INTRODUCTION TO WATER TREATMENT & ABSTRACTION

 

PROCESS CONTROL LOOPS

A process control loop is an automated method of ensuring the correct level of a chemical at any point in the treatment process. If you follow the animation below you will see a typical method for automatically correcting chemical dosage to achieve a desired result.

 

This process can be used to inject & control the dose rate of many different chemicals, including many used within the water industry.
This process can control the injection of gases into water all that is required is to replace the dosing pump with a chlorinator or sulphurnator.
Some of the chemicals that use the process control loop are listed below.

Chemical Name	Chemical Used for :---
Chlorine gas	Disinfection
Sulphur Dioxide gas	Reducing & controlling Chlorine residual
Sodium Hypochlorite	Disinfection
Sodium Bisulphate	Reducing & controlling Chlorine residual
Caustic Soda	Adjusting pH levels
Acid	Adjusting pH levels

The list of chemicals is very substantial & not all sites use or require the same treatments.