Protection of Water Desalination Plants from Red Tide effects in U.A.E.

1. United Arab Emirates UniversityCollege of EngineeringDepartment of Civil & Environmental Engineering Protection of Water Desalination Plants from Red Tide effects in U.A.E. Advisor: Dr. Hassan DarwishImran Ahmed HabibBaniHashem 200305629 Saeed Mohamed Al Marzooqi 200411497 Mohammed Al Abodi 200411501 HumaidKhalifaJumaa 200410618 Second semester 2009/2010

2. Outline Introduction Objective Definition Desalination plants study Intake process Suggested solutions Conceptual design

3. Outline Study Sea wall Study Beach well Compare between two alternative and final decision Project management Conclusion

4. Introduction Red tide: microscopic single-celled plants known as phytoplankton that live in the sea Causes of red tide are : • Human activity • Ocean movements • El Nino phenomenon

5. Effects of red tide in general Red Tide affect human, sea water and marine organisms. • For sea water it affect its color and smell. • For marine organisms it makes them die where it decreases the percentage of oxygen in water. • It affects human’s health & desalination plants.

6. Red tide in the UAE and its effect • Main problem in UAE because it leads to the close of desalination plants in many places in UAE and this table show the results of red tide in desalination plant :

7. Red tide in the UAE and its affection

8. Objectives • Identify problem extent in water desalination plant and its effect. • Identify different cases of water desalination plant and their design limitations. • protect coastal areas and the desalination plants from red tide and avoid closing them by designing a number of alternatives. • Find recommendations for the environment and water authority.

9. Desalination plants study • We visited three desalination plants: • Umm Al Nar plant in Abu Dhabi in 12-11-2009 • Ghalilah desalination plant in RAK in 17-12-2009 • Al Zawrah desalination plant in Ajman in 23-11-2009

10. Process of Filtrations in the plants Intake Process Barriers Stationary Screens Net screen opening Traveling Screen Chlorination Sand filters Cartage filters Membranes Add Dissolved solids drinking water

11. Barriers • Used for warning plant • Keep oil away from water inlet • Made from plastic, steel and concrete • Easy to maintain and remove • It will allow rid tide to inter the intake 11

12. Barriers 12

13. Stationary Screens • It is the second part of intake process • Steel metal screens (10 cm X 30 cm) opening • Protect the intake from large size of pollution

14. Stationary Screens

15. The net screen opening • Objective: kept the material or sand and the sizes of this material are from 1 mm to 5 mm. • Idea in this stage : The velocity of the water in the net screen openings should be less than 2.0 ft/s (0.6m/s) at maximum design flow and minimum screen submergence.

16. The net screen opening • The size of the algae that caused red tide is around 40 μm. • Main Problems faced if red tide enter: • In this stage any thing between 1-5 mm will kept in the net screen opening but the algae can escape from this stage. • Also another problem the toxic come with the algae can escape from this stage.

17. Traveling Screen • Type of water filtration device that has a continuously moving mesh screen that is used to catch and remove debris. • Traveling screens can be used to catch leaves, sticks, grass, jellyfish, trash, green mussels, shells, hydroids, seaweed, and plastic.

18. Traveling Screen Screening Apertures Available: 1/8" to 3/4" mesh openings Traveling Screen Advantages: 1- high travel speed for extra debris handling capacity. 2- self-cleaning nozzles. 3- high efficiency seals. 4- seize proof bearings. 5- long life chains.

19. Process of Filtrations in the plants Intake Process Barriers Stationary Screens Net screen opening Traveling Screen Chlorination Sand filters Cartage filters Membranes Add Dissolved solids drinking water

20. Suggested solutions • Have a beach wells for intake • Use ultra filtration system (nano filtration) • Use dissolved air flotation (DAF) system • The intake should be from undersea bed • Build 1 Km2 wall to keep sea water inside.

21. 1- Beach wells for intake • Beach wells extracting seawater quality can provide a reliable quantity and better quality water than surface intakes due to natural filtration and underground detention

22. 1- Beach wells for intake Advantages • Would be an alternative instead of sea water • Water will be filtered • Cheap Disadvantages • Need distance between well and other (large area) • Not working every where • Salts in soil layers

23. 2- Ultra Filtration System • It is a process using membranes with pore sizes in the range of 0.1 to 0.001 micron • Advantages and disadvantages

24. 3- Use DAF system • How its work? • Advantages and disadvantages

25. 4- undersea bed Advantages • Under sea surface by 6m • Avoid oil flow • Water is filtered • Easy to maintain Disadvantages • Very costly • Doesn’t used until now

26. 5- Build 1 Km2 wall

27. 5- Build 1 Km2 wall Advantages • Use it like a tank • Long life • Safety method in oil spreading • No entrance for red tide Disadvantages • Need maintenance • Costly • Green algae inside area

28. Beach well • Second design we will discus it in detail is the Beach well. • In our case study (Al Zawrah plant) we have two testing beach well, this testing well help as a lot in calculation and design. • Eng. Mohamed Lotfi help us a lot, also we use Abu Dhabi ground water atlas to get the missing data.

29. Detailed design for beach well • Determine number of beach well needed: • Plant demand = 15 million gallon/day • flow of one well = 128 m3/hr = 675,745 gallon/day So, • 15 million gallon/day ÷ 675,745 gallon/day = = 22.2 well, that mean we need 23 well.

30. Detailed design for beach well • number of beach well needed: • In fact we have to use all the 23 wells to have the adequate amount of flow for the plant, in this situation we will be in risk if any well breakdown. • So we will increase the number of wells to 30 to be in safe side.

31. Detailed design for beach well • Determine distance between wells: • We use the unconfined steady flow to a well equation, the equation is:

32. Detailed design for beach well Where: • Q , Flow Rate (m3/hr) • K , Coefficient of permeability (m/day) • Y , Depth of the water flowing in the aquifer (m) • y1 , height of the screen (m) • y2 , Water depth in the end of the drawdown curve (m) • r1 , radius of the well (m) • r2 , Distance between each well (m) “require” • note: T = KY where T is Transmissivity (m2/day)

33. Detailed design for beach well

34. Detailed design for beach well • Determine distance between wells, so : Q = 128 m3/hr so, y1 = 40 m r2 = 50 m y2 = 80 – 4 = 76 m T = 84 m2/day r1 = 4 inch = 0.2032 m

35. Detailed design for beach well • Determine area to construct the beach well on it: • We multiply 50 m by 15 (number of beach well require in one row) * 2 rows That means we will need an area of( ( 50 +1 m ) * 15) * (50 +1 ) = = (751 x 51) m2

36. cost of beach well • The cost of one beach well is shown in table: • Total cost = 30 * 108,080 = 3,242,400 Dhs

37. Construction considerations for sea wall • Al Zawrah desalination plant needs 15 million gallon/day. • plant closed for two weeks because of red tide so 14 days × 15 million gal./day = 210,000,000 gallon • Suggested volum is 450 x 450 x 6 =1215000 m3 Which is equal 320,969,101.5 gal. 320,969,101.5 gallon /15 million/day ≈ 21.4 day 37

38. Al Zawrah Plant and design of the wall 38

39. Material specifications • Concrete strength equal to 50 MPa to carry the huge loads affecting the wall. • sheet piling dimension is 500 mm width, 106 mm height, 56.3 kg/m2 weight and 5 mm thickness. 39

40. Elements concentrations in Arabian Gulf • Type V cement is recommended to resist the high dissolved concentrations elements in the gulf. 40

41. Dimensions of cross section of sea wall • By prokon program we put dimensions which meets our needs. • We consider some loads like wind, wave and water load. • Dimensions are in meter. 41

42. Moments on the wall 42

43. Steel arrangement for the wall • Number of bars required for one meter =maximum reinforcement/cross sectional area. • we chose the minimum size between front and back sides which is steel bar 16mm 43

44. Moment loads on base

45. Steel arrangement for the base • we chose the minimum size for the horizontal which is steel bar 16 mm 45

46. Steel arrangements for the base & wall

47. Comparison between Sea wall and Beach well 47

48. Continue comparison between Sea wall and Beach well 48

49. Cost of steel sheet piling • The 510 m site length for each side and we need sheet piling for 3 sides so the total length will be 1530 m. • 1m2 of sheet piling has 56.3 kg • 12 m length * 0.5 m width *56.3 kg/m2 =337.8 kg • 337.8 kg = 0.33 ton • 1530 m / 0.5 m/sheet = 3060 sheet pile. • 3060 pile * 0.33 ton/sheet = 1010 tons • 1010 tons * 2870 Dhs/ton = 2,898126 Dhs

50. Base volume for one side =0.6 * 3.5 * 500 = 1050 m3 Wall volume for one side =0.5 * 7 * 500 = 1750 m3 Total volume =4 *(1050 +1750) = 11200 m3 Total cost = 11200 m3* 1100 Dhs = 12,320,000 Dhs Cost of concrete 50