Organic-rich secondary products of food industry and wastewaters are important sources of nutrients. We propose a technological alternative to recover these nutrients and grow microalgae cultures: the e-BioPond, assisting microalgae cultivations by the introduction of microbial electrochemical technologies.

Biochar has been largely studied as agricultural soil amendment, capable of favouring soils properties, acting as carbon sink over long term, stimulating soil microbial communities in several important soil processes. The improvement of biological activity, as well as chemical and physical properties of soil is at the basis of conservation agriculture, the green solution to counteract impacts of agronomic practices. It has recently proposed that the electro-active properties of biochar may play a fundamental role in improving all these benefits. In particular, the electro-active properties of biochar can be enhanced, to obtain a new category called electro-active biochar (e-biochar).

e-biochar was found to behave like organic redox-active molecules (e.g. humic/fulvic substances), but it was also considered as a relatively more electro-conductive material. More recently, some authors reported that the presence of biochar promote microbial metabolisms through direct interspecies electron transfer (DIET) in soils. e-biochar as environmentally sustainable electron donor/acceptor for biogeochemical redox reactions and it acts as rechargeable reservoirs of bioavailable electrons, i.e. the so-called “geobatteries”. Functional groups can participate in reversible surface (interfacial) redox reactions with other ambient species, including electro-active microbial

Further, redox processes involving the donation and acceptance of electrons play an important part in soils, such as in nutrient cycling, decomposing organic matter, including biochar, can be regarded as an electron-pump supplying electrons to more oxidised species present in the soil system.