Control Systems in Water Treatment plants
Title: Control System for Water Treatment Plant.
Date of Submission: 6th March , 2016.
Author: Mr. Ganesh Kulkarni.
Designation: Manager – Global Services.
Water treatment is the process of treating water to make it useful for defined purpose. The purpose can be drinking, household purpose, Medical purpose and Industry. Every Industry has specific norms and local codes which need to be strictly followed during treatment of the Water.
Raw Water Collection is the starting point for most of the plants, where the raw water is pumped through remote locations. Lift stations / Booster pumps are used at remote stations to pump the water to the plant. Control systems are needed to distribute the load of remote pumping locations. Control systems in such plants also help in remote monitoring and diagnostics of the process. The control network can be established on Radios or Fiber, based on geographical conditions.
Raw water is then passed through the mechanical screens to remove visible solid material. The Mechanical screens are typically skid-based and have a dedicated control system. Mechanical screen’s control system can be interfaced to SCADA system for remote monitoring and control. This part of the process is called head-works where initial filtration is achieved. This filtered water is then forwarded to Clarifiers, where settling process is used to purify the water further. Typically clarifiers will have scrapper arm at the bottom to collect the Waste and scum pump at the top to collect floating waste material. This is more a mechanical system to purify the water.
After clarifiers, filters are used to treat the water further where filtration is achieved in microns. Series of filters is used based on quality of water expected. Filters like Media filters, Ultra filters, GAC filters, Ion Exchange filters are used to treat the water to a great extent. Sometimes RO system is also used based on solids content of the water. Typically filters have valve sequences which need to be followed for filtration. Filters also need to be cleaned by a process called backwash. Backwash also has valve sequences to be controlled through the control system. Backwashing can be done based on Time or Volume mode and respective Time / Volume calculations need to be done in the Control system.
The treated water from filters is stored in big storage tanks and then distributed throughout the city. Based on distribution tanks and distribution area, the control system is provided for continuous and regulated water supply. Cotmac has been always instrumental in design and installation of such control systems for Water domain.