Hyderabad: Researchers from the Centre for Environment and from department of civil engineering at JNTU-Hyderabad have come out with a method to use sludge generated by pharmaceutical and bulk drug companies to make bricks. About 200 drug units are located in Hyderabad, Medak and Ranga Reddy districts.

The bricks are made out of the sludge by using cement, lime and bentonite as binding materials along with strengthening material of fly ash, silica fume and quarry dust, which are harmful air pollutants.

The researchers developed the bricks by curating them for 28 days. The bricks were found to be of BIS standards. The best composition of strong bricks was found to be 10 per cent sludge, 30 per cent fly ash, 30 per cent silica fumes, 10 per cent cement, 10 per cent lime, 5 per cent bentonite and 5 per cent quarry dust.

But with the bricks containing pollutants such as silica fume and pharmaceutical sludge which consists of harmful heavy metals such as lead and nickel how safe is it to use them? Dr V. Himabindu, associate professor, CES, JNTU-H, who led the research says, “We conducted two toxicology studies on the bricks in our lab and found they were safe.”

Pharmaceutical sludge comes under hazardous waste category and it is sent to Dundigal for processing. A Swedish report had noted that the sludge was seeping into open land. Its capacity had already been exceeded.