High-Value Processing and Utilization for Digested Manure Effluent Treatment: Advances and Challenges

Digested manure effluent is a potential resource for the production of liquid organic fertilizer and reused water. The purpose of this review is to provide a comprehensive understanding on the advances and challenges to high-value processing and utilization for digested manure effluent treatment. The main problem that restricts the utilization of digested manure effluent is that there is not enough land for consumption. Reasonable and efficient treatment of digested manure effluent is the key to promoting healthy development and sustainable operation. Digested manure effluent can increase yield, improve quality, and enhance the stress resistance of crops. In addition, digested manure effluent can also be used in seed soaking and feed applications. Membrane treatment techniques for the concentration of digested manure effluent can recover water and produce liquid fertilizer. It mainly includes pressure-driven membrane, osmotic-driven membrane, membrane distillation, and their combined technologies. However, membrane concentration of digested manure effluent still has challenges such as high cost and membrane fouling that restrict development. Thus, several potential approaches have been proposed to address these challenges. These approaches can be largely classified as pretreatment, process optimization, and government-guided source control. In this paper, we critically reviewed the properties and utilization of digested manure effluent. Meanwhile, the performance of different membrane concentration processes was provided. Furthermore, key technical challenges of high-value processing and their potential countermeasures were delineated.