Sustainable biomass management in EELTH

The sustainable management of biomass and bio-waste in the daily business operation of EYATH was on the “table” of the FORWARD GREEN exhibition of TIF-HELEXPO and in particular in the context of the HELEXPO DIALOGUES (Forum on renewable energy sources, climate change, circular economy, biomass and biowaste), organized in Thessaloniki (March 7-9, 2024). EYATH was represented by the Director of Sewerage Facilities, Kostas Kotoulas, who presented the work carried out in the management of biomass, from collection to its utilization, at the Thessaloniki Sewage Treatment Facility (SWTP).

As Mr. Kotoulas said, in the central biological purification of Sindos, which receives daily around 150,000 sq.m. of wastewater, “has been carried out over the last three years in a series of major projects in the general philosophy of saving energy through the exploitation of the biogas produced by anaerobic digestion, with the parallel use of the resulting biomass”, always in the context of the circular economy. These projects are the upgrading of sludge dewatering with centrifugal machines, the expansion of anaerobic digestion, the treatment of biogas to remove hydrogen sulphide and the reconstruction of the cogeneration machines with a total capacity of 2.5MW, according to Mr. Kotoula. “The new element in the process is the application of two-stage processing in anaerobic digestion and dehydration, resulting in a sanitary dehydrated biomass product with a solids content of more than 30%. This material (30-35 tn/day) is available in plants for the production of soil improvement and organohumic preparations, while during the growing seasons it can be used directly in agriculture”, he noted.

The biogas produced from the digestion, now processed, feeds the cogeneration machines since the end of 2022 and covers part of the electricity consumption of EELTH. Last month the coverage of the facility reached 80% of needs. At the same time, as Mr. Kotoulas explained, the sludge thermal drying unit is being rebuilt which can produce a dry product of more than 92% solids, further reducing the unit’s residue. This, together with the other by-products of EEL (sand, cuttings) are available in the soil improvement units, constituting the primary biomass material for these preparations.

Finally, Mr. Kotoulas presented the limitations of the new legislative framework, European directives and especially climate change, which will form the basis on which policies and strategies will be formulated in the future, requiring of course the mobilization of private and public funds.

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