Millipore Pollution Index Tester

Millipore Pollution Index TesterWorking Principle:

SDI instrument (i.e. pollution index meter) can calculate and measure the relative amount of suspended matter in the influent. When the incoming water passes through the 0.45 μ m membrane, the SDI value reflects the speed at which particulate matter in the water clogs the 0.45 μ m pore membrane. The reason why the American Society for Testing and Materials (ASTM) chose 0.45 μ m pore size membranes is that they are more susceptible to clogging by colloidal substances rather than hard particulate matter such as sand or scale. The SDI value usually serves as a "warning" to ensure that particulate matter in the incoming water does not clog the reverse osmosis membrane.

Millipore Pollution Index TesterIntroduction:

SDI is calculated based on the flow attenuation of sampled water filtered through a 0.45 μ m microporous membrane at a pressure of 0.207MPA over a certain period of time. SDI value is one of the effective methods for characterizing the colloid and particle content in pretreated effluent, and is an important indicator for ensuring the effective operation of membrane separation processes such as reverse osmosis. The pipeline water pollution index tester has the advantages of easy installation of diaphragms, rapid adjustment of pressure, and small testing errors. The instrument mainly consists of a water inlet joint, ball valve, pressure regulator valve, pressure gauge, A-type quick connector, filter, and connecting pipe fittings.

Calculation of SDI:

If the flow rate decays into slow droplets before filtering for less than 15 minutes, it is recommended to use the following formula to calculate: SDI=100/T, where T - the time (in minutes) from the start of testing to the decay of droplets; If it does not decay into slow droplets after 15 minutes of filtration, calculate using the following formula: SDI=100 (1-t1/t2)/T, where t1 is the time required to collect 500ml of water sample during initial testing (in seconds); T2- The time (in seconds) required to collect 500ml of water sample after T (minutes); T - Corresponding to t2, 5, 10, and 15 (minutes) can be selected respectively.

The MFI corrected pollution index is an improved characterization method for SDI. The testing process is the same, but the calculation method is different. It is a curve graph of the relationship between t/V and V at the time t of filtering the volume V (L) of the water sample. The slope of the curve in the linear part (filter cake filtration stage) is calculated as the MFI value. Convergence's MFI tester uses professionally designed filtering fixtures and membranes to ensure uniform flow field distribution and filter cake formation. The impedance, temperature, and pressure of the membrane will be measured and used for calibration in MFI calculations This method overcomes some shortcomings of SDI in characterizing water quality and can effectively reflect the influent water quality, such as the linear correlation between MFI and colloid and suspended particulate matter content. Based on the filter cake filtration principle, it can effectively correct membrane resistance, temperature, and pressure, predict the time required for a certain amount of decrease in reverse osmosis membrane flux, and guide the pretreatment process.