RO membrane system

Figure 8.1 Shows the projected performance of an RO membrane system with ideal, marginal and inadequate pretreatment.1 After an initial period over which time new membranes stabilize performance, a system with ideal performance will show only a slight decline in performance with time due to compaction and the inevitable fouling and scaling that will occur despite good pretreatment and system hydraulics. Marginal pretreatment exhibits more rapid decline in performance than the system with ideal pretreatment. Initial cleaning may be able to revive most of the performance, but after time, foulants and scale that were not removed become irreversibly attached to the membrane and cannot be cleaned away. The RO system with inadequate pretreatment will show very rapid decline in performance that typically cannot be recovered by cleaning the membranes. An RO system with less than ideal pretreatment faces frequent cleaning intervals and short membrane life. Frequent cleaning and membrane replacement costs money, time, and the environment.

With the advancement of membrane technologies and engineering in the integration of MF, UF, NF, and RO membrane systems, and possibly a liquid membrane system, wastewater reclamation can provide high quality water for underground water replenishment and direct household nonpotable use, and source water for ultra-pure water applications. Membrane technology provides several advantages over conventional treatment processes ... 

Organic foulants obtained from UF (Kolon Membrane, Gwacheon, Korea), and RO (4-stage spiral-wound PA-type TFC-RO membrane system, Woongjin Chemical, Seoul, Korea) membranes of a large-scale municipal water... 

Table 2.11 RO membrane system performance projection (Hydranautics)...

Figure 3.38 (a) Process design flow schematic of a brackish water RO membrane system. Welton-Mohawk site, (b) Process design flow schematic of a brackish water RO membrane system. Rio Grande site. 

Figure 3.47 Process flow schematic of a MF-RO membrane system water reclamation plant.

The filtered raw water then flows to a high-pressure pump, which feeds the raw water at a typical pressure of 400 psi through the RO membrane system. Valves and pressure gauges between the micrometer filter, the high-pressure pump and membrane modules control the flow of water through the system and monitor its operation. 

Seawater RO desalination plants typically consist of the following key components intake pretreatment system filter effluent transfer pumps high-pressure pumps, piping, and RO membrane system energy recovery system and permeate conditioning (posttieatment) facilities. 

---