1. Ochre Pelletising and use for phosphate Removal from sewage effluent 2 nd February 2005 Jonathan Aumônier

2. Introduction Pelletising Process Lab results – phosphate removal Micrographs Windlestone trial Planned work

3. Requirements for Pellets Physical Strength – (Crush and handling) Resistance to degredation in water Resistance to degredation through biological activity Size Retained Reactivity of Ochre Retained Phosphate Capacity High Porosity No “Film” or “Matrix” Binder System No Leaching of metals

4. Extrusion Trial ‘Z’ Blade Mixer-Extruder Cutting Extruded Product Mixer Blades

5. Pan Pelletising

6. Θ Water & Liquid Binder Powder Feed Water & Liquid Binder Powder Feed Small Pellets Large Pellets Product Pan Angle Θ Rotational Speed ω

7. Pelletising Equipment Vibrating Hopper Variable Speed Helical Feed Screw Dust Extraction 70cm Diameter Pelletising Pan ASDA Washing-up Bowl

8. Ochre Sources and use Skinningrove - initial physical test Silwood - MScs - 1 st Nafferton Farm trial Acomb - Current lab work - 2/3 of Windlestone pellets - Some to Leitholm Polkemet - 1/3 of windlestone pellets - Leitholm Horden - 1/3 of Leitholm - ESL Nafferton Farm - Stock of pellets

9. Phosphate remover from solution with varying initial P – after 24 hours Initial P (mg/l) P removed (mg/l) Data from Lawrence Bowden

10. Rate of phosphate sorption Time (s) Phosphate load on pellets (mg_P/g) Data from Lawrence Bowden

11. Rapid P Sorption tests Residence time (s) Solution Concentration (mg/l P) Feed Concentration 1 mg/l P Data from Frances Brett

12. Phosphate removed from solution with varying ionic strength of KCl Molar strength of solution KCl % Removal 100% 80% Data from Lawrence Bowden

13. Ochre pellet before reaction with phosphate solution x100

14. Ochre pellet before reaction with phosphate solution x800

15. Ochre pellet after reaction with phosphate solution x65

16. Ochre pellet after reaction with phosphate solution x100

17. Windlestone trial details (Horizontal Flow) Feed taken from site final effluent Initial rate 2.7 m 3 /hr reduced to 0.75 m 3 /hr 0.96 m 3 of pellets Contact time 7½min increased to 24 min Sampled input and output every 25 hr

18. Windlestone trial details (Vertical Flow) Feed taken from site final effluent Flow Rate 0.75 m 3 /hr 0.88 m 3 of pellets Mean contact time 90 second (unsaturated flow) Mean contact time 25 minutes (fully saturated flow) Sampled input and output every 25 hr

19. Ochre pellet reaction vessel: Windlestone WWTW – Horizontal Flow Images: Jonathan Aumônier Slide: Kate Heal Inflow Outflow Effluent percolates through ochre Gravel

20. Final STW Sump at Windlestone Inlet for Trial Outlet from Trial

21. Mono – Progressive Cavity Pump

22. Results for Windlestone Trial (Horizontal Flow) Date Removal Fraction Feed Phosphate Mg/l P

23. Windlestone spot results Results from samples after maintenance to clear the overflow Input P (mg/l) Output P (mg/l) Flow rate (m 3 /hr) % Removal 1.0050.3162.768.6 1.6090.5892.763.4 4.8561.3502.772.2 4.1811.1642.772.2 0.5550.0920.8483.5 1.1780.2440.7579.3

24. Ochre pellet reaction vessel: Windlestone WWTW – Vertical Flow Inlet Pipe From Pump In-line Strainer Spray Bars Inlet Sample Line

25. Ochre pellet reaction vessel: Windlestone WWTW – Vertical Flow Inlet - 0.75 m3/hr 500mm Saturated Zone U Bend Outlet Spray Bar

26. Results for Windlestone Trial (Vertical Unsaturated Flow) Date Feed Phosphate Mg/l P Removal Fraction 0.75 m 3 /hr mean residence time 90 sec Mean Removal 26%

27. Planned Work Continue Windlestone trial with saturated flow More locations Laboratory tests on ochres and binders Laboratory continual flow trials

28. Flow Columns in the Lab

29. Ochre pellet after reaction with phosphate solution x65