Role of Polyelectrolytes in Wastewater Treatment

Effluent Treatment or Industrial wastewater treatment consists of mechanisms and processes which are used to treat water that have been contaminated by anthropogenic, industrial or commercial activities prior to its release into the environment. Industrial wastewater serves as one of the important pollution sources that add up in polluting the water environment. The sewage sludge produced is subjected to sludge treatment. Many problems are associated with wastewater collection and treatment such as foaming, solid accumulation, high BOD, sludge de-watering, heavy metals and offensive odour. But such treatments are no more complicated processes, since there are chemicals that are applicable for the treatment. These chemicals follow various treatment mechanisms in various different standards, which include from chemically treating raw wastewater before discharging it into the environment, to recovering valuable resources from sludge treatment and wastewater.
Conventional treatment consists of a combination of physical, chemical, and biological processes for removal of suspended solids, organic & inorganic contaminants, germs and microbes from wastewater. When using total wastewater treatment solutions, these chemicals remove and eliminate harmful pathogens, expel hazardous chemicals, detergents and toxins, reduce odour and improve water colour, and separate and extract valuable substances and clean water from the wastewater.
Polyelectrolytes are regarded as polymer chains with an electrolyte group on every repeat unit. When dissolved in a polar solvent, these polymers are charged due to dissociation of small counter ions that leave behind a charged micro ion. These are formulated in a way so as to be used as coagulants and flocculants as well as a sludge dewatering agent in the waste water treatment plants. Flocculants are chemicals responsible for bringing about secondary settling and sludge dewatering. They carry active groups with a charge which helps in counterbalancing the charge of the particles. Coagulants are referred to as chemicals that are used to help in the removal of colour and turbidity present in untreated, raw water and are used for their attributes like quick flocculation, precise pH value, etc.
Based on electrolyte group present in the chain, polyelectrolytes are categorized into anionic, cationic and non – ionic species. Cationic polyelectrolytes have positively charged group for use in coagulation of negatively charged flocs through electrostatic interactions. They are useful in various process of effluent r wastewater treatment, depending upon their molecular weight and charge density. Anionic polyelectrolytes have negatively charged group on each repeating unit, acrylamide-based polymers being the most available type. They are widely useful as flocculants, rheology modifiers, and adhesives and immensely used in municipal wastewater and effluent treatment. Anionic flocculants are also used in enhanced oil recovery, decolouring, paper making, mineral processing, etc. Non – Ionic Polyelectrolytes are organic high molecular weight polymers, used in flocculating colloidal suspensions, water clarification, sludge dewatering, etc.
In general, aqueous solutions having pH value more than 4 have negative charged suspended particles whereas having pH less than 4 contains positively charged suspensions. This might help in analysing the type of polyelectrolyte to be used in the treatment.
Chemtex Speciality Limited is a well-known manufacturer and supplier of liquid and powder polyelectrolytes. For more information on our range of products, visit www.chemtexltd.com/products-and-solutions/water-treatment...

Taken on: September 15, 2023

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