T’puram: Kerala Water Authority (KWA) has finalised a tender for alum procurement for its head works division, Aruvikkara, even as the executive engineer’s office has sought permission to invite a separate tender for polyaluminium chloride (PACL), highly placed sources said. The move comes amid an alum shortage and concerns over the cost and effectiveness of the two chemicals used in water purification.The KWA work order provides for 741.67 tonnes of Alum Grade IV for the head works division for six months. The supplier is ICS Chemical Industries, Kolkata.The tender is expected to help ensure adequate availability of alum for water treatment operations, particularly during the monsoon, when increased turbidity in raw water can raise the requirement for chemical purification.However, the authority is also exploring PACL as an alternative. The executive engineer’s office has sent a letter to the KWA head office seeking permission to invite a separate tender for PACL, sources said. The proposal is yet to be finalised, as the head office has not taken a final decision on the use of PACL.KWA had earlier faced difficulties in procuring adequate quantities of alum, traditionally used in water purification, due to ongoing war in the middle east. Officials attributed the shortage to disruptions in the supply of sulphuric acid, a key component in alum manufacturing, following the Middle East conflict.“We repeatedly approached vendors regarding supply but could not obtain sufficient quantities. We have procured 20 tonnes, but it may not last for 10 days once monsoon inflow increases. Therefore, we initiated preparations to shift to PACL,” said a KWA engineer.Officials said the Aruvikkara plants require around 20–30 tonnes of alum every month. Ensuring regular procurement is therefore important to prevent disruptions in treatment operations and maintain the supply of treated water to the capital region.According to a senior KWA source, PACL costs around Rs 40 per kg, compared with Rs 37 per kg for alum. However, the official pointed out that PACL requires only around 1kg for purification, while 2kg of alum may be needed under comparable treatment conditions.“Though PACL costs more per kg, its lower dosage requirement makes it potentially more economical,” the source said.Based on these figures, the chemical cost would be Rs 74 for 2kg of alum against Rs 40 for 1kg of PACL. The actual cost advantage would depend on raw-water quality, dosage and treatment efficiency.Officials also said PACL has greater effectiveness as a coagulant compared with alum. However, KWA has not previously used PACL, and the head office is yet to finalise the proposal for its introduction.
