Investigating the possibility of iron recovery from water treatment plant sludge with planetary ball mill and acid digestion process

 Both the number of water treatment plants and their sludge volume increases by population. Considering the presence of high amounts of valuable coagulants in water treatment plant sludge, it’s recovery and reuse is sought to be one of the practical and cost effective solutions for sludge management in water treatment plants.

 Iron sludge was collected from the sludge dryer bed of Jalaliyeh water treatment plant in Tehran. A planetary mill device was used to prepare samples and to investigate the effect of mechanochemical process on sludge recovery as an Iron based coagulant. XRD, XRF, TEM، MP-AES tests were performed on the sludge sample before and after the mechanochemical process. Ethical considerations were observed in all stages of the study.

 The results of this study showed that the use of a planetary mill leads to more recovery of iron, so that at 1 N acid concentration, iron recovery increases from 23.5% in the unmilled sludge sample to 60.5% in the milled sludge. Phase and chemical structure changes of sludge after planetary mill were clearly visible in XRD analysis.

 The results showed that by combining mechanochemical and acid digestion, it is possible to significantly improve ferric chloride recovery in terms of acid consumption and final product quality; so that the iron based final product could be used for industrial wastewater treatment.