• When synthetic detergents are used in hard water, calcium and magnesium ions form strong and insoluble complexes with surfactants and precipitate out of solution (Folke, 1999).

• For example manganese oxidizing bacteria attached to the inside surfaces of hydroelectric pipelines are known to produce insoluble manganese deposits thick enough to upset streamline flow (Marshall,1 978).

• In strongly alkaline conditions, the solubilized metal ions transform into insoluble form through a precipitating agent such as lime.