Tipe: • Slow sand filtration • Rapid (gravity) sand filtration • Rapid (pressure) sand filtration
Pengertian.? • Sand filtration is a water purification process in which water is passed through a porous bed of filter medium • Slow sand filtration? • Rapid sand filtration?
Perbedaan? • Slow sand filters are distinguished from rapid sand filters by the biologically active sand medium (including the Biofilm), and slow detention times. • In a mature sand bed, a thin upper sand layer called a Schmutzedecke (Biofilm) forms. The Biofilm consists of biologically active microorganisms that break down organic matter while suspended inorganic matter is removed by straining. • Rapid sand filters utilize primarily a physical removal process, are periodically backwashed for cleaning, and operate with long detention times. • Slow sand filters are cleaned by periodically scraping the existing Biofilm.
RAPID SAND FILTER SLOW SAND FILTER • Effective size: 0.35-0.50 mm • Uniformity coefficient: >1.3/1.7 • Filtration Rate : ~ 5 m3/m2.jam • Effective size: 0.15-0.35 mm • Uniformity coefficient: 2-3 • Filtration Rate : 0.1-0.2 m3/m2.jam
Mekasnismeproses.. • Mechanical, Phisical • Biological LapisanBiofilm
Backwash. When is Backwashing Needed? • The head loss is so high that the filter no longer produces water at the desired rate; (Filter Mampet) • Floc starts to break through the filter and the turbidity in the filter effluent increases; (Effluent keruh)