Aquatic plant treatment system (ATPS) based on duckweed for cleaning the liquid fraction of digestate

Composting plants combine compost and energy production using the Anaerobic Digestion (AD). However, the AD process generates residue of whose the liquid fraction is polluting and therefore needs to be subjected to expensive waste treatments with the loss of the value of the mineral elements. It is than necessary to develop technologies allowing, from one side, the treatment of liquid fraction and, from the other side, the uptake of those minerals as plant nutrients. The purpose of the project DUCK-TECH was to provide a solution to these aspects through an integrated biological approach, i.e., an aquatic plant treatment system (ATPS). In more details, an ATPS for liquid fraction treatment was realised using duckweed and, in particular, its ability to recover nitrogen and phosphorous and, simultaneously, to reduce COD and pollutants. Duckweed become green biomass useful for realize new bioproducts. In this study, the aim was to compare the environmental performances of a traditional wastewater treatment plants (WWTP) with the aquatic plant treatment system (ATPS) based on duckweed.