Treatment of ammonium-rich swine waste in modified porphyritic andesite fixed-bed anaerobic bioreactor

► Modified WRS was used for anaerobic digestion of ammonium-rich swine waste. ► The ammonium was definitely adsorbed by the modified WRS. ► A big amount of microorganisms immobilized on the modified WRS. ► The trace metal and calcium ions dissociated from the modified WRS. ► High methane yield and COD removal was achieved compared to other systems.