Nowadays, the use of wastewater treatment facilities is necessary due to the scarcity of quality water resources. Nanofiltration plants are becoming more and more interesting, since they require less energy than other systems. These figures shows the nanofiltration plant located at Plataforma Solar de Almería (PSA) and its instrumentation schema. This facility has three nanofiltration membranes that can be used in parallel or in series form depending on the position of the FV0I valve. Its operation consists of the residual water source (which has been simulated by the feed tank) is introduced into the system, which maintains a flow setpoint using the pump FB2, divided into three branches or lines:

• Permeate, corresponding to water already treated.
• Concentrate, corresponding to water rejected due to its high concentration of pollutants.
• Recirculating used to regulate the transmembrane pressure (through the FV1B valve) with which it is necessary to work and that cannot be higher than 6 bar to avoid rupture of the pipes and membranes.

This plant is configured to control the flow and electrical conductivity (CE) of each branch, as well as the transmembrane pressure, through the pump FB2, recirculation valve FV1B and concentrate FV1A.

A SCADA system supervises and controls the processes.