Migration of harmful elements in municipal sludge under high-temperature oxidation conditions

Municipal sludge is produced in large amounts and is difficult to treat. Incineration is the most direct and thorough treatment method. In order to study the feasibility of sintering for municipal sludge treatment, the municipal sludge reforming process was studied under high-temperature oxidation conditions. The results showed that the sludge reforming process could be divided into four stages: the precipitation and evaporation of adsorbed water, the precipitation and combustion of the volatile, the combustion of the residual volatile and solid carbon, and the decomposition of salts and the melting of sludge. An increase in the heating rate resulted in more intense sludge combustion and improved the sludge reaction capacity and combustion performance. After burning at 1300 °C, Si, Ca, Mg, Al, K, Na, and Cu formed new phases and entered the slag. 75% of P remained in the slag. 80% of the S formed SO2 and entered the flue gas. Cl formed gaseous chlorides like HCl upon combustion and entered the flue gas. As sintering is a feasible method for treating municipal sludge, care must be taken to limit the amount of P that ends up in the ore.