ANALISIS PENGARUH UKURAN BUTIR BATU ANDESIT PADA FILTER ANDESIT TERHADAP PH DAN KADAR LOGAM FE DAN MN AIR ASAM TAMBANG

The problem that often arises from mining activities is acid mine drainage or it can be abbreviated as AAT. AAT is water with a low pH value and has heavy metal content caused by mining activities. AAT needs to be processed to comply with water quality standards stipulated in the Minister of Environment Decree No. 113 of 2003. Andesite has alkaline minerals, namely pyroxene minerals. In addition, andesite has intermediate minerals, namely hornblende and biotite. These minerals can make acid mine neutral and reduce metal levels. The researcher took the variable of andesite stone grain size variation to study the effective grain size for AAT processing. Based on this, the aim of this study is to examine the effect of andesite grain size as a filter media with respect to pH and Fe and Mn metals in AAT. AAT processing is carried out by filtration using andesite as the filter media. Researchers used andesite stone with grain sizes of 4 mesh, 6 mesh, 8 mesh and 20 mesh. After testing, it was found that the 20 mesh grain size experienced the highest pH increase up to 6.0. At the Fe level there was no decrease, while the Mn level found the lowest decrease in the grain size of 20 mesh, namely 1.35 mg/l.