Metso’s Low Solids Measurement is an online measurement technology for municipal and industrial wastewater treatment plants that enables measurement of a media with very low solids contents in difficult applications like centrifuge centrate. The technology also offers savings per centrifuge in polymer and centrifuge usage. The system is based on LED and laser technology. It dearates, filters and measures the process solids along with possessing self-cleaning capabilities to keep the measurement optics clean for continued accurate measurement. The device can be connected online to the process and is able to measure continuous sample flow through the system by utilizing an integrated centrifugal pump. The device has two light sources, LED and laser, that measure absorption, scattering and depolarization of these sources as they pass through the flowing media. The measurement cell has a sapphire glass with high optical properties. The cell and sample lines are automatically cleaned at given intervals. The device continuously measures the suspended solids content within the range of 0 to 5000 mg/l and also the entrained air index, which indicates overdosing of polymer. –