This standard specifies the construction requirements for sludge drying beds, a common method for dewatering sewage sludge. It covers the general layout, dimensions, composition of filtering media like sand and gravel, and the design of the underdrainage system.
Requirements for sludge dewatering equipment, Part I: Sludge drying beds-sand, gravel and underdrains
Quick Reference Values
Maximum bed width6 m
Typical bed length10 to 30 m
Total depth of sand layers200 to 300 mm
Total depth of gravel layers300 to 450 mm
Slope for underdrain pipes1 in 100 to 1 in 200
Freeboard above sand level400 to 500 mm
Practical Notes
Proper grading and sourcing of sand and gravel as per the tables is crucial to prevent clogging and ensure long-term performance.
The 6m maximum width is a practical limit for manual removal of dried sludge; for mechanical removal, this can be adjusted.
Consider providing a roof over the beds in areas with high rainfall to improve drying efficiency and prevent washout.