CLARIFIERS and its types, working of clarifier

Types of clarifiers, working of clarifiers, uses of clarifiers in water treatment system, design of clarifiers

1. CLARIFIER N. ACHYUT BABU 18021A0108 PRESENTED BY

2. OBJECTIVE: TO VISIT NEARBY CLARIFIER TO KNOW HOW IT IS WORKING . TO UNDERSTAND THE IMPORTANCE OF CLAFIERS IN THE WATER TREATMENT.

3. CONTENTS:- WHAT ARE CLARIFIERS? TYPES OF CLARIFIERS PRIMARY CLARIFIER WORKING AERATION SECONDARY CLARIFIER DESIGN PARAMETERS OF CLARIFIER DESIGN A CLARIFIER FOR A VILLAGE

4. What are Clarifiers?   CLARIFIERS ARE SETTLING TANKS TO BUILT WITH MECHANICAL MEANS FOR CONTINOUS REMOVAL OF SOLIDS BEING DEPOSITED BY SEDIMENTATION . GENERALLY USED TO REMOVE SOLID PARTICULATES AND SUSPENDED SOLIDS FROM LIQUID FOR CLARIFICATION. CONCENTRATED IMPURITIES DISCHARGED FROM THE BOTTOM OF TANK ARE KNOWN AS SLUDGE PARTICLES THAT FLOAT FROM THE SURFACE OF THE LIQUID ARE CALLED SCUM

5. Types of Clarifier: There are two types of clarifier RECTANGULAR CLARIFIER CIRCULAR CLARIFIER

6. RECTANGULAR CLARIFIER: C ommonly used in very large or space constrained municipal and industrial spaces, removes both settled and suspended solids from liquids.

7. CIRCULAR CLARIFIER: Circular clarifiers use slowly rotating rake arms to separate solid particulate. The floor (or) bottom of clarifier has a slope of 1:20 towards centre . As the particles settle, angled rake arms move the concentrated slurry toward the center of the tank, where it is removed.

8. PRIMARY CLARIFIER: Primary clarification is the physical treatment process of removing solids before biological treatment. Floatable material (scum) are removed from the surface by skimmers and settle able solids (sludge) are collected on the bottom by a rakes. The expected range for percent removal in a primary clarifier is 90%-95% settleable solids, 40 %-60% suspended solids

9. WORKING: LAUNDER: It is an endless open channel of size 0.3m X 0.3m along periphery of clarifier.

10. TOP VIEW SECTIONAL VIEW The Scraper Arms will move slowly so that the water inside the clarifier will not disturnbed . The Scraper Arms complete 1 Revolution in 38 minutes.

11. AERATION: Aeration is the process of bringing water and air into close contact in order to remove dissolved gases, such as carbon dioxide, and to oxidize dissolved metals such as iron. It can also be used to remove volatile organic chemicals(VOCs)in water. Primary Clarifier

12. SECONDARY CLARIFIER: Microorganisms such as bacteria and protozoa can use the small particles and dissolved organic matter not removed in primary clarifier as food. In a secondary clarifier which operates in the same manner as the primary clarifier described previously. Some of the solids collected in the secondary clarifier (return activated sludge) are sent back to the aeration tank.

13. DESIGN PARAMETERS OF CLARIFIER: Surface loading of 40 m 3 /day.m 2 i.e , Settling velocity of 40 m/day Design depth = 3 – 5m Design settling time = 1 – 2 hours.

14. Design a clarifier to treat water for Rajanagaram of population 10,000 ? * Q = 135 X 10,000 = 1350 m 3 /day * Design surface loading = 40m/day (or) settling velocity * Area of clarifier, A = 1350 m 3 /day = 33.75 m 2 40 m/day π D 2 = 33.75 m 2 4 D = 6.6 m * Assuming the depth = 3 m * Voume = Area x depth = 33.75 x 3 ≈ 102 m 3

15. CONCLUSION: Circular Clarifiers are more efficient than the Rectangular clarifiers. 90%-95% settle able solids, 40%-60% suspended solids are removed in the Clarifier. So, most of the water is treated in the Clarifiers only.

16. REFERENCES: “Down to Earth” by Centre for Science and Environment, Fortnightly, New Delhi. Howard S, Peavy , Donald R, Teorge George, “Environmental Engineering”, Mc- Graw -Hill Book Company, New Delhi, 1985. K.N. Duggal, “Elements of Environmental Engineering”, S. Chand & Company Ltd., New Delhi, 2012. K.V.S.G Murali Krishna, “Rural, Municipal and Industrial Water Management”, Reem Publications, New Delhi, 2012. Santosh Kumar Garg, “Water Supply Engineering” Khanna Publications, New Delhi. 6 Most important learnings of the class from Prof. KVSG MURALI KRISHNA .

17. ACKNOWLEDGMENTS: I would like to thank Prof. KVSG MURALI KRISHNA for giving me this wonderful opportunity to do powerpoint Presentation on Clarifiers and for guiding me through these important concepts. This helped me to increase my knowledge .

18. THANK YOU