Some operating definitions are provided to help you further understand your machine:
Permeate Rate [Product Water Rate (Qp)] is the flow rate of purified water which has passed through the membrane element and out of the membrane element housing; expressed in gal/min (gpm) or gal/hr (gph) [in metric, liter/min (Lpm) or cubic meters/hour (m3/h)]. Specified permeate rates are normally at 77ºF (25ºC).
Concentrate Rate [Waste Water Rate (Qc)] is the flow rate of water containing rejected solids to drain in gpm or gph (Lpm or m3/h).
Feed Rate (Qf) is the flow rate of incoming water in gpm or gph (Lpm or m3/h). Feedwater rate equals permeate rate plus concentrate rate.
Recovery equals permeate rate divided by feed rate and is expressed as a percentage. For example, 33% recovery means that out of a given feed rate, 33% is produced as purified water (permeate).
Concentration equals the Total Dissolved Solids (TDS) concentration of a solution expressed as milligrams per liter (mg/L) or conductivity (microSiemens/cm).
Cf | = | Feed Concentration |
Cp | = | Permeate Concentration |
Cc | = | Concentrate Concentration |
Cavg | = Average Concentration in Machine | |
Salt (Ionic) Rejection equals the percent of dissolved salt rejected by the membrane element, calculated from an average concentration over the membrane.
Salt (Ionic) Passage equals (100% - rejection) or the percent of dissolved salts passed through the membrane element.
An example of how to calculate salt rejection and recovery is given below:
Figure 1.4
Principles of Operation
3