The granule in the UASB of OB Koomi plant was selected as microorganism source to be used basing on its high sulfate reducing activity and structural and physiological stability. According to the 'Waste Management Act' and statistics of Ministry of Environment, synthetic wastewater was prepared $Cu^{2+}$ concentration 100~600 ppm and sulfuric acid-based waste with pH 2. Lactate was chosen as an optimal carbon source for maintaining the stability of granule and maximizing the sulfate reducing activity. With regard for the degradation rate of this carbon source, the hydraulic retention time was fixed for 48 hours in continuous treatment operation. Selected microorganism was acclimated to acidic wastewater gradually and the activity of granule was monitored simultaneously. Granule was inactivated around pH 2, so that the sulfate reduction activity and buffering capacity was decreased greatly. The treated water was recycled to overcome the inactivation problem below pH 2. By recycling, the $Cu^{2+}$-contamianted pH 2 waste was met with recycled stream containing sulfide and buffering capacity and was neutralized and $Cu^{2+}$ was removed effectively before entering anaerobic bioreactor. Recycle and sandfilter were employed in the process and by continuous treatment operation pH 2 waste with $Cu^{2+}$ concentration 600 ppm was successfully treated to $Cu^{2+}$ below 0.1 ppm and pH 7±0.3.
