Treatment of Manure and Digestate Liquid Fractions Using Membranes: Opportunities and Challenges

This review examines how membrane technologies can be used to process nutrient-rich manure and digestate liquids, which often cause membrane fouling due to their high content of organic matter, solids, and mineral compounds. It summarizes the key physico-chemical properties of these effluents and explains how different solid–liquid separation methods interact with these complex variables. The paper outlines the major factors influencing membrane fouling, along with approaches for inspecting membranes and analyzing foulants. It also discusses how feed characteristics, operating conditions, pH control, flocculation–coagulation, and cleaning strategies affect system performance. Finally, it highlights techniques for recovering nutrients such as ammonia-nitrogen and phosphorus, as well as removing heavy metals from farm effluents.