This month we are focusing on Drinking Water & Turbidity. In the UK water suppliers place high priority on assuring the quality of water provided to their customers. Strict standards for the quality of the UK public supply are laid down in national regulations derived from the EU Drinking Water Directive. These standards are based on advice from the World Health Organization (WHO).
Why we monitor Turbidity in the Drinking Water Process
There are many things that can affect the quality of drinking water and the government regulations set the level of Turbidity that is permissible. The measurement of Turbidity is a key test of water quality and is an excellent early indicator of process problems. High intake levels cause filter problems and blockages, whilst an increase in Turbidity in the final water stage can point to filter failure and the possibility of cryptosporidum and other contaminants in the water.
Higher levels of Turbidity in drinking water can indicate that people are at higher risk of developing gastrointestinal diseases. Contaminants like viruses and pathogenic bacteria can attach themselves to the suspended solids, these solids then interfere with disinfection when particles act as shields for the virus and bacteria.
Using Turbidity as a control parameter can assist dosing and energy savings. Dosing levels can be adapted to suit the performance of the site and hence save money when Turbidity is low. Water Treatment plants can also react quickly to changes in the inlet Turbidity, preventing problems with the final water quality. Filter Backwashing is a critical part of the drinking water production process, water flow is reversed and increased in order to flush out debris and particles. It can be automatically controlled by using a Turbidity Monitor to monitor the effectiveness of the backwash process, thus reducing water usage.
How we monitor Turbidity in the Drinking Water Process
The measurement of turbidity can be carried out in a number of ways. Operator observation will allow experienced site personnel to make good process control decisions, however this is very dependent on the knowledge of the operator and can lead to problems during times of increased workload, holiday or sickness.
Handheld Turbidity Monitors offer a more consistent set of data, however they are still dependent on operator skill and only provide information when the site is manned causing the process to be uncontrolled overnight and at weekends.
Continuous On-Line Monitoring reduces the need for time-consuming laboratory analysis and removing operator dependency from the measurement. Real-time monitoring provides more accurate and reliable process control. This improves plant efficiency by providing stability and continuity to the treatment process.