Investigating the recovery efficiency of alum by acidification of aluminium hydroxide sludge :

Abstract

Alum has been used for the treatment of water for millennia to flocculate negative colloidal particles, organic substances, other contaminants and a variety of ions. Alum sludge produced from water treatment plants contains aluminium hydroxide mixed with suspended solids in raw water. Existing practices for the subsequent handling of this sludge regard it as a waste product rather than a potential resource. However, the disposal or efficient re-utilization of the derived alum sludge has, until recently, not been considered to be a major imperative. Disposal of sludge is routinely performed either to landfill, or via sewer to a municipal wastewater treatment plant; with some small-scale options also used in various cases. With the increasing cost of disposal, the declining availability of landfill and the need for ‘greener’, more sustainable and much more efficient reuse options to be implemented, new technological solutions are required. The aim of this research is to study aluminium sulphate (alum) recovery efficiency from alum sludge in aqueous solution by acidification process using sulphuric acid. The results of the experimental works showed that the recovered alum volume produced from the sludge after acidification process is the best value with percent recovery 64%.