Objective 1
Demonstration of a range of simple, flexible and cost-effective decentralised treatment systems for digestate’s valorisation, turning it into a suitable fertiliser or soil amender
LIFE DIMITRA aspires to practically demonstrate a spectrum of circular and climate change mitigation based systems for the valorisation of biogas digestate, via sustainable pathways, that will be, by design and intention, restorative aiming at recovering process water and nutrients in new biobased fertilisers and at minimizing risks induced by storing, managing and direct land use of digestate. This will take place in the following plants: (1) DEMO 1: After the mechanical separation of the whole digestate, the solid fraction will be either composted or chemically treated producing a solid organic fertiliser, while the liquid fraction will be condensed by a novel and patented evaporating system of very low energy consumption, into another solid organic fertiliser, producing simultaneously high quality process water and an inorganic N-fertiliser by scrubbing off evaporator’s gas emissions. (2) DEMO 2: The liquid fraction from the mechanically separated digestate will be sieved and filtered to retain and sufficiently separate suspended solids. The effluent will be subjected to reverse osmosis in order to obtain a ‘purified’ stream (permeate) and the concentrate, which will contain most of the input stream nutrients. These could stand as process water and liquid organic fertiliser respectively. The solids from the screw press, sieve and ceramic filter will be aerobically stabilised producing a solid organic fertiliser. The DEMO plants will be installed in two different European countries (GR, IT), adjacent to existing AD plants. The capacity as well as the long-operating periods of the DEMO plants will ensure the demonstration of technological schemes in operational environment, thus validating their technical viability at the targeted TRL 7.