NOVELTY - City river sludge and wastewater with chemical oxygen demand of 2000-3500 mg/L are mixed, poured to culture tank, and pork soup and hydrochloric acid solution are added to mixture. Hydrochloric acid solution is added to mixture. The mixture is stirred, air is blown, cultured, maintained, and water upper layer is removed. Wastewater is maintained at 28-35 degrees C, and pork soup and hydrochloric acid solution are added to wastewater. Hydrochloric acid solution is added to mixture, stirred and cultured. Silk floc and activated sludge are added to wastewater to reduce acidity in wastewater.    USE - Reduction of chemical oxygen demand during culturing of acidic wastewater (claimed).    ADVANTAGE - The method provides acidic wastewater with chemical oxygen demand removal rate of more than 95% by economical and environmentally-friendly method.    DETAILED DESCRIPTION - City river sludge and wastewater with chemical oxygen demand of 2000-3500 mg/L are mixed, poured to culture tank, maintained at 28-35 degrees C, and pork soup and 4 %mass hydrochloric acid solution are added to mixture. 10 %mass Hydrochloric acid solution is added to mixture, and pH is adjusted to 5-6. The mixture is stirred, air is blown, cultured for 5-8 days, and stirring is stopped, maintained for 2-3 hours, and water upper layer is removed. Wastewater with chemical oxygen demand of 3500-4000 mg/L is maintained at 28-35 degrees C, and pork soup and 4 %mass hydrochloric acid solution are added to wastewater. 10 %mass Hydrochloric acid solution is added to mixture, pH is adjusted to 4-5, stirred, and air is blown, cultured for 8-10 days, and stirring is stopped. The mixture is maintained for 2-3 hours, and water upper layer is removed. Wastewater with chemical oxygen demand of 5000-6000 mg/L and butyl octanol are mixed, and river sludge is added to mixture and maintained at 28-35 degrees C. Pork soup and 4 %mass hydrochloric acid solution are added to mixture. 10 %mass Hydrochloric acid solution is added to mixture, and pH is adjusted to 3-4, stirred, air is blown, maintained for 10-12 days, and stirring is stopped. The mixture is maintained for 2-3 hours, and water upper layer is removed. Air is blown to pool, and wastewater with chemical oxygen demand of 2000-3500 mg/L and butyl octanol are added to pool, maintained at 28-35 degrees C. Pork soup and 4 %mass hydrochloric acid solution are added to mixture. Sodium carbonate is added to mixture, and pH value is adjusted to 4-5, stirred and cultured for 15-17 days, and stirring is stopped. The mixture is maintained for 2-3 hours, and water upper layer is removed. Wastewater with chemical oxygen demand of 2000-3500 mg/L and butyl octanol are mixed, and maintained at 28-35 degrees C. Pork soup and 4 %mass hydrochloric acid solution are added to mixture. 10 %mass Hydrochloric acid solution is added to mixture, and pH is adjusted to 3-4, stirred, and air is blown, cultured for 15-17 days, and stirring is stopped. The mixture is maintained for 2-3 hours, and water upper layer is removed. Wastewater with chemical oxygen demand of 3500-4000 mg/L and butyl octanol are maintained at 28-35 degrees C. Pork soup and 4 %mass hydrochloric acid solution are added to mixture. 10 %mass Hydrochloric acid solution is added to mixture. The pH of mixture is maintained at 3-4, stirred, cultured for 15-17 days, and stirring is stopped. The mixture is maintained for 2-3 hours, and water upper layer is removed. Black lower sludge containing small amount of fluid mud is removed. Silk floc and activated sludge are added to wastewater to reduce acidity in wastewater.