The Suspended Solids Density Meter from Markland Specialty Eng. provides continuous real-time knowledge of primary, secondary, return-activated and backwash sludge, slurry and silt concentrations in pipes, tanks and clarifiers. It allows users to program underflow pumps to shut off before biosolids or feed solids density becomes too thin. It helps in optimizing polymer dosing and equipment variables for enhanced de-watering. This process control instrument uses the inherently safe attenuation of non-radioactive ultrasound (no permits/no approvals needed). Readings are not affected by the color of particulates or fluid. It may offer early awareness of breaks in filtration material when used to measure filtrate concentrations. A sensor on the meter (available as an inline pipe spool piece or throw-in style probe) transmits and receives the ultrasound waves. It sends out a pulse of sound, receiving a strong echo and reading zero when the solution is clear. When particles are present in the liquid, they absorb or deflect the sonic energy, the echo is reduced in amplitude and the meter reads the suspended solids density. The output signal, sent to a computer/control system, provides continuous SS readings and enables calculation of mass flow rate. The inline pipe spool piece sensor is non-intrusive. The throw-in style probe may also be used as a single point interface level detector, allowing operators to program de-sludge pumps to turn on when the rising sludge blanket domes in contact with it. Each style is simple to install, calibrate and clean. Equipped with a continuous awareness of sludge densities at critical points in the treatment process, plants are better able to make adjustments and program control systems to improve effectiveness and efficiency, qualities which translate into material and energy savings.