Pengapuran dan Penambahan Bahan Organik untuk Meningkatkan Reduksi kromium (Vi) : Upaya Bioremidiasi Lahan Bekas Tambang di Kalimantan Selatan

Previous study stated that concentration of hexavalent chromium [Cr(VI)] is significantly correlated with soil pH and organic carbon content. In order to determine influence of soil pH and organic matter addition on concentration of Cr(VI), lime and organic matter were added to soils and incubated for 8 weeks. Concentration of Cr(VI) was determined at the end of incubation period. Results of the experiment showed that liming of 2.5 ton per hectare produced the highest reduction of Cr(VI) compared to other liming addition and changed the soil pH from 7.15 to 8.27. Subsequent increase in the amount of lime addition to 20.0 ton per hectare resulted in increased soil pH, but the reduction of Cr(VI) did not significantly increase. Optimal soil pH for Cr(VI) reduction in this experiment is reported at the range of soil pH 7.15 – 8.27. Moreover, addition of 2.0 ton per hectare of organic matter increased reduction of Cr(VI) from 7% to 59%. However, when the amount of organic matter added to soils increased to reach 10.0 ton per hectare, reduction of Cr(VI) did not change significantly