Abstract: This invention uses multiple pairs of electrodes acting as electrical conductivity sensors that are secured at specific locations within spiral wound membrane elements and their interconnecting components of a reverse osmosis or nanofiltration pressure vessel. Each electrode pair might be attached to a wire cord to be inserted through and sealed against a vessel end cap into the permeate carrier tubes and interconnecting components of the membrane elements, or each electrode pair might be attached to a battery and a wireless transmitting device. Conductivity measurements from the sensors would be communicated to a microprocessor, which would evaluate each permeate conductivity measurement relative to other permeate conductivity measurements, as well as relative to derived or measured conductivities in the saline water in calculating a percent salt passage value specific to the location of each permeate sensor.

Abstract: This invention is connected to the influent or effluent stream of an SDI filter holder assembly that might otherwise be applied in the manual measurement of the flow rates and times as required to calculate a silt density index. The invention is based on its ability to provide data collection external to the filter holder assembly in digitally measuring the flow rate and water temperature proceeding to or from the filter assembly and in automatically incorporating those readings into a microprocessor for calculating the silt density index and in normalizing the index value for the effects of variation in initial filter permeability and water temperature, and in minimizing the effect of increasing cake solids on the SDI value as related to the decreasing flow of water-borne solids to the filter surface.