Abstract:
Wastewater from the laboratory of the Mineral Resources Analysis and Investigation Division containing a toxic heavy metals including arsenic (As) cadmium (Cd) and chromium (Cr) which above the standard values for industrial wastewater. Therefore, the treatment process is required to treat wastewater before discharge to the environment. In addition, the Mineral Resources Analysis and Investigation Division has a limestone residue which can be utilized as adsorbent. Thus, the objective of this research was to determine the optimal condition for reduce heavy metal with limestone residue. In the study, the amount of heavy metals were measured by the Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) method. From the obtained results, it was found that the optimum conditions for heavy metals adsorption were pH = 1, adsorption time 15 minutes, and a optimal of limestone at 5.0 g per 20 ml of wastewater. The heavy metals adsorption efficiencies by limestone residue were higher than 98%. The results of this study found that limestone was effective in adsorbed arsenic (As) cadmium (Cd) and chromium (Cr) equal to 98.39 , 98.77% and 99.16% respectively. Furthermore, the addition of limestone can reduce the acidity of treated wastewater. Therefore, it can be stated that limestone that is left over from the analysis process can be utilized as adsorbent with an effective for treating heavy metal wastewater.