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Probability of Aluminium Toxicity in Water Treatment Plant Itanagar: A Case Study

Omem Paron, Mongam Bole, Rita Tiwari and Ajay Bharti

Itanagar Water Treatment Plant is one of the oldest water treatment plants serving the community of this region. It supplies water to most of the part of Itanagar. Senkhi River has been chosen as the source of water supply to Itanagar Township. The river has a minimum discharge of 8857 MLD which is sufficient for the water requirements of Itanagar Township even beyond the year 2021. The quality of river water satisfies the requirements predicted by Public Health Engineering department. The treatment plant has been using Alum as a coagulant in treatment process for the past 12 years. The backwashed water along with the settled sludge from the plant is released into nearby locality which carries a significant amount of suspended matter. Therefore, layer of sludge is supposed to be deposited on the meeting point of backwashed water and the river. Due to release of such sludge and backwashed water, the soil at the disposal site and sediment of the river could get affected by aluminium toxicity in near future. Recent studies showed that alum may produce aluminium toxicity at certain situation, especially at lower pH. Due to this or some other reasons, alum is being replaced by other chemicals. Experimentation work including both field and laboratory tests were conducted to determine the aluminium concentration in the soil and water at the place where the backwash water and sludge from Itanagar Water Treatment Plant are discharged off.