POLAROGRAPHIC-DETERMINATION OF NICKEL AND CHROMIUM IN SEWAGE-SLUDGE

The contents of Ni and Cr in sewage sludge with high and low amounts o f heavy metals were investigated by polarography. The DIN-digestion (a qua regia) was used, and the resulting solution was treated with H2O2/ UV (90 degrees C, 60 min) for further destroying of the organic materi al. Besides, the solution of the DIN-digestion was examined with AAS ( flame) and ICP-OES. With the determination of Ni it was shown that aft er digestion with aqua regia no further treatment with H2O2/UV is nece ssary. Contrariwise it was found that for the determination of Cr a H2 O2/UV photolysis is necessary followed by further steps to get good ag reement with AAS and ICP results as well as with the certified values of a sludge of the Community Bureau of Standards.