1. PRELIMINARY WASTEWATER TREATMENT

2. PRELIMINARY TREATMENT Municipal wastewater treatment can be divided into Preliminary, Primary, Secondary and Tertiary Treatment as well as sludge disposal Preliminary treatment incorporates pumping, screening, comminuting and grit removal

4. Examples of Screen Types PROFILE BAR LOOPED WIRE RESISTANCE WELDED

5. Curved Bar Screens

6. Inclined Bar Screens

8. Wedge Wire Screens The screens are also non-plugging, self-cleaning and abrasion-resistant.

9. Sieve Bends

10. Drum Screens from Wedge Wire

11. Special Application Retaining Screens

32. http://www.krebs.com/tech_pdf/ sizing_sel.pdf Design of hydrocyclones

34. Final Remarks on Preliminary Treatment Preliminary treatment removes solids from wastewater – primarily those which would not be effectively removed or degraded A solid waste is generated which needs to be disposed of. Needs to be handled with care and regarded as infectious. Most commonly disposed of by land filling or combustion

35. Water Treatment Intake Screens Protection of Equipment

38. These underwater photos compare screens over adjacent under- water intakes at a Consumers Power Company station in West Olive, Michigan. The stainless steel screen (left) is completely clogged with zebra mussels. The biostatic copper alloy screen (right) is almost completely free of mussels. It was fabricated by Wheelabrator.