Application of Effluent from Anaerobic Digestion of Biomass to Condition the Soil: A Review of the Literature

Abstract

Literature Review: Anaerobic digestion technology has significant potential in the treatment of organic waste, with varying levels of efficiency depending on the approach taken to the process. In addition to biogas production, it is also possible to obtain the digestate from anaerobic digestion, a nutrient and carbon-rich product, which is a relevant source for soil biota and fertility. Applying digestate to the soil helps in the recovery of degraded and contaminated areas due to its richness in nutrients and organic matter. When applied, it initiates the colonization of plants, colonies of fungi and bacteria, mineralizes nutrients, and promotes environmental recovery. Anaerobic digestion, when integrated with other processes such as composting, gasification, and pyrolysis, can enhance the capacity to sequester carbon in stable forms in the soil, thus reducing greenhouse gas emissions and increasing the potential for biomass (raw material) energy utilization. Study Objectives: To review the existing literature regarding the application of digestate as a soil conditioner and its benefits to plants (crops). Materials and Methods: Original articles related to the application of digestate in soil were selected through a search on the Web of Science and Science@Direct databases from the CAPES periodical portal. Conclusion, Results, and Implications: The selected articles present results indicating that digestates can be used as soil conditioners, leading to increased organic matter, microbial activity, nutrients, physical quality, and plant benefits, thus contributing to the circular economy. However, there is a need for further studies related to the agronomic responses of digestate application to plants.