The occurrence of metals in composted municipal wastes and their removal

The organic fraction of municipal wastes has been composted on the laborato ry scale. In the obtained compost the content of cadmium: cobalt, copper, m anganese, nickel, lead and zinc were determined, as well as the speciation i.e, the form of their occurrence, making use of Rudd's method of sequentia l extraction. The investigations also concerned the way of removing these m etals from the compost by means of leaching with solutions of sulphuric and nitric acid, as well as by electrochemically separating the metals from th e solution after the compost had been leached with sulphuric acid. It has b een found that the application of the electrochemical method with varying p H values of the leaching solution within the range of 6.8-2.8 allows for th e separation of 83.5% Cd, 55.0% Co. 65.4% Cu, 59.4% Mn, 70.3% Ni, 90.5% Pb and 56.2% Zn.