At the end of this lesson you will be able to: Learning Objectives At the end of this lesson you will be able to: Understand the importance of chlorine testing Demonstrate the chlorine testing procedures Learning objectives. At the end of this lesson you will be able to: Describe the basic principles for the operation of the HACH© pocket chlorine colorimeter Demonstrate the operation of the HACH pocket chlorine colorimeter in accordance with the manufacturer’s instructions 1

Introduction The Water Corporation has a memorandum of understanding with the Department of Health to supply safe drinking water to consumers. In simple terms, turbidity is a measure of how cloudy a water sample appears. 2

Check calibration of all chlorine meters regularly. Introduction Following a 2002 audit by the Department of Health the following changes were made: Standardise all chlorine meters to HACH Pocket Colorimeters (also HACH DR 800 & 2000 series units). Check calibration of all chlorine meters regularly. Train all users to ensure competence. 12 months given to develop resources and train everyone. The ability of light to pass through water depends on how much suspended matter is present. Turbidity may be caused by large amounts of silt, micro-organisms, plant fibres, sawdust, wood ash, chemicals and coal dust. 3

Introduction Chlorine standards are difficult to make, preserve and store for field use. (i.e. 1.0 mg/L chlorine). The Water Corp settled on using HACH SpecCheck secondary standards – they can only be used for 2 years from date of manufacture. 4

Introduction Having made all these changes we could ensure that progress was made towards: all staff using the chlorine meters being competent. all instruments kept in excellent working condition. 5

Why add chlorine to water? Chlorine forms the main barrier against disease in the disinfection process which means that chlorine is the most important of all chemicals to test in the drinking water supply. 6

Importance of chlorine testing Chlorine testing is an essential part of managing the water supply. Results from your tests are recorded, checked and abnormal results investigated. Incidents must be reported and action must be taken immediately. 7

Disinfection processes used Chlorination - most common method used. Chloramination - sites along the Mundaring to Kalgoorlie pipeline Ultra violet irradiation - Leonora & some other regional sites with RO systems (as a pre-treatment to protect the membranes). 8

Chlorine chemistry The reaction between chlorine and water is shown as: Cl2 + H2O → HOCl + H+ + Cl- chlorine water hypochlorous hydrogen chloride acid ion ion Note: HOCl - free residual chlorine. 9

Chlorine also reacts with ammonia in water to Do you know? Chlorine also reacts with ammonia in water to form the chloramines - monochloramine, dichloramine and trichloramine. The proportion of hypochlorous acid in water depends on the: temperature pH ratio of chlorine and ammonia. N H Cl monochloramine dichloramine trichlroamine 10

Chemical hazards Chemicals used are safe if handled with care - DPD free chlorine and DPD total chlorine powder. Always practice good hygiene habits – wash your hands after using the chemicals. Click on the hot text for more information. 11

Chemical hazards Chemicals required are safe if handled with care- DPD free and DPD total chlorine. Always practice good hygiene habits. N,N - diethyl-p-phenylenediamine 11