1. Egham Water Treatment Works
Flow: 2920 m3/h

2. Source
Thames River

3. Screening
With surface boom

5. Rotating Mesh Screen

7. Debris from Screens

8. Pre-ozone in-line injector
Purpose: to help with coagulation
They also add pre chlorine to breakpoint any ammonia
needed ~80% of time?

9. Pre-O3 injector and static mixer
4 elements
700 mm diameter
196 mbar headloss
97% transfer efficiency

10. Gravity Settling Tanks
Sludge blanket
submerged conical sludge collectors
can be barely seen here
suspended from above

11. Nigel describing sludge cones to class

12. Dual Media rapid filters
Anthracite & Sand
siphons (good practice)

13. Intermediate Ozone Building

14. Liquid Oxygen Tank

16. Liquid oxygen equipment

17. LOX handling
Heat transfer

18. Ozone Generator
Trailigaz
One of 3 units
only one in use that day

19. Ozone Generator
No blue glow, because of pure O2

20. Intermediate O3 Monitor
Purpose of inter ozone: disinfection
criteria: 0.4 mg/L residual after 4 minutes in contact tank

21. GAC contactors Modular design
Avoided need for expensive in place concrete
problems with leaks

22. Final Disinfection Free chlorine Addition of sulfur dioxide
shoot for a residual of about 0.5 mg/L
requires a dose of ~ 2-3 mg/L
Addition of sulfur dioxide
to achieve target FRC
THMs are low (~30 ug/L)
except when prechlorinating
final pH is about 7

23. Sludge Centrifuge