NON-FERRIC ALUM IN DRINKING WATER APPLICATIONS : Indian Perspectives

Iron–free Aluminium sulphate is commercially popular as Non-ferric Alum (NFA) in India. Likewise, Alumino-ferric alum is popular as Ferric-alum. Al-based and Fe-based coagulants find applications in water and waste-water treatment. Iron-based coagulants broadly include coagulants like ferric chloride and ferric sulphate etc.

In Al-based coagulants, Alumino–ferric being more popular because of easy availability and cheaper price unlike Non-ferric alum. Non-ferric alum should not be confused with alum other than Iron-based coagulants. It is proven fact that Fe-based coagulants scores better over Al-based coagulants over various performance parameters. Both the categories of coagulants ie Al-based and Fe-based, have benefits and limitations depending on applications. Fe-based coagulants perform better in wastewater applications than Al-based coagulants, which is more popular in drinking water treatment.

In India, Ferric Alum is made from Bauxite and Iron-Free Alum (Non Ferric Alum) from Alumina. In USA, Iron free-Aluminium sulphate or Non Ferric alum has been certified by the National Sanitation Foundation (NSF) for use in the treatment of drinking water at a maximum dosage of 150 mg/L. Bureau of Indian Standard, IS 260:2001 Second revision clearly specifies the use of Aluminium sulphate, non-ferric as a coagulant for clarifying oils & fats and purification of water having large oil content. IS 260:2001 doesn’t clearly mention about the use of Iron-free Aluminium sulphate as a coagulant in drinking water treatment. It is being extensively used in drinking water treatment in Americas, European Union Nations, and some part of Africa & Asia. Our neighborhood nations like Bangladesh & Srilanka are also using it in drinking water treatment. In India water supply authorities are still reluctant in using Non-ferric Aluminium sulphate in drinking water treatment instead of conventional Ferric alum.

In India water supply authorities are still reluctant in using Non-ferric Aluminium sulphate in drinking water treatment instead of conventional Ferric alum. The prominent reasons for this, are absence of clear and authentic government reports & relevant Indian Standards on the use of NFA as a coagulant in drinking water treatment, inability in taking policy decision of switching over to new product from conventional one, cost factor, unawareness of the product.

 Therefore to bridge this gap of taking policy decision by the government authorities in this regards, it is imperative to encourage more R & D in the use of Aluminium sulphate, non-ferric in drinking water treatment of raw water from different sources. Detailed study in treating this coagulant with different sources of water intended for drinking water, from different locations across the country be carried out.

This need of the time has driven motivation  to determine the effectiveness of this Non-Ferric Alum as a Coagulant and to evaluate its suitability in drinking water treatment with regards to health & safety and economic considerations in post treatment. Although Alumino-ferric is recommended for drinking water applications and is being used extensively till date, is under scanner due to reasons already pointed out.

Therefore detailed study shall be carried out to give insight into the effectiveness & suitability of Non-ferric Alum in drinking water treatment in Indian context.