### **Figure 3.**

*Examples of application of membrane technology for water treatment. (A) Diagram of an FO-RO system for integrated SWRO and wastewater recovery. Water from the wastewater is extracted by osmosis through the FO process and dilutes the seawater before entering the RO process. (B) OMBR (osmotic membrane biological reactor) system comprising a bioreactor containing submerged FO membranes and an RO unit that re-concentrates the draw solution and produces water.*

*Graphene Oxide-Based Membranes as Water Separation: Materials, Preparation… DOI: http://dx.doi.org/10.5772/intechopen.105371*
