The use of polyaluminium chloride as a restoration measure to improve water quality in tropical shallow lakes

O uso de cloreto de polialumínio como medida de restauração da qualidade da água em lagos rasos tropicais

Abstract

Aim  The aim of this study was to evaluate the performance of the coagulant Polyaluminium chloride (PAC) in water quality improvement of six eutrophic shallow lakes in Brazilian semiarid region.

Methods  We evaluated the effect of PAC in turbidity, humic substances (UV₂₅₄), total phosphorus and chlorophyll-a concentration through laboratory jar tests.

Results  The results showed that PAC had a good performance in reducing total phosphorus concentrations and turbidity, with a reduced efficiency in removing chlorophyll-a and humic substances by sedimentation of flocks formed.

Conclusions  Addition of PAC is a potential tool for water quality improvement of eutrophic shallow lakes in Brazilian semiarid region but its efficiency depends on the pH and particulate and dissolved organic matter concentration in the lake or reservoir water.

Keywords:  coagulation; phosphorus removal; turbidity removal; lake restoration; semiarid region