Flocculation and chlorination process control Jar test and Chlorine demand test

1. Flocculation and chlorination process control Jar test and Chlorine demand test

2. Contents Chemicals and preparation of solutions Flocculation control: Jar test Chlorination control: Chlorine demand test Jar test practical procedure

3. Chemicals and preparation of solutions

4. 1. Chemicals and preparation of solutions • Aluminium Sulphate mother solution 1 % = 10 g Aluminium Sulphate / litre clean water = 10.000 mg/litre Dissolve 10 g. in a small volume of water and pour the solution into 1 litre of clean water. If a scale is not available, prepare the mother solution by using a “spoon” as a measurement unit ≈ 1 spoon / litre clean water • Chlorine mother solution (Using Calcium Hypochlorite HTH 70%) 1 % chlorine = 14 g HTH/litre clean water = 10.000 mg Cl2/litre

5. 2. Flocculation control: Jar test

6. 2. Flocculation control. Jar test Laboratory

7. Process Material: 6 bottles/jars with 1 litre of raw water each 1 jar with mother solution (MS) Turbidity meter (final turbidity < 5 NTU) Syringe to measure volumes Watch Wand Add MS (2 ml, 4 ml, 6 ml, 8 ml, 10 ml, 12 ml) in the raw water bottles Stir for about 10 min. and leave the solution to settle for 30 min. Choose the right jar Dosage calculation for a 30.000 litre tank of raw water Example: [6 ml (MS) (1 %) / 1000 ml] x [10 g Al /1litre (MS)] x 30.000 litres = 1.800 g Al [6 ml (MS) /1000 ml] x [1spoon /1litre (MS)] x 30.000 litres = 180 spoons Al Dosage implementation (manually or with dosage pumps) 2. Flocculation control. Jar test

8. 2. Flocculation control. Jar test Watch out for choosing the right dosage. Aluminium excess.

9. 3. Chlorination control: Chlorine demand control

10. Process Material: 6 marked buckets with 10 litres of clean raw water (flocculated) 1 jar with mother solution (MS) Chlorine tester (Final optimum chlorine = 0,5 mg /l aprox.) Syringe to measure volumes Watch Add MS (1,0 ml, 1,5 ml, 2,0 ml, 2,5 ml, 3,0 ml and 4,0 ml) in the raw water buckets Stir for about 10 min. and leave the solution to settle for 30 min. Choose the right bucket Dosage calculation for a 30.000 litre tank of raw water Example: [2,0 ml (MS) (1 %) /10.000 ml] x [14 g Cl2 /1litre (MS)] x 30.000 litres = 284 g Cl2 Dosage implementation (manually or with dosage pumps) Handle with caution 3. Chlorination control. Chlorine demand test

11. 4. Jar test practical procedure

12. 4. Jar test practical procedure 1. Aim To establish the quantity of Aluminium Sulphate needed to decrease the turbidity of a certain volume of raw water bellow a given value, generally 5 NTU. 2. Applications - Mass water treatment. - Pretreatmet of raw water with high turbidity (specialized water). 3. Importance High turbidity implies an increase in chlorine consumption in the treatment process. It also leads to more frequent maintenance, particularly filters, to shorter lifespan of equipment and to upsetting taste and appearance for consumers. Excess of aluminium is toxic.

13. 4. Jar test practical procedure • 4. Materials • Clean water • Aluminium sulphate • 7 jars • 1 spoon • 6 litres of raw water • 1 watch

14. 4. Jar test practical procedure 5. Procedure Pour 1 litre of clean water into a jar and 1 litre of the raw water sample in each of the other 6 jars. Fill a spoon with Aluminium Sulphate (10 g.)

15. 4. Jar test practical procedure 5. Procedure Pour the Aluminium Sulphate in the jar with clean water. Vigorously stir until the complete dissolution of the chemical.

16. 4. Jar test practical procedure 5. Procedure The solution is namedmother solution (MS) 1%. Using a syringe, growing quantities of mother solution 1% will be taken.

17. 4. Jar test practical procedure • 5. Procedure • Pour 1 ml. of MS to the first jar • 2 ml to the second jar • 4 ml to the third jar, 8 ml to the fourth, 16 ml to the fifth so that each jar duplicates the concentration of the preceding. It is also possible to use different quantities.

18. 4. Jar test practical procedure • 5. Procedure • Stir vigorously to favour coagulation. • Stir very slowly in the same direction for 10 min. • Let it settle for 30 min.

19. 4. Jar test practical procedure 5. Procedure When 30 minutes or the time agreed has expired we will observe a colour gradient. We will not select the clearest, but the jar where less mother solution was added among those sufficiently clear.

20. 4. Jar test practical procedure 5. Procedure If none of the jars comes up with clear water, after checking the turbidity as explained bellow, we shall repeat all the process although adding 24, 34, 46, 60 and 76 ml. Only after checking again that a cleaner source is still not available. If all are sufficiently clear, we shall repeat all the process with smaller amounts 0.1, 0.2, 0.5, 0.75 y 1 ml. Only after checking again that the source still does not meet turbidity requirements without any treatment.

21. 4. Jar test practical procedure 5. Procedure Check that turbidity is below 5 NTU or 20 NTU, by pouring very carefully the sample into a measuring column (turbidity meter). Avoid the dissolution of solids settle at the bottom of the jar.

22. Thank you……….