Its wide range of usage is in water treatment, because it can act as an coagulant, flocculant, precipitant and emulsion breaker. As coagulant and flocculant, aluminum sulfate successfully removes turbidity, suspended solids and colloidal color,reduces biochemical oxygen demand (BOD) and extremely clarifies potable, process and wastewaters.

Application

In the construction industry, it is used as waterproofing agent and accelerator in concrete.

Also used as foam fire extinguisher 

Aluminium sulfate reacts with sodium bicarbonate to which foam stabilizer has been added, producing carbon dioxide for fire extinguishing foam. 

The carbon dioxide is trapped by the foam stabilizer and creates a thick foam which will float on top of hydrocarbon fuels and seal off access to atmospheric oxygen, smothering the fire. Chemical foam was unsuitable for use on polar solvents such as alcohol, as the fuel would mix with and break down the foam blanket. The carbon dioxide generated also served to propel the foam out of the container, be it a portable fire extinguisher or fixed installation using hoselines. Chemical foam is considered obsolete in the United States and has been replaced by synthetic mechanical foams, such as AFFF which have a longer shelf life, are more effective, and more versatile, although some countries such as Japan and India continue to use it.

Technical Specification