TITLE:
Drainage Bed: A Natural System for WTP Sludge Dewatering and Drying with Different Coagulant Chemicals in Tropical Countries
AUTHORS:
Marcelo M. Barroso, Cali L. Achon, Renan F. Reis, João S. Cordeiro
KEYWORDS:
Sludge, Dewatering, Drying, Drainage Bed (DB), Geotextile Blanket
JOURNAL NAME:
Journal of Water Resource and Protection,
Vol.6 No.11,
August
20,
2014
ABSTRACT:
This
study seeks to evaluate the mechanisms for dewatering sludge from Water
Treatment Plants (WTP) in a natural system that uses nonwoven polyester
geotextile blankets named Drainage Bed (DB). Dewatering mechanisms are divided
into two stages: Drainage and Drying Phases. For the Drainage Phase, the
results showed that the solids content of the Aluminum Sulfate sludge reached
8.9% to 18.3% and the PACl sludge 1.8% to 6.5%, the volume reduction on this
phase exceeding 50% and 74%, respectively. The final solids content, after the
Drying Phase, was greater than 28%, reaching 90%. In the Drainage Phase the
lower the Surface Application Rate—SAR [kg/m2] is, the greater the drainage
flow will be. In the Drying Phase, moisture and insolation were key factors in
drying sludge. Thus, the Drying Phase in the DB takes special attention for
being virtually nonexistent in dewatering technologies in a closed system
(confined) without exposure to solar energy. The use of the DB as a natural
system for dewatering WTP sludge in tropical countries proved to be a promising
alternative, because of its efficient removal of water from sludge coupled with
operational simplicity and low costs, provided there is area available.