Synthetic or natural polyelectrolytes have an important role to play in the treatment of water and wastewater. In this article, a comperhensive review on the different uses of polyelectrolytes in the fields of potable and industrial water supply and industrial and municipal effluent treatment have been discussed.
Polyelectrolytes have been used for different purposes in the field of potable water supply such as : removal of organic matter, suspended solids, bacteria, algae, trihalomethane precursors, colour and turbidity, water softening, desalination, improvement of mass transfer zone of ozone used for disinfection and it improve the process of direct filtration and the management of water treatment sludge. In the field of industrial effluent treatment polyelectrolytes have been applied in : trace metal removal, dissolved air flotation process, radioactive effluent treatment, conditioning anaerobically digested sludge, treating oil contaminated industrial wastewater treatment of tannery effluents, removal of suspended solids from time-sulfied unhairing effluents, detoxification and decolorization of kraft pulp mill effluents, ore enrichment plant waste water containing sprucewood tannins.
Polyelectrolytes, generally, have revolutionised the treatment processes, increasing the efficiency of the processes to a level which could not be dreamt of in the past, reducing the cost of chemicals required, producing compact relatively smaller quantities of compact sludge that can drained and disposed of easily and simplifying handling and dosing of the chemicals.