Sand Filtration

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?

Parameter desain SSF

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

Operasi

Mekasnisme proses..

1. Mechanical, Phisical

2. Biological Lapisan Biofilm

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)

BackWash

Expansion area = 20-50 % dari ketinggian bed filter