E-NEWTRIENTS: BIOELECTROCHEMICAL SYSTEMS AT THE SERVICE OF AGRICULTURAL SCIENCES

It is estimated that demand for food will continue to increase, as a result of population growth, but at the same time, food production will increasingly face huge constraints, such as water scarcity, soil desertification and the increase of fertilizers prices. Wastewater derived from food production chains should be treated in a sustainable way, to minimize environmental contamination, while maximizing the recovery of valuable fractions, such as plant nutrients. Bioelectrochemical systems (BES) have been proposed as solutions to treat different kinds of wastewaters and recover nutrients through bio-electrochemical reactions. In my project, new types of BES are studied, fabricated with biocompatible and biogenic materials starting from vegetable scraps, which could be applied as mean of organic matter and nutrients recovery from organic-rich wastewater streams coming from important agro-food chains, such as farming and agro-industrial productions. This novel type of BES was named ‘microbial recycling cells’ (MRCs). Biochar produced from controlled pyrolysis of plant materials is electro-conductive and can be used as base to fabricate MRCs, which can be used for this scope. Other materials like earthenware were also used in MRCs architectures, as electrolytic conductors and structural frames. After being enriched of nutrients from wastewaters, biochar-based MRCs can be fully recycled to produce soil improvers and renewable fertilizers. In soil applications, the electrochemical properties of biochar influence soil biogeochemical reactions, with important implications in plant nutrition and the environmental implications of soil-plant systems (e.g. carbon sequestration, CH4 emissions, etc.). The PhD project was hold in 3 different work packages: WP1) Selection of MRC architectures and optimization of e-biochar properties, WP2) Study of the microbial electrochemical processes driving nutrients deposition, WP3) Study of the properties of nutrients-enriched biochar derived from MRC after their life-cycle, as soil improvers of agricultural soil fertility, with both amending and fertilizing properties.