Use of alum sludge in flue gas treatment

Despite global efforts towards reducing carbon emissions and transitioning to renewable energy sources, coal is anticipated to remain a fixture in both national and international energy policies for the foreseeable future. In our country's 2053 vision for a sustainable environment and circular economy, the aim is to eliminate pollutant emissions, minimize waste generation, repurpose waste for economic benefit, and maximize the utilization of domestic resources. This research investigates the efficacy of using drinking water treatment sludge for the removal of flue gases generated from the combustion of fossil fuels through a wet treatment method. Notably, there is a dearth of studies in both local and international literature on the utilization of drinking water treatment sludge as an absorbent material for flue gas removal. Alum and iron sludges sourced from Istanbul Water and Sewerage Administration (ISKI) drinking water treatment plants were analyzed for their properties. The study focused on the simultaneous absorption of SO2, NO, CO2 at varying rates in the gas mixture in aqueous alum and iron sludge solutions at varying ratios in a batch system. In experiments using 100 ml aqueous solutions with alum and iron cake at a 1/30 solid/liquid ratio, SO2 gas was completely absorbed with 100% efficiency in alum solution within the first 40 minutes, whereas iron solution achieved 78% efficiency. While 1 g of alum cake solution at 1/30 Solid/Liquid ratio had the capacity to absorb 80 mg SO2 gas, this amount was found to be 60 mg in iron cake solution. Results indicate that both iron and alum sludge can effectively absorb SO2 gas in the wet clarifier system, thus potentially alleviating the system's burden and promoting sustainable development through waste reuse.