Research on removal and recovery of heavy metals in urban sludge

The paper researched of the content and form of heavy metals in the municipal sludge, showed: the copper's content is as high as 4386.2mg/kg, and the zinc is 2170.6 mg/kg. So they have high recycled value; Copper and zinc in the municipal sludge exist in their forms of sulfide, organic combination and residual. it has a very low level of toxicity. Therefore, the municipal sludge can be used as resources after being treated properly. The detailed extractions are performed in 4.0 of pH value at room temperature in 4 hours, and copper and zinc can be carried out safely. Using improved ferrite method and lime milk as neutralization, copper and zinc recovery from sewage sludge extract fluid by acetic acid-H2O2,The result was obtained that copper and zinc recovery was 94% and 98% and the residual extract fluid could be discharged legally in the process conditions that the initial concentrations of FeCl3 NeSO4 was 0.10/0.05mol/L, and the FeCl3/FeSo(4) adding volume Fe2+ : Fe3+(mol value)=1 : 2&Fe3+/Mn+ (Cu2+, Zn2+) =10, the pH value was 9, temperature was ordinary temperature, the reaction time was one hour.