Biogas slurry concentration hybrid membrane process: Pilot-testing and RO membrane cleaning

Abstract The integrated membrane technology, consisting of MF, UF, and RO membrane, was used for the concentration of biogas slurry to realize the recovery of fertilizer and water. The pilot test proved the feasibility of the integrated membrane technology in this application. The RO membrane can concentrate the biogas slurry with the concentration factor of 5. RO membrane shows over 97% removal for COD and NH3-N, allowing less than 50 ppm of COD and NH3-N transport to the permeate side. The RO membrane suffered both organic and inorganic fouling. The optimal strategy for eliminating the fouling in this study is the receipt of NaOH + SDS + STPP → HCl. The salt rejection maintained at around 97.0% by this strategy, and the flux recovery had a sharp increase (~ 50.0%) after the addition of this multiple agent.