India, Nov. 10 -- The firecrackers have been burst, the festivities are over, and Hyderabad's streets are being swept clean. But while the visible remnants of Diwali disappear within days, the waste itself has a much longer journey.

For sanitation workers, the clean-up means additional shifts, heavier workloads and exposure to potentially hazardous materials. For the city's waste-management system, it raises a more complicated question: what happens to the tonnes of firecracker debris, discarded decorations and other festival waste collected from the streets?

Some material can be recovered and recycled. Much of it is mixed with regular municipal waste. But how much ultimately gets processed or ends up in a landfill remains difficult to ...