Coagulation control method and system

A method of automatically controlling coagulation of contaminants in a fluid stream that is treated through a coagulation tank, a flocculation tank, and a sedimentation tank, the method comprising:

• receiving, by a controller, a set of measurement signals from each of a plurality of sensors, the plurality of sensors including:
• a turbidity meter configured to measure turbidity of the fluid stream at a position upstream of the coagulation tank,
• a first spectrophotometer configured to measure an absorbance of light at one or more predetermined wavelengths by the fluid stream at a position upstream of the coagulation tank,
• a pH meter configured to measure a pH of the fluid stream at a position upstream of the coagulation tank,
• a temperature probe configured to measure a temperature of the fluid stream at a position upstream of the coagulation tank,
• a second spectrophotometer configured to measure an absorbance of light at one or more predetermined wavelengths by the fluid stream at a position downstream of the sedimentation tank, and
• a trihalomethane (THM) sensor configured to measure a THM level in the fluid stream at a position downstream of the sedimentation tank;
• determining, by the controller, based at least on the set of measurement signals from the plurality of sensors, a coagulant dose to be administered to the fluid stream in the coagulation tank to obtain a contaminant level below a predetermined threshold value;
• and
• causing, by the controller, the determined coagulant dose to be administered to the fluid stream at the coagulation tank.